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cms^ M I T H 8 N I A N 



CONTRIBUTIONS TO KNOWLEDGE, 



YOL. XIX 




ETERV MAN 13 A VALtJABLF. MEMBEK OF SOCIETY, WHO, BY HIS OBSERVATIONS, RESEABOHES, AND EXPERIMENTS, FBOCVRF.S 

KNOWLEDGE FOB MEN. — SmITHSON. 



CITY OF WASHINGTON: 
PUBLISnED BY THE SMITHSONIAN INSTITUTION. 

MDCCCLXXIV. 




s 



V 



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COLLINS, PRINTER, 
705 JAYNH ST. 



ADVERTISEMENT. 



Tms volume forms the nineteenth of a series, composed of original memoirs on 
different branches of knowledge, published at the expense, and under the direction, 
of the S"" ' hsonian Institution. The publication of this series forms part of a general 
plan adopted for carrying into effect the benevolent intentions of James Smithson, 
Esq., of England. This gentleman left his property in trust to the United States 
of America, to found, at Washington, an institution which should bear his own 
name, and have for its objects the ^^ increase and diffusion of knowledge among 
men." This trust was accepted by the Government of the United States, and an 
Act of Congress was passed August 10, 1846, constituting the President and the 
other principal executive officers of the general government, the Chief Justice of 
the Supreme Court, the Mayor of Washington, and such other persons as they might 
elect honorary members, an establishment under the name of the "Smithsonian 
Institution for the increase and diffusion of knowledge among men." The 
members and honorary members of this establishment are to hold stated and special 
meetings for the supervision of the affairs of the Institution, and for the advice 
and instruction of a Board of Regents, to whom the financial and other affairs are 
intrusted. 

The Board of Regents consists of three members ex officio of the establishment, 
namely, the Vice-President of the United States, the Chief Justice of the Supreme 
Court, and the Mayor of Washington, together with twelve other members, three of 
whom are appointed by the Senate from its own body, three by the House of 
Representatives from its members, and six persons appointed by a joint resolution 
of both houses. To this Board is given the power of electing a Secretary and other 
officers, for conducting the active operations of the Institution. 

To carry into effect the purposes of the testator, the plan of organization should 
evidently embrace two objects : one, the increase of knowledge by the addition of 
new truths to the existing stock; the other, the diffusion of knowledge, thus 
increased, among men: No restriction is made in favor of any kind of knowledge; 
and, hence, each branch is entitled to, and should receive, a share of attention. 



ADVERTISEMENT. 

The Act of Congress, establishing the Institution, directs, as a part of the plan of 
or.^anization, the formation of a Library, a Museum, and a Gallery of Art, together 
^vi°h provisions for physical research and popular lectures, while it leaves to the 
Regents the power of adopting such other parts of an organization as they may 
deem best suited to promote the objects of the bequest. 

After much deliberation, the Regents resolved to divide the annual income into 
two parts— one part to be devoted to the increase and diffusion of knowledge by 
means of original research and publications-the other part of the income to be 
applied in accordance with the requirements of the Act of Congress, to the gradual^ 
formation of a Library, a Museum, and a Gallery of Art. 

The following are the details of the parts of the general plan of organization 
provisionally adopted at the meeting of the Regents, Dec. 8, 1847. 



DETAILS OF THE FIRST PART OF THE PLAN. 



I. To INCREASE Knowledge. — It is proposed to stimulate research, hy offering 
rewards for orirjinal memoirs on all subjects of investirjation. 

1. The memoirs thus obtained, to be published in a series of volumes, in a quarto 
form, and entitled '' Smithsonian Contributions to Knowledge." 

2. No memoir, on subjects of physical science, to be accepted for publication, 
which does not furnish a positive addition to human knowledge, resting on original 
research; and all unverified speculations to be rejected. 

3. Each memoir presented to the Institution, to be submitted for examination to 
a commission of persons of reputation for learning in the branch to which the 
memoir pertains; and to be accepted for publication only in case the report of this 
commission is favorable. 

4. The commission to be chosen by the officers of the Institution, and the name 
of the author, as far as practicable, concealed, unless a favorable decision be made. 

5. The volumes of the memoirs to be exchanged for the Transactions of literary 
and scientific societies, and copies to be given to all the colleges, and principal 
libraries, in this country. One part of the remaining copies may be offered for 
sale; and the other carefully preserved, to form complete sets of the work, to 
supply the demand from new institutions. 

6. An abstract, or popular account, of the contents of these memoirs to be given 
to the public, through the annual report of the Regents to Congress. 



ADVERTISEMENT. V 

II. To INCREASE Knowledge. — R is also i^^oposed to appropriate a portioji of the 
income, annuallij, to special objects of rcsearcli, under the direction of suitable 
persons. 

1. The objects, and the amount appropriated, to be recommendod by counsellors 
of the Institution. 

2. Appropriations in different years to different objects; so that, in course of time, 
each branch of knowledge may receive a share. 

3. The results obtained from those appropriations to be published, with the 
memoirs before mentioned, in the volumes of the Smithsonian Contributions to 
Knowledge. 

4. Examples of objects for which appropriations may be made: — 

(1.) System of extended meteorological observations for solving the problem of 
American storms. 

(2.) Explorations in descriptive natural history, and geological, mathematical, 
and topographical surveys, to collect material for the formation of a Physical Atlas 
of the United States. 

(3.) Solution of experimental problems, such as a new determination of the 
weight of the earth, of the velocity of electricity, and of liglit; chemical analyses 
of soils and plants; collection and publication of articles of science, accumulated 
in the offices of Government. 

(4.) Institution of statistical inquiries with reference to physical, moral, and 
political subjects. 

(5.) Historical researches, and accurate surveys of places celebrated in American 
history. 

(G.) Ethnological researches, particularly with reference to the different races of 
men in North America; also explorations, and accurate surveys, of the mouiads 
and other remains of the ancient people of our country. 



I. To DIFFUSE Knowledge. — It is piroposed to pidiJish a series of reports, gicing an 
account of the neio discoveries in science, and of the changes made from year to year 
in all branches of knowledge not strictly 2)rofessional. 

1. Some of these reports may be published annually, others at longer intervals, 
as the income of the Institution or the changes in the branches of knowledge may 
indicate. 

2. The reports are to bo prepared by collaborators, eminent in the different 
branches of knowledge. 



yi ADVERTISEMENT. 

3. Each collaborator to be furnished with the journals and publications, domestic 
and foreign, necessary to the compilation of his report; to be paid a certain sum for 
his labors, and to be named on the title-page of the report. 

4. The reports to be published in separate parts, so that persons interested in a 
particular branch, can procure the parts relating to it, without purchasing the 
whole. 

5. These reports may be presented to Congress, for partial distribution, the 
remaining copies to be given to literary and scientific institutions, and sold to indi- 
viduals for a moderate price. 

The following are some of the subjects ivhlch may he emhraced in the reports: — 

I. PHYSICAL CLASS. 

1. Physics, including astronomy, natural philosophy, chemistry, and meteorology. 

2. Natural history, including botany, zoology, geology, &c 

3. Agriculture. 

4. Application of science to arts. 

II. MORAL AND POLITICAL CLASS. 

5. Ethnology, including particular history, comparative philology, antiquities, &c. 

6. Statistics and political economy. 

7. Mental and moral philosophy. 

8. A survey of the political events of the world; penal reform, &c. 

III. LITERATURE AND THE FINE ARTS. 

9. Modern literature. 

10. The line arts, and their application to the useful arts. 

11. Bibliography. 

VI. Obituary notices of distinguished individuals. 

n. To DiFTHSE Knowledge.-/. .•. proposed to puLUsh occasionally separate treatises 

on subjects of ijaieral interest. 

1. Thoso treatise, may occa>„o„aIly consist „f valuable memoirs translated from 

l3e T'"?"' "' °' """'" "'■"""'' """" "'■' "'"■"=«''" Of "» I-«""ion, or 
"T ;, f *"°°" """'"""' '■"'■ "'= >""" =-M'™i'i°" "f a given subject. 



ADVERTISEMENT. vii 



DETAILS OF THE SECOISTD PART OF THE PLAN OF ORGANIZATION. 

This part contemplates the formation of a Library, a Museum, and a Gallery of 
Art. 

1. To carry out the plan before described, a library will be required, consisting, 
1st, of a complete collection of the transactions and jjroceedings of all the learned 
societies of the world; 2d, of the more important current periodical publications, 
and other works necessary in preparing the periodical reports. 

2. The Institution should make special collections, particularly of objects to 
verify its own publications. Also a collection of instruments of research in all 
branches of experimental science. 

3. With reference to the collection of books, other than those mentioned above, 
catalogues of all the different libraries in the United States should be procured, in 
order that the valuable books first purchased may be such as are not to be found 
elsewhere in the United States. 

4. Also catalogues of memoirs, and of books in foreign libraries, and other 
materials, should be collected, for rendering the Institution a centre of bibliogra- 
phical knowledge, whence the student may be directed to any work which he may 
require. 

5. It is believed that the collections in natural history will increase by donation, 
as rapidly as the income of the Institution can make provision for their reception; 
and, therefore, it will seldom be necessary to purchase any article of this kind. 

G. Attempts should be made to procure for the gallery of art, casts of the most 
celebrated articles of ancient and modern sculpture. 

7. The arts may be encouraged by providing a I'oom, free of expense, for the 
exhibition of the objects of the Art-Union, and other similar societies. 

8. A small appropriation should annually be made for models of antiquity, such 
as those of the remains of ancient temples, &c. 

9. The Secretary and his assistants, during the session of Congress, v/ill be 
required to illustrate new discoveries in science, and to exhibit new objects of art; 
distinguished individuals should also be invited to give lectures on subjects of 
general interest. 



In accordance with the rules adopted in the programme of organization, each 
memoir in tliis volume has been favorably reported on by a Commission appointed 



ADVERTISEMENT. 

for its examination. It i.s however impossible, in most cases, to verify the states 
mcnts of an author; and, therefore, neitlier the Commission nor the Institution can 
be responsible for more than the general character of a memoir. 



The following rules have been adopted for the distribution of the quarto volumes 
of the Smithsonian Contributions : — 

1. They are to be presented to all learned societies which publish Transactions, 
and give copies of these, in exchange, to the Institution. 

2. Also, to all foreign libraries of the first class, provided they give in exchange 
their catalogues or other publications, or an equivalent from their duplicate volumes. 

3. To all the colleges in actual operation in this country, provided they furnish, 
in return, meteorological observations, catalogues of their libraries and of their 
students, and all other publications issued by them relative to their organization 
and history. 

4. To all States and Territories, provided there be given, in return, copies of all 
documents published under their authority. 

5. To all incorporated public libraries in this country', not included in any of 
the foregoing classes, now containing more than 10,000 volumes; and to smaller 
libraries, where a whole State or large district would be otherwise unsupplied. 



OFFICERS 



OF THE 



SMITHSONIAN INSTITUTION. 



THE PRESIDENT OF THE UNITED STATES, 

Ex-officio PRESIDING OFFICER OF THE INSTITUTION. 

THE VICE-PRESIDENT OF THE UNITED STATES, 

Ex-qfficio SECOND PRESIDING OFFICER. 

MORRISON R. WAITE, 

CHANCELLOR OF THE INSTITUTION. 

JOSEPH HENRY, 

SECRETARY OF THE INSTITUTION. 

SPENCER F. BAIRD, 

ASSISTANT SECRETARY. 

PETER PARKER, 

JOHN MACLEAN, \ Executive Committee. 

WILLIAM T. SHERMAN, 



REGENTS. 



Henry Wilson, . . 
Morrison R. Waite, 
Hannibal Hamlin, . 
JuuN W. Stevensom, 
Aaron A. Sargent, . 
Samuel S. Cox, . . 
Ebenezer R. Hoar, . 
Gerry W. Hazletox, 
John Maclean, . . 
Peter Rarker, . . 
William T. Sherman, 
Asa Gray, .... 
J. D. Dana, . . . 
Henry Coitee, . . 



Vice-President of the United States. 
Chief Justice of tlve United States. 
Member of the Senate of the United States. 



(b cc 



CC (C 



Memher (f the House of Reprcsentatices U. S. 



1.1. !.(. 



Citizen of New Jersey. 

'.' of Washi)t(jton. 
it li 

" of Massachusetts. 
" of Connecticut. 
" of Pennsylrania. 



MEMBERS EX-OFFICIO OF THE INSTITUTION. 



Ulysses S. Grant, President of the United States. 

Henry Wilson, Vice-President of the United *SV«fcs. 

Hamilton Fish, Secretary of State. 

B. H. Bristow, Secretary of the Treasury. 

W. AV. Belknap, Secretary of War. 

George M. Robeson, Seci-etary of the Navy. 

J. A. J. Creswell, Postmaster- General. 

George H. Williams, Attorney- General. 

Morrison R. Waite, Chief Justice of the United States. 

M. D. Leggatt, Commissioner of Patents. 



HONORARY MP^MBER. 



Columbus Delano. The Secreiary of the Interior. 



TABLE OF contents; 



ARTICLE I. 



ARTICLE II. 



ARTICLE in. 



Introduction. Pp. 16. 

Advertisement . . . . . . . . iii 

List of Officers of the Smithsonian Institution . . . . ix 

(\o. 240.) Problems of Rotary Motion presented by the GYROscorE, 
THE Precession of the Equinoxes, and the Pendulum. By Brevet 
Maj. -General J. G. Barnard, Colonel of Engineers, U. S. A., A.M., 
LL.D., Member of National Academy of Sciences. 1871-1873. 4to. 
pp. 7-4. 

The Precession of the Eqnino.xcs and Nutation as resulting from the Theory 
of the Gyroscope ........ 1 

On the Motions of Freely Suspended and Gyroscopic Pendulums, and on 

the Pendulum and Gyroscope as exhibiting the Rotation of the Earth . 15 

On the Internal Structure of the Earth considered as affecting the Phe- 
nomena of Precession and Nutation . . . . .33 

New Addendum ........ 42 

(No. 241.) A Contribution to the History of the Fresh-Water Alg^ 
OF North America. By Horatio C. Wood, Jr., M.D., Professor of 
Botany, and Clinical Lecturer on Diseases of the Nervous System in 
the University of Pennsylvania; Physician to the Philadelphia Hospital, 
etc. October, 1872. 4to. pp. 274. Twenty-one colored plates. 
Preface . . . . . . . * . . v 

Introduction ........ 1 

Fresh-Water Algas of the United States ..... 9 

Class Phycochromophyceae ...... 9 

Order Cystiphora3 ...... 10 

Family Chroococcacese . . . . . .10 

Order Nematogeneaj . . . . . .15 

Family Oscillariacese . . . . . .16 

Family Nostochaceaa ...... 23 

Family Rivulariaceae ...... 43 

Family Scytonemacese . ..... 55 

Family Sirosiphonacese ...... 67 

Class Chlorophyllaceae ...... 77 

Order Coccophycese ...... 73 

Family Palmellacea; . '. . . . .78 

Family Protococlacese ...... 85 

Family Volvocinea; ...... 98 

Order Zygophyceae . . . . . .100 

Family Desmidiacese . . . . . .100 

Family Zygnemacese . . . . . .169 



' Each memoir is separately paged and indf xed. 



SIT 



TABLE OF CONTENTS. 











174 










175 










176 










182 










186 










188 










203 










205 










213 










214 










. 215 










217 










221 










. 225 










. 229 










. 235 

249 
. 253 



Order Sipliophyceaj . 

Funiily Ilydrogastrca; 

Family Vaucheriacefc 

Family Ulvaccae 

Family Confcrvaeeic 

Family tEdogoniaceae 

Family Chroolepidese 

Family CliKtophoraeeaj 
Class Khodopbycese 

Family Porphyracesc 

Family Chaiitransiaccse 

Family Batrachospermaceaj 

Family Lemaneaceae 
Supplement 

Geographical List of Species 
Bibliography 
Index 
Explanation of the Plates 

ARTICLE IV. (No. 262.) An Investigation of the Orbit op Uranus, with General 
Tables of its Motion. By Simon Newcomb, Professor of Mathematics, 
United States Navy. October, 1873. 4to. pp. 296. 
Introduction ......■■ 

Chapter I. Method of Determining the Perturbations of the Longitude, 
Radius Vector, and Latitude of a Planet by direct Integration. 
Notation and general differential formulas 

Formation of the required derivatives of the perturbative function 
Correction of these derivatives for terms of the second order 
Integration formulae for perturbations of radius vector . 
Development of functions of rectangular co-ordinates 
Integration of perturbations of radius vector 

Formulae for perturbations of longitude to terms of the second order 
Motion of the orbital planes ..... 

Perturbations of the second order depending on the motion of the orbital 
planes ..... 

Reduction of the longitude to the ecliptic 
E.\pressions for the latitude 

Chapter II. Application of the Preceding Method to the Computation 
of the Perturbations of Uranus by Suturn. 
Data of computation 

Numerical e.xpressions for E and its derivatives 
Perturbations of radius vector 
Perturbations of longitude 
Perturbations of latitude 

Chapter IIL Perturbations of Uranus produced by Neptune and Jupiter 
Adopted elements of Neptune ..... 
Development of li and its derivatives for the action of Neptune 
The term of long period between Neptune and Uranus . 
Perturbations of the longitude produced by Neptune 
Perturbations of the radius vector produced by Neptune 
Perturbations of the latitude produced by Neptune 
Perturbations produced by Jujiiter 



6 

10 
12 
13 
14 
17 
22 
24 

25 
27 
29 



31 
34 
44 
49 
51 

53 
54 
55 

58 
60 
61 
62 



TABLE OF CONTENTS. 



2V 



Chapter IV. Terms of the Second Order due to the Action of Saturn 
Preliminary investigation of the orbit of Saturn 
Perturbations of Saturn and Uranus .... 
Formation of the expressions for the terms of the second order 
Perturbations depending on the square of the mass of Saturn . 
Perturbations depending on the product of the masses of Jupiter and 

Saturn .... ... 

Chapter V. Collection and Transformation of the preceding Perturba 

tions of Uranns. 
Terms independent of the position of the disturbing planet 
Secular variations ..... 

Auxiliary expressions on which the perturbations depend 
Reduced expressions for the latitude of Uranus . 
Positions of Uranus resulting from the preceding theory 
Elements III of Uranus ..... 
Chapter VI. Reduction of the Observations of Uranus, and their Com 

parison with the preceding Theory. 
Reduction of the ancient observations 
Their comparison with the provisional theory 
Discussion of the modern observations . 
Reduction of the Results to a uniform system 
Adopted positions of fundamental stars . 
Discussion of corrections to reduce the difl"erent observations to a homo 

geneous system ..... 

Table of these corrections .... 

Results of the observations from 1781 to 1830 . 
Observations from 1.830 to 1872 .... 
Table to convert errors of right ascension and declination of Uranus iuto 

errors of longitude and latitude 
Tabular summary of results of observations, 1830 to 1872 
Corrections to be applied to the positions of Uranus in the Berlin Jahr' 

buch and the Nautical Almanac to reduce them to positions from the 

provisional theory ....... 

Chapter VII. Formation and Solution of the Equations of Condition 
Resulting from the preceding Comparisons. 

Expressions of the observed corrections to the longitudes of the provi- 
sional theory in terms of the corrections to the heliocentric co-ordinates 

Expressions of the same quantities in terras of the corrections to the ele- 
ments of Uranus and the mass of Neptune . . 

Table to express errors of heliocentric co-ordinates as errors of elements 

Discussions and solutions of the equations thus formed . 

Concluded corrections to the elements of longitude 

Corrections to the inclination and node of Uranus 

Chapter VIII. Cojnpletion and Arrangement of the Theory to fit it for 

Permanent Use. 
Correction of the coefficients of the long inequality between Uranus and 

Neptune for the terms of the second order 
Concluded elements, or elements IV of Uranus . 
Long-period and secular perturbations of the elenicnis . 
Table of these perturbations from A.D 1000 uniil A D 2200 
Mean elements of Uranus .... 

Expressions for the concluded theory of Uranus . 



65 
68 
69 

76 

77 



79 
80 
81 
93 
98 
99 



106 
110 
111 
111 
113 

115 

120 
123 

126 

127 
131 



151 



158 

ICl 
162 
165 
173 
173 



178 
181 
182 
184 
184 
185 



TABLE OF CONTENTS. 

Chapter IX. General Tables of Uranus. 
Enumeration of the quantities eontaiued u, the several tables . 
Precepts for the use of the tables . • • • ^^^ 

Examples of the use of the tables • • • ' _" gOG 

Tables of Uranns • • • * ' .279 

Subsidiary tables ■ • • 



190 
195 



SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE. 

. 2-iO 



PROBLEMS OF ROTARY MOTION 

PRESENTED BY 

THE GYROSCOPE, 
THE PRECESSION OF THE EQUIIv^OXES, 



Aim 



THE PENDULUM. 



BT 

Brevet Maj.-Gen. J. G. BARNARD, 

COLONEL OP ENOrNEERS U. S. -A., A.M., LL.D., MEMBER OF NATIONAL ACADEMY OP SCIENCES. 



[ACCEPTED FOR PDB LIGATION, OCTOBER, 1871.] 



ADVERTISEMENT 



The three following papers were read at intervals before the National Academy 
of Sciences, and subsequently presented to the Smithsonian Institution for publi- 
cation. 

JOSEPH HENRY, 

Secretary Smithsonian Institution. 



(iii) 



THE PRECESSION OF THE EQUINOXES AND NUTATION AS RESULTING 
FROM THE THEORY OF THE GYROSCOPE. 



In a paper published in the American Journal of Science, in 1857, and in Bar- 
nard's American Journal ot" Education' [No. 9] of the same year, I remarked: — 

" The analogy between the minute motions of the gyroscope and that grand 
phenomenon exhibited in the heavens, the ' precession of the equinoxes,' is often 
remarked. In an idtimate analysis, the phenomena, doubtless, are identical," &c. 

It is the object of the present paper to deduce the analytical expressions of this 
phenomenon directly from the theory of the gyroscope. 

A brief summary of the processes used and results arrived at in the paper referred 
to is necessary as a preliminary. 

Let A, B, (\ D (Fig. 1) be a solid body of any shape, retained by the fixed point 
(within or without its mass). Ox, Oy, and Oz are the three co-ordinate axes, 

Tiff. 1. 




fixed in space, to which the motion of the body is referred. Ox~^, Oy,, Oz^ are the 
ihxee principal axes belonging to the point 0, and wliich, of course, partake of the 



' "TliP Plicnomcna of the Gyroscope Analytically Examined." 
October 1871. 



(1) 



2 PRECESSION OF THE EQUINOXES AND NUTATION 

body's motion. The position of the body at any instant of tinic is determined by 
those of the moving axes. 

For tlie purpose of determining tlie positions of the axes Ox^, Oij,, and Ozj^, with 
reference to tile (lixed in space) axes Ox, Oy, Oz, three auxiliary angles are used. 

If we suppose the moving plane of a-j y^, at the instant considered, to intersect 
i\w fixed plane of xy in the line N N' and call the angle xON=^i', and the angle 
b(>t\vccn tlie planes xy and x^y^ (or the angle zOz{)=Q, and the angle NOxj^=z^ (in 
the figure these angles are supposed acute at the instant taken), these three angles 
will determine the positions of the axes Ox^, Oyi, Oz^ (and hence of the body) at 
any instant, and will themselves be functions of the time . and the rotary velocities 
about the ax(>s of a-j, v/i, and z^, may be expressed in terms of them and of their 
differential coefhcients. 

A^'hen a body is a solid of revolution, revolving with an angular velocity «, about 
its axis of figure, and acted upon by the accelerating force of gravity (the fixed 
point being in the axis of figure), the general equations of rotary motion (by 
processes fully developed in the jjaper referred to)^ take the form 

sm^ d- --=— — (cos Q — cos w) 
at A 

df = ndt -\-cos Od^^ 
In which 

M is the mass of the body. 

A its moment of inertia about an equatorial axis throurrh 0. 
C " " " " its axis of figure. 

(J the force of gravity. 

y the distance OG from centre of gravity to the point of support. 
(.) the initial value of 0, or its value at the instant when the body has no other 
motion than the rotation n about its axis of fio-ure. 

Eliminating ^^J between the first two equations (1), and putting 



My '■lA^g~ X 



3. sin^ Q^^ = ^1 [sin^ 0-2/3^ (cos 0-cos ca)] (cos 0-cos c.). 



df ~ X 
and the first equation (1) becomes 



sin^olj'^^ 2/3^1 (cos e-cosc) 

quantity /3=^ (?_ *^« , 

'■iA\ g~2y^W^' "^^y "^ ^'^^'y S'"^^* "^^ consequence of the 

rotary velocity, n, being great, or (« being small) in consequence of the ratio 



4. 

The 



nowm""^^"' '''"."" ''''•^ """' °'°'''^' '''^''' ^'■°" P^'^^o" ^^ f" «« equations (of that paper) (9) 
(10), (II), corrcspondrnff to n) (S) C9^ of this- >,„+ 4V,^ i , , ""' ^'^' """ I'''P*'n ('';. 

1 fa" '-'^' ^°''' v^-* o'this; but the subsequeutdevelopiucuts were original. 



RESULTING PROM THE THEORY OF THE GYROS COTE. 3 

-, being very great. In the phenomena of the gyroscope, the tirst condi- 



tion obtams ; in the case of the earth, attracted by the sun or moon (« being small), 
it is easy to show that the alternative condition is fulfilled.' 

Putting - - equal to zero in equation (3) we get Q^a for the viaximnm of 0, and 
ctt 

for the minimum, the equation, 

cos 6=—l3^-\-i/l-\-2l3^ cos «+/:(* 
in which, if (3 is very great, the value of cos 6 differs but slightly from that of coso. 
Hence by introducing a new variable a, equal to o — 0, and deducing the values of 
dJ and (by development) of sin^Q and cos (neglecting the higher powers of v) and 
substituting in (3) and (4), they become (omitting, as relatively small, cos w in the 
factor cos cj-|-4.3^). 



5. . ^di^ 



■^ 2u sin a — 4o^tt* 



6. 'lj;=^3 

at 



' ^7i/ sniij 
Equation (5) gives by integration and putting /? (^j^^^Jc, 

7. ?f^-— 5 sin ij sin "Jd 
which substituted in (G) gives 

8. ^f=\h^mm 

dt /i* 

9. ^ 1 A-;__l sin2Z-i! 

2.i^ 4ii^ 

If we make o;=90°, sin cj=l, in equation (6), deduce the value of dt, and sub- 
stitute in (5) we get, 

10. rl.],- ^^ 

I 1 

the differential equation of the cycloid, generated by a circle of which the diameter 

is -?i^o, and havin" a chordTi— «. 
2,^^' =" 2ir 



' For the earth the moments of inertia, A and C, with reference to principal axes through tlie centre, 

71 \ C^ 
(lilTer verv little. The value of 3 ma}' therefore be appro.\imatelv written ^ I , and the denominator 

is to be replaced (17) by Substitute the value of L (19) and put, for the sun, ' ^"1° (25), 

sin fl r' 



n I C 

and the value of i3 becomes — / , which is verv larffe, 

2<i,>/3(C-A)coso' ^ " 



The value as depending on the moon's attraction is (2Sa), — / L-TL'^! — of the same orde 

'^ ° ^ ^ 2n,>/3(C-^) cose 

of magnitude as before. 



4 PRECKSSION OF THE EQUINOXES AND NUTATION 

If the viiluc of ij is not 90'', the diamrter of this circle will be ,5 sinu; but the 
quantity -^^ then measures an angle of an arc of a small circle having a radius 

=sin (j; and the chord of the curve is reduced in the same proportion as its sagitta, 
and the curve is still a cycloid. 

The axis of figure _<7^/-a/cs therefore about the vertical through Oas if it was attached 
to the circumference of a small circle of the minute diameter specified, the centre 
of wliich circles moves with a uniform horizontal velocity, which velocity is the 
mean rate of gyration ; or the motion may be compared to that of a cone having its 

vertex at and diameter of base =:—-— sin u (the axis of figure constituting an 

element of this cone) rolling upon a fixed conical surface, all the elements of which 
make, with the vertical, the angle u; but this imaginary cone is not fixed in the body 
(save in tlie exceptional case of the moments of inertia A and (7 being equal). For 

the rotary velocity of the body is v, while that of the cone is 2,'3 (■/= 

Siiu-e the rotary velocities of the body and cone are different, the instantaneous 
axis cannot move along the chord of the cycloid, nor vnth uniform velocity. 

The common methods of investigating the Precession of the Equinoxes, founded 
upon the incipient rate of motion of the instantaneous axis, involve this error, which 
does not become apparent, simply because the moments of inertia A and Care, for 
the earth, so nearly equal. 

The instanta;ieous axis will describe a prolate cycloid having the same chord as 

the common one ^-^^, and a sagitta := --^sin o (^ — l). 

The mean rate of gyration is given by the coefficient of t in equation (9); it is 
2/(1)^' ^^ subs'^ituting values (2) for /i and ?.; 

11. 3l 

Cn 

Thus far I have supposed that at the origiii of time, or at the moment when the 
accelerating force connnenced to act, the body had no other motion than a rotation, 
w, about its axis of figure. It remains to prove, that if, at this instant, there are 
small (compared to n) velocities about either or both the other principal axes, the 
rate of gyration will be the same. 

The solution will be perfectly general if we suppose at this instant a velocity, m, 
about the axis of x only, and assume at same m.,ment 0=c„, .?>=90°, we should get, 
instead of equations (3) and (4), the two following :— 

12. sin=0/^'''-r'^^^/>'sin=0 2^'"" sin ^''»% n n 

d('~L A AT "~ 1- (™sO— cos(j) 

—m- (cos 0+cos w) j (cos 0— cos w) 



di, Cn 
dt 



%ivr -Z = ^2 ('^"^ ^-co« ")+'« sin CO 



RESULTING FROM THE THEORY OF THE GYROSCOPE. 5 

Substituting in these o — u for 0, rejecting all small quantities of the second order 
(among which is nr), and introducing 3 and Z (see equations '2) 



13. -^^2u(smcj—23 P»A— 4i^V- 



14. 



9 dt- \ ' \^ 

^^—9-? \^ urn 



^=23 I 



(It ' S'A. sin (J sin o 
The integral of (13) (using k with its already given value) in (7) is 

15. '^'^-, — A ^^'^ " —ml sur a:^ 

Substitute in (14) and integrate 

16. ^= JL Z:<_( i^_ "L_) sin 2Jd 

23^ \4;J^ 2A:Sin(j/ 

The coefficient < in (16) is identical with that of equation (9), — ~ , showing 

that although the character of tlie gyratory motion is altered, and the axis of 
figure, instead of moving on a common cycloid (which forms cusps) and coming 
periodically to rest, moves along a prolate cycloid or even ivlthout undulation, yet 
the rate of gyration is unchanged. 

If (j=90° and m =j ?'-. « a"d -- become zero for all values of t, and the body 

gyrates horizontally Avitliout nutation.^ 

In all that precedes, the revolving body has been supposed retained by a fixed 
point in its axis of figure, but not at its centre of gravity, while the accelerating 
force, being gravity itself, acts through that centre. 

If, instead, the fixed point by which the body is retained is the centre of gravity, 
and the accelerating or disturbing forces any other whatever (provided their direc- 
tion is invariable and their resultant acts through a fixed point of the axis), the 



* This is the case referred to in the preceding paragraph in which tlie moment of the accelerating 
force (or couple) is equal to that of (what I have styled in the work before referred to) the "deflect- 
ing force," which has for its value the expres-sion - — -. 

That this case should arise, a determinate relation between m, n, and g, expressed by the equation 

mn My . 

=- '-, )s necessary. 

9 G 
When this relation exists, the movement niav be represented by the rolling of a conical surface (the 
locus, in the body, of the instantaneous axis), described aljout the axis of figure with the angle 

(approximately) equal to ~— , upon another, all of the elements of which make, with the vertical, 

the angle o — —J- (when u is not 90'^, the centrifugal as well as tlie deflecting force affects tiie 

relation between m, n, and [/). 

But no such relation is essential to the gyration expressed by (11) ; and. in the case of the preces- 
sicm of the equinoxes, the supposition of rolling cones is not realized. There are, probably, no two 
instants of time at which the precessional movements of the axis arc identically the same. 



e PRECESSION' OF THE EQUINOXES AND NUTATION 

equations will be precisely the same, the moments of inertia A and C, referring to 
principal axes throuirh the centre of gravity, and Mg expressing the mtensity of the 
resultant of the forces, and y the distance from the centre of gravity of the point 
throu"-h which the resultant acts. 

In expression (11) Mf/y is the moment of the force with respect to the point 0, 
dividcHl by the sine of the angle (0) whicli its direction makes with the axis of 
figure. Denote that moment by L. Then the expression for the velocity of gyra- 

tion (11) becomes, 

L 
17. • .. ■ „ 

On sm U 

If the body in question, like the earth, is acted upon by forces, the resultant of 
whicli does not pass through its centre of gravity, its movements about that centre are 
precisely the same as if that centre were fixed ; in other words, it will gyrate about 
the line connecting its centre and the origin of the force with a velocity denoted 
by expression (11). In the case of the earth, however, the direction of the disturb- 
ing force and its moment are constantly changing, and I have to assume something 
not proved in what foregoes, viz., that the elementary gyration at each moment of 
time will be likewise expressed by (11) ; an assumption not (probably) strictly true, 
since, when the forces are constant in direction and intensity, equation (14) shows 
(the value of h, ecpiation (15) being substituted) that the gyratory velocity, though 
its mean is always expressed by (11), varies at each instant unless the value of m 
has a certain relation to that of Ic. 

Since the integral of these varying elementary displacements shows, under all 
cir(;umstances of constantly directed force (though these elementary motions of the 
axis exhibit all possible directions with regard to that of the force), a mean rate of 
gyration expressed by (11), we may assume that the fact will hold good though 
the direction and moment of the force chanse.^ 

In the case of the earth there is probably no instant of time at Avhich it is revolv- 
ing exactly about its axis of figure ; the quantity m has, for it, in all cases, a finite 
(though exceedingly small) value ; neither observation nor (scarcely) analysis can 
detect the minute diurnal (nearly) nutations which belong to the diurnal cycloidal 
movement ; and hence the presumption that the gyration is at all instants perpendicu- 
lar, or nearly so, to the direction of tlie force, and hence that even its elementary 
values vary little from expression (11).- 



' Sucli an assumption is mado in all the investigations not, like Laplace's, purely analytical, with- 
out always giving the true grounds on which it should be based. 

» In reality, if the moment L remains the same for different values of e, the elementary displace- 
ment produced by the gyration is independent of o, for, though the expression . ^ varies inversely 

. , , ,. Cn sin S 

as sin 9, yet the radius of the small circle on which the displacement takes place increases in like 
proportion. Again, that a revolving body should gyrate around a given a.xis it is not necessary that 
the accelerating force .should be always parallel i„ direction to that axis, but that it should remain in 
the uioying plane through the a.Kis of figure and the given axis. The general equations of rotation 
wouhl be the same. 



RESULTING FROM THE TUEORY OF TUE GYROSCOPE. 



Let a, be the equatorial diameter of the earth. 
6, be the polar diameter, 
p, its variable density. 

(7, its moment of inertia about the polar axis. 
A^ its moment of inertia about an equatorial one, 

e= , earth's ellipticity. 

a 

S, the absolute attractive force of the sun, or its attraction upon a unit of 

mass at a unit's distance. 
r, the mean distance of centres of sun and earth, x, ij, z being rectangular 
co-ordinates of any element of the earth's mass, dm ; the origin being 
the earth's centre, tlie axis of z the polar one, of x an equatorial one 
in a plane passing through the sun's centre, of y an equatorial one per- 
pendicular to this plane. 
The moment of the sun's attractive force upon the earth is shown in various 
works on precession [vide Mr. Airy's " Figure of the Earth," Encyc. Metropolitana) 
to be (0 being the angle of earth's axis with line drawn to sun). 

1 8. "3^ rrr p ^^"—^") ^^^ ^-^n ^^^ ^"^ ^ ^^^ ^ 

the integral being taken through the spheroid. 

Tlie quantity under the signs of integration may be written 

p (jx--\-ij") dm — p (y"-|-s') dm, the integral of the first terra of which is C, and of 

the second A. 

Hence the moment of the sun's force (18) 

19. ^{C—A) sin cos 0=L 

Hence the gyration produced upon the earth by the sun's force aoout the line 
of its direction is (17) 

cos ; and in time df. 



20. 



21. 



r^n C 
3S C—A 
C 



cos -0 dt 



n 



Let EST be a great circle in the plane of the ecliptic, 
EE' an equatorial one, PE'TP' a great circle through 
the tropics, PSP' one through the sun in any position, 
C the centre of the cartli, and PCP' its axis. SCP' is 
the angle 0. If the sun moves in the ecliptic from E 
(the equinox) towards T with an angular velocity Wj, 
nj, will be the value of the arc ES. In the spherical 
triangle P'ST, right-angled at T, Ave have cos P'S (or 
cos 0)=cos PTcos ra=sin TE' sin SE. 

TE' is the inclination of the equator to the ecliptic ; 
call this /. Then 

cos fl^sin 1 sin n-ft 




8 PRECESSION OF THE EQUINOXES AND NUTATION 

The elementary gyration about the line .^C will be therefore, (21) 
09 M ^^Z:A sin / sin «,/ dt. 

If this rotation about SC is decomposed into components about the lines TC and 
EC, they will be 

23_ ^^_ ^A sin / sin- v,t dt. 



«/•" C 



01 ^ sin /sin nd cos nd dt. 

^"*- . m^ G 

Th3 component (23) represents a rotation of the pole about TO, the radius of its 
motion being PB, or cos / To obtain the actual value as an arc of a great circle, 
of this minute displacement, it nuist be multiplied by cos /; and to refer this to the 
pole of the ecliptic as angular motion, it must be divided by sin 1} Performing 
these operations, integrating, and remembering that by Kepler's laws 

_ =i^=Mj- (r=number of units of time in one year), we get, for precession, 
jj 2'" 

Zn-rC—A J, 3 w, C—A j ■ ^ , 
25 — I cos I.t ~ cos 1 sm Ind. 

In G ^n G 



And for nutation 
26. 



3 ru G — A • T n t 
i sni i cos Ind. 

\n G ' 



lit 
The first term of (25) is the mean solar precession ; making t = — , it gives for the 

annual solar precession 

07 Q "1 G—A J- 

li. 6—n — --. — cos /. 

11 G 

Expression (26) is the solar nutation, and the second term of (25) gives the 
equation (f the equinoxes -in longitude, or the fluctuating terra of the precession cor- 
responding to the nutation. 

These expressions correspond to those obtained by the ordinary solutions. They 
differ from most of them, however, in having C in the denominator instead of A, 
an error of those solutions I have alluded to before, which, however real, analyti- 
cally, exerts no important influence on the result. 

By the above method the precession is the integral of the components of 
gyration about a solstitial diameter of tlie ecliptic, which line itself, by the pro- 
cess of precession, has an angular motion equal to that precession, the real effect 



-'p 



In the spherical triangle PP'T in wliich P" is the pole of the ecliptic 
and PP an arc of a great circle throusrh which the pole P has moTcd (equal to (23) x cos /), and 

the sides P"P are = /, the angle PP"P (or the elementary precession) =£^. 

sin / 



RESULTING FROM THE THEORY OF THE GYROSCOPE. 9 

being a revolution about an axis (the pole of the ecliptic) pei-penclicular to the 
plane of that angular motion. In other words, if wc integrate directly equation 

(23) and make ;^=— ^, and ' :=n{', we shall get 

28. 3"i7t^^sin/; 

and this will be the total angular motion of the pole P about the solstitial line TC 
in one revolution of ilie sun ; but by this very motion of the pole the equinoxes 
have moved an angle measured by this displacev-tent referred to the pole of the 
ecliptic— th.^i is, by the angle expressed by (27) — and the solstitial line 7'Chas of 
course, undergone the same movement, and the next annual gyration will be about 
the consecutive line T C, and so on; producing a continuous motion of the pole 
P about the pole of the ecliptic P". 

To obtain the precession due to the moon, it is necessary to substitute in (19) for 

- , ^^ , in which HP is the attractive force of the moon and (/•) its mean distance. 

But T^ (time of moon's revolution) is, bv Kepler's laws, ^n'-. r'Yr==FM -?- >: iTttT = — 

(calling the mean angular velocity of the moon n^ and the ratio of earth's mass 

to that of moon's mass, >;) (28a); hence = — '~. 

{rf l-\-yi 

If i is the inclination of the moon's orbit to the equator during any one revolu- 
tion (regarded as constant for that time), we should obtain for the precession and 
nutation, referred to the pole of tlic moon^s orbit, expressions analogous to (25) 
and (26). 

Although the moon's disturbing effect, as above- expressed, is almost exactly 
double that of the sun, yet the larger divisor ?u, introduced by integration, renders 
the value of (26) and of the fluctuating term of (2-3) very small for the moon — say 
about ith the corresponding values for the sun. Hence these terms are usually 
disregarded in the lunar expressions. 

The elementary precession due to the moon o.lout the pole of its ovn orbit would 
be by (25) 

on 8 "^' C—A . J, 

29. -^ — —^ — ^ _ — cos t dt. 

2ji(1+57) C 

From this, by the usual methods, can be deduced tlic real precession and nuta- 
tion. But it will be more in harmony with the object of this paper, and indeed 
more elegant, to reduce the (juration produced by the moon directly to precession 
and nutation. 

If we substitute for 7>,, '"- , and sin )" for sin /, in (28) wc shall get, for the 

total gyration ahovt the line of greatest dedination, produced by one revolution of the 
moon in its orbit, the expression : 

30. 3 -.^-.Tt^-sini. 

n(l+>7) G 

2 December, 1871. 



10 PRECESSION OF THE EQUINOXES AND NUTATION 

1,1 wliich the lino of greatest deelination is regarded as stationary during the single 
revoUition, and taking a eonsecutive position for the next; but it will be m hai- 
inonv witli the fact, and allowable, to regard the line as in contniuous motion and 
the above amount of gyration to be uniformly spread over the time ~^, of the revo- 
lution, producing thus an elementary gyration, in the time (//, of 
■ o, ^ "•^"' £""^- sin i dt. 

Let fS^ be a great circle in the plane of the ecliptic; T O: the line of equinoxes, 

NON' the line of moon's nodes, Ti^ii the equator, 
and NinMN' the moon's orbit crossing the equa- 
tor at m. The line of the moon's maximum 
declination, OM, will be 90° from the line Om. 
The pole E of the earth is supposed to undergo 
a displacement by gyration about OJ/representcd 
■^ by EE'\ the precession produced will be the 
^ angle EOE'; the nutation, the angle E^E'. 

In the spherical triangle Nm'f the angle at N 
is = /', the inclination of moon's orbit to ecliptic; 
the angle at X is the supplement of /(inclination 
of tlie equator) and the angle at m' is i (or the 
variable inclination of the moon's orbit to the 
equator), and the side rX is = iij (calling the angular velocity of the moon's 
node ».,y, therefore, 

32. cos i = cos /' cos / -|- sin /' sin I cos 71/ 

and 



/ E' 


E 




\ti 


/" \ 




^--"^^ 


';\ 


A 






; 


l>>^^/ 






"*T 




F 




/^ 


\:::^ 


M' 


^^ 





83. 



tang ?7/t ^ 



sni n^t 



sin /cot /'—cos /cos n/ 



In the spherical triangle mvi'°f 

'^^- tang vif = cos / tang m'^r 

OS is the line of maximum declination of the sun, or the solstitial diameter of the 
ecliptic about which the annual gyration produced by the sun is made. As the 
inclination / of th(> moon's orbit is small, the arc 3131', drawn through il/- is 
approximately (Hpial to mr, and the angle 310^ difi'ers immaterially from the com- 
plement of «JT; lience by (3:3) and (3-ij 

35. tang ilL1/'=^ ^:^^ /^si" ^h* cos /sin F sin n^t 

sm /cot /'—cos /cos nJ~miTcos T—cos /siiT/ cos n/ 

If the gyration about 031 (31) is decomposed into components about 031' and 0-, 
we shall have for the first (calling the coefficient of sin i.df, K) 

^^- A'sini cos il/J/W/, 

and for the second 

^"^^ K sin i sin 313rdL 



RESULTING FROM THE THEORY OF THE GYROSCOPE. H 

To refer the displacement expressed by (36) to the pole of the ecUptic 0, as 
angukir motion, we must (see note page 8) multiply by cos M'F or (from which it 
differs but slightly) cos i and divide by sin /; we thus obtain for the elementary 
precession 

38 — ^*^ cos MM' sin i cos i d(, 

sin/ 

and for nutation 

3i?. K sin MM' sin i dt. 

The maximum value of the arc MM' is about 11° 56'; the line MO describing 
during an entire revolution of the moon's nodes an elliptical cone about OS of 
which the minor semi-diameter {SM') is 5° 8^' (about), and the semi-major 11° 56'. 
By conceiving the elementary motion of the pole of the earth (or its gyration) as 
at each instant about the line MO, as it makes its conical revolution, the undulating 
nature of that motion, or the "nutation," is easily conceived. 

Approximate values of sine and cosine of MM' may be determined from (35); 
wliich, substituted with those of i (32) in (38) and (39), will enable us to integrate 
and obtain very accurate expressions for the lunar precession and nutation.'*' But 
these expressions, nearly free from errors of approximation, may be more elegantly 
determined as follows : When the angle of the moon's orbit with the equator is 
minimum, the angle /=/—/'; when maximum /=/-(-/' (epochs corresponding to 
vj^=^ and n^f =7c); the angle MM' is zero, and the corresponding rates of pre- 
cession are by (38) 

(a) A-?^?^Pfor;V=0. 

2 sur / 



(6) 

When Vjt^^^n, we have 



j^sin 2(14-1') f , 

K ^ — ' — -' tor iiJ=7t. 

2 sin / ' 



,,„, sin 1 ■ ,,,,- cos /sin /' 

cos MM =1 - , sm MM- 



V 1 — cos'7 cos"' /' V 1 — cos' 7 cos' r 

cos if i^^cos / cos- /', COS i'=cos /cos /', sin /=l/l— cos' /cos' /' (the three 
first being the residuals of exact analytical expressions after omission of c^uantities 
of inappreciable magnitude). 

Hence, by (38), the rate of precession for n^t^^^n is 

(c) K cos / cos' /' * 

Assume the formula for precession to be 

Z(/^+P'sin «3<+P" sin 2n,t); 



* When the moon's orbit intersects the ecliptic in a solstitial line, the element;! ry procession Kcos i 
(29) about its own pole is reduced, with but slight error, to th(' same about the ecliptic pole, by 
simple ranltiplication by cos /' : a result coinciding with the above. 

"' See Additional Notes, p. 51. 



12 



I.RECESSION OF THE EQUINOXES AND NUTATION 



the rates of precession will be 

,, '7f(P+ „3F+2«3n ioYn,t=0 

J K(P- n,P'^2n,P") " n,f= 7t 

Jc') KiF-2n,P") " nJ^h^ 

Equating («) to ((t'), &c., we deduce 

P=l cos / (cos- /'+COS 2/')=cos I (1—^ siir T) 

P'-_ 1_ sm2^;cos2/^_ j^ ^^g j^gi^ 2/' cot 2/ 

■^ 2^3 sill / "a 

P"_ L cos / Ccos /'—cos 2/')= — ,"3 cos / sin^ P. 



4/13 



Hence the formula for precession may be written 

44 ? "^' ^—"^ cos l\( 1 -'^ sinV) <— ^ sin 21' cot 2/sin «3^ 



2.«(l+>7) G 



sin- / sin 2nd . 

4«3 J 



Similarly we would get for the nutation 

4o - ? cos / cos rist. 

2«(l+>:) C «3 

The ratio of actual lunar precession to what it would be were the moon's orbit 
in the ecliptic, is therefore expressed by 

1— I sin- /'=0.99 (very nearly).' 

The third term of (44) indicates a slight periodical variation from the true 
elliptic motion referred to in the next paragraph. There should be a corresponding 
term in (45) which may be obtained by the same process, bvit they are both too 
minute to enter into computations. 

> It is worthy of remark that the formulse of Laplaee [3100] and [3101] (Dowditch) contain no 
such coefficient qualifying tlie mean lunar precession, though one is found in all the more popular 
solutions; neither do they contain the term (quite minute) in 2n^t of (44), but, on the other hand, 
contain terms in 2n.^v (corresponding to the terms in 2»,< of 25 and 2G), which, referred to in the 
fourth par. (page 9), are generally omitted as inappreciable. 



RESULTING FROM THE THEORY OF THE GYROSCOPE. 13 

If we multiply tlic coefficient of sin nj in (44) by sin /, we shall have the \alue 
as an arc of a great circle of this fluctuating displacement called tlie equation of the 
equinoxes in longitude. The coefficient thus modified will represent the minor semi- 
diameter, and that of the nutation proper (45), the major semi-diameter of the 
ellipse of nutation ; they have the ratio cos 2/ : cos / nearly. This ellipse has its 
major axis (equal to about 18" of arc) directed towards the pole of the ecliptic. 

The period of its description — is that of the revolution of the moon's nodes. At 

the same time a minute ellipse of semi-annual nutation due to the sun is super- 
imposed upon this. It has its longer axis (about one second of arc) likewise directed 
to the pole of the ecliptic. The smaller axis is to the major as cos /: 1. 

It is easy to show that the precession caused by tlie sun and moon is equal (with 
slight difference due to the ratio we have just been considering) to what it would be 
if those bodies were uniformly distributed in solid rings over circles (in the plane 
of the ecliptic) about the centre of the earth, having radii equal to their mean dis- 
tances. In this case, unless there was a particular relation between the couple 
producing- the initial rotation of the earth and that arising from the attraction of 
the two rings, there would be an extremely minute nutation, of which the period 

would be (see equation 9) -,-, = T^v'y '^vhich is almost identical with the siderial 

2k 11 C 

the ratio being ., • 1- If we suppose the primitive rotation of the earth 

n ' '-" 

to be that alone, about its axis of figure n, then the nutation will exhibit tlie com- 
mon cycloidal motion of equation (10); but its total amount would be but about 
Jf second of arc. 

5 5 

An explanation of the deviation of rifled projectiles will be found in what is 
said (pages 8 and 9) in reference to the conversion of gyration about a shifting 
axis into precession about an axis perpendicular to the plane of motion of the 
first. Elongated rifled projectiles, while they maintain almost unaltered their 
" angle of elevation," are found to deviate with great uniformity from the vertical 
plane of projection, in a direction corresponding to the twist of the gun, while 
spherical projectiles (fired from rifled guns) having precisely the same rotary 
motion, do not so deviate ; showing that the cause of the phenomenon is something 
else than the direct action of friction or pressure of the air. 

In the remarks made in the paragraphs just referred to, it is explained how 
the consecutive small annual gyrations about the line from the centre of the earth 
to the sun (in the tropics) become, in their integral, the movement which we call 
precession, about an axis perpendicular to the plane of motion of that line, inasmuch 
as each small primary gyration causes a corresponding shifting of the line about 
which it takes place. Something very similar occurs to produce the deviation of 
elongated projectiles. In issuing from the gun, the resultant of the atmospheric 
resistance (denoted by the arrow R) coincides with the axis of the projectile, and it 
has no other effect than to retard the motion of translation ; but the action of 
gravity caiises the trajectory to curve downwards, and the direction of the atmo- 
spheric resistance becomes oblique to the axis of the projectile (at «'), and (in 



/27l\ 

aay ( — ), 



14 



PRECESSION OF THE EQUINOXES AND NUTATION. 



almost all lonus of projectiles) passes ahovc, not tlirougli, the centre^ of gravity 
(J. We have then the essential conditions of gyration, viz., a solid of revolution 
revolving rapidly about its axis, and a dynanuc "couple" (/. e., tlie inertia of the 



-""S^ 
--t^ 




projoctil(>'s motion of translation acting through its centre of gravity, and the 
resistance of the air acting tlirongh a point of the axis more or less distant from (j) 
tending to turn the projectile upwards about a horizontal (or " equatorial") axis 
through 7, and there is in fact, at each instant, an elementary gyration about a. line 
through r/, parallel to R (the atmospheric resistance). If this line retained an 
invariable direction, the integral effect of these elementary gyrations would be to 
revolve do%vn the axis of the projectile, and we should ultimately find it assuming 
horizontal and even sub-horizontal directions, lint such cannot be the case ; the 
direction of the axis is no sooner deviated, laterally, from its original direction, than 
a (nearly) corresponding change takes place in the direction of the resistance It 
(since from the elongated form of the projectile, the direction of its motion follows 
pretty nearly that of its axis) and in that of the line (parallel to R) about which 
gyration takes place. The integral of such a series of elementary gyrations, accom- 
panied by a corrrxpond'iDri horizontal angular motion of the line about which they 
take place, is angular motion about a line perpendicular to the plane in which that 
line shifts direction, that is, about a vertical. Hence the vertical direction (or 
"elevation") of the axis of tlie projectile remains constant, or nearly so, while its 
liorizontal direction undergoes a progressive angular precession (if I may so term 
it), and the deviation of riiied projectiles is thus seen to have analogy with the pre- 
cessi6n of the equinoxes.' 

In what precedes I do not profess to throw new light on a. subject so thoroughly 
studied as the Precession of the Equinoxes; my object has been rather to make 
evident the analogy that exists between " the minute motions of the gyroscope and 
that grand phenomenon exhibited in the heavens," and to show how a common 
analysis applies to both. 



' II is quite probal.le that there are other cause, of .Irviation, Ihe friction of the air bein- (iu case 
of long ranges) one. E.vperimental facts are iicuacd for a full discussion of this .subject. 



ON THE 



MOTlOiNS OF FREELY SUSPENDED AND GYROSCOPIC PENDULUMS, AND 

ON THE PENDULUM AND GYROSCOPE AS EXIllBmNG 

THE ROTATION OF THE EARTH. 



Let the point of suspension of the penduhim be taken as the origin of rectangu- 
lar co-ordinates, the axis of z vertical (downwards), and those of x and y in the 
plane of the horizon, the former directed to the east, tlic latter to the north. 

The forces which act on the pendulum (considered as concentrated in its centre 
of oscillation) are 

1st. Gravity, the resultant of the earth's attraction, and of the centrifugal force 
of its rotation. 

2d. The tension of the pendulum cord. 

3d. The force of inertia, the components of which are represented by the differ- 
ential coefficient ---^- -'■{ i-^-; and 
at' at' at' 

4th. Tlie disturbing forces arising from the earth's rotation. 

5th. The resistance of the air. 

If we represent the length of the string by /. its tension by N, and the force of 
gi-avity by g, and neglect the forces named in the 4th and 5th categories, we shall 
have the three equations : 

fVx Nx 

~de~ T 

(Vz Nz , 

-9- 



df' I 

The forces due to the earth's rotation which disturb the relative motions of a 
projectile, or any material particle moving near the eartli's surface, have been 
expressed by Poisson (Journal de I'Ecole Polytechnique Cahier, 26) as follows : — ' 

' These expressions are perfecth' jreneral and applicable to all problems Tvhich involve relative 
motions near the earth's surface, whether of solids or fluids. They (or their equivalent) appear in 
the work of Laplace (Mec. Cel., Vol. IT,), as well as of Poisson (from whom I have quoted them), 
in the investi<rations of the motions of projectiles. It is somewhat extraonliiiaiy that l)oth of these 
great analysts should have failed to perceive their remarkable application in the motions of the 
gyroscope and pendulum, to the exhibition of the earth's rotation, although the latter has seemed to 
desire such an exhibition in the sentence: "Quoique la rotation de la torre soil niaintenant etablie 

(15) 



1 I ; r E N D U L U -M A^V GYROSCOPE 



16 

dz 



ft Of 

(2) i'=-2«e^«"^^ 

Z =—2)i -, ■ COS ;i. 

111 wliicli >. is tlio latitude and n tlie angular velocity of rotation of the earth. 

These analytical expressions make their appearance in the transformations of 
the equations of motion, near the earth's surface, expressed in co-ordinates referring 
to fixed axes, into otliers referring to tlie moving axes ^vhic]l are used in this 
analysis. But these forces can be obtained and their origin bettqr understood by 
tlie following considerations. 

The centrifugal force of a material point at rest on the earth's surface at the 

2 2 2 1 

given latitude will be ^' ^ ^^^ {r being the earth's radius). If it has a small 

rcos;i / ^^2. 



(«rcos;i+-^j 



dx ^ dt 
relative velocity jj to the east, the centrifugal force will become . 

(Xt ^2 ^ COS A) 

Subtracting the former expression from the latter (omitting -,^, j we get for the 

centrifugal force arising from the relative velocity - - the expression 2« -. 

dt J dt 

dx 

The component of this in the direction of the axis of ^ will be — 2n sin X , , which 

corresponds to the value of F (equations 2) of Poisson, and is to be added to the 
second member of the second of equations (1). 

The component of the force just calculated in the direction of the axis of Z is 

— 2n cos /I — 
dt 

This force corresponding to Poisson's value of Z is to be added to the second 
member of the third of equations (1). 

A body moving on a meridian of the earth's surface from south to north will 
have the moment of its quantity of motion, with reference to the earth's axis, 
diminished ; in virtue of which it will press with a certain force towards the east 



avec toute la certitude que les sciences pbysiques coniportent, cependant une preuve directe de ce 
phcnomune doit intcrcsser les gcometres et les astronomes." The former, in making a partial appli- 
cation to the pendulum, of his investigations, absorbed, apparently, in the single object of proving 
that the accuracy of the instrument as a measure of time was not afiTected, has inadvertently assumed 
that the disturbing force normal to the plane of oscillation is "trop petite pour ^carter sensiblement 
le pendule de son plan et avoir aucune influence appreciable snr son mouvement." (.Journal de I'Ecole 
Poly. Cahier, 26, p. 24.) It is truo, indeed, that the force he mentions, even if permitted free 
action, will have but an inappreciable influence upon the time, and none whatever when, as in the 
chronometer, the plane is constrained to fixedness ; but the effect is cumulatwe in changing the 
azimuth of the freely suspended pendulum. 

These same disturbing forces, introduce.! ab.nir will, the attractions of the sun, moon, and earth, 
into the general equations of equilibrium „r fhmis, produce in a very simple manner the differential 
equations fur the tidal motions. {Vide American .Journal of Science, ISGO.) 



AS EXHIBITING THE ROTATION OF THE EARTH. 17 

and the moment of the force thereby developed is equal to -- (the moment of its 

quantitj' of motion). This moment for the pendulum in any latitude ?„, is ur" cos" 'A, 

of which the differential coefficient, taken with reference to 2 as a function of /, is 

7*} 
— 2h/-^ sin 7^ cos X--, which is the moment of the force required. Dividing by the 

. d7. 
radius of rotation, r cos A, we have -\-2nr sin 'a ,j for the exin'cssion of the force 

which (acting positively in the direction of the axis of a-) is to be taken with the 
plus sign. 

In the system of rectangular co-ordinates which I am using "^ corresponds to the 
velocity expressed by r ^^ ; and substituting it therefor, we have for a disturbing 
force in the direction of the axis of x the expression 

%i sin 7!\^ 

lu almost precisely the same way it may be shown that a body falling towards 

the centre of the earth with a velocity - " will have the moment of its quantity of 

. ... „ <iz . . 

motion dmnnished by 2;;/ cos" ^if gi^'i^^g i"!**^ to the force 

2n cos A — 
dt 

The sum of tlicsc two expressions constitutes the disturbing force Xof Poisson, 

and is to be added to the second member of the first of equations (1), and these 

equations become' 

d'x . Nj: ^ . d// , ^ dz 

(3) ^+Y = -2MsmX^ 

drz , Nz ^ ^d!x 

-wH — T^^<] — ■in cos X ,-- 
dt'~ I -^ dt 



' There are really other disturbing forces (comparatively slight iiiflecd) than the X Y and Z of 
Poisson (ei.[uation 2), as a])pears from th(! following considerations : — 

Draw a lino through the origin of co-ordinates parallel to the axis of the earth, and project the 
moving body on the plane of y z. The distance of the projection from the line will be y sin >. + 2 cos j., 
the distance of the body from the plane of yz being. r: hence there will Ije a centrifugal force 
relatively to this line, due to the earth's rotation, tending to increase the ordiuatcs a: y z by its 
components 

n^ a; 

«= sin \ (>/ sin %+z cos \) 
n' cos A (y sin x-\-z cos x) 
With these expressions added, respectively, to the second members of equations (H), they correspond 
to those found in Carniidiael (f'alcnl. of Operations), who quotes from GaHjraitli and Houghton 
(Proc. R Irish Acad., 1851). They express forces of the second order in minuteness, compared 
with those expressed by equations (2), and, insensible in their effects, are neglected in all di.scu.ssioiis. 
They arc noticed here only to recognize their existence and to show their origin. 
3 January, 1873. 



jg THE PENDULUM AND GYROSCOPE 

Since ^"-+v/^+2==r, Avc have x <?x+Z/ <b+^ <^'=0- Hence multiplying equa- 
tions (3), respectively, by dx, dij, and dz, and adding, wcliave 

dx cPx-\-dy dhj-^dz dh _ 
' cW -^ 

dx^-ird>f+dz^ ^ , 
(3). -^-dl^'^-—^'+' 

This expression is independent of n, and the velocity at any point of the path 
depends, in the same way as does that of a pendulum vibrating over a motionless 
earth, upon the heiglit of f dl. The plane of vibration of the chronometer pendu- 
lum is maintained in a fixed relative position, thereby differing from a "freely sus- 
pended" pendulum. It will be seen hereafter, in treating of the gyroscope pendu- 
lum, tliat tlie forces wliich maintain this relative fixedness are equivalent to a force 
varyinir directly as the angular velocity, applied at the centre of gravity, normally 
to tlie patli. Such a force will have no influence upon the velocity. Hence the 
time of vibration of the chronometer pendulum is not affected by the earth's rota- 
tion, nor by the azimuth angle of the plane of vibration.^ 

IMuUiplying the first of equations (3) by v/, and the second by x, and adding, we 
get:— 

d^x d"i/ c ■ ■,/ di/ , dx\ , o ^ ^^2 

Integrating : — 

(4) y^—x'^jL=n sin 7. Oi>'+?/")+C+2/i cos T.jyaz 



The above (4) expresses that the moment of the quantity of motion about the 
axis of z is equal to a constant C (depending upon any arbitrarily given initial 
^alue) increased by what is due to the constant angular motion n sin X, and by the 

area 2 J ydz (in tlie case of ordinary plane vibration this is the projection on 



» Tliis conclusion is not invaliiiated by flie introdiu'tion of tlie disturbing forces of the ordor /)' 
referred to in note to p. It, for, since the arc of vibration of the chronometer pendulum is exceedingly 
small, z may be considered as equal to /, the pendulum's length, and.?/ as very minute. Those forces 
will thence be 



2 rrl sin 2ji 
1V I cos^ X 



The third of these is an incremrnt to gravity, and the first tends to prolong vibrations in the prime 
vertical. The second is null in its effects, since, being always positive, it retards the vibration in 
one direction as much as it accelerates it in the other. But they are all inappreciabbj minute, the 
last being, for the seconds pendulum, an increment to the force of gravity at the equator of about 

1.800.000.000' ''•'''"■^''^'■"S "'c time of vibration by about ^j- ]^^ . The first has the con- 

o.bOU.OOO.OOO 

rary tendency to increase the time of vibrations if made in a prime vertical (or any other plane 
than a meridian), but its cflect is equally inappreciable even when (as in the prime vertical) it is a 
ina.Minura, ' ' 



AS EXHIBITING THE ROTATION OF THE EARTH. 19 

the plane of yz of tlie circular segment included between the arc and chord of 
vibration), multiplied by n cos ?.. This multiplier, which is the component of the 
earth's rotation about a diameter of the earth normal to that passing through the 

locality, indicates that the term 2)i cos T^j y dz expresses a disturbance produced by 

this complementary component. As this term for vibratory motion is small and 
periodic, passing through nearly equal positive and negative values in the course 
of a double vibration, it follows that u sin "X, expresses the mean increment of angu- 
mortion, or, in other words, that, to the plane or spherical vibrations exhibited by 
the pendulum over a motionless earth, there is, superadded, in consequence of this 
rotation, a uniform azimuthal motion measured by the earth's rotating velocity mul- 
tiplied by the sine of the latitude. This is the material fact or peculiar feature of 
the freely suspended pendulum, and we see that it is exhibited by equation (4) 
generally for all ordinary vibrations, whether plane or spherical. We shall see 

hereafter, however, that the disturbing term of equation (4) '2n cos ;i J y dz expresses 

a tendency to a like motion about the complementary axis, and that, on tlie sup- 
position of an infinite velocity, this tendency may be realized, and the plane of 
motion, by the joint effect of the two components, turn around a parallel to the 
earth's axis, with an angular velocity equal and contrary in direction to n. 

In the case of very small deviation^ from the vertical, the equations (3) may be 
solved as follows : The variations of z then become of the second order of minute- 
ness compared with those of cc and ;/< and oniitting them we have between x and y 
and their differentials the relations 

d'^x , Nx . dii 

^^^ -^+-^-2«s.n?-/=0 

d^y Ny ■ dx 

-^+-^+2»i sin ^^^ =0 

the integrals of which are (Gregory Examp. p. 390), 

a:=-f 2 {D cos ^t-^E sin (it) 
^ 3^=— 2 {D sin (it—E cos [it) 

in which to /3 is given both the values obtained from the quadratic equation 

ffo — ttj /3"=fli /3 * 

in which «o^ ? '^i^= — 2u sin 7., a^^\ ; hence solving the quadratic 



f>-\l±U^i{^) 



Substituting the values of Oo, &c., and oniitting the second term under the radi- 
cal as inappreciably small, we have 



g_ 
I 

y=G sin {fit — t) in tlie given equations. 



* This equation, i- j3'=2)i sinji/3, can be got by substituting the integrals x^Ccos (9/ — t), 



20 



THE PENDULUM AND GYROSCOPE 



^=n sin Z±J'^- 

Ropresenting tlicsc two valiu-s by /3i and /^s, equations (5) may be put in the 
form (l)y writing for 1), and E„ C\ cos e^ and C\ sin £„ &c., and reducing) 
x= C, cos (/3i<— fi)+ f 2 cos (/32^— fa) 
y^ — C, sin (/3i<— fi)— t'o sin {(5^1— s^) 

Assumino- for /=0, a— and ';'^^0, it will give fi = f2=l 7t, and the above 

become 

x=(7i sin /^i^+Tz sin /?2< 
y=Ci cos[iil-\-C\ cos/ia^ 

Instead of the arbitrary constants C^ and (X we may write \{A^B) and |(^— 5), 
at the same time substituting the values of ^^ and /?3 and developing; by which 
the preceding equations become (putting n sin ?t=?i') 

a--=J. cos p. i! sin ti! t-\-B sin P- ;; cos ir! t 

(«) .-^ .- 

?/=A cos p < cos n't—B sin S' y gin «'^ 

If we transfer the co-ordinates now referring to (relatively) fixed axes, to others 
moving with the relative angular velocity w', that is, if we transfer to axes making 
at any instant the angle h. sin ;i< with the fixed ones, the new co-ordinates will 
have the values 

x'=^x cos n't — y sin id 

y'=x sin n'i-\-y cos h'< 

or, substituting values of x and y, 

w 



x'^B sin I 



t 
I 



y'^A cos K- 1 

J'roin which we may obtain 

• A^ x'^-\-B- y'^^A' B' 

which is the equation of an ellipse, having A and B for semi-transverse and semi- 
conjugate axes. If i^=() the ellipse becomes a right line, hence the earth's rota- 
tion causes an azimuthal motion of this line, or of the axes of the ellipse if the 
motion is elliptical, equal to the component of that rotation about the local axis 
and in the reverse direction. 

The motions of the "gyroscope pendulum," which is but the ordinary gyroscope 
with an exceedingly long arm (or distance y, of my analysis, from the point of 
support m the axis to the centre of gravity), are indicated "by equations precisely 
similar to the above, deduced from an identical analysis; always assuming, as in 
the solutions just given, that the arcs of vibration are small, so that vertical motions 



AS EXHIBITING THE ROTATION OF THE EARTH. 21 

may be disregarded. To prove this, I refer to iny expression (/i) and the context, 
in ray analysis of the "Gyroscope."' 

, , Cn 

(") -yM ^^ 

for the deflecting force, as. I call it (a force due to the rotation of the disk with 
angular velocity n, and acting, at the centre of gravity, norraully to the plane of 
angular motion of the disk-axis, or of the arm of the gyroscope pendulura), in 
which M is the mass, C its moment of inertia about the disk-axis, y the distance 
from its centre of gravity to point of suspension, and 'i\ the angular velocity. 

Disregarding the vertical motions represented by on account of the smallncss 
of the arcs, - - and y -,y (I substitute I for the y mentioned above) would repre- 
sent very nearly the components of angular velocity of the centre of gravity. 
Substituting these for v^ we shall get the components of the "deflecting force," 
and the equations of motion will be, 

d'x Nx _ C)i dy 
^t^~f'~~fM di 

d^y Ny Cn dx 

~M^~f^^¥Mdt 

d?z . Nz , 



dt ' I 



These equations are identical in all but the value of the coefficients with (3), 
when transformed to (8)2, under the same license. Of course the motions of the 
gyroscope pendulum would have the same solutions, the mean azimuthal motion of 

the nodes of its orbit being expressed by half the coefficient of - ^, — ,r„ ,>, or, since 

dt 2rM 

the moment of inertia A, of the gyroscope, with reference to a principal axis 

through the point of support, is (Z being supposed to be very large compared to the 

dimensions of the disk) very nearly PIT, the mean azimuthal motion is more simply 

expressed by - - . 

This may be more generally proved as follows : Tlie first of the general differ- 
ential equations (equations 4 of my analysis) of gyroscopic motion is 

sm- d -^-=-— (cos — c) 
dt A^ 

in which 0, counted from the inferior vertical, is the variable inclination, and 4- the 
azimuth angle of the disk-axis or pendulura arm, and c a constant depending on 

initial values of Q and - . 

dt 



" Sec American Journal of Science, 1857, and Barnard's American Journal of Education, 1857. 



22 TlIK PENDULUM AND GYROSCOPE 

Develop cos 0=-(l-siir 0)' and we get 

d^_ Cn A I 2 lz:^_i siir 0-i sin' 0-&c.) 

For ordinnvy ranges of pendulum vibration the terms involving positive powers 
of sin (which express an excess of uodal motion for large excursions) may be 
omitted, and wc have 

di~~~~ "lA^ A sin=0 

Thus wc see that for small vibrations, whether spherical or plane, the azimuthal 

Cn 
motion is made up of a uniform progression of the nodes -^, and a fluctuating 

term Avhich represents the angular velocity in the oih'd. Indeed we have, in the 
second term, the motions of tlie spherical pendulum. 

If we suppose the pendulum to have been propelled from a state of rest in the 

vertical, '^^- must have a finite value when is indefinitely small, and c must hence 

dt Qi^ 

be unity. Hence we see that at the very outset the initial value -^^ "^^ist be attri- 
buted to ~, and that the pendulum reacquires it at every return excursion, that 
dt 

is. whenever diminishes indefinitely. Hence the pendulum continues to pass 

through tlie vertical at every return. The horizontal pro- 
jection of the curve would be a series of loops radiating 
from a common centre. For each complete vibration 

the intenrral of '^--dt would represent the entire angular 
2A 

motion of the nodal axis (much exaggerated in the dia- 
gram) from .4. to A, &c., and the integral of the remain- 
ing terms should be 'in. These loops are in fact but 
the path a pencil attached to a common pendulum 
would trace upon a paper beneath, turning with uniform 
angular velocity about the projection of tlie point of suspension. 

Though the numerator of the fraction —-^^-\ becomes zero for the case iust con- 

A sin^ ■' 

sidered, it is evident that, at the moment of passing through the vertical, the limiting 
value must be considered hifinity, and that the integral through tlie infinitely short 
time of passage nuist be n; for the azimuthal position undergoes, at that instant, 
an increment (or decrement) of a semi-circumference. There is an identical case 
in the spherical pendulum. Regarding plane as the final limit of narrowing spheri- 
cal vibrations, it is evident that the azimuthal velocity of passage by the vertical 
becomes very great and has its limit infinity when they pass iJiroiujJi the vertical. 

This expression ^jl^^l"'^! ^^ /^J^ nearly) is a very different thing from the 




■mean 



precession" of the gyroscope, -^^W, given in my analysis. The latter is 



AS EXHIBITING THE ROTATION OF THE EARTH. 23 

the mean azimuthal motion of the body itself, the former that of the nodes of its 
orbit. The hitter is strictly true only for very great values of fS ; the former, 
rightly interpreted, is always true, though it has no special applicability except for 
(as in the gyroscope pendulum) small values of /3. The harmony of the two 
expressions is easily shown. 

Practically the gyroscope is made up of not only a rotating disk, but a non- 
rotating frame. In estimating the "deflecting force," therefore, in the expression 
(a) C should apply to the disk alone, and 31 and y to the entire mass of disk frame 
aild stem. 

The solutions that have been given of equations (4)., for the freely suspended 
pendidum are restricted to very small motions ; the following is general. 

Transfer equations (4) to polar co-ordinates by substituting for x, y, z the values' 

.7=:? sin ^ sin 
y^l cos 4) sin 
z =^l cos B 

in which ^ denotes the azimuth of the pendulum measured from the north, and Q 
its deviation from the vertical, and we get 

( -T^='i -sill A-4- „ . ^ „ .-- o^ ( cos d) sur B dB 

at ' I' sm- d sur- Q J 

in which C is a constant depending on arbitrary initial values of ^, the final term 

dt 

corresponding to the last term of (4). 

At the equator we have ?„^0, and the azimuthal velocity expressed by the third 

term of (7) becomes ^,-- fcos A sin" Q dd, which being periodic, produces but 

snr^v/ 

very minute change in the plane of vibration. If the pendulum is propelled, 

from a state of rest in the vertical, in the direction measured by the angle <^ 

from the meridian, this angle will be but very slightly aftccted by the minute 

values of the above expression during the outioard excursion, and the increment 

wliich '? receives Avill be almost exactly neutralized {quite so if cos ^ were abso- 
dt 

lutely invariable) during tlie return, and the angular velocity due to the term will 
again become zero; which cannot happen unless the pendulum again pass through 
the vertical on its return, in which case ^ will be as little varied during the return ; 
(otliericise ^ will, during the return, pass through all possible values from to ^tt, 
and integration is impracticable). Hence we may assume <p as constant, and, as in 
any other latitude, tlie term in question is, multiplied by cos ?., the same as at the 
equator, Ave may generally integrate that term for plane vibrations, considering 
^ constant, and putting C=0. Equation 7 thus becomes, 

,ox d^ ■ „ „0 — sin cos 

(8) -i=H sm X — 71 cos X . „ 

^ ^ dt sin^e 



' The following analysis, as far as equation (9), is modified from Galbraith and Houghton. 
Proc. R. I Acad. 



24 



THE PENDULUM AND GYROSCOPE 



If the amplitude's of the vibration arc very minute, so that may be substituted 
for sin m (1), the integral becomes 

.,)N ■ ^^"^^,j sin ;i— ^w cos ?. cos^) 

^' ' dl o 

expressing the precession in azimuth, n sin ;i, precisely as it results from the former 
analysis (equation 6). The sliglit periodic disturbance expressed by the second 
term of (i)) escaped that analysis, however, owing to the omission of the terms 

involving dz. 

In the above integrals the angle ^ must be taken at 180° greater or less on one 

side of the vertical than on the other, and the parts of ^-|* expressed by it will have 

contrary si"-ns. Hence the curve described in each complete excursion, disregard- 
in'' the superadded uniform azimuthal motion expressed by the first term of the 
second member of (9), will have the form of an excessively attenuated leminiscate, 
or figure of 8. " 

For greater amplitudes equations (8) will apply until becomes nearly equal to 
180°; if Q equals or exceeds 180°, it cannot he assumed that the pendulum will 
pass through the zenith (the condition for ^ to remain nearly constant), and the 
integral becomes inapplicable and erroneous. 

The foregoing integrals involve the condition that the pendulum shall pass 
through the vertical, and imply that vibration is induced by propulsion from a 
state of rest in the vertical. But, in the usual form of the experiment for exhibit- 
ing the rotation of the earth, the pendulum starts from a state of relative rest at 
the extremity of the initial vibratory arc. 

If we disregard the symbolic integral of (7), as may be done, since the minute 
periodic disturbance it measures has no intiuence upon the permanent azimuthal 
motion, that equation will become 

f \ d(p . ^ , C 



dt ^l' sin^ d 

The second term of the second member is identically the equation of the " spheri- 
cal pendulum." The latter, we know, exhibits an azimuthal motion of the apsides 
of its orbit, very minute when C is small, but incomparably greater than the horary 
azimuthal motion when, C being large, the conjugate dimensions of the orbit 
approaches equality to the transverse, and of which the limit corresponding to per- 
fect equality of these dimensions is for one vibration, 

00. 7tr-^^=J_-i 1 

as may be deduced from the expression for U„, par. 731, Peirce, Analyt. Mech., or 
from expression [79] and [83] of Mec. Cel. (Bowditch), by making a=.b and deter- 
mming the corresponding values of c and dt. 

In the case under consideration the value of C will be determined by making 
dl ~^ ^°^ ^^^^ commencement of motion, 0^,9.,, hence 
C=—n V sin X sin- 0, 



Sec Additional Notes, p. 51. 



AS EXHIBITING THE ROTATION OF THE EARTH. 25 

The pendulum will not move in a plane passing through the vertical, but on a 
conical surface differing slightly from such a plane, and there will ensue a slight 
apsidal motion reverse to, and diminishing, the apparent horary motion. 

(l>) The equation ™^ = — is usually solved by the aid of elliptic in- 

^^ ^ (It Z^sin-e /■-— 2- ^ ^ ^ 

tegrals {vide Prof. Peirce's Analyt. Mech., p. 418); but for present objects the 

ordinary processes of integration are preferable. 

From equations (8)2 and (4) may easily be deduced, neglecting terms containing 

V, and bearing in mind that 

x'^-\-y"^^l- — Z-, X dx-\-y dij^ — z dz, 

— Zc?z 
(e) di= 7 — , 

in which the upper or lower sign of the radical is to be taken according as dz is 
positive or negative, that is, as the pendulum is descending or ascending. The 
quantity under the radical may be put in the form {vide Mec. Celeste, Bowditch, 
Vol. I. p. o2). 



2g{a~z){z-h)(zJ^Q 



in which 

2g~ a +77 
(,. r..J^g i^-cr) (P-b^ 

_ (t- — or — ab — b-) 

a and b being the greatest and least values of z. 

If now we transfer the origin of co-ordinates to the lowest point of the spherical 
surface by substituting for z, a, and b, l—v, 1 — a, I — /3, and replace C and dt in (Z>) 

f 
by the values above found, we shall have (putting /-[-■ =zp) 



d^ 







«+6 v{2l—n) [(p—n) («— a) (/i— ?01^ 

the varying sign of the radical being understood. If we develop the two factors 
(21 — w)-' and (p — u)~', and multiply the results, we shall ha\c 

,7^_ kP-o.')(l'^^)f bhi r I I /i I l^t 

Strike out the common factor 7, and remove the factor 2p= into the denominator 
of the first radical factor (which factor then becomes ^(/_a) (l—b)=Va[3), ^nd 
the above integral becomes {vide Hirsch, Integral Tables, pp. 160-164), writing V 
for — a/3+(rx+/5)H — u\ 

4 January, 1373. 



26 



ie) 



THE PENDULUM AND GYROSCOrE 



-cons t. 



In onlcv that tlic arcs in tlie ahove expression should continually increase with 
tlie time, the positive or negative sign must be applied to the radical ^Z U accord- 
ing as u is increasing or diniinisliing: taken from »=a to ?(=/3 (or the converse), 
tlie arcs all become =7t, and the non-circular functions vanish. 

Hence the azimuthal angle passed over by the pendulum in its motion from a 
lowest to a highest point of its orbit (or the converse) is expressed by 
1 r, 1 _ /I , 1\ , 1 ,— /\ ,1,3 \a+/3 

1 /I ,1,3 ,15 \/3(a+/3)- 1 ,j \ 

-I /-T./I1 1_L S , 15 105 w5(«+/3)' M(^+^)U&c"l 

Tlie sum of the terms after unity included in the brackets is the ratio by which 
the azimuth angle exceeds a quadrant; or, if the integral is taken through an entire 
revolution (relatively to tlie a2>sides), it, multiplied by 27t, is angle -of advance of the 
apsides per revolution. 

For motion nearly oscillatory, of whatever amplitude {i. e., a being small and /3 
arbitrarily large), or for spherical motions of considerable amplitude (a and (3 taken 
witliin limits not exceeding say one-third of 7, corresponding to a swing of over 
UU°), p, always greater than 21, differs but slightly from that magnitude. Giving 
p tliat value, and tiiJving tlie angle ^ for a complete vibration, or a semi-apsidal 
revolution, we have the formula. 

If a and ^ are both small and nearly equal, and d the angle of which they are 

the versed sine, then 1^=1 sin^ 6, and the apsidal motion corresponding to the 

second term of the above (the following terms neglected) becomes f 7t sin^0; agree- 
mg with the expression (a), on p. 24, when developed for the same case. 

If the pendulum moves nearly horizontally in a great circle, that is, if a-\-^=2l 
andaf3=P (nearly), then p, C, and r are each infinitely great, and (/) becomes 



t,.=i.[i+i+|+_i_+i_+&,]^, 



AS EXUIBITING THE ROTATION OF THE EARTH. 27 

which denotes that the line of apsides moves through a quadrant while the pendu- 
lum is passing, through 180° azimuth, from a higliest to a lowest point ; in other 
words, that the highest and lowest points are diametrically opposite, and the apsides 
are apparently stationary. This theorem is true (as shown by Prof. Peirce), what- 
ever be the inclination of the great circle, though it cannot be generally made evi- 
dent by the above formute. 

If in (c) we make transformations and substitutions already described, develop 
the factor (p — ^l)~'% integrate between the limits u^a, «=/3, and double the result, 
we shall have for the time of one vibration, or one semi-orbital revolution, 

^^ ^-^''7fpL^+^^'*--p' +U:4A-7^;-2^^+l2;4-6)-p3— 
2.4.6" 4p^ "T" J 

and if a^O, that is, if the motion is purely oscillatory, then p=2/, and this becomes 

and more generally for any value of a and [i not exceeding the versed sine of thirty 
or forty degrees : 

When a and ^9 are both small, as in most pendulum experiments, the terms after 
the first in the brackets may be omitted, and we havQ the ordinary expression for 

the time n I 

^' . . . 

In the expression {g), omitting all the terms in brackets after the second, it is 

evident that that term will measure the apsidal motion for the time n I-; and hence 

that the total integral of equation [a) taken through that time will be, 

and if we denote by (p' the angle of azimuth of the apsidal line measured from its 
initial direction, we shall have, at any time t, substituting for a and [i, I (1 — cos d-^ 
and I (1 — cos (}2), 



(Jc) <^'=r« sin ;i + J J|.(l— cos 00 (1— cos OJ J 



or, since Q^ is always small. 



70 ^'=^\J^ sin X ± y ^Jl^J'^sin Q,'} 



The angle 0. being given, Q^ is determined for the ordinary pendulum experiment 
by the consideration tliat the constant C, of which the value is found p. 24, is the 
moment of the quantity of motion. As c is very minute, the actual velocity at the 



28 



THE I'EXDULUM AND GYROSCOPE 



lowest point will bo, sensibly, i/Jgl {l—cos d'i), and hence the moment at that point 
will be I sin 6, ^Ogi(^\—cos%)=^C=^—nl' sin X siir Q.,, from which deducing the 
value of sin 0^ imd substituting iu (//), we have 
(/ j (^'— )t sin X ^ 1 — ^sin= 02 j< 

Tiie second term in brackets is the retardation from the true horary motion ; it 
l)eing implied, of course, that the amplitude of oscillation is preserved unimpaired. 
Though small, this retardation would be sensible, especially if Q, had a considerable 
magnitude, say eight or ten degrees, though inappreciable for very small oscillations. 

Practically, the resistance of the air constantly diminishes the value of Qo, and 
failure to procure a perfect state of rest to the pendulum before it is set free, or 
currents of air, may give quite different values to G and c, and determine the cha- 
racter of the orbital motion to be progressive instead of retrograde ; and it is gene- 
rally observed that the conjugate dimension of the orbit increases (probably owing 
to the resistance of the air) as fio diminishes. In this way the apsidal motion due 
to the orbit may acquire a value quite considerable compared to the proper horary 
motion, which will apparently be sensibly retarded or accelerated. By observing, 
at any ])eriod of the experiment, the value of Oj and Q^. ^^^d the direction of the 
orbital motion, the coefficient of t in the formula (//) will give the theoretical rate 
of aziniutlial motion at that instant. 

If the orbital motion is retrograde and 

4 • . I W 



{m) sin 01= n sin 1 I— - 

3 \//(l 



iil(\ — cos 62) 

the Hue of the apsides would be stationary. For Columbia College, where n sin 
X=00004:717, witli a pendulum of 2G feet in length, and a value of O2 of 6°, this 
would give Oi=3',3, the actual semi-axes of the projection of the orbit being about 
two feet nine inches and one-third of an inch. 

It would generally te sufficiently accurate to substitute for 1— cos 0„, i sin^ a,, 
by wliich formula (//j would become more simply, 

('•') <?'=[« sin X+ '^-^j sin 01 sin Q^ It 

in which it is seen that the deviation from the proper horary motion is proportional 
to the area of the projection of the orbit. 

The above, or (//), expresses the azimuthal motion as it would be were there no 
other forces acting than those included in the investigation, in which case Q^ and Q, 
would be mvariable. In point of fact there are practically numerous disturbing 
lorccs, of which, however, the resistance of the air is the most considerable, and 
through which 0. and e, are incessantly changing, and it is not improbable that the 
duuuje o/.7>ape of the orbit may, in itself, cause some variation of direction of the 
luie ot apsides: a matter which cannot be decided until the problem of the spheri- 
cal pendulum is solved with the resistance taken into account. 



ce-m^lfl'tlr'T °',"" l^""';" '■ '"'" '' "" P'"''' ^"'1'*!--^' "^"tion of a body attracted l,y a 
ceut..l foue p.o,.onu,„al ,u the distance, iu a n.ediu.u whieh resists either directly or as the square 



AS EXHIBITING THE ROTATION OF THE EARTH. 29 

To get a clearer idea of what is expressed by the periodic term of (7), — 2 n cos "k 

J cos ^ sill" Odd (which corresponds to the integral J y dz of (-!)), we must revert 

to the latter equation. Conceive the pendulum propelled from a state of rest in 
the vertical, with a very great angular velocity, denoted by v, in the plane of the 
meridian. Were the earth motionless, it would continue to whirl in this plane, 
passing through the zenith at every revolution. Introduce the element of the 
earth's rotation, and the two terms of equation (4) containing n take effect, by the 
first of whicli the plane of revolution moves in azimuth with the angular velocity 
n sin /I. The second expressing that there wUl be an increase of the moment of 
tlic qiiantity of motion about the vertical after a time T proportionate to tlie area 

generated in that time) y dz. Under these conditions this area is cumulative, 

and at the end of one revolution expresses the area of the circle of radius 1. Let 
us suppose that the plane of motion turns about a line parallel to the complementary 
terrestrial axis with an angular velocity n cos ^. At the end of the time T (sup- 
posed very small) tlie plane will make with the meridian the angle n cos T^T, and 
as the quantity of motion in its own plane is vl, its moment referred to a vertical 
axis will, from zero, have become (•/- sin (/} cos XT'), or, substituting the small arc 
for its sine, 

vT- n cos 7.T 

But T, for one revolution, is expressed by — hence the above becomes 

V 
2)1 cos ?. 7X P 

The area of the circle which is generated in the same time is nl' and is expressed 

by the integral Cy dz, and it is easy to show for each successive revolution that 

the area J y dz multiplied by 2ii cos X corresponds to an increment of the moment 

of quantity of motion about the vertical which it would receive from a turning of 
the plane about the complementary axis through the angle u cos 7^ i. 

Hence, for the particular case under consideration, the second term of second 
member of equation 4 expi-esses an angular motion about the complementary axis 
of which n cos 7. is the velocity. The resultant of this, and the azimuthal com- 
ponent, is rotation about an axis parallel to that of the earth, and opposite in 
direction to the earth's rotation. 

The above theorem can be analytically demonstrated. The quantity N, expres- 
sive of the tension of the cord, is made up of the centrifugal force due to the pen- 
dulum's relative angular motion and of the variable component of the force of 
gravity (neglecting, as we have done, quantities of the order »'-). If this centri- 

fugal force is so great that the component of gravity may be neglected, - will 

c 

of the velocity, indicates no apsiflal motion aceonipanyinp: tlio decrense of parameters of the orbit. 
Neither, liowever, does it indicate tlie enlargement of the minor axis 'initially very small) so uni- 
versally observed in tiie penduhiiu experiments. 



30 



THE PENDULUM AND GYROSCOPE 



reduce to the constant r' {v being tlic impressed angular velocity of pendulum 
movement), and the second and third of equations (3) will yield the cquatioii- 
_'^'C,, cos ?.— 2 sin X)=—v- (y cos ?.—z sin X)— i/ sin Ti 

the intcEjral of which is 



y cos A-2 sin ;^=_^'1J^+^ cos vt-\-B sin vt 



The above is independent of n; y cos 1—z sin X is tlie value of the new co-ordi- 
nate of y' wlien the axis of // is changed to parallelism to that of the earth. Hence, 
as tlius transformed, this co-ordinate is unaffected by the earth's rotation, the plane 
of pcnduhnn motion must turn (if it turns at all) about such an axis. 

The assumption for ^=0, of //=(), z=l, '^ji—lv, -,/=0, gives 

at dt 

B—l cos ;i 
(10) hence y cos X—z sin A= — ^? sin A (1— cos i-t)-\-l sin {vi—7C) 

The second term of the second member of the above gives precisely the value 
which the first member would have, were the plane of pendulum motion stationary 
or were it turning Avith any angular velocity about an axis parallel to the earth's. 
Tlie first term is, owing to the assumed high value of r, very minute, and is periodic, 

the period being equal to , the time of the pendulum's revolution in its circular 

V 

orbit. Owing to its minuteness and periodicity, this term may be neglected, and 
equation (10) becomes 

y cos ?, — 2 sin "k^l sin [vt — ?.) 

to satisfy which, and at the same time the three differential equations (3) (omitting 
g, as we have found reason to do in (10), and also omitting terms containing iu, in 
the developments), requires the following values for the co-ordinates : — 
x=l sin nt cos (^vt — A) 

y—l [cos X sin («<_;\,)-[-sin 7. cos nt cos {vt—X)^ 
z=:l [—sin ?i sin (r/_a)-}-cos A cos 7d cos (v<— X)] 

Changing tlie axes of y and z by turning them through the angle X, we should 
have for new co-ordinates, 

a;'=/ sin nt cos (vt — X) 

y'=I sin (r/— X) 

z'=I cos nt cos (vt — X) 

If we now change the plane of yz by moving it through the variable angle 7if 
about the axis of y\ we get, 

x"=0 

y"=I sin (r/— X) 

^'~l cos {vt — X) 

y'^-\-z"'^P 



AS EXHIBITING THE ROTATION OP THE EARTH. 31 

These values show that the plane of pendulum revolution turns ahout an axis 
parallel to the earth's with the relative angular velocity n; or, in other words, that 
the plane preserves its parallelism to itself in space. 

If we had a succession of peniluhnns rigidly connected with each other, the dis- 
turbing effect of gravity would be eliminated. Such a succession would be simply 
a gyroscope, and the gyroscope, mounted in gimbals and set running in a meridian 
plane, would exhibit the apparent rotation of its disk around an axis parallel to the 
earth's axis equal and contrary to that cf the earth; wliich is simply saying that as 
the earth revolves the plane of the disk maintains its parallelism to itself, and if we 
suppose its axis directed at a star in the plane of the equator, it would follow that 
star so long as the rotation of the disk is sustained.^ 

The pendulum experiment, in its ordinary form, exhibits not the whole rotation 
of the earth, but only one component of it; the component which belongs to an 
axis passing through the locality. It is perhaps quite as interesting and important, 
as being the only experimental demonstration we can have of a principle difficult 
of comprehension, but as fundamental to mechanics, since its enunciation by Euler, 
as the corresponding one of the decomposition of linear velocities, viz., that of the 
decomposition into distinct components, of rotary velocities. The plane of the pen- 
dulum appears to turn relatively to the surface of the earth simply because the 
earth turns just so much underneath it, the earth really revolving about the local 
axis with a certain calculable component of velocity. The earth turns at the same 
time with another component of velocity about another axis (the complementary one), 
and the joint effect, or the resultant of the two components, is the rotation about 
the polar axis. The second component, very great as we approach the equator, 
where the first vanishes entirely, is not exhibited by the pendulum, and is only 
detected by analysis as a slight disturbance. Convert the pendulum into tlie gyro- 
scope, however, and this second component appears equally with the first. 



' OwinjT to the friction of the girabali?, there would be, practically, besides the motion above 
described, a motion of tlie axis in the plane of the meridian, north or south, according to the direc- 
tion of the disk rotation; this angular motion might be greater or less than the equatorial motion, 
but would be, with a well-constructed apparatus, independent of it, at least for the brief time during 
which a gyroscope experiment would last. 



ON THE 



INTERNAL STRUCTURE OF THE EARTH CONSIDERED AS AFFECTING 
THE PHENOMENA OF FllECESSION AND NUTATION. 



TriE equations of precession and nutation are, as is well known, entirely indepen- 
dent of any particular law of density, and are functions only of the absolute values 
of the moments of inertia about the equatorial and polar axes A and 6',' and are 
independent indeed of the figure of the earth, except so far as it affects the values 
of these moments. 

Moreover, if the earth, instead of being solid throughout, is (as supposed by most 
geologists) a solid shell inclosing a fluid nucleus, it is only necessary (leaving out 
of consideration the pressure that may be exerted on the interior surface by the 
fluid) that the shell should have these moments of inertia. Mr. Poinsot'^ has obtained 
as the results of calculation for a homogeneous spheroid, values of precession and 

nutation identical with those of observation, by taking the ellipticity at , and 

Yi (the ratio of mass of moon to tliat of the earth), at -— . 

88 

We have, assuming a uniform density, indicating by a and h the equatorial and 
axial radii, and by e the ellipticity : — 

C=J% «' Z^=(approx.) -% n ¥ (l+4e) 
15 lo 

A=^.n («* i+a^ &')= A^i V- (l+3e) 
If e is taken at ^^ ^ then — r= . But all meridian measurements of 



' I assume, of course, the equality of all moments of inertia. A, about the equatorial axes, and 
overlook all questions as to the non-S3-ramctr3' of the earth with respect to its axis of figure or to the 
equator; for, in fact, neither the rotation of the earth nor any observable celestial phenomena reveal it. 

' Connaissanec fles temps, 1858. 

5 January, 1872. ( 33 ) 



34 PRECESSION OF TUE EQUINOXES AND NUTATION 

the oartli iiulicat. an ollipticity greater rather than less than J^-^; *^id the latest 
determination makes it ^,J.,t by giving which valne to e wc obtain — ^=299" 

Therefore tlie obs(>rv(>d precession is to that which wonld result in a homogeneous 
spheroid, from the fornudas, with tlie latest determined value of e introduced, as 

299 : oil. 7, provided tlie relative mass of the moon lx< but -^^X 

The value of Ti' "^vould be the same for a homogtmeous shell of which the inte- 

rior surface had the same eH!pticUy, c, as the exterior ; or it would be the same for 
a shell of which all the elementary strata had the same cllipticity, in which the 
density constant through each stratum, should vary according to any law, from 

24 

stratum to stratum. The ratio of 299 : 312.7, so nearly unity (= 0.96 ^^, nearly), 

wliilc tlie ratio of mean to surface density of the earth is so high, indicates nearly 
uniform cllipticity of stratification, and hence fluidity of origin; while, on the other 
liand, the considerable inequalities in tlie equatorial axes indicated in the note 
below are iucompatible with the hypothesis of actual fluidity beneath a thin crust, 
and are, to the measure of their probability, a disproof of it. 

The effect upon the axial movements of such a shell Avhich would result from the 
pressures of an internal fluid has been made the subject of an elegant mathematical 
investigation by W. Hopkins, F.R.S., in the Philosophical Transactions of 1^39- 
40-42. On the supposition of a uniform density of shell and fluid, and the same 
cllipticity for inner and outer surfixces of the shell, the precession will be the same 

* Airy, "Figure of the Earth," Eucyc. Metroj). ; Guillcmiu: Madler, Am. Journ, of Science, Vol. 
30, I8G0, makes the iiolar compression of greatest meridian 



292.109 



of smallest meridian 

302.004 

(Article translated by C. A. Schott, U.S. Coast Survey, from Prof. Hcis' "Astronomie, Mctcorologie 

tt Geographic," Nos. 51, 52. 1859.) 

t Appendix "Figure of the Earth" to the "Comparisons of Standards of Length," published 

18G6 by the British Ordnance Survey, gives for a "spheroid of revolution," " '^= ; for a spheroid 

of three axes, —-=-_-_, —^'^ sisss ' ~<r^ 32(i.<Jb ' The probabilities of the latter sup- 
position to the former being 154 : 138. 

J There is yet great uncertainty as to the relative mass of the moon, and as long as that point is 
unsettled, so is also the ratio of observed to calculated precession. Laplace, from observations of 

the tides at Brest, fixed it at ^_ , which number is adopted by Pontecoulant. Former determinations 
from the observed nutations make it g^y^S ' ^^^ sf ^^^ ^^'^ determination from the coefficient of 
nutation of Lindenau. Guillemin gives gg-, and these two last numbers coincide nearly with that 
used by Poinsot. A discussion by Mr. Wm. Ferrell, member of National Academy of Sciences, of tidal 
observations made for a series of years at the port of Boston, as well as those at Brest, gives results 
coulirmatory of the larger ratio of Laplace. Serret (Annates de I'Observatoire Imp. 1859) assumes 

83 ""'^ ^'^"'" %'^- = -3U6 = ^•^'^•^-^- Tlicse ratios are adopted by Thomson and Tait, §§ 803, 
823. Archdeacon Pratt (" Figure of the Earth," 4lh ed. 1871) adheres to Laplace's determination. 



IN RELATION TO THE EARTH'S INTERNAL STRUCTURE. 35 

and the nutation essentially the same as for a homogeneous spheroid ; but for tlie 

actual case of a heterogeneous fluid contained in a heterogeneous shell he finds 

that the ellipticity of the inner surface of the sliell must be less than that of the 

exterior in the proportion of the observed precession to tlie precession of a homoge- 

7 
neons spheroid of same external ellipticity, a proportion which he assumes to be , 

in accordance to the then received numbers for ellipticity, and for the mass of the 
moon. 

Tlie fulfilment of the condition, in the actual constitution of the earth, is improb- 
able ; for the isotliermal surfaces are in all ])robability (and indeed by liis own 
mathematical conclusions) of progressively greater ellipticity from the surface in- 
wards, lie finds, however, tlie requisite decrease of ellipticity in the fluid surfaces 
of equal densltij, assuming the well-known hypothetical law of density of Laplace 

sin ch 
n= A — /^^; hut we know not the influence which pressure has upon solidification, 

and it seems probable that the interior surface of the shell would conform nearly to 
the surfaces of eqiuil temperature. The demand whicli he makes for 800 or lOOO 
miles thickness of shell is therefore a minimum (for the data used), while the more 
prohuble result is a much greater thickness or even entire solidity. But however 
elegant may be Mr. Hopkins' analysis, the basis of the structure is but slender, and 
those results have not been generally accepted as fully decisive of the question. 

Sir Wm. Thomson, F.Il.S., brings forward (Philosophical Transactions, 1863; 
also Thomson's and Tait's Treatise on Natural Philosophy, 1867) arguments 
against the popular theory of a thin crust, which are more forcible. A thin crust 
would itself undergo tidal distortion, and the height of the apparent tides of the 
ocean be thereby much reduced, while i\ic-actu(xl precession would be diminished 
in the same ratio; that is, the differential forces of the sun and moon would expend 
themselves in producing these solid tides instead of producing precession. 

From a theoretical investigation (given in a separate jiapcr in the same volume)' 
of the deformation experienced by a homogeneous elastic spheroid under the influ- 
ence of any external attracting force, he arrives at the result that, if the earth had 
no greater rigidity than steel or iron, it would yield about | as much to tide-produc- 
ing influences as if it had no rigidity — more than | as much if its rigidity did not 
exceed that of glass. Moreover, the apparent ocean tides (or difference of high 
and low water level) would be (li II is the measure for a perfectly rigid earth) 

0.59 //, if the earth had the rigidity of iron or steel only; -, II if it had that of 

1 4- 

glass. -* 

As to precession, the centrifugal force of the crowns of the tidal elongation would 
balance \ of the dynamic couple residting from the sun's or moon's attraction 
if the earth had only the rigidity of glass, and -| if it had only that of steel. 

" That the eflective tidal rigidity, and what we call the precessional effective 



' Sec also " Treatise on Natural Philos.," § 832 el scq. 



CG 



PRECESSION OF THE EQUINOXES AND NUTATION 



rigidity of the oartli, may be several times as much as tliat of iron (which Avould 
nuike tlie i.lienoi.uma, both of the tides and precession, sensibly the same as if the 
earth were perfectly rigid), it is enough that the actual rigidity should be several 
times as great as the actual rigidity of iron throughout 2U00 or more miles thick- 
ness of crust." 

A theorem fundamental to the establishment of the above propositions is, that a 
revolving spheroid destitute of rigidity, a homogeneous fluid one, for instance, 
would have no precession. Sir W. Thomson docs not mathematically demonstrate 
this tlieorem, but by use of an hypothesis gives an elegant illustration of its truth, 
for which, though to me it is convincing, I prefer to substitute the following 
demonstration. 

Such a splicroid, all the particles of which revolve about an axis Avith a common 
angular velocity v, and attract each other by the law of universal gravitation, 
would have tlic form of an ellii)soid of revolution, the ellipticity of its meridional 

section being ^ "' .* (See " Figure of the Earth," Encyc. Metrop., par. 33, by Prof. 

Airv.) Attracted by the sun, its tides would be expressed by the terms of [2316] 
]Mcc. Cel., Book IV (Bowditch). Of these three terms, the first (a function of the 
declination only of the attracting body) and the third (the semi-diurnal oscilla- 
tion) express tidal elevations symmetrically distributed on each side of the equator, 
Avhich would, hence, exert no influence through the centrifugal forces of their 
masses, upon precession. The second therefore, or ilic diurnal tide, is alone to be 
considered. 

Conceive a meridian plane passed through the sun at any declination, the 
"couple" exerted by its attraction Avould be exerted wholly to turn the spheroid 
about an equatorial axis normal to this plane. "VVe have therefore to investigate 
what dynamic couple, with reference to this same axis, will be exerted by the cen- 
trifugal force of the diurnal tidal protuberance. As the calculation involves the 
state of things at but a single instant of time, the angle, iU-\-~> — 4> "lay be written 
CT and counted from the meridian of the sun: p, the uniform density of the fluid, 
taken as unity. 'J'he height, y, of the diurnal tide will be expressed for all parts 
of the spheroid by 

15 S* 
(l"*) «=-- - sin cos sin ?„ cos 7. cos rat 

-I 'J 

in which 1 is the polar distance or complement of the latitude of the locality, and 
the declinaticm of the sun. If, with Laplace, we put cos X=//, and sin A=l/]U^"^ 
tlie mass of the elementary column of height y will be yd^i ('/©, and its centrifugal 



* 



(lhc\ng tlic force of gravity at the equator of the hypothetical spheroid. 
The expression, in the original, for the diurnal oscillation, is 

y-. sin Fcos Fsin o cos 9 cos (nl4-G — 4.) 



•■•"(■- i) 

The notation of my paper on the precession of the equinoxes is substituted, and the assumed value 
w e introduced. 



IN RELATION TO THE EARTH'S INTERNAL STRUCTURE. 37 

force (the radius of the spheroid being taken at unity, and the variation, assumed 

slight, due to eUipticity, disregarded) n'-i/d^i JvrV l—fi'. The component of this 

tending to tilt the spheroid about the axis in question is u"// (/i.i '/cjV 1 — /i" cos cr, 

and its moment n^y d(i dxs /<y 1 — ,«" ^^* ^• 

Substituting the value of >j (47), the above becomes 

11^ sin cos (If^i dxTi f-C (1 — u~) cos" ct 

2/-V 

Integrating, first with reference to ,(/ from ^:^ — 1 to |(/=:-|-l, then with reference 
to cT from to 2 7t, we get, as the expression for the couple due to "the centrifugal 
force of the crowns of the tidal elongation," resisting the sun's action, 

(48) 27t""-f sin cos Q 

AN^c have found (19) for the moment of the sun's force, producing precession, 
the expression 

M (C—A) sin cos 

Q 

and (46), (C — J)^ - rre [h being taken at unitv) and e, as already stated, is for 
a homogeneous fluid spheroid = . Making these substitutions, the above ex- 

prcssion becomes identical with (48). The precessional force of the sun is, there- 
fore, exactly neutralized by the centrifugal force of the tidal swelling. 

The theorem could, doubtless, be demonstrated for a revolving fluid spheroid 
in equilibrium, of Avhich the density of the strata varies. Without extending any 
further the mathematical analysis, it will be sufficient to remark that the calculation 
of the tidal elevations is, identically, that of equilibrium of form of the revolving 
body subjected to a foreign attraction, and in the calculation the motion of rotation 
is disregarded, and the centrifugal force, which expresses its entire effect upon the 
form, alone considered. Under this point of view, equilibrium of form is, necessarily, 
equilibrium (or stability) of position. For if any effective turning force exists, it 
must, in order not to interfere with equilibrium of form, either be so distributed as 
to give each individual particle of the spheroid its proper relative quantity of turn- 
ing motion, or it must be a distorting force. The first alternative cannot be admit- 
ted ; the second is excluded by the hypothesis of equilibrium. Hence, there can 
be no turning (or precessional) force. 

The accuracy of the foregoing analysis is complete,Vxcept that the consideration 
of rehitice motion of the particles is excluded. But Laplace shows (p. 604, Vol. IT, 
Bowditch) that as the depth of the ocean increases, the expressions for the tidal 

' Tlicro are slight errors of approximation : 1st, in the tidal expression (47) itself; 2d, in the above 
integration which disregards the variation of the radius; and, 3d, in the value of C — A. They neutra- 
lize each other iu the final result. 



38 TRECESSION OF THE EQUINOXES AND NUTATION 

oscillations j-iveu bv the dynaniir tlioory ai)proximate rapidly to those of the 
"cquilihrium theory," witli which, when the depth is very great, or the spheroid 
wholly fluid, they are essentially identical. INIoreover, he shows (p. 219, Vol. I) 
that the rc)7/rt(/ motions of the particles, when the depth is small, may be disre- 
garded. Wiien the spheroid is wliolly fluid, all the relative motions of the particles 
are of the same order as the vertical ones and exceedingly minute ; and the forces 
of inertia tliercby developed are insensible compared with those we have been con- 
sidering.' 

By parity of reasoning the truth of Sir W. Thomson's propositions concerning a 
solid but yielding spheroid is made evident ; for exactly in the same ratio to the 
tides of a fluid .spheroid that the solid tidal elevations are produced (the actual 
ellipticity of the earth being nearly that of equilibrium with the centrifugal forces), 
will the precessional couple due to the tide-producing attraction be neutralized by 
their centrifugal action.- That a thin solid crust, such as geologists generally 
assume, Avould yield and exhibit tidal elongations, seems without calculation very 
probable ; l)ut if Sir W. Thomson is correct as to the rigidity required in even a 
■wholly solid earth, the hypothesis of a thin crust must be abandoned, and it would 
seem indeed that rigidity several times as great as the actual rigidity of iron 
throughout 2000 or more miles thickness of crust would be incompatible with a 
very high internal temperature. 

AVithout having recourse to Sir W. Thomson's profound analysis, the necessity, 
in ordc>r that there shall be no sensible solid tidal wave, of a very high rigidity 



' The forpgoiii£? demonstration docs not conflict with Laplace's theorem that ocean tides do not 
affect the preces.sion ; for his tlieorcm apjilies only to a shallow ocean over a rigid nucleus, of 
which o:'(^an the processional couple, by altered attractions, pressures, and centrifugal forces due to 
generation of living forces in the fluid, is transferred to the nucleus. I have already alluded to 
the minuteness of Uie motions of the particles of a fluid spheroid. The remarks ap|)ly, cl fortiori, 
to those of an elastic aolid. Vihralorij motions, properly speaking, cannot e.xist, for the elastic 
forces extremely minute are always held (sensibly) in equilibrium l)y the distorting forces. The 
solid surface would oscillate in the same sense that the ocean tides oscillate, i. e., by a "forced'' 
tide-wave. 

' " It is interesting to remark," say Thomson and Tait (§ 848, " Treatise, &c."), " that the popular 
geological hypothesis of a thin .shell of solid material, having a hollow space within it filled with 
liquid, involves two effects of deviation from perfect rigiility which would influence in opposite ways 
the amount of precession. The comparatively easy yielding of the shell must render the effective 
moving couple due to sun and moon much smaller than it would bo if the whole interior were solid, 
and, on this account, must tend to diminish the amount of precession and nutation. But the effective 
moment of inertia of a thin solid shell, containing fluid in its interior, would be nuicli less than that 
of the whole mass if solid throughout; and the tendency would be to much greater amounts of pre- 
cession and nutation on this acconnt." 

The co-efficient of precession of the "thin solid shell" would be (p. .34) the same, nearly, as that of 
the spheroid of which the homogeneous strata have the same ellipticity. Its precession-resisting 
couple (48) due to tidal distortion would be just what is necessary to develop its proportional influ- 
ence upon the precession of that shell, upon which the fluid contents can e.\ert influence only through 
their pressure. This is identically I'rof Hopkins' problem. The /7un shell of popular geological 
hypothesis would, however, be subject to tidal distortions scarcely inferior in magnitude to those of 
a wholly fluid spheroid; by which, as we have seen, the sun and moon's "moving-couple" is wholly 
neutralized throughout the whole spheroid. 



IN RELATION TO TUE EARTH'S INTERNAL STRUCTURE. 39 

for the earth, may be made evident from the following considerations : A rod of 
steel extending towards the snn from the centre to the snrface of the earth, would 
be elongated by the difierential force of the sun's attraction 0".975, or one foot, 
nearly. The height of the solar tide of a homogeneous fluid spheroid is 1".355 ; 
but the mutual attraction of the elevated particles produces 0".793 of this, and the 
remaining 0'''.542 is the proper measure of the direct action of the solar force. In 
tlie case of tlie rod the elastic forces of the steel alone are considered ; in the 
splieroid gravitation is the sole binding force. The maximum extension of the 
rod per unit of length would be expressed by the decimal .000000055 corre- 
sponding to a tensile force of 1.S7 lbs. (taking the coefficient of elasticity at 34 
millions lbs.) per square inch.''' The necessity of the extreme rigidity demanded 
by Sir W. Thomson is recognized when it is seen how excessively minute would be 
the elastic forces developed in tlie production of distortion, in a rigid earth spheroid, 
commensurable with fluid tide-waves.^ 

In a paper "On the Secular Cooling of the Earth" (Trans. E.S.E., 1862, and 
Appendix to " Treatise, &c."), Sir W. Thomson applies a solution of Fourier to 
the determination of the interior temperature and its rate of increase downwards. 



'" See Additional Notes, p. 51. 

' M. Delaunay, President of the French Academ}', after quoting (Comptes rcndus 1808) from the 
paper of Sir W. Thomson to wliich I have already referred, the results of IIoi)kius and some corro- 
borating remarks from Sir W. Thomson's paper (referred to above), says: "Ainsi, on Ic voit, I'ob- 
jeetion raise en avant par AI. Hopkins, contre les idees generalement admises par Ics geologues sur 
la fluidite interieure du globe terrestre, est regardee par plusieurs savants anglais comme parfaitement 
foiidee. Je suis d'un avis diametralement oppose: je crois que 1' objection de AE. Hopkins ne repose 
sur aucun fondement reel." M. Delaunay then refers to an experiment made under liis direction with 
a glass vase 0" 24 in diameter, as furnishing decisive proof that the "viscosity" of a lifpiid as per- 
fectly fluid as water even, is sufficient to cause it to take up the rotary motions of its enveloping 
shell, provided that those motions are relatively slow, as arc those which constitute the precession 
and nutation of the earth; and he goes on to say: "Hence it does not appear to me possible to 
arlniit that the effect of the perturbing forces to which precession and nutation are due extend only 
to a portion of the mass of the terrestrial globe ; the entire mass ought to be carried along (entraincc) 
by the perturbing actions, whatever may be the magnitude attributed to the interior fluid portion, 
and consequently the consideration of the phenomena of precession and nutation can furnish no datum 
for estimating the greater or less thickness of the solid crust of the globe." 

M. Delaunay seems to be unaware that Sir W. Thomson coincides with Prof Hopkins only in 
this (as the sequel of the very paper quoted shows), that he demands a great thickness of crust, and, 
moreover, that the interior, to the depth of this crust, shall be not merely "solid," but possessing a 
rigidity "several times as great as that of iron." I have endeavored to show that Sir W. Thomson's 
argument is irrefragable; but, based upon wholly different considerations, it is certain that no degree 
of "viscosity" assigned to an internal liquid will refute it. 

I have remarked, at the outset of this discussion, that Prof Hopkins' results "have not been gene- 
rally accepted as decisive;" but I cannot admit that, as a test of their tenability, the experiment of 
M. Delaunay possesses the crucial character which he attributes to it. Yiscosity, considered as an 
accelerating force tending to impart to a fluid the rotary motions of an enveloping shell, is directly 
proportional to the surfiice of contact, and inversely to the mans of contained liquid ; in other words, 
it varies inversely as the diameter of the enveloping shell. The effect of viscosity of tlie fluid con- 
tents of the earth compared to those contained in a similar spherical envelope of only ten inches 
diameter, would be expressed (nearly enoun-li) by the fraction ' -^ . 



40 PRECESSION OF THE EQUINOXES AND NUTATION. 

assuming a uniform primitive melting temperature of 7000° Fall., and a lapse of 
100 millions of years since the cooling process connnenced. 

"The rate of increase of temperature from the surface downwards Avould be sen- 
sibly ^\ of a degree per foot for the first 100,000 feet or so. Below that depth the 
rate of increase per foot would begin to diminish sensibly. At 400,000 feet it 
would liave diminished to about jl^ of a degree per foot. At 800,000 feet it would 
have diminished to less tlian ^V of its initial value, that is to say, to less than ^^V^ 
of a degree per foot; and so on, rapidly diminishing. Such is, on the Avhole, the 
most probable representation of the earth's present temperature, at depths of from 
100 feet, where the annual variations cease to be sensible, to 100 miles, below 
which the wliole mass, or all except a nucleus cool from the beginning, is (whether 
liquid or solid) probably at, or very nearly at, the proper melting temperature for 
the pressure at each deptli." 

The high rigidity demanded is difficult to conceive of in connection with a 
temperature in the solidified mass " at or near" that of melting, extending down- 
wards indefinitely towards the centre of the earth. Hence Poisson's reason- 
ing, wliicli results in showing that the earth to have become thoroughly cooled and 
to have been subsequently reheated, svperfickdJij, harmonizes better with the 
demand for rigidity than that of Leibnitz, which supposes it to be now cooling 
from a (throughout) incandescent liquid state. In the latter case the law of actual 
temperature as deduced from Tourier's formula? (as expressed above by Sir W. 
Thomson) would extend to the centre; in the former case only to the unmelted 
portion or to the "nucleus cool from the beginning." 

lleferring to the increase of temperature, with depth observed in mines, &c., 
Poisson remarks: "^Fourier et ensuite Laplace out attribue ce phenomene a la 
chaleur d'origine que la terre conserverait a I'epoque actuelle et qui croitrait en 
allant do la surface an centre, de tel sort qu'elle fut excessivement elevee vers le 
centre * * * en vertu de cette chaleur initiale la temperature serait aujourd'hui 
de plus de 2000 degres a une distance de la surface egale sculemcnt an centieme 
du rayon ; au centre elle surpasserait 200,000 degres. * * * Mais quoique cette 
explication ait ete generalement adoptee, j'ai expose, dans mon ouvrage, les difficultes 
qu'elle presente, et qui m'ont paru la rendre inadmissible, * * * je crois a\oir 
demontrc que la chaleur developpee par la solidification dc la terre a du se dissiper 
pendant la duree de ce phenomene, et que de];)uls loi/gfemjis il n' en svhsisic 2>hts 
aucnne trace." (Theorie dc la Chaleur.) 

Poisson, as is well known, attributes the increase of temperature, with depth, 
observed in the earth's crust, to the passage, at a remote period, of the solar system 
through hotter stellar regions, the temperature of which, he argues, should differ 
from place to place. Even a hypothetical case of the illustrious author, conform- 
mg to his theory, of an increased supei-ficial temperature, 5000 centuries ago, of 
200° C. diminishing by cooling (by transition to cooler stellar regions) to 5°, 500 
centuries ago, and, subsequently, to the actual mean temperature, would scarcely 
meet the present demands for time, of palfcontolo<;v ; while the determinations of 
the conductivity of the earth's crust made near Edinburgh show, according to Sir 
^^. 'Ihunison, a necessity for increments of temperature of 25°, 50°, arid 100° 



IN RELATION TO THE EARTH'S INTERNAL STRUCTURE. 41 

(Fall.), for past periods of only 1250, 5000, and 20,000 years, and authorize him 
to pronounce Poisson's hypothesis impossible, without destruction of life, or relega- 
tion of the date to so remote an era as to demand an intensely heated stellar region. 

A reheating after solidification which should again fuse the surface to great 
depths would be, it seems to me, as " inadmissible" for the origin of observed sub- 
terranean temperatures, as the heat originally " developed by the solidification of 
the earth." Hence, the hypothesis of a reheating to fusion of the surface by 
impact of meteoric bodies Avould be likewise excluded by Poisson's theory of in- 
ternal temperatures. 

In the paper referred to (p. 39), Sir Wm. Thomson discusses the probable circum- 
stances of solidification of the earth, assuming the known crust-materials (granite, 
&c.), in a molten state, as the constituent, and reasons that in consequence of the 
great condensation of granite in freezing, solidification must commence at the centre, 
and that "there could be no complete permanent incrustation all round the surface 
" till the globe is solid, with, possibly, the exception of irregular, comparatively 
" small spaces of liquid ;" such separation of constituents in the process of crystal- 
lization taking place in all liquids composed of heterogeneous materials, and, indeed, 
is observa^jle in the lava of modern volcanoes. He infers from the probable 
phenomena developed, into the discussion of which he goes at some length, " rc- 
" suits sufficiently great and various to account for all that we see at present, and 
" all that we learn from geological investigation, of earthquakes, of upheavals, and 
"subsidences of solid, and of eruptions of melted rock." 

Still we Avould, if possible, find reason to attribute a lower than " the proper 
melting temperature" 'to the solidified interior. Ice, indeed, preserves its rigidity 
unimpaired up to the point of fusion, and there may be a few other substances that 
have the like property; but it seems to be an exceptional one. The known constitu- 
ents of the earth's crust certainly do not possess it, at least under ordinary pressures. 
If, as suggested by Prof. Joseph Le Conte (Am. Journal of Science, Nov. Dec. 1872), 
the "conductivity" be increased by pressure mi^ condensation^ such diminished 
temperatures may obtain. 



January, 1872 



^2 NEW ADDENDUM. 




NEW ADDENDUM.^ 

A TKW words arc in placo lierc concerning the results of the late Prof. Hop- 
kins' investigation (against which M. Delaunay's objections, (note, page 38,) are 
especially directed), briefly stated, pages 34, 35. They are as follows: First for 
IIOMOGENEOUSNESS. "Supposing the earth to consist of a homogeneous spheroidal 
sliell (the ellipticities of tlie outer and inner surfaces being the same) filled with a 
fluid mass of the same uniform density as the shell;" then, "the precession will 
be the same, whatever be the thickness of the shell, as if the whole earth were 
lioinogcneous and solid." 

Second, for heterogeneousness, his result may be thus expressed: 

(a) P,_P'=.pJl- 

" where P^ denotes tlic precession of a solid homogeneous spheroid of which the 
ellipticity =(?,, that of the earth's exterior surface, and P' the precession of the 
earth, supposing it to consist of an interior heterogeneous fluid contained in a 
heterogeneous spheroidal shell, of which the interior and exterior ellipticities are 
respectively e and f„ the transition being immediate from th,e entire solidity of the 
slicU to tlie perfect fluidity of the interior mass." 

In the multiplier of -, second member of (a), q is the ratio of external to internal 

polar radius of the shell ; s depends on the varying ellipticity and density of the 
strata of equal density of the shell ; Ji depends on the density of the fluid interior. 
For a thin crust the coeffi^;ent in question is unity nearly; for a thick one it will 
be somewhat greater if e be less than fj. 

It cannot fail to be observed that, ixnder the conditions just before expressed for 
homogeneousness—i. c, equality of external and internal ellipticities — we get from 
tlie formula (s becoming zero) the same result, i. e , P' = P„ as for that case. 

In accordance with rational hypothesis as to the internal condition of the earth, 
equalities of ellipticities for the surfaces of a thin crust (and corresponding equality 
of densities), or closely approximate equalities would be expected. The necessity 
for a thick crust arises, therefore, from the alleged discrepancy between the observed 
and calculated annual precessions (50 seconds and 57 seconds), which, according 

to Frof Hopkins, makes '~ = |, nearly, assuming the moon's mass j\, and 

the earth's ellipticity ^J^. (The real discrepancy is probably very much less. See 
page 34, et sequentia.) 



. ' y'"" "'■'5'""' Addendum, hurriedly written while the work was in the printer's bands, has been, 
in what follows, somewhat modified and amplified. 



NEW ADDENDUM. 43 

If, in applying the expression («), the symbolic fraction, for a first approximation, 
be omitted, we have, according to above assumption of discrepancy, e = le,. This 
value of £ will be in excess ; hence, the thickness of crust deduced from it will err 
the other way, and a determination on this basis will give a thickness which must, 
in fact, be exceeded. 

The limit of solidity, proceeding inwards, may and probably docs depend upon 
both temperature and pressure. Isothermal surfaces Prof. Hopkins finds to have 
incrcasbuj ellipticities. Surfaces of equal pressure, deduced from the hypothetical 

law of density, A^-^^, have diminishing ellipticities, and if qh^ — 150° the above 
b 

law agrees sufficiently well with the actual ellipticity and ratio of surface to mean 
density of the earth. This law for e = |fi demands a thickness of crust of j the 
radius, or 1000 miles. This is a minimum, since the actual surface of solidifica- 
tion (lying between this and the corresponding isothermal surface) would have 
greater (and hence too great) ellipticity. 

Before commenting upon this application, and upon the real meaning of tlie 
formula, I return to the case of homogeneousness. Some of tlie results arrived at 
by the analysis of Prof. Hopkins may be illustrated by the following considera- 
tions : The fluid spheroid, treated of p. 36, is subjected, by the attraction of the 
sun, to the distortion expressed by (47). This distortion, as shown by the form 
of the expression, is equivalent to an exceedingly sliglit rotational displacement^ 
of figure about an equatorial axis, such as would be caused by displacing through a 
still more minute angle the planes of diurnal rotation. It is one of the beautiful 
results of the analysis to show tliat the change in the direction of the centrifugal force 
due to this slight obliquity of the planes of rotation is equivalent to turning forces at 
all points of the fluid exactly proportional to their distances from the equatorial axis. 

Let now a rigid shell, exactly conforming internally to the external surface of 
the fluid, be applied, and the Avhole turned back until the planes of rotation are 
restored to perpendicularity to their axis ; the precessional efl'ect of the attracting 
body now operates upon the whole mass ; for there are no longer counteracting 

tidal protuberances. If we take that part of (47) which is due to the direct action 

o a 
of the sun, viz., — sin Q cos sin X cos ?. cos cj (for, the protuberances being repressed 

' <7 
by the shell, the pressures on its interior which replace tliera will arise only from 
the direct action), and estimate it as a pressure and calculate the elementary couples 
for an internal ellipticity, e, we shall find the integral couple (and tliis corresponds 
with Prof. Hopkins' result) to be identical with (48) viz., exactly that due to the 

' The required angle of the displacement is the height of the tidal wave (47), for o = 0, divided 
(If 

by — for an ellipse of ellipticity, e, (2e sin \ cos ji). Prof Hopkins shows that the corresponding 

divergence of the planes from perpendicularity develops a couple = — « n'e multiplied by the sine 

15 

"4 S 

of twice this arc (or twice the arc itself). Performing the operations we get, ~-^ ne — - sin $ cos 0, in 

l.T 

which we have the solar conple (ID) and (4S), which causes the displnconicnt, since e = -: (C — A.) 



^^ NEW ADDENDUM. 

couple which the sun would exert on the fluid mass considered as a solid.^ It would 
increase the precessioual force of the sJiell in the ratio ^^ of the analysis. By 

virtue of this pressure tlie fluid tends to transform its own precession into an 
augmented precession of tiie shell. 

It requires, however, but an extremely minute angular separation of the axes of 
the shell and fluid to generate counter-pressures equivalent to those which caused 
the separation.^ The divergence cannot, therefore, be progressive, but is simply a 
minute oscillation of tlie two axes, or a rotation around each other. In the latter 
form it appears in tlic analysis which, otherwise, gives to the internal fluid mass a 
precession identical vi/h tltat of the enveloi>iiHj shell. 

Prof. Hopkins conflnes his analysis for tlie case of homogeneousness to equal 
ellipticitics for the bounding surfaces of the sliell. Excepting the case of sphe- 
ricity for the inner surf\ice, the result would be the same — viz., an unchanged pre- 
cession, however the ellipticities might differ. 

I now return to the formula («) and remark, that it is an inaccurate expression 
for a sliglit difterence (Pj — P') due to the fact that the spheroid is heterogeneous — 
that it is not capable of being made a test of internal fluidity, or a measure of thick- 
ness of cnist. 

I have already shown that for homogeneousness the couple due to pressure on 
the inner surface of the sliell is identical with the sun-couple upon the fluid mass 
solidified, a result ajiproxiinately true (as will be shown hereafter) if the density 
of tlie fluid strata vary. Hence, if we take the sum of the sun-couple exerted on 
a shell of interior and exterior ellipticities, e and fj, and of the pressure-couple 
developed in the fluid,^ and divide by the moment of inertia of the entire mass and 
by (J, we shall have the rate of gyration of the entire mass considered as a solid. 

Referring to Prof. Hopkins' analysis and symbolism, the quotient will be* 

(-) ^ J"^ sin 2A -^^^ ^^^ ^"^ 

a (a,) = 1 p' - da 



' The lever arm is also 2e sin x cos %. Multiply the above by this arm, by g, by the elementary 
surface rf ^ </ o, and, again, by cos b, and we get the elementary component tending to tilt the shell. 
The integral, with proper substitutions, is equivalent again to (19) or (48). 

' There is anollic:r [.rocess which may take effect in neutralizing internal pressure. I have remarked 
(last par. p. 6), that, considered as a perfectly rigid body, the precessional motions of the earth 
cannot be preciseb/ those assumed. In fact, our imperfect integrals of the conditional differential 
equaUons present the anomaly of a varied motion in which the generating force does no work ; no 
yielding to the tilting couple having place. There are necessarily some, too minute to be detected, 

nutational movements. In case the precessional force were augmented by so large a ratio as 'f 

q" — 1 
would be for a thin shell, these nutational movements would surpass in magnitude those necessary 
to generate the required counteracting pressures. 

' I use provisionally Prof. Uopkins' computations for this, involving /^ f'a'da'; its erroneous- 
ncss will appear hereafter. 

* "^hc symbols ^, a, <o, correspond to S, 9, n, of p. 7 ; p' is the density of stratum, solid or fluid, 
■•r "inch . ,s the ellipticity, and a' the polar radius ; a, is the external, and a the interna pclar 
radius of the shell. 



NEW ADDENDUM. 45 

S 
Denote the moment of inertia of the entire spheroid by /j ^ -^7ta(«.) 

" shell " /' =^7t[a(«,)-o(a)] 



Q 

nucleus " /" = _ _ 71 a (a) 



Then a (aj = - L / a (oj _ a ((()) 

and the above expression, reduced to precession, will become 

Prof Hopkins gets for the precession of tjie same spheroid considered as fluid 
witliin the shell, (his symbolic abbreviations used in both cases) 

(yi) + (72) \ ' 2" — 1/ 

In this last expression (^^i) and (^o) denote coefficients of gyration wliich one 
and the same couple (i. e. the centrifugal force, by pressure on the shell and by 
reaction on the fluid mass — the assumj^dou Icing made that the latter, having its 
proportionate force on each particle, gyrates as a solid) produce upon the shell and 
fluid mass respectively. They should be therefore inversely proportional to the 
respective moments of inertia of the shell and nucleus, rendering the expressions (.r) 
and (//) identical. 

But this apparent identity is brought about by assuming that Prof Hopkins' 
expression for the pressure-couple on the shell arising from the sun's attraction on 
the fluid to be identical (or at least approximately so) with that which would be 
exerted on the same heterogeneous fluid solidified ; by Avliicli assumption I introduce 

in {x), -J — -, Avhich is Prof. Hopkins' symbolic abbreviation of 



— ^-^- ) : instead of 
-a (a) I 



da 
<7(«i)— (7(«) '' ""''""""" t[CT(«i)a(a)] 
wliich latter expression belongs to the case just specified, of the solidified fluid. 

Now in the case of nature — /'. e. the earth with the received hypothetical laws 
of density and ellipticity, the two expressions difl'er in a ratio (about 4 : 3) so 
greatly exceeding unity, as to forbid the assumption of approximate equality. The 
error of the first expression will be better appreciated by referring to the quan- 



' The interpretation of (,r) and (ij) is obvious. P is the coefficient of precession for a homoqe- 
neous shell of uniform ellipticity f ; instead thereof let the shell be heU'rorjeneous with same internal 
surface, but of an external ellipticity t,. P for such a shell will have a fractional increment denoted 
by the ratio s. By the pressure of the internal fluid the precessional coefficient of this shell will be 

still further increased by a ratio denoted (a result of the analysis) by ^' . But the shell is con- 

cf — ] 
strained to carry along and to take up a common precession with the nucleus, and the coefficient will 

be thereby diminished in a ratio of (.r) or (according to Prof Hopkins) the corresponding ex- 
pression of (y). Since P—P^ ^, expression {a) is readily deducible from {ij). 



46 



NEW ADDENDUM. 



tities (j/,) and (7,) in (y). The brief account given, p. 43, will show how, as re- 
sulting from tlie analysis, a rotating homogeneous fluid enveloped and confined by 
a shell reacts, with a pruclical rigidity conferred by rotation, against the shell, 
(when the respective axes of rotation are slightly separated) and thereby receives 
an angular motion "precisely as if it were solid," (Phil. Trans., 1839, p. 394). It 
is clear that, through this interaction, the shell, likewise, must receive an angular 
motion, and that these several angular motions must be in inverse ratio to the 
respective movements of inertia of shell and nucleus ; and so, for homogeneous- 
ncss, the analysis makes them. AVhen we come to heterogeneousness, the same 
modus operandi is (and rightly) attributed to the fluid ; and again, most clearly, 
the relative angular motions of shell and fluid should be in above-mentioned in- 
verse ratio; whereas their ratio is quite differently computed to be — of which 

the value has just been given. The error (for there is clearly one) is in the com- 
putation of the pressure-couple developed in the fluid and exerted upon the shell 
by centrifugal force, wlien their axes of rotation are slightly separated. 

The same error of computation (exhibiting itself by the identical symbol, -^ \ 

enters into the expression for the pressure-couple developed by solar attraction, and 
introduces ofj dn the above symbol as the third term of the second factor of (?/). 

Without going into lengthy discussion, it is sufficient to remark that both tlie 
centrifugal foice and the foreign attraction produce in the strata of equal density 
of a heterogeneous fluid, sp)ecial covfiguratlons, and expend themselves in so doing; 
and, moreover, that tlie prior establishment of these forms of equilibrium is 
assumed, and necessarily assumed, in the analysis. It is, therefore, unwarrantable 
to integrate (as is done) througli the fluid mass these forces, as free forces, to get 
its pressure upon the shell. ^ 

I have shown, I think, that in the expression (?/) the first factor should be corrected 

to be, as it is in (x^, -. . 

The correction consists in substituting for ^^i^ in the fhst factor of (>/), — 

(/o) ' o (aj— ff (rt) 

instead of ~ — - [or its value, p. 45]. The same correction for - -A_ , introduced 
9 — i ?* — 1 

into the second factor, would require e I" p''," da to be substituted for the second 

o da 



term of numerator of (r). But that (r) sliould belong to entire solidity we require 

"a rfaV , '-' 

oP-j ' '^«'- ^"ow these quantities difl"er inappreciably, for taking the entire 



/; 



' It is obvious that the taking account of the internal motions by wliich the configurations pro- 
duced by foreign attraction adapt thoniselvcs to the diurnal rotation, does not meet the point made. 

' Altliough the errors in the two cases liave tlic same expression, it does not follow that the cor- 
rections should be ulenlical. The configurations of strata of like density due to foreign attraction 
are superinduced on the previously established configurations due to the centrifugal force, which 
have the varying ellipticity /. The correction should involve this ellipticity, and it is probable that 
the above symbol is, if we disregard the slight i„lenwl 7nolions, the true one. Indeed, I think I may 
venture to affirm, that, given a heterogeneous fluid wholly enveloped by a rigid bounding surface, 



NEWADDENDUM. • 47 

Q 

integrals from zero to a^ and multiplying by - - 7t, the last becomes (Thomson and 
Tait, § 825), 

2 

^ Ma^" (ej — i m) ==CS — 3(, for the earth as actually constituted. 
o 

And the first (deduced from liopkins, Phil. Trans., 1840, pp. 203 and 204), is 

(nearly) 

- Ifa^^ ei= C — A, for same spheroid with unifonn internal cUipticitics. 
o 

(il/= mass of the earth). 

[The value of the first, using the constants of density of Archdeacon Pratt, 
"Figure of the Earth," 4th ed., p. 113, is somewhat less than this last expression.] 
Now ??2 = 2 Itj (ratio of centrifugal force to gravity) and hence 2 (fj — j/h) is very 
little less than Cj. For a fluid nucleus, the inequality would be still less. 

Hence it appears that both (x) and (y) (when corrected) express very nearly 
the precession of the solidified earth; and, moreover, that tlie effect upon preces- 
sion due to the variation of internal cllipticity is very small, the precession of the 
earth considered as rigid being, essentially, that corresponding to uniform cllipticity; 
or what is the same thing, that of a homogeneous sjfheroid of its exicrncd J'orm. 

Tliis also appears in the comparison of the value of , as established from 

A 

observation, and the resulting calculated cllipticity. The first is .00327 and tlie 

second ^ir (Thomson and Tait, § 828). Now a homogeneous spheroid of the 

(J 4 

latter ellipticity would have for — ^^— a value (e — 4e-) of .00332 ; a difference 

of about Jg. Variations in the constants which enter into the expressions for 
internal density give rise to variations in the calculated ellipticity — and, of course, 
in the resulting precession ; but if the external cllipticity is defined by a rigid shell, 
the effect of internal variation is, in the case in liand, almost nil. Hence, had 
the hypothetical consolidation of the earth, of p. 43, been carried to tlie very 
centre, no material approximation to the desired correction of ^ in the calculated 
precession would have been found. ^ In fact, the problem for heterogencousness 

subjected to a foreign attraction, and a condition of static equilibrium assumed, tlie pressure-couple 
exerted by the fluid on the shell cannot difler from that which the attraction would exert on the 
solidified fluid. 

In the case of homogeneousncss, I have arrived (p. 43: the results, though based on an cllipticity 
corresponding to fluid equilibrium, hold good for any sntall ellipticity) at the exact expression for the 
pressure-couple, from the function expressing the tidal protuberance due to the foreign attraction. 
The tidal conflguration of the heterogeneous earth, wholly liquefied, would result from the transcen- 
dental analysis of Hopkins, pp. 203, 204, or of Thomson and Tait, § 822-824, and the maximum 
height would be one foot, very nearly; but the pressure function cannot be readily deduced. It 
would depend on gravity and [§ 825] "the value of C — A may be determined solely from a 
knowledge of surface or external gravity, or from the figure of the sea level without any data regard- 
ing the internal distribution of density." 

* It is curious, to say the least, that there should be ground for the remark that the expressions (a) 

C 1 ( s ) 

and (y), which latter, with its author's valuation of -'' , raav be writcn -J ^ "f" h ( P, g'^e 



48 



NEW ADDENDUM. 



•was i)ractically solved under Prof. Hopkins' treatment of it when it was shown 
that for lioinoo-eneousncss, the precession for internal fluidity was the same as for 
solidity, and when it appeared that the analysis applied would exhibit the action 
of the hctero"-cncous fluid as if disposed in strata of like cUipticity with that of the 
inner shell surface. The erroneous computation of pressures has merely the effect 
of exaggerating in a like ratio the densities of all the fluid strata. Hence, and 
hence only, a resulting precession differing materially from that which would result 
from solidity. 

In conclusion, I remark, 1st. The analysis of Prof. Hopkins, in its application 
to a homogeneous fluid and shell, seems to establish (and the result is confirmed 
by its harmony with tidal phenomena as developed in p. 43) that the rotation im- 
parts to tlie fliiiil a 2rrac(lcal rigidity' by which it reacts upon the shell as if it were 

with decreasing internal ellipticities, for fluidity of nucleus less precession than would belong to soli- 

7 T" 

dilij. This is obvious since his .— — is greater than the ratio — ,- (nearly) which should take its place 
on the latter hypothesis. ^ 

' I do not concur with Sir "William Thomson in the opinions quoted in note, p. 38, from Thomson 
and Tait, and expressed in his letter to Mr. G. Poulett Scrope ("Nature," February 1st, IST'i), so 
far as regards fluidity, or imperfect rigidity, within an infinitely rigid envelope. I do not think the 
rate of precession would be affected. 

That no increase arises from fluidity I have endeavored to show ; and it is unquestionably a 
corollary of Prof Hopkins' investigations. As regards imperfect rigidity, Sir William Thomson 
bases his argument upon the assumption that "the whole would not rotate as a rigid body round 
one ' instantaneous axis' at each instant, but the rotation would take place internally, round axes 
deviating from the a.xes of external figure, by angles to be measured in the plane through it and the 
line prrpcndicular to the ecliptic in the direction towards the latter line. These angular deviations 
would be greater and greater the more near we come to the earth's centre. ***** Hence the 
moment of momentum round the solsticial line would be sensibly less than if the whole mass rotated 
round the axis of figure." 

If I do not misunderstand his language, Sir William Thomson assumes that the same bending 
distortion which would ensue from the application of a couple to the external portions of a non- 
rotating spheroid, would, equally and idenlically, take place in a rotating one : thus causing the 
angle made by the planes of the external rings of matter and the solsticial line to be increased ; 
with a corresponding diminution of the component of Cn about this line. 

In the case specified by him (an extreme one) while sensible and important nutational movements 
would ensue, the mean ^ij-ecessj'on would be insensibly affected ; but I do not think precisely swc^ 
clastic yielding would take place. 

As an extreiye case of an infinitely rigid and infinitely thin shell containing matter completely 
destitute of rigidity, take the fluid spheroid of p. 36, and conceive it enveloped by such a shell. It 
is still, as shown, p. 43, susceptible (and susceptible only) of the extremely minute deflections of 
its planes of rotation by which precession is completely annihilated. Confer now upon the con- 
tents of the shell rigidity, uniform, or varying from surface to centre, continuously or discontinu- 
ously, in any arbitrary manner, and you have every possible case of imperfectly rigid matter con- 
tained within a perfectly rigid crust. I can attribute no other efi"ect to the conferred rigidity than 
a restoration of llio lost precession — in whole or in part ; nor can I suppose the shell enveloping 
imperfectly rigid matter to change its obliquity more than that which contains the fluid ; regard 
being had to conditions of equilibrium without reference to living forces generated. 

I must remark that this hypothetical case, though as admissible for argument as any other form 
of " preternaturally rigid" crust, is exceptional. With a shell of finite moment of inertia, having 
some comparable relation to that of the fluid contents, the precession, instead of being annihilated, 
would be that due to the entire mass 



NEWADDEXDUM. 49 

a solid mass, while its pressure imparts to the shell the requisite couple to preserve 
the precession unchanged. 

2d. The same practical rigidity is, with entire reason, attributed to the heteroge- 
neous fluid by which (leaving out of view minute relative oscillations wliich do not 
affect the mean resultant in other natural phenomena and should not in this) tlic 
shell and fluid take a common precession. 

3d. The two masses retaining their configurations, mutual relations, and rotary 
velocities, essentially unaltered by the hypothesis of internal fluidity, it would be 
a violation of fundamental mechanical principles were the resulting precession not 
identical with that due to the entire mass considered as solid, 

4th. The common and identical precession of fluid and shell resulting from the 
analysis, is indispensable to any conception of precession for the eartli as composed 
of thin shell and fluid ; for otherwise internal equilibrium would be destroyed and 
the " figure of the earth" cease to have any assignable expression. The entire 
mass, fluid and solid must (without invoking the aid of "viscosity"), be "carried 
along in the precessional motion of the earth." The analysis I have e.\amined de- 
monstrates the possibility and exhibits the ratlonule of such a conununity of pre- 
cession, but fails in the attempt to exhibit a test of the existence or absence of 
internal fluidity. 

5th. The powerful pressures that would be exerted upon a tidn and rigid shell 
would probably produce in it noticeable nutational movements;' while if the shell 
be not of a rigidity far surpassing that of the constituents of the cognizable crust, 
the " precessional motion of the earth" would, owing to the neutralizing effect of 
tidal protuberances, scarcely be observable. 

' Vide p. 44, and note 2: without reference to conventional "Xutation" wliicli is but a form of 
precession. In connection with these relative motions of shell and fluid, it is in jdace to allude to 
the " Yindication of Mr. Hopkins' method against the strictures of M. Delaunay," by the late 
Archdeacon Pratt (" Figure of the Earth," 4th ed., p. 132). He reasons, that, if at any moment, 
the crust and fluid be arranged as to density, " exactly as if they had been hitherto one solid mass 
and be moving alike, this state cannot possibly continue." For the shell will be acted upon not 
only by the foreign attraction but by the fluid pressure, and will " begin to move quicker," with a 
precession due to both the thence arising couples. That this should not occur requires, he esti- 
mates, the counteracting centrifugal force of a tidal protuberance, in a crust supposed 100 miles 
thick, of seventy -four feet. 

The writer does not seem to be aware that the author whom he vindicates finds no such relative 
acceleration of the shell {vide p. 44, § 2, of this Addendum) as resulting from the pressure; and, 
strangely, for an authority on the " Figure of the Earth," fails to recognize that "an elevation of 
the outer surface of the crust" — that is a -tidal distortion — of a single fool, would relieve the shell 
from all pressure. This is, perhaps, a natural result of the use of au expression (Prof. Hopkins') 
for the pressure which disregards the influence of "Figure." 



March, 1873, 



^ ADDENDUM. 



ADDENDUM TO NOTE I, Page 38. 

The apparent antasonisra between the theorem of the text and that of Laplace sug-gests a few 
additional words. The theorem of Laplace is that " in whatever manner the waters of the ocean 
act upon the earth, either by their attraction, their pressure, their friction, or by the various resist- 
ances which tiiey suffer, they communicate to the axis of the earth a motion which is i-en/ nearbj 
equal to that it would aciiuire from the action of the sun and moon upon the sea, if it form a solid 
mass with the earth." (Mec. Cel, Bowditch [3345].) 

The theorem i.s demonstrated in two distinct, quite different, manners. The last demonstration is 
founded ui>on the principle of the " conservation of areas;" and as the result of this dcmoustration 
the proposition is stated in the above quoted words. 

The first demonstration is purely analytical, and, after stating that " this fluid" (i. e. of the ocean) 
"acts upon the terrestrial spheroid by its pressure and by its attraction," Laplace proceeds to find 
the analytical expressions for the precession and nntation-producing couples due to this pressure and 
to this attraction as they are modified by the attraction of the sun and moon upon the fluid. He 
then proceeds to calculate these couples for the material substance of the ocean, considered as rigidly 
connected (or forming a solid mass) with the earth. He finds the couples, so calculated, respectively, 
identical in the two cases, and epitomizes the result as follows : " the phenomena of the precession 
of the equinoxes and the nutation of the earth's axis are exactly the same as if the sea form a solid 
mass with the spheroid which it covers." [32S'7.]I 

But this demonstration is limited by the assumption that " the sea ■niiollj' covers the terrestrial 
spheroid or nucleus, that is of a regular depth, and suffers no resistance from the nucleus;" and bulh 
demonstrations imply an ocean of (relatively) small depth. 

Under the last motlioned treatment of the subject the proposition of Laplace and that which I 
demonstrate are but the extreme phases exhibited by the solution of a problem, according as the 
datum be that the depth of the sea is minute (in which case its entire precession-producing couple, 
not effectively exerted upon its own mass, is almost wholly transferred to the solid nucleus) ; or 
that the nucleus is very small, in which case the lost precession-producing couple of the fluid is but 
in small part transferred to the nucleus — or wholly disappears with the vanishing of the latter. 

I think, however, that the last-mentioned (first in point of order) demonstration of Laplace is not 
as general as the language quoted [3287] would indicate. The omission of variations of the radius- 
vector, 11, in all the integrations gives rise to errors which do not seem to me to be identical in the 
two processes by which the couples are calculated, when the variation of depth is very small. 

An apt illustration of the above remarks is derived from the supposition— as admissible as any 
other— that, the depth, y, is constant. In this case, whatever he the ellipticily of the solid nucleus, 
the value of y (the height of the diurnal or precession-affecting tide, see [2253] [3333] and also p. 36) 
is zero, and, of course, the couples [3272] and [3273] become zero— as will be found by performing 
the integrations in those equations. So, of course, do expressions [3284] and [3285] become zero, 
with V made constant. But these last should not be zero except for the case of sphericity of the 
nucleus." The expressions do, not seem to me capable of sustaining the inference which I have 
quoted [3287], when the depth of the sea is uniform; a case which most naturally presents itself to 
the mind. 



' A sl.oll of slight internal ellipticity and small uniform thickness has a precessional coefficient of fonr-fifths the 
va „e o that o a shell ho.nuled hy suvfaces of equal ellipticity. Hence in general the variations oi R (or the 
elhpticilyj pioduce elfects inseusihle compared to those of the depth. 



ADDITION AL NOTES. 51 

Mr. Aii-y (Tides ami Waves, Art. 127) base.s his demonstration of the theorem exclusive!}' upon 
the priiiciiile of the conservation of areas, remarking at the outset, " if the earth and sea were so 
entirely disconnected that one of them could revolve for any length of time with any velocity, in- 
creasing or diminishing in any manner, while the other could revolve with any other velocity changing 
in any other manner, we could pronounce nothing as to the effect of the fluctuation" (tidal) " upon 
precession." 

A spheroidal nucleus wholly covered by an ocean of uniform depth, suffering no resistance, docs 
not seem to me to lack much for fulfilling the above conditions. 

If velocities are generated in the waters of the ocean by solar (or lunar) attraction, the centrifugal 
forces due to them might be looked to (though not alluded to by Lajilace) as agents for transferring, 
from the fluid to the nucleus, the precession-producing couples due to the fluid mass, especially in 
the above hypothetical case. It will be found, however, by reference to the expressions [2200], 
that they give rise to no oouple, and are, moreover, very minute. 

The motion which the displacements [22G0] [22G1] indicate is a slight oscillation of the axis of 
the fluid envelope, moving as a solid, about the axis of the nucleus, the angular distance between 
these axes being slightly less than 2 seconds: it is, I presume, that which a non-rotating shell would 
have were the attracting body, with constant distance and declination, to move, with angular velocity 
M, in right ascension. In the case in hand it is the fluid shell which revolves and, suffering no 
change of form, would be itself affected )jy its proper processional couple to the excluaiou of the 
oscillation above described. 



ADDITIONAL NOTES. 



Note to page 11. 
'" The process indicated is a more legitimate carrying out of the methods peculiar to this paper 
than what follows in the text. The tangent of MM' (35) may be (approx.) taken for the sine, and the 
cosine taken constant at unity, as may also be the cos /'. 

From (32) we may calculate by developing and neglecting terms in which sin' 7' enters 
sin i = (1 — cos' i)< = sin / — sin I' cos / cos nj 
sin i cos i = sin /cos I — sin /' cosSZcos nj — A sin'/' s\n2r cos'n^t 
Introducing these values in (38) and (30), and integrating wo get expressions identical with 44 
and 45, except a (practically) immaterial difference in the coefficient of I in the first which becomes 
1 — ^ sin'/' instead of 1 — f sin'/'. 

Note to page 24. 

"' The foregoing interpretation of the symbolic integral in (T), adopted with hesitation from 
authors cited, is based on assumed constancy of the angle <f. ; but this angle necessarily varies, 
slowly indeed, but progressively, by the azimuthal motion measured by n sin x. The conditions for 
the formation of a leminiscate are not, therefore, rigidly fulfilled. It will be found, however, taking 
into account a complete excursion, that the slight increment which will enure to the moment of the 

quantity of motion, sin's -?., from this cause on one side of the vertical, will be neutralized on the 

at 

other, in consequence of the opposing signs of cos 4>, in opposite azimuths; or, at least, the rrsullaiit 

increment or decrement will ba a quantity of the second order in minuteness, and hence, affecting 

only in the same degree the azimuthal motion -~. 

dt 

Note to page 39. 
'" The differential attraction of the sun on any length dx of the rod, at distance ;;; from the earth's 

/ S S \ 

centre is ( ^^ 1 dx, r being sun's distance. Integrate from x = x^o x^=R 'the earth's 

U'' — *) 1 ' 

radius). 



52 ADDITIONAL NOTES. 

(1) s/_i A L^ + a) 

^^^ . [r—Ji r' r — xr'l 

The above divitUd liy tlie cooflicicnt of da.stieity E will give tbc elongation per unit of length at 
any point. Multiply by dx anil integrate from ;t = to ;t = ^, and the total elongatioa is 

E Xr — R 2r' ^ '^ \ r h 

R I R" 1 R' 



lo.r (i _] ^^ ^L 1-"^ &c., the foregoing will reduce, approximately to 

° V r / r 2 /■••' 3 r'' 



Since 

2 STT 

3 E r^' 

If ^1/"= earth's mass, <7 = gravity at its surface, and - the ratio of 71/ to S, and m the ratio of 

length of rod of weight E dicr sipmre inch .section) to R, we shall have : H = ncjE', E=:mgR, and 
the above expression for total elongation becomes: 

(2) l^R^ 

Take ."^ =_- ^^^^^ - = -A^ ■ i;^4000 X 5280 feet; ?? =310000: m = .4T2 (the latter value 
r 92000000 23000 

based on E = Z^ niiirns lbs. per square inch, and a steel rod of that section to weigh 3.4 lbs. per foot 

length) and the total elongation (2) becomes 0^'.975. The maximum extension per unit of length is 

S R'' n R' 

at the centre, and is found by putting x = (> in (') fi"d dividing by E. It is = = 

E r' m r^ 

.000000055, indicating a strain of 1".87 per square inch. The ratio of the total elongation (2) to 

the total length of the rod R is two-thirds of the above, indicating about that ratio for the ellipticities 

of superficial and central strata of a steel globe distorted by the sun's attraction ; a result thus rudely 

calculated which differs little from that given in Thomson and Tait, § 837. 



SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE. 

241 ^ 



A CONTRIBUTION 



HISTORY OF THE FRESH-WATER klGM 



NORTH AMERICA. 



BY 

HORATTO C. WOOD, Jr., M.D., 

PBOFESSOR OF BOTANY, AND CLINICAL LECTDRER ON DISEASES OF THE NERVOUS SYSTEM IN THE 
DNIVERSITY OF PENNSYLVANIA; PHYSICIAN TO TUE PHILADELPHIA HOSPITAL, ETC. 



[accepted for publication, PEBr.UARY, 1S72.J 



ADVERTISEMENT. 



The following memoir was referred for examination to Dr. John Torroy and Dr. 
F. A. P. Barnard, of Columbia College, New York. They recommended its pub- 
lication provided certain changes were made in the manuscript. These having 
been made by the author, the work is published as a part of the series of " Smith- 
sonian Contributions to Knowledge." 

JOSEPH HENRY, 

Secretary, S. I. 
Washington, October, 18'i2. 



(iii) 



PREFACE. 



Of all the various branches of Natural History, none has been more enthusias- 
tically and more successfully prosecuted in the United States than Botany. The 
whole field has been most thoroughly occupied, save only as regards certain of the 
lower cryptogams, and amongst the latter, it is the fresh-water Algre Avhich alone 
can be said to have been almost totally neglected. In this fact lies my apology for 
offering to the scientific public the following memoir. 

In doing this, so far from thinking that the work contains no error, I hasten to 
disarm criticism, and to ask with solicitude for a favorable reception, in view 
of the difficulties of the investigation, which I have conducted alone, and almost 
unaided. 

The investigation was first undertaken in connection with my elementary studies 
of Materia Medica and Therapeutics, and has since been prosecuted at intervals 
amidst the distractions of medical teachings and practice, and in some cases Avith- 
out immediate access to authorities. The field covered is so wide that it is almost 
impossible to exhaust it, and, if it were not for rapidly increasing professional 
engagements, I would gladly devote more time to the subject ; but, as it is, I must 
leave to others to carry on the work thus begun. 

While saying this, it is but just to state that nothing here published has been 
done hastily, but that all is the result of arduous and conscientious investigation. 

A very large part of my material has been of my oAvn gathering, and was 
studied whilst fresh; but I am indebted to several persons fol' aid by collections. 

First of all, I desire to offer my thanks to Dr. J. S. Billings, U. S. A., and to 
Professor Kavencl, of South Carolina; to the former for assistance in various 
ways, and for collections made nrar AVashington City ; to the latter for very large 
collections made in Texas, South Carolina, and Georgia. I am also indebted to 
Mr. C. F. Austin for a large collection gathered in Northern New Jersey, to Mr. 
William Canby for some beautiful specimens obtained in Florida, to Professor 
Sereno Watson for Rocky Mountain plants, and to Dr. Frank Lewis for a number 
of White Mountain desmids. 

These various collections were partly dried and partly preserved in a watery 
solution of carbolic acid or of acetate of alumina, both of which I have found more 
or less satisfactory preservatives. 

The present investigations embrace all families of the fresh-water algae except 
the Diatomacece, which, as every one knows, are so numerous as to constitute in 

(V) 



yJ P 11 e p a c e . 

tlicnisolvcs a spocial study. As I liavc paid no attention to these plants, they are 
of course not included in this memoir. 

In the synonymy I have generally followed Trof. llabenhorst. The original de- 
scriptions of tlie forms, especially those of the older authorities, are very frequently 
so meagre and obscure, that the species cannot be recognized by them Avith any cer- 
tainty. VroL Rabenhorst has gone over the ground most carefully, with access to 
the whole literature of the subject <and probably to all extant type specimens, and his 
decisions are, no doubt, as accurate as the circumstances will allow. To attempt to 
diifcr from them, to go behind his work to the original sources and make fresh 
interpretations, would cause endless confusion. I have, therefore, nearly always 
contented myself with his diclum, and have referred to him as the authority for the 
names used. 

The following references were omitted through a misunderstanding from the first 

portion of the text. 

Page 14. Ciil<t!<pha:Tium duhium, Grunnow. Rabeniiorst, Flora Europ. Algarum, Sect. I. p. 55. 

" 15. Mei-ixmopedia convolula, Brebisson. Rabe-NDORST, Flora iJurop. Algarum, Sect. I. p. 58. 

" 18. OsciUaria chlorina, KIjtzing. Rabenhorst, Flora Europ. Algarum, Sect. I. p. 97. 

" 18. 0. Frohlichii, Kutzing. Rabeniiobst, Flora Europ. Algarum, Sect. I. p. 109. 

" 19. 0. nigra, Vauciier. Rabenhorst, Flora Europ. Algarum, Sect. I. p. lOt. 

" 19. 0. limosa, Agaruh. Rabenhorst, Flora Europ. Algarum, Sect. I. p. 104. 

" 21. Chthonoblastus repens, Kutzing. Rabenhorst, Flora Europ. Algarum, Sect. I. p. 1.32. 

" 22. Lyiujhija muralis, Agardh. Harvey, Nereis Boreali- Americana, pt. III. p. 104. 

In tlie text after the "■Habitat,'" a name is quoted as the authority therefor; if 
such a name be in brackets, it signifies that the specimens were simply collected by 
such individual, but that the identification was made by some one else ; when there 
is not a name unuidoscd in brackets, it is meant that the identification was made by 
the author of this memoir. 



Since the present memoir has gone to press, I have received from the author a 
copy of " Alg;t! Khodiacese. A list of Rhode Island Alg?e, collected and prepared 
by Stcplien T. Olney, in the years 184:6-1848, now distributed ixoin his own her- 
barium." 

In the introduction to this list, Mr. Olney says: "Of the fresh-water species, I 
have few for distribution. These were obtained mainly in the environs of this 
city, and were placed in twenty-seven small vials in Goadsby's solution, and sent 
to Prof Harvey, who submitted them to the judgment of the most learned Eng- 
lish botanist in this particular department, G. H. K. Thwaites, Esq., then of Bris- 
tol, England. The large number of species found in this collection, in so limited 
a range, and collected within a very short period, is surprising, and shows what 
moie persistent collections will develop. I have not time to collate the numerous 
pubUcations of the lamented Prof. Bailey, or I might have made the list of this 
portion of Rhode Island plants more complete." 

The chlorosperms of this list are as follows: — 
Porphyra vulgaris, Ag.-IIarv. Ner Bor. Am. 3. 5.3. Newport 
Bangiafuscopurpurea, Lyngb.-Harv. Ner. Bor. Am. 3. 54. Southern Rhode Island. 



rilEFACE. yij 

Enleromorpha inteslinalis, Lyngb.-IIarv. Ncr. Bor^ Am. 3. 50. Providence to Newport. 

Enleroinorpha coiKprfssa, Grev.-Harv. Ner. Bor. Am. 3. 50. Southern Rhode Island. 

Enteroinorpha olathrala, Grev.-IIaev. Ner. Bor. Am. 3. 50. Newport. 

Ulva lalissima, L.-IIarv. Ner. Bor. Am. 3. 59. Providence. 

Ulva lactuca, L.-Harv. Ner. Bor. Am. 3. GO. Providence. 

TelraHporalacunosa, Cn&.w. -YLary. Ner. Bor. Am. 3. 61. T. perforata, Hwi^EX M.is,. Providence. 

Telraspora lubrica, Aa. Providence. 

Batrachosperinum pulcherrinium, Hass. Providence. 

Balrachospermum moniliforme, Roth.-IIarv. Ner. Bor. Am. 3. 03. Providence. 

Ghaelophora endivaefolia, Ag.-Harv. Ner. Bor. Am. 3. 09. Providence. 

Draparnldia glomerata, Ag.-Harv. Ner. Bor. Am. 3. 72. Providence. 

Stigeoclonium minutum, KiJTZ. Providence. 

Cladoplwra riqxstris, L.-Harv. Ner. Bor. Am. 3. 74. Newport. 

Cladophora (jlaucescens, Griff.-Harv. Ner. Bor. Am. 3. 77. Rhode Island. 

Cladoplwra refracta, Roth.-Harv. Ner. Bor. Am. 3 79. Southern Rhode Island. 

CJadopihora Rudolphiana, Ag.-Harv. Ner. Bor. Am. 3. 80. Providence. 

Cladopjhora gracilis, Griff.-Harv. Ner. Bor. Am. 3. 81. Little Conipton. 

Cladophora fracla, Harv. Ner. Bor. Am. 3. 82. Rhode Island, Bailey. 

Chselomorpha serea, Dillw.-IIar. Ner. Bor. Am. 3. 86. Newport, etc. 

Chaetomorpha Olneyi, Harv. Ner. Bor. Am. 3. 86. Little Compton. 

Chselomorpha longiarliculata, Harv. Ner. Bor. Am. 3. 86. Little Compton. 

var. crassior, Harv. Ner. Bor. Am. 3. 86. Little Compton. 
Chaetomorpha sutoria, Berk.-Harv. Ner. Bor. Am. 3. 87. Newport. 
Zijgnema mal/ormatum, Hass. 1. 147. Providence. 
Zi/gnema catenaeforme, Uass. 1. 147. Providence. 

Zi/gnema Thwaitesii, Olney, n. s. Near Z subvenlricosum, Providence. 
Zygnema longalum, Hass. 1. 151. Providence. 

Zj/gnema striata, Olney, n. s. " Colls evidently striated," Tliwaites. Providence. 
Tyndaridea bicornis ? Hass. 1. 102. Providence. 
Tyndaridea insignis? Hass. 1. 103. Providence. 
Mesocarpus parvulus, Hass. 1. 109. Providence. 
Mougcolia genujlexa, Ag.-Hass. 1. 173. Providence. 
Vesicidiferaconcalenata, "B-Ass. 1.201. Providence. 
Vesiculifera aequalis, Hass. 1. 205. Providence. 
Vesicidi/era bombycina, Hass. 1. 208. Providence. 
Vesiculifera Candollii, Hass. 1. 208. Providence. 
Bulbochaete Tliwaitesii, Oi,ni.y, n. s. Providence. 
Lyngbya majuscula, Harv. Bor. Am. 3. 101. Providence. 
Sphaeroplea virescens, Berk. Providence. 
Sphaeroplea puncialis, Berk. Providence. 
Tolypothrix distorta, Kutz.-Hass. 1. 240. 

Calothrix confervicola, Ag -Harv. Ncr. Bor. Am. 3. 105. Providence. 
Calothrix scopulorum, Ag.-Harv. Ner. Bor. Am. 3. 105. Providence. 
Hyalotheca dissiliens, Brev.-Ralfs. De.s. 51. {Glocopirium.) Providence. 
Hyalotheca mucosa, Eiirh.-Ralfs. Des. 53. Providence. 
Didymoprium Grevillii, Kijtz.-Ralfs. Des. 61. Rhode Island, Bailey. 
Didymoprium Borreri, Ralfs. Des. 58. Rhode Island, Bailey. 
Desmidium. Swarizii, Aq.-Rai,ys. Des. 61. Throuf,'hout United States, Bailey. 
Aptogonum Baileyi, Ralfs Des 209. Worden's Pond, Rhode Ishxnd, Bailey. 
Micrasteiias rotata, Ralfs. Des. 71. Providence. 
Micrasterias radiosa, Ag. -Ralfs. Des. 72. Maine to Virginia, Bailey. 
Micrasterias furcala, Ralfs. Des. 73. Worden's Pond, Rhode Island, Bailey. 
Micrasterias Crux-Melilensis, Ralfs. Des. 73. Maine to Virginia, Bailey. 
Micrasterias truncata, Vi'RS.\i.-\'<.\\.vs. Des. 75. United States, Bailey. 



Viii PREFACE. 

Micrasteriasfoliacea, Bailey-Ualf& Desm. 210. Wordcn's ro.id, Rhode Island, Bailey. 

Miaraslerias Bayleyi, Ralfs. Desm. 211. Rliode Island, Bailey. 

Euadrum obloiigum, Ralfs. Des. 80. Rhode Island, Bailey. 

Euadrum crasmm, Kutz.-Ralfs. Des. 81. Rhode Island, Bailey. 

Euastrum ansatum, Eiirh.-Ralfs. Des. 85. E. hlnale Kntz. I'rovidence. 

Euastrum elegans, Kutz.-Ralfs. Des. 89. Providence. 

Euastrum binale, Ralfs. Desm. 91. Providence. 

Gosmarium cucumis. Corda.-Ralfs. Desm. 93. United States, Bailey 

Cosmarium Uocidatum, Ralfs. Des. 95. Providence. 

Gosmarium 3IenegJnnu, Breb. -Ralfs. Des. 90. United States, Bailey. 

Gosmarium crcnalum, Ralfs. Des. 96. Providence. 

Gosmarium amcenum, Breb. -Ralfs. Des. 102. Providence. 

Gosmarium or natum, RAhTS. Des. 104. Providence. 

Gosmarium connalum,BREii.-'RAhFS. Des. 108. Providence. 

Cosmarium Gucurhita, Ralfs. Dos. 109. Providence. 

Gosmarium grandituhcrculatum, Olney, n. s. ; "near G. cucumis, but with largo tubercles on the 

frond." Providence. 
Staurast7-um orbiculare, Ralfs. Des. 125. Providence. 
Slauraslrum hirsutum, Ualfs. Des. 127. Providence. 
Slaurastrum Eyslrix, llALFS. Des. 128. Providence. 
Slaurastrum gracile, Ralfs. Des. 136. Providence. 
Slaurastrum telracerum, Ralfs. Des. 137. United States, Bailey. 
HloMraslrum cyrtoceruyn, Rrf.b.-Ralfb. Des. 139. Providence. 
Tetmemoras Brebissoni, Ralfs. Des. 145. Providence. 
Tetmemoras granulalus, Ralfs. Des. 14G. Providence. 
Penium margarilaceum, ljnETi.-l\iS.LFS. Des. {Glosterium Eur.) Providence. 
Penium Digitus, Breb.-Ralfs. Des. 151. (Closlei-ium lamellosum.) 
Docidium nodulosum, Breb.-Ralfs. Des. 155. Maine to Virginia, Bailey. 
Docidium Baculum, Breb.-Ralfs. Des. 158. United States. Bailey. 
Docidium nodosum, Bailey-Ralfs. Des. 218. United States, Bailey. 
Docidium constridum, Bailey-Ralfs Des. 218 Worden's Pond, Bailey. 
Docidium verrucosum, Bailey-Ralfs. Des. 218. Rhode Island, Bailey. 
Docidium verticillatum, Bailey-Ralfs. Des. 218. Worden's Pond, Bailey. 
Glosterium Lvnula, EnRH.-RALFs. Des. 163. New England, Baijey. 
Glosterium moniliferum, Ehrii. -Ralfs. Des. 163. New England, Bailey. 
Glosteriiem striolatum, Eiirh. -Ralfs. Des. 173. New England, Bailey. 
CZos^enwm CM.sjrtda/in)!, Bailey-Ralfs. Des. 219. Worden's Pond, Bailey. 
Pediastrum tetras, Ralfs. Des. 182. New England, Bailey. 
Pediaslruvi heplactis, Ralfs. Des. 183. Providence. 

Pediastrum Boryanum, Menegh.-Ralfs. Des. 187. Maine to Mexico, Bailey. 
Pediastrum ellipticiim, ETass. -Ralfs. Des. 188. Maine to Virginia, Bailey 
Scencdcsmus quadricauda, Breb.-Ralfs. Des. 190. Maine to Virginia, Bailey. 
Scenedesvms obtusus, Meyen. -Ralfs. Des. 193. Maine to Virginia, Bailey. 



INTRODUCTION. 



Although beset with difficulties in the outset, no branch of natural science 
offers more attractions, when once the study is fairly entered upon, than the fresh- 
water alga;. The enthusiasm of the student will soon be kindled by the variety 
and beauty of their forms and wonderful life processes, and be kept alive by their 
abundance and accessibility at all seasons of the year ; for unlike other plants, the 
winter with them is not a period of counterfeited death, but all seasons, spring, 
summer, autumn, and winter alike, have their own peculiar species. They have 
been found in healthy life in the middle of an icicle, and in the heated waters of 
the boiling spring ; they are the last of life alike in the eternal snow of the moun- 
tain summit and the superheated basin of the lowland geyser. 

In their investigation, too, the physiologist can come nearer than in almost any 
other study to life in its simplest forms, Avatching its processes, measuring its forces, 
and approximating to its mysteries. Sometimes, when my microscope has revealed 
a new world of restless activity and beauty, and some scene of especial interest, as 
the impregnation of an oedogouinm, has presented itself to me, I confess the 
enthusiastic pleasure produced has been tempered with a feeling of awe. 

To any on whom through the want of a definite pursuit the hours hang heavy, 
to the physiologist who desires to know cell-life, to any student of nature, I can 
commend most heartily this study as one well wortliy of any pains that may be 
spent on it. 

An aquarium will often, in the winter time, give origin to numerous interesting 
forms, but it is not a necessity to the fresh-water algologist; besides his microscope 
and its appliances, all that he absolutely needs is a few glass jars or bottles and 
the fields and meadows of his neighborhood. 

The great drawback to the investigation of these plants has been the want of 
accessible books upon them. In the English language tliere is no general work 
of value, and the various original memoirs arc separated so ftir and wide in the 
Continental and English journals, as to be of but little use to most American 
readers. The Flora Ei(rop<Tum AJcjarnm Aqiiw Dulcis et Stih)narma\ of Prof Ka- 
benhorst, has done much to facilitate the study, and its cheapness brings it within 
the reach of all. It merely gives, however, brief diagnoses of the various species, 
but with the present memoir will, I trust, suffice for the American student, at least 
until he is very far advanced in his researches, 

1 November, 1871. / 1 ^ 



2 INTRODUCTION. 

A certain amount of experience and knowledge of the subject greatly facilitates 
the collection of these plants, but scarcely so much as in other departments of cryp- 
togamic botany, since most of the species are so small that the most experienced 
algulogist docs not know how great the reward of the day's toil may be until he 
pkices its results nud(!r the object glass of his compound microscope. In order to aid 
those desirous of collecting and studying these plants, I do not think I can do 
better than give the following hints as to when and where to find, and how to 
preserve them. 

There are three or four distinct classes of localities, in each of which a different 
set of forms may be looked for. These arc : stagnant ditches and pools ; springs, 
rivulets, large rivers, and other bodies of pure water ; dripping rocks in ravines, 
Sec. ; trunks of old trees, boards, branches and twigs of living trees, and other 
localities. 

In regard to the first — stagnant waters — in these the most conspicuous forms 
arc oscillatoriaj and zygnemaceae. The oscillatorite may almost always be recog- 
nized at once, by their forming dense, slimy strata, floating or attached, gene- 
rally with very fine rays extending from the mass like a long, delicate fringe. 
The stratum is rarely of a bright green color, but is mostly dark ; dull greenish, 
blackish, purplish, blue, &c. The oscillatoria; arc equally valuable as specimens 
at all times and seasons, as their fruit is not known, and the characters defining 
the species do not depend ixpon the sexual organs. The zygnemas are the bright 
green, evidently filamentous, slimy masses, which float on ditches, or lie in them, 
entangled amongst the Avater plants, sticks, twigs, &c. They are only of scientific 
value when in fruit, as it is only at such times that they can be determined. 
Excepting in the case of one or two very large forms, it is impossible to tell with 
the naked eye with certainty Avhether a zygnema is in fruit or not; but there are 
one or two practical points, the remembrance of which will very greatly enhance 
the probable yield of an afternoon's search. In the first place, the fruiting season 
is in the spring and early summer, the latter part of March, May, and June being 
tlie months when the collector will be best repaid for looking for this family. 
Again, when these plants are fruiting they lose their bright green color and become 
dingy, often yellowish and very dirty looking — just such specimens as the tyro 
would pass by. The fine, bright, green, handsome masses of these algse are rarely 
worth carrying home. After all, however, much must be left to chance; the best 
way is to gather small quantities from numerous localities, keeping them separate 
until they can be examined. 

Adhering to the various larger plants, to floating matters, twigs, stones, &c., in 
ditches, will often be found filamentous algtc, which make fine filmy fi-inges around 
the stems, or on the edges of the leaves; or perchance one may meet with rivulariae 
or nostocs, &c., forming little green or brownish balls, or indefinite protuberances 
attached to small stems and leaves. These latter forms are to be looked for 
especially late in the season, and whenever seen should be secured. 

In the latter part of summer, there is often a brownish, gelatinous scum to be 
seen floating on ditches. Portions of this should be preserved, as it frequently con- 
tains interesting nostocs and other plants. 



INTRODUCTION. 3 

In regard to large rivers, the time of year in which I have been most successful 
in such localities is tlic latter summer months. Sj_>rin(jfi and small bodies of clear 
water may be searched with a hope of reward at any time of the year when 
they are not actually frozen up. I have found some exceedingly beautiful and 
rare algre in such places as early as March, and in open seasons they may be col- 
lected even earlier than this. The desmids are most abundant in the spring, and 
possibly most beautiful then. They, however, rarely conjugate at that time, and 
the most valuable specimens are therefore to be obtained later — during the summer 
and autumn months ; at least, so it is said; and the experience I lu^ve had with this 
family seems to confirm it. Rivulets should be watched especially in early spring, 
and during the summer months. 

From the time when the weather first grows cool in the autumn, on until the cold 
weather has fairly set in, and the reign of ice and snow commences, is the period 
during which the algae hunter should search carefully all wet, dripping rods, for 
specimens. Amongst the stems of wet mosses — in dark, damp crevices, and little 
grottos beneath shelving rocks — is the algse harvest to be reaped at this season. 
Nostocs, palmellas, conjugating desmids, sirosiphons, various unicellular alga^, then 
flourish in such localities. My experience lias been, that late in the autumn, 
ravines, railroad cuttings, rocky river-banks, ifcc, reward time and labor better tlian 
any other localities. 

The vaucherias, which grow frequently on wet ground, as well as submerged, 
fruit in the early spring and summer in this latitude, and are therefore to be col- 
lected at such times, since they are only worth preserving when in fruit. 

In regard to algae which grow on trees, I have found but a single species, and do 
not think they are at all abundant in this latitude. Fartlier south, if one may 
judge by Professor Kavenel's collections, they are the most abundant forms. 
• Although perhaps of but little interest to the distant collector, yet for the sake 
of those living nearer, I will occupy a few lines with an account of the places 
around Philadelphia which will best repay a search for fresh-water algae. As is 
well known, below the city, there is what is known as the "Neck," a perfectly level 
extent of ground lying in the fork between tlie rapidly approaching rivers, Schuyl- 
kill and Delaware. This is traversed by numerous large ditches, and, especially 
just beyond the city confines, has yielded to me an abundant harvest. My favorite 
route is by the Fifth Street cars to their terminus, then across the country a little 
to the east of south until the large stone barn, known as " Girard's Barn," is 
reached. A large ditch lies here on each side of the road, which is to be followed 
until it crosses the Pennsylvania Railroad, then along this to the west, until the 
continuation of Tenth Street crosses it. Here the ditches cease, and the steps are 
to be turned homeward. From Girard's barn to the crossing just alluded to, 
ditches great and small lie all along and about the route, ditches which have often 
most abundantly rewarded my search, and enabled me to return home richly laden. 
The best season for collecting here is from March to July, and again in October, 
when some of the nostocs may be looked for. 

Crossing the river Delaware to the low country below and above the city of 
Camden, the collector will find himself in a region similar to that just described, 



. INTRODUCTION. 

and like it cut up by numerous ditches, in which are pretty much the same forms 
as in the "Neck." But by taking the Camden and Atlantic cars for twenty to 
forty miles mto New Jersey to what is known as the " Pines," he wiU get into a 
very different country ; low, marshy, sandy grounds, with innumerable pools, and 
streams whose dark waters, amber-colored from the hemlock roots over which they 
pass, flow sluggishly along. I have been. somewhat disappointed in my collections 
in such localities. Fresh-water algse do not appear to flourish in infusion of hem- 
lock, and consequently the streams are very bare of low vegetable life. On the 
other hand, in pools in the more open places, my search has been repaid by find- 
ing some very curious and interesting forms, which apparently are peculiar. 

North of Philadelphia are several places, Avhich at certain seasons will richly 
reward the microscopist. Along the Delaware Eiver, there is a similar country 
and flora to that of the " Neck." But back from the river things are quite dif- 
ferent. The North Pennsylvania Eailroad passes near Chelten Hills, some eight 
miles or so from the city, through some deep rock cuttings, which are kept con- 
stantly dripping by numerous minute springs bursting from between the strata. 
At the proper season, these will yield an abundant harvest. Besides these, there 
is also a stream of water with ponds running along by the road, Avhich should be 
looked into. I have seldom had more fruitful trips than some made very early in 
the spring to this locality ; but then it was in little pools in the Avoods, and espe- 
cially in a wooded marsh or meadow to the left of the road, some distance beyond 
the station, that I found the most interesting forms. 

The Schuylkill River and its banks have aft"ordcd materials for many hours of 
pleasant work. In the river itself a few very interesting forms have been found ; 
but it is especially along its high banks that the harvest has been gathered. 

The dripping rocks and little wood pools in the City Park are well worth visiting; 
but the best locality is the western bank, along the Reading Railroad, above Mana- 
yunk, bctAvcen it and the upper end of Flat Rock tunnel. Down near the river, at 
the lower end of the latter, will be found a number of beautiful, shaded rocky pools, 
which, in the late summer, are full of Chaetopliora and other algre. Along the 
west rocks of the river side of the bluff", through which the tunnel passes, are to 
be found, late in the fall, numerous algte. It is here that the Palmella Jessenii 
grows in such abundance. 

West of the city, in Delaware and Chester Counties, is a well wooded and 
watered, hilly coulitry, in which, here and there, numerous fresh-water algte may 
be picked up. 

As to the preservation of the algse— most of the submerged species are spoiled 
by drying. Studies of thom should always, when practicable, be made whilst fresh. 
Circumstances, however, will often prevent this, and I have found that they may 
be preserved for a certain period, say three or four months, without very much 
change, in a strong solution of acetate of alumina. 

An even better preservative, however, and one much more easily obtained, is 
carbolic acid, for I have studied desmids with great satisfaction, which had been 
preserved for five or six years in a watery solution of this substance. In regard 
to the strength of the solution I have no fixed rule. Always simply shaking up 



INTRODUCTION. 5 

a few drops of the acid with the water, until the latter is very decidedly impreg- 
nated with it, as indicated by the senses of smell and taste. 

Almost all species of algae which arc firm and semi-cartilaginous, or almost 
woody in consistency, are best preserved by simply drying them, and keeping them 
in the ordinary manner for small plants. The fresh-water alga; wliich bear this 
treatment well belong to the Phycochromojihycea', such as the Nostocs, Scytonema, 
&c., the true confervas not enduring such treatment at all. When dried plants 
are to be studied, fragments of them should be soaked for a few minutes in warm, 
or for a longer time in cold water. 

The only satisfactory way that algoe can be finally prepared for the cabinet is by 
mounting them whole or in portions, according to size, for the microscope. Of the 
best methods of doing this, the present is hardly the time to speak; but a word as 
to the way of cleaning them will not be out of place. Many of them, especially 
the larger filamentous ones, may be washed by holding them fast upon an ordinary 
microscope slide, with a bent needle or a pair of forceps, and allowing water to 
flow or slop over them freely, whilst they are rubbed with a stiffish camel's-hair 
pencil or brush. In other cases, the best plan is to put a mass of the specimens in 
a bottle half full of water, and shake the whole violently; drawing ofi" the water 
from tlie plants in some way, and repeating the process with fresh additions of 
water, until the plants are well scoured. At first sight, this process would seem 
exceedingly rough, and liable to spoil the specimens, but I have never seen bad 
results from it, at least when practised with judgment. The water seems so to 
envelop and protect the little plants that they are not injured. 

After all, in many instances it appears impossible to clean these algae without 
utterly ruining and destroying them — the dirt, often seeming to be almost an inte- 
grant portion of them ; so that he who despises and rejects mounted specimens, 
simply because they are dirty and unsightly, will often reject that which, scienti- 
fically speaking, is most valuable and attractive. 

In finally mounting these plants, the only proper way is to place them in some 
preservative solution within a cell on a slide. After trial of solution of acetate of 
alumina and various other preservative fluids, I have settled upon a very weak 
solution of carbolic acid, as the best possible liquid to mount these plants in. 
Acetate of alumina would be very satisfactory were it not for the very great 
tendency of the solution to deposit minute granules, and thus spoil the specimens. 
As every one knows, the great difliculty in preserving microscopic objects in the 
moist way is the perverse tendency of the cells to leak, and consequently slowly to 
allow entrance to the air and spoil the specimen. 

As I have frequently found to my great chagrin, the fact that a slide has re- 
mained unchanged for six months, or even a year, is no guarantee that it will remain 
so indefinitely. It becomes, therefore, exceedingly important to find some way of 
putting up microscopic objects that can be relied on for their preservation. Where 
carbolated glycerine jelly or Canada balsam can be used, the solid coating which 
they form around the specimens constitutes the best known protection. Except in 
the case of the diatoms, however, these substances so shrivel and distort the fresh- 
water alga? immersed in them as to utterly ruin them. I lost so many specimens 



g INTRODUCTION. 

by the old ways of mounting, that, becoming disheartened, I gave up all idea of 
making a permanent cabinet, until a new cement, invented by Dr. J. G. Hunt, of 
this city, was brought to my notice. This is prepared as follows:— 

" Take damar gum, any quantity, and dissolve it in benzole; the solution may be 
hastened by heat. After obtaining a solution just thick enough to drop readily 
from the brush, add enough of the finest dry oxide of zinc— previously triturated 
in a mortar with a small quantity of benzole— until the solution becomes white 
when thoroughly stirred. If not too much zinc has been added, the solution will 
drop quickly^from the brush, flow readily, and dry quickly enough for convenient 
work. It will adhere, if worked properly, when the cell-cover is pressed down, 
even when glycerine is used for the preservative medium. Keep in an alcohol- 
lamp bottle with a tight lid, and secure the brush for applying the cement in the 
lid of the bottle." 

Its advantages lie in the circumstance, that the glass cover can be placed upon 
the ring of it whilst still fresh and soft, and that in drying, it adheres to both cover 
and slide, so as to form a joint between them of the width of the ring of cement, 
and not, as with asphaltuni, gold size, «&c., simply at the edge and upon the outside 
of the cover. It is readily to be seen how much less liability to leakage must 
result from this. The method of mounting with it is as follows: A ring of any 
desired size is made, by means of an ordinary Shadbolt's turn-table, upon a slide, 
Avhich is then placed to one side to dry. When required for use, the specimen, 
cover, &c., being all prepared and ready, the slide is again placed upon the turn- 
table and a new ring of cement put directly upon the old one. The specimen is 
immediately placed within the ceU thus formed, and the requisite quantity of the 
carbolated water placed upon it. The cover, which must be large enough to entirely 
or nearly cover the cement ring, is now picked up with the forceps, the under side 
being moistened by the breath to prevent adhesion of air-bubbles, and placed care- 
fully in position. It is now to be carefully and equably pressed down with some 
force. By this, any superfluous water is squeezed out and the cover is forced down 
into the cement which rises as a little ring aroimd its edge. The pressure is best 
made with a stift' needle, at first on the centre and then upon the edges of the cover, 
which may finally be made slowly to revolve luiderneath the needle point. The 
slide may then be put aside to dry; or, better, an outside ring of the cement thrown 
over its edge in the usual manner. Where a deep cell is required, several coats of 
the cement should be placed one over the other, each being allowed to dry in 
turn. If time be an object, and only a shallow cell be necessary, the first ring of 
cement may be dispensed with, and the whole mounting of the specimen be done 
in a few minutes. Even with this cement and the utmost care in mounting, the 
cabinet should bo occasionally inspected, for there will always be some slides into 
which air will penetrate. When such are found, eff"orts may be made to stop tlie 
leak by new rings of cement overlaid upon the old, but very often entire remount- 
ing of the specimen is the only satisfactory cure. 

The classification which I have adopted in this memoir is that of Professor Ra- 
bonhorst. I have finally selected it, not as being absolutely natural, but as conve- 
nient, and as rarely doing much violence to the natural relations of the various species. 



liSITRODUCTION. 7 

Our knowledge of the life-history of the algtc must make very many advances 
before the true system can be developed, and abstinence from adding to the present 
numerous classifications is an exhibition of self-control not very common. 

There are, however, certain great groups, which are already plainly foreshadowed, 
and which no doubt will be prominent points in the perfected classification. 
Amongst these are the Conjiigatcp., or those plants in which sexual reproduction 
occurs by the union of two similar cells. In the present paper all the plants of 
this family described are together, since the diatoms are not noticed ; but in Ilaben- 
horst's work the latter plants are very widely separated from their fellows, and this 
seems to me the weak point of the Professor's system. 



TABLE OF CONTENTS. 









PAOB 


Advertisement .... 


* 




iii 


Preface 


. . 


• ••••••• 


V 


Introduction .... 


PAGE 




1 


Class Phycochbomophtce^ 


9 


Order Zygophyce^ 


100 


Order Cystiphoe^ 


10 


Family DESMiDiACEiE 


100 


Family Chroococcace^ . 


. 10 


Family Zygnemace^ 


159 


Order Nematogene^ . 


15 


Order SiPHOPHYCEiE 


174 


Family Oscillariace^ 


. IG 


Family HYDROGASTREiE 


175 


Family Nostochace^ 


23 


Family VAUCHERiACEiE . 


I7r, 


Family Rivulaeiace^ 


43 


Family Ulvace^ 


182 


Family Scytonemace^ 


. 55 


Family Confervace,?; 


186 


Family Sirosiphonace^ . 


. C^ 


Family (EDOGONiACEiE 


188 






Family Chroolepide^ 


203 






Family Ch^tophorace^ . 


205 


Class Chlorophyllace^ 


. 77 


Class RHODOPHYCEiE 


213 


Order Coccophyce^ 


. 78 


Family Porphyrace^ 


. 214 


Family Palmellace^ 


. 78 


Family Ciianteansiace^ . 


. 215 


Family PROTOCOCLACEiE . 


. 85 


Family Batraciiospermace^ . 


217 


Family VoLVOCiNEiE 


. 98 


Family Lemaneace.e 


. 221 



09K 

Supplement 

Geographical List of Species ^-'^ 

235 
Bibliography . - 

Index „.....•• 249 

Explanation of the Plates 253 



(ix) 



FRESH-WATER ALG/E OP THE UNITED STATES. 



Class PIIYCOCHROMOPIIYCEJE. 

PlcmtcB uni- vel multicellulares, in aqua vigentes vel extra aquam in 
muco matricali nidulantes, plerumque familias per cellularum gencrationes 
successivas ortas formantes. 

Cytioderma non siliceum, combnstibile. 

Q/tioplas7na phycochromate coloratnm, nucleo dcstitutum, granulis 
amylaceis plerumque nullis. 

Propaijatio divisione vegetativa, gonidiis immobilibus vel sporis tran- 
quillis. 

Unicellular or mvlticelMar plants living in water, or incased in a mater- 
nal jelly out of it, mostly in families formed from successive generations 
of cells. 

Cytioderm not siliceous, combustible. 

Cytioplasm an endochrome, brown, olivaceous, fuscous, &c., destitute 
of nucleus, mostly witliout starch granules. 

Propagation by vegetative division, by immovable gonidia or tranquil 
spores. 

The phycochroms are plants at the very bottom of the scale, distinguished by 
the simplicity of their structure and the color of their protoplasm, which, instead 
of being of the beautiful green that marks chlorophyll, is fuscous, or yellowish, 
bluish, brownish, or sometimes particolored, and rarely greenish, but of a shade 
very distinct from the chlorophyll green, more lurid, bluish or yellowish, or oliva- 
ceous in its hue. The nucleus appears to be always wanting. The cell wall is 
oftentimes distinct and sharply defined, but in many instances it is not so, the 
walls of different cells being fused together into a common jelly in which they are 
imbedded. In a large suborder the wall is replaced by a sheath, which in some 
genera surrounds cells with distinct walls, in others, cells without distinct walls, 
and in still others, a long cylindrical mass of endochrome, which may be looked 
\ipon as a single cell. 

Many of the phycochroms are unicellular plants in the strictest sense of the word, 
but more often the cells are conjoined, so as to form little families, each cell of 
which is in a sense a distinct individual capable of separate life, yet the whole 
bound together into a composite individual, llarely tlie pliycochrom is a multi- 

2 January, 1872. ( 9 ) 



10 



FRESn-WATER AhGJE OF THE UNITED STATES. 



b 



cellular plant in the stricter use of the term. Increase takes place by the multipli. 
cation of cells by division, and also by the formation of enlarged thick-walled cells, 
to wliich the name of spores has been given, although it is entirely uncertain 
whether they are or are not the result of sexual action. There are numerous 
peculiar forms of cell multiplication by division occurring ii; these plants, the dis- 
cussion of Avhich will be found scattered through the remarks on the various 
families and genera. 

The method of reproduction, and in fact the life history in general, of the phy- 
cochroms, is still involved in such mystery, that I am not aware that absolute 
sexual generation has been demonstrated in any of them. This being the case, it is 
not to be wondered at that many have conjectured as possible, and some have roundly 
asserted as true, that the phycochroms are merely stages in the life history of higher 
plants ; that they are not species, and, consequently, that any attempt at describing 
such is little more than a busy idleness. In regard to some of them it has certainly 
been rendered very probable that they are merely fixed stages of higher plants. 
On the other hand, in the great bulk of the forms, no proof whatever has been 
given that they are such. They all certainly have fixed, definite characters, capa- 
ble of being expressed and compared, so that the diff'crent forms can be defined, 
recognized, and distinguished. If, therefore, future discoveries should degrade 
them as subordinate forms, names will still be required, and definitions still be 
necessary to distinguish them one from the other, so long as they are common 
objects to the microscopist. 

If Nostoc commune, for example, were proven to be a peculiar state or develop- 
ment of Polytricum commune, I conceive it would be still known as Nostoc commune. 
But, as previously stated, no proof whatever has as yet been furnished for the vast 
majority of the plants of this family, to show that they bear any such relation to 
higher plants ; and until some such proof is forthcoming, certainly the only scien- 
tific way to act, is to treat them as distinct species. 

Order CystipIlOrSC. 

Plantae unicellulares. CelluliB singute vel plures in familias consociatoe. 
Unicellular plants. Cells single or consociated in families. 

In this order the cells are oblong, cylindrical, spherical, or angular. They are 
sometimes single, or more commonly are united by a common jelly into families, 
which sometimes are surrounded by distinct coats. The mucus or jelly, in which 
the cells are imbedded, is mostly, but not always, colorless, and varies in firmness 
from semifluid to cartilaginous. The division of the cells may take place either in 
one, two, or three directions or planes. 

Family CHROOCOCCACEiE. 

Character idem ac ordine. 
Characters those of the order. 



FRESU-WATER ALG^ OF THE UNITED STATES. H 

Genus CHROOCOCCUS, Njegeli. 

CelluliE globosse ovales vel a pressione rautua plus minus angulosse, solitariie vcl in familias con- 
sociatse, libersie (a vesica matricali non involute); cytiodcrmate acliromatico, horaogeneo, siepein niuco 
plus minus finuo couliuente; cytioplasmate ffirugiuoso vcl pallide ca;ruleo-viridi, non rare luteolo vel 
aurantiaco, iuterdum purpurascente. Generationum successivarum divisio alternatim ad directiones 
tres. 

Syn. — Protococcus, Ag. et Ktz., &c., ex parte. Plenrococcus, Menqh. 
Globulinee et Protosphaeriae, Turpin, ex part. 

Cells globose, oval, or from mutual pressure more or less angular, solitary, or consociated in free 
families (not involved in a maternal vesicle) ; Cytioderm achromatic, homogeneous, often confluent 
into a more or less Ann mucus; cytioplasm a;ruginous or pale bluish-green, not rarely yellowish or 
orange, sometimes purplish. Successive generations arising by alternate division in three directions. 

C. refractus, Wood. 

C. cellulis in familias solidas arete consociatis, plerumque snbqnadratis, saspius triangiilaribus, 
rare angulosis; familiis sa;pius lobatis; cytiodcrmate tcnui, vix visibile, acliroo; cytioplas- 
mate subtiliter granulate, subfusco vel subluteo vel olivaceo, valde refrangente. 

Diam.— Cell gAir"— suVn". rare in cellulis singulis ^^Vu"; famil. ^^^-^"—^\-^". 
Syn. — G. refractus, Wood, Prodromus, Proc. Amer. Philos. Soc, 1869, 122. 
Eab. — In rupibus irroratis grope Philadelphia. 

Cells closely associated together into solid families, mostly subqnadrate, very often triangular, 
rarely mnltiangular ; families often lobed ; cytioderm thin, scarcely perceptible, transparent ; 
cytioplasm finely granular, brownish, olivaceous, or yellowish, highly refractive. 

Remar'ks. — The color of this species varies from a marked almost fuscous brown 
to a light yellowish-brown, the lighter tints being the most common. Tlie cells 
are remarkable for their powerful refraction of the light, resembling often oil as 
seen under the microscope, especially if they be the least out of the focus. They 
are very closely joined together to form the families, many of which are composed 
only of four cells. Often, however, a large number of the cells are fused together 
into a large, irregidar, more or less lobate family, and these sometimes are closely 
joined together into great irregular masses. I have occasionally seen largo single 
cells with very thick coats, whose protoplasm Avas evidently undergoing division. 
Are such a sort of resting spore ■? The color of the protoplasm varies. Perhaps the 
more common hue is a sort of clay tint. Bluish-olive and a very faint yellowish- 
brown are not rarely seen. The species grows abundantly on the wet rocks along 
the Reading Railroad between Manayunk and the Flat Rock tunnel. 

Fig. 5, pi. 5, represents different forms of this species; those marked «, magnified 
750 diameters; h, 470 diameters; c, 950 diameters. 

C. miilticoloratiis, Wood. 

C. in strato mucoso inter algas varias sparsus ; cellulis singulis et sphocricis, vcl 2-4 (rare 8) ant 
angulis aut semispha;ricis aut abnormibus in familias oblongas eonsociatis ; cytiodcrmate cra.s.so, 
byalino, hand lamelloso; tegumentis plerumque nullis, interdum subnullis; cytioplasmate ple- 
rumque homogeneo, interdum subtiliter granulato, vel luteo-viride vel creruleo-viridc vel luteo 
vel subnigro, vel brunneo, vel saturate aurantiaco, sajpe ostro tincto. 

I>;am.— Cell., sing, sine tegm., 5/5^" cum teg. Tfi,^"; cell, in famil. sing, j/jru"— js^'sb-" 
xara. long. 5555 — use t '^l. jjg^ — J505 • 



12 FRESH-WATER ALG^ OF THE UNITED STATES. 

Syn.—C. muUicoloralus, Wood, Prodromus, Proc. Amcr. Philos. Soc, 18G9, 122. 

Eab.—\n nipibus bumidis prope Philadelphia. 

C. occurring scattered in a mucous stratum with other algte ; cells spherical and single, or else 
angular senii-sjjherical or irregular and associated together iu oblong families of from 2-4 
(rarely 8); inner coat thick, hyaline, not lamellate; outer coat generally wanting, sometimes 
indistinctly present ; endochrome mostly homogeneous, sometimes minutely granular, either a 
yellowish-green or bluish-green, or yellowish or brown, or blackish, sometimes tinged with 
bright lake. 

The cells of this species do not appear to have any tendency to unite to form 
large masses or fronds. On the contrary they are generally very distinct. Their 
color varies very much, in a larger number of instances they were a decided yellow- 
ish-green, tinged at some point or other with a beautiful lake. When several cells 
are formed by division out of one cell, a similar division of the very thick surround- 
ing gelatinous coat follows separating them finally entirely one from the other. I 
have seen a single cell which appears to be an encysted form of this, of which I give 
a drawing. 

Fig. 6, pi. 5, represents different forms of this species magnified 260 diameters. 

C. fherinopIi!lii)«, Wood. 

C. cellulis singulis aut geminis vel quadrigeminis ct in familias consociatis, oblongis vol sub- 
globosis, iuterdum angulosis, baud stratum mucosum formantibus; tcguraento crassissinio, 
achroo, haud lamelloso, homogeneo ; cytioplasmate viride, interdum subtiliter granulato, inter- 
dum homogeneo. 

Diam. — Celluloe singulce sine tegumento longitudo maxima-^ gVij", latitude maxima ja'oTy"- 

Syn. — C. therniophilus, Wood, American Journal Science and Arts, 1869. 

Hab. — Benton Springs, Owen Co., California (Mrs. Parz.). 

Cells single, geminate, or quadrigeminate and consociated into families, oblong or subglobose, 
sometimes angular, not forming a mucous stratum ; tegument very thick, transparent, not 
lamellate, homogeneous ; cytioplasm green, sometimes minutely granulate, sometimes homo- 
geneous. 

Remarks. — Remarks upon this species will be found under the head of Nostoc 
calidarium, W ood. 

Genus GLOEOCAPSA, Ktz. 

" Cellula; sphericK aut singulaj aut numeross in familias consociata; ; singulte tegumento vcsiculi- 
forme (cytiodermate tumido) inclusce, post divisionem spontaneam iu cellulas duas filiales factam 
utraque tegumento se induit, dam amba? tegumento matricali involute remanent; cellularum harum 
Chalinra iterum in duas cellulas divisione continuo repetita, tegumentum ataviaj restat et sese cxten- 
dens familiam totara circumvelat. Cytioderma crassum, ssepe crassissimum, celluls lumen crassitie 
ffiquans vel superans, achromaticum vel coloratum, plerumque lamellosum ; lamella vel strata non 
raro discedentia. Cytioplasma a;ruginosum, casrulco-viride, chalybeum, rufescens, luteo-fuscum, &c. 
Cellularum divisio directione ad tres dimensiones alternante. Cellulie generationum ultimarum 
minores quam priorum sunt." (Rab.) 

Syn. — Glohulina et Bicliatia, Turpin, ex part. 
Gloeoca2)sa, Ktz., ex part. 
Microcystis, Menegil, ex part. 

Cells spherical, either single or associated in numbers into families; the single cell included a 
vesicuhform tegument (the tumid cytioderm); this cell then underRoin- division into two dau-hter- 



FRESH-WATER ALG^ OF THE UNITED STATES. 13 

cells, each of which has a distinct tegument, the whole being surrounded with that of the old mother- 
cell. This process of division is then repeated again and again, the original cell-wall remaining and 
surrounding the family thus formed. Cytioderm thick, often very thick, equalling, or exceeding in 
diameter the cavity of the cell, achromatic or colored, mostly lamcllated, lamellae or strata not rarely 
separating. Cytioplasm of various colors, aeruginous, bluish-green, chalybeate, reddish, yellowish- 
fuscous, &c. Division of the cells occurring in three directions. The last generation of cells smaller 
than the earlier ones. 

Cr. sparsa, Wood. 

G. in strato mucoso sociis algis variis sparsa; cellulis sphnericis, vel oblongis vel ovatis, 2-8 in 

familias consociatis; familiis subglobosis vel subovatis, intcrdum nuraeroso-aggregatis ; tegu- 

mentis internis aureofuscis, firrais, rarisslme coloris expertibus, horaogeneis, vel laraellosis; 

tegumentis externis achromaticis, rare subachromaticis, plerumque vix visibilibus ; cytioplas- 

mate homogeneo. 
Z'lam.— Max. cell, oblong, sine tegura. long., 53V/'; ^^^■•izon"; cell, glob., sine tegum., 

STsW; cum tegum., y^Vs"; fam., 7}^". 

Syn. — G. sparsa, Wood, Prodromus, Proc. Amer. Philos. Soc., 18G9, 123. 

Eab. — In rupibus irroratis prope Philadelphia. 

G. scattered in a mucous stratum composed of various algoe ; cells spherical, or oblong, or ovate, 
associated together in families of from 2-8; families subglobose or subovate, sometimes aggre- 
gated together in large numbers ; inner tegument yellowish-brown, firm, rarely colorless, homo- 
geneous or lamellate; external tegument achromatic, rarely subachromatic, gcncrallv scarcely 
visible. 

liemarks. — Tliis species was found in a rather firm, grumous or gelatinous coat- 
ing of a light brown color, growing on the rocks at Fairmount Water Works, 
chiefly composed of a very minute nostochaceous plant, but contained numerous 
other algse. The color of the tegument is yellowish-brown, sometimes with some 
red in it, sometimes with something of a greenish tint. This inner colored coat 
is not generally more than once or twice lamellate, often it is not at all so. This 
species seems somewhat allied to G. styopJiila, but diflcrs slightly in the form of 
the cell, and more especially in not having a distinct thallus, and in the families 
being small and containing but few cells. 

Fig. 7, pi. 8, represents this species, magnified 750 diameters. 

Genus C.ELOSPH.ERIUM, N^geli. 

Thallus parvus, e cCllulis minimis in familias periphoricas consociatis vel in stratum pcriphericnm 
simplex et in muco tegumentis celerrime confluentibns formato nidulantibus compositus. Celki- 
larura divisio, initio generationum serierum, in omnem fit directionem, turn deuique alternatim 
ad superficiei spha;rica; utramque directionem. 

Thallus small, composed of very small cells consociated into peripheral families, or in a simple 
peripheral layer, inclosed in their quickly confluent teguments. Division of the cells at first in all 
directions, afterwards only in each direction on the surface of the sphere. 

C. dubiiini, Grun. ? 

C. thallo microscopico, snbgloboso vel cnorme, natantc, congregato; cellulis globosis aut sub- 
globosis; cytioplasmate pallide ajrugineo, subtiliter granuiato. 

Diam.—CM. plerumque ^^V^" = .OOOIG"; rare j^V^" = .00025"; fam. X5V55" — rsViJo" = 
.00083"— .0033". 



14 FRESH-WATER ALG^ OF THE UNITED STATES. 

ifo^.— Ill aquis stagnis, prope Philadelphia. 

Thallus microscopic, subglobose or irregular, floating, aggregated ia great numbers; cells glo- 
bose or subglobose; cytioplasm finely granulate, pale a;ruginous green. 

Remarlcs.—l found this beautiful little plant forming a dense scum on a stag- 
nant brick-pond, below the city, in the month of July. The scum was of the 
" color of i)ea-soup," and so thick was it, that I think a quart of the plants might 
have been readily gathered. The fronds were of various sizes, and many of them 
were apparently undergoing division — some of them seemed to have little fronds 
in their interior. They were composed of an exceedingly transparent firm jelly, in 
which the cells were placed, often so as to leave the central parts of the frond 
empty, merely forming a sort of filament-like layer around the edge. Barely they 
were in such numbers as to be crowded together over the whole surface of the 
frond. In some of the younger fronds the cells formed a little ball within the jelly, 
instead of being scattered through its outer portion. I have seen some large single 
cells three or four times the size of the ordinary frond cell, swimming amongst the 
plants, of which they are apparently the reproductive gonidia. Their cell-coats 
are very firm and thick. The fronds themselves are often closely aggregated 
together into little masses, and I think it probable that there is a state of the 
plant, in which the jelly becomes softened and the fronds more or less fused together 
in protococcus-like masses. This plant appears to be the same as the European G. 
duhium, but diff"ers from the description in the fronds not attaining to anything 
like the size. It is very prabable, however, that this depends upon age or circum- 
stances of growth, and that American plants may be found as large as the 
European. 

Genus MERISMOPEDIA, Meten. 

Cellula; globosaj, aut oblonga;, aut ovalcs, tegumentis confluentibus, 4, 8, 16, 32, G4, 128 in fami- 
lias tabulatas, unistratas consociata;. Thallus planus, tenuis, plus minus quadratus, in aqua libere 
natans. Cellularum divislo in planitiei utramque directionem. 

Cells globose, oblong, or oval, joined together by their confluent coats into tabular families of 4, 
8, 16, 32, 64, 128. Thallus, a more or less quadrate plane, swimming free in the water. Division 
of the cells occurring in all directions in the one plane. 

I?I. nora, Wood. 

M. thallo membranaceo, distincte limitato, cellulis nnmerosissimis composito ; cellulis ovalibus, 
arete approximatis, 16 in familias consoeiatis, dilute cseruleo-viridibus, iuterdum medio con- 

strictis; thalli margiuibus rectis, integris. 

Syn.—M. nova, Wood, rrodromus, Proc. Amer. Philos. See, 1869, 123. 

Diam.— Cell. ad. ^t^^ts" = 0.0025". 

Mab.—la flumine Schuylkill, prope Philadelphia. 

Thallus membranaceous, distinctly limited, composed of very numerous cells ; cells oral, closely 
approximated, consociate in families of 16, light bluish-green, sometimes constricted in the 
middle; margin of the thallus straight and entire. 

BemarJcs—The only specimens I have over seen of this species were found grow- 
ing in the Schuylkill River adherent to, or entangled in, a lot of filamentous algiE. 



FRESn-WATER ALGiE OF THE UNITED STATES. 15 

The frond is very sharply defined, and, under a low power, is of a uniform bluish- 
green tint. The cells are associated in primary families of 16, of a number of 
which the thallus is composed. The species appears to be most closely allied to 
M. mediterranean Naeg., from which it differs very essentially in the size of the fronds, 
and perhaps even more closely to M. glauca, the only character separating it from 
which is the straight margin. I have myself some doubts whether it ought not to 
be considered as merely a form of M. glauca. 

Fig. 8, pi. 8, represents this species, magnified 400 diameters. 

Itl. conToluta, Breb. 

M. thallo membranaceo, oculis nudis visibili, plus minus convolute; familiis c cellulis gcuiinis et 
in subfamilias dispositis, 256 compositis, interdum familiis duabus in familia guraiua conjunc- 
tis; cellulis spbaericis aut oblongis; cytioplasmate homogeneo, viridi. 

Diam.—Cd\. ^ttW =0.00017"; fam. long. ^\^" = .00"; lat. ^\^" = 0.01". 

Eah. — In aquis quietis prope Philadelphia. 

Thallus membranous, visible to the naked eye, more or less folded; families composed of 25(5 
geminate cells, arranged in subfamilies, sometimes two of these families conjoined with a com- 
posite family; cells spherical or oblong; cytioplasm homogeneous, green. 

Remarks. — When my Prodromus was published, the only specimens of this plant 
which I had seen were contained in a mounted slide given me by my friend Dr. J. 
Gibbons Hunt, of this city. Since then I have found it growing in a very shallow, 
quiet, but fresh, sweet pool at Spring Mills, making a distinct green layer upon the 
mud many feet in extent. Of course, there were millions of specimens in this layer. 
The fronds are irregular in shape, often somewhat ovate, sometimes subquadrate, 
variously torn, and not rarely somewhat lobate. Their edges are frequently very 
sharply defined and rendered firm and prominent by several rows of cells being 
crowded closely together along them. The cells in the body of the frond are arranged 
in large parallelogrammatic families, composed of 256 cells. There are 16 cells on 
each side, the families being parallelogrammatic rather than square, owing to the 
oblong shape of the cells. This cell family is composed of four subfamilies, each 
containing 64 cells. These are again subdivisible into four more or less distinct 
groups of 16 cells each. The cells are, finally, generally closely geminate, each 
pair being very distinctly separated from its neighbors. In certain stages of growth, 
as immediately after a general division of the cells, two of the large cell-families 
spoken of are often temporarily joined together to form a huge family of 512 cells, 
but soon separate one from the other. 

Order j^ematog'enese. 

Plantse multicellulares vel pseudo-multicellnlarcs. Ccllulre fdum (trichoma) forraantes et ple- 
rumque vagina tubulosa homogenea vel lamellosa inclusa?. Tricbomata aut simplicia aut ramificata. 

Plants multicellular or pseudo-multicellular. Colls forming a filament, and generally included in 
a tubular lamellate or homogeneous sheath. Filaments either simple or branched. 



16 FRESH-WATER ALG^ OF THE UNITED STATES. 

Family OSCILLARIACE^. 

Trichomata simplicia baud vero multicellularia, sed distincte articulata, plerumque vaginata, mo- 
tiouibus variis pnudita. 

Filaments simple, not strictly multicellular, but distinctly articulate, mostly vaginate, moving in 
various ways. 

Genus OSCILLARIA, Bosc. 

Trichomata simplicia, plerumque distincte articulata, rigida, recte vel parum curvata, rarius cir- 
cinata vel spiralitcr convoluta, plerumque tete colorata, motu triplici psedita, in muco matricali 
nidulantia vel vaginula tubnlosa angustissima utroque fine aperta iuclusa; articuli fronte disciformes. 
(R.) 

Filaments simple, mostly distinctly articulate, rigid, straight, or somewhat curved, very rarely 
circinate or spirally convolute, capable of three motions, floating in a maternal jelly, and shut up 
in a fine tubular sheath, open at both ends ; joints from the front disciform. 

The oscillaria are very peculiar plants, which flourish almost in every situation 
in which fresh water is to be found. The purest springs are not always free from 
their presence, although they occur most abundantly in stagnant pools and ditches, 
where animal or vegetable matters are undergoing decay. AVhen viewed in mass, 
floating upon some foul pool, few objects in the vegetable world are better calcu- 
lated to excite disgust. A dark, slimy scum reeking with its putrescent surround- 
ings, they seem to ofter nothing of pleasure or interest. But, when brought home 
to the table of the microscopist and placed beneath his object-glass, they startle 
the observer by the wonders of their life-history. Living rods, writhing, twisting, 
bending, curling, creeping, gliding hither and thither ; incessant, apparently cause- 
less, motion, occurring too in what to most minds is the very type of fixity and 
passivity — a plant. No marvel, then, that they are so famous. 

The structure of an oscillatoria is about as simple as it can be. An outside 
colorless cellulose sheath, which is probably in the uninjured filament closed at the 
end, although, as seen by the microscope, violence and age have often torn it open. 
Within is a long rod of variously colored endochrome, distinctly articulated by, at 
great or less intervals, breaks in the color, which appear as dark lines under a low 
power, but, under a higher objective, arc revealed as narrow linear portions of 
protoplasm lighter and more transparent than the rest. Frequently at the joints 
there is a marked tendency to separation between the successive articles, and a very 
decided contraction of the endochrome on each side, so as to leave a little gutter, 
or dividing trench. The endochrome is sometimes homogeneous, sometimes con- 
tains numerous granules, which are, however, never amyloid in their nature. 

The color of the endochrome varies very greatly in the difl"erent species. Slate 
color, blue, greenish, olivaceous, are among the most common hues. According 
to Dr. Ferdinand Cohn (Botan. Zeitimg, 1867, p. 38; Sitzung, 13th Dec. 1866, 
der Schlesischen Gesellschaft fiir vaterliindische Cultur), the coloring matter of the 
oscillatoria consists of true chlorophyll, and a substance which he calls Phycocyan, 
but which he states to be diff"erent from Phylwhyan of Kiitzing, the Phyr^iocJirom 
of Nirgcli, and also from Phycwyun of the latter authority. The chlorophyll is, 



FRESII-WATER A L G .E OF THE UNITED STATES. 17 

of course, soluble in ether and alcohol but not in water ; but the Phycocyan (Cohn) 
is insoluble iu alcohol and ether, but soluble in water after the death of the oscil- 
latoria. It is precipitated out of its solution by acids, alcohol, and metallic salts, 
as a blue jelly, but potash and ammonia tiirow it down as in a colorless, gelatinous 
mass. I have myself frequently noticed that oscillatoria after death will yield a 
bluish coloring matter to water, but thought that such coloring matter was the 
result of a partial decomposition, and I think that Professor Cohn has by no means 
established as a fact that his Phycocyan exists in the oscillatoria during life. 

As to the method of reproduction of these plants, we are as yet almost entirely 
in. the dark. Individuals do multiply by the breaking up of the internal endo- 
chrome into masses or sections through a separation at the joints. These little 
masses frequently grow immediately into new individuals. Sometimes, however, 
they roll themselves into a ball, but whether they then have the power of coating 
themselves with a protective wall and passing into a sort of resting spore or not, I 
cannot say. 

The specific characters of the oscillatoria arc derived from the color, form, mode, 
and place of growth, &c., of the large common mass, its thickness, consistency, 
the absence or presence of radii, &c. Descending to the individual filament, the 
characters are drawn from the size, the color, the length of the articulations, and 
the shape of the uninjured ends. Thus, it is to be noted, whether tlie latter arc 
gradually narrowed (attenuated), or preserve their size to the very point, whether 
they are acutish or obtuse, rounded or truncate, whether they are straight or con- 
stantly curled. The activity and modes of motion are also to be remarked. Some 
species merely glide across the field of the microscope, some are constantly curling 
and uncurling at their ends, some bending to and fro almost like a pendulum, some 
are very sluggish, others very active and restless. 

After all, however, it must be confessed that the specific characters are very un- 
satisfactory, much more so than in any other phycochroms which I have studied. 

A very large number of European forms have been described, some few of which 
I have been able to recognize. I have also ventured to name a few forms appa- 
rently distinct, but have refrained from going farther into their specific study, 
because I have found it so unenticing, and my time has been so limited. 

Professor Bailey, in Silliman's Journal, N. S., vol. iii., states that he has identified 
a few species of this family, although with great hesitation and doubt. At the 
time he wrote there were really no known grounds upon which specific unity could 
be predicated in these plants, and I therefore think that his identifications arc of 
but little value, although holding the most profound respect for his abilities as a 
naturalist. The list he gives is as follows : — 

0. tenuissima, Ag. Warm Springs of Washita. 

O. (enuis, Ag. Providence, Rhode Island. West Point, New York. Culpepper 
County, Virginia. 

O. decordcans, Gener. Common everywhere on pumps, &c. 

O. muscorum, Ag. West Point, New York. 

O. nigra, Vauch. West Point, New York. 

0. corium, Ag. 

3 February, 1872. 



18 



FllESn-WATER A L G .E OF THE UNITED STATES. 



O. Cllloi'ilia, KiiTZiNO. 

O. iuterdum in strato sordidc viritli iiatrtiilc, interclum in aqua diffusa; trichomatibus rectis, 
vividu inovcntibus, vel arlicuUitis ct cum cytioiilasmuto granulate, vel inarticulatis et cum 
cytioiilasniato haud granulatu; cytioplasmato liyaliuo, iuterdum coloris fere expertibus, 
iiilerdum dilutissimc viride; apiculo haud attcuuato, ubtusc rotuudato, recto ; articulis dia- 
metro suba;qualibus. 

Diam.-j^W'-^oW = .000U"-.000l". 

Hab. — In stagnis prope Philadelpbia. 

Som'etimes swimming on the water as a dirty-greenish stratum, sometimes diffused in the water; 
filaments straight, actively moving, either articuUated and having the cytioplasm filled with 
blackish granules, or else neither articulate nor granulate, cytioplasm hyaline, almost colorless, 
or with a faint greenish tint; ends of the filaments not attenuate, straight, obtusely rounded; 
joints about equal to the diameter. 

Remarks.— 1 found this species in the month of August, 1869, in one of the 
stagnant brick-ponds below the city. It occurred as a sort of floating scum, or 
else diffused through the water, which was then opaque and greenish. It resembled 
so a protococcus in gross appearance that I did not think of its being an oscilla- 
toria until I placed it under the microscope. The filaments are almost colorless, 
and, in most instances, are very distinctly granulate and artigulate. The dissepi- 
ments are in such cases clear and transparent, perfectly free from granules. This 
form is very close to the descriptions of the European 0. cldor'ma, Ktz., but differs 
somewhat from descriptions, chiefly in habit of growth. The filaments, when in 
mass, are often seen to be curved under the restraining force of the glass cover, 
but when free I think always straighten themselves. 

Fig. 1, pi. 1, represents a single filament, magnified 750 diameters. 

O. Frohlichii, Ktz. ? 

O. strato indefinito, tenue, viride; trichomatibus la?te viridibus, subreetis, vivide oscillantibus, 
ad genicula uonnihil pellucidis et leviter contraclis et rarissinie granulatis; articulis diametro 
2, 3, 4 plo brevioribus ; cytioplasmate obscure aut distincte minutissime granulato ; apiculo 
haud attenuate, late rotundato. 

X»iam.— 5 Jgij"— VVijiy" = O.0O0G6"— 0.0004. 
Hah. — In flumine Schuylkill. 

Stratum indefinite, thin, green ; filaments bright green, straighti.sh, vividly oscillating, some- 
what pellucid at the joints, where they are slightly contracted and very rarely granulate ; 
articles 2, 3, 4 times shorter than the diameter, cytioplasm obscurely or distinctly very mi- 
nutely granulate ; apex not attenuate, broadly rounded. 

Itemdrhs.—l found this species growing upon the bottoms of the shallows in the 
Schuylkill River and its larger tributaries, forming a somewhat badly defined 
stratum, rather, indeed, a coating on tlic mud than a definite stratum. The motion 
is exceedingly active, the filaments bending and gliding, and their apices con- 
stantly curling and extending in all directions. The apices are very blunt. The 
filaments are not often seen woven and twisted together into a mass composed 
simply of themselves, but arc stuck together loosely, each filament remaining 
straightish, with numerous little masses of mud between them. I have not been 



FRESH- WATER A L G .E OF THE UNITED STATES. 19 

able to identify the species positively, but have referred it with doubt to 0. FroJdi- 
c7i li. 

Fig. 2, pi. 1, represents the end of a filament. 

O. nig:ra, Vauch. 

O. .strato plus minus conipacto, amplo, plerumquo natante, atro-viride, cum radiis longis; trielio- 
matibus plerumque flexuosis; apicc obtuse rotundato ; articulis diametro | plo brevioribus- 
dissepimentis distiucte grauulati-s ; cytioplasmate pallide cajsio. 

' Hah. — In fossis stagnis prope Philadelphia. 

Stratum more or less compact, ample, broad, mostly floating, blackish-grccn, with long radii • 
filaments mostly flexuous; apices obtusely rounded; joints j shorter than broad; dissepi- 
ments distinctly granulate ; cytioplasm pale-grayish. 

Remarks — This species is found in thick, rather loose strata, floatin<j, especially 
when old, on stagnant waters, or adhering to plants, &c., or the muddy shores and 
bottom of ditches, foul aquaria, &c. The color of the stratum is a very dark 
blackish-green, with a peculiar, glossy, repulsive appearance. The single filaments 
are of a pale-bluish neutral tint, sometimes a little greenish, very much curved 
and entangled, or more rarely straightish. Their motion is active. The measure- 
ments do not quite equal those given by European authorities, but otherwise the 
plant agrees well with their descriptions. 

Fig. 3a, pi. 1, represents the mass of the plant as seen with the naked eye; fig. 
37^, shows a number of filaments slightly magnified; fig. Ic, a broken portion of a 
filament magnified 260 diameters, with the sheath projecting beyond the endo- 
chrome ; fig. 1(7, the end of a filament still more highly magnified. 

O. liiuosn, Agardh. 

O. tricliomatibus subrigidis ot subrectis, vivide oscillantibus, CTruleo-viridibus, in stratum niuco- 
sum laHe saturate viride et modice longc radians ct iiatans collcctis et intcrtextis, dislincte 
articulatis ; articulis diametro subtequalibus, interdum duplo brevioribns (post divisionem), 
ad gcnicula distincte constrictis; dissepimentis hand granulatis ; apiculo obtuso, haud atten- 
uato, interdum recto, interdum curvato ; cytioplasmate granulato. 

^''ani— iju'oo" 

Hab. — In stagnis prope Camden, New Jersey. 

Filaments straightish and somewhat rigid, vividly oscillating, lihiish-green, interwoven into a 
bluish-green, floating stratum, with moderately long radii, distinctly articulate; articles about 
equal to the diameter, or after division one-half shorter, at the joints distinctly constricted ; 
dissepiments not granulate ; apices obtuse, not attenuate, sometimes straight, sometimes 
curved ; cytioplasm granulate. 

EemarJiS. — I have found this species floating on foul ditches near Kaighn's 
Point, New Jersey, in the month of ^Maj'. The color of the stratum is a very pure 
deep-green; the single filaments vary from a rather bright deep-green to a pale blue- 
green, according to the power under which they are seen. The apices are not at all 
attenuate. The constriction at the articles is scarcely visible with a lower power than 
■|th. The stratum is rather thin, with a good deal of dirt adhering to its bottom. 



20 FRESn-WATER A L CwE OF THE UNITED STATES. 

W'lu'ii grown in a hotlli-, tin- plant appears as a very thin stratum growing np tlie 
sides. The agreement uf this phmt with the descriptions of the European 0. Umosa 
is very close, so that I do not think it can be separated from it, although in 0. 
Umosa the dissepiments are said to be distinctly granular. 

Fi<^. 4, pi. 1, represents a tilamcnt of the American plant magnified 1250 dia- 
meters. The color and form are closely counterfeited, but the characteristic sepa- 
ration of the endochrome into parts at the joints is decidedly exaggerated. 

O. iicgiccia, Wood. 

O. trichomatibiis niodice brevibus, aut dilute purpuraceo-plumbeis aut plumbeo-cinereis, pler- 
umque rectis, aut stratum mucosura atro-purpureum baud distincte radiante fonnantibus, aut 
in strato gclatinoso baud radiante subplumbeo dispersis et cum algis aliis intermixtis, rare 
oscillantibus sed lente sesc moventibus; articulis diametro fere 4 plo brevioribus ; dissepi- 
moutis plerumque baud granulosis, rare iudistincte granulosis; apiculo obtuse rotuudalo, 
interdum breviter nonuibil attenuate. 

Syn. — 0. neglecla, Wood, Prodromus, Proc. Amer. Philos. See, 1869, 124. 

Diam. — xsVif ' = 0066. 

Hab. — In stagnis prope Philadelphia* 

Filaments rather short, of a dilute purplisli-lead color, or leaden-gray, generally straight, either 
forming a mucous, blackish-purple stratum without marked rays, or diffused with other algaj 
in a gelatinous mass, rarely oscillating but gliding; articles about four times shorter than 
broad ; joints for the most part not granulate, rarely indistinctly granulate ; ends obtusely 
rounded, occasionally short, somewhat attenuate. 

Rcmarhs. — I have found this plant in the shallow ditches along the track of the 
Norristown Railroad above Manayunk, growing in two dift'erent ways. In the one 
it forms a distinct, soft, gelatinous, floating stratum of a very dark purplish color, 
consisting of nothing but interwoven filaments, and provided with long rays. In 
the other, the plant is largely mixed with diatoms and other alga; into a thick, 
gelatinous stratum without rays, whose color is a dirty slaty tint, which, however, 
is not all distinctive, and often varies as the proportion of the diff'erent constituents 
varies. The color of the single filaments is a slaty, almost neutral tint. The 
cytioplasm is remarkable for the numerous very minute spots more transparent and 
with less color than the surrounding parts. The ends of the filaments are often 
abruptly obtuse, frequently however there is a very short taper. Motion does not 
appear to be very active, and seems especially to be gliding, rather than a bend- 
ing to and fro of filaments. 

Fig. 5(«, pi. 2, is an outline drawing of a filament magnified 450 diameters ; 56 
is a portion of a filament. 

©. iinpcratoi*, Wood. 

0. m strato mucoso, plerumqne natante, olivaceoatro, longe radiante; trichomatibns rectis aut 
subrectis, tranquillis, dilute viridibus vel saturate olivaceis, baud oscillantibus, sed ambulan- 
tibus; apiculis nonnihil attenuatis, late rotnndatrs vel subtruncatis, curvatis ; articulis diame- 
tro 5-12 plo brevioribus, ad gcnicula indistincte contractis ; cytioplasiuate homogeueo, 
olivaceo-viride; vaginis firmis, ad genicula distincte transverse striatis. 

Syn.—O. imperator, Wood, Prodromus, Proc. Aracr. Pbilos. Soc, 1869, 124. 
Diam.— .002". 



FRESII-WATER ALGJE OF THE UNITED STATES. 21 

Hab. — In stagnis prope Pliiladelphia. 

0. occurring in an olive-black, niiicous stratum, mostly swimming and with long ra_ys ; filaments 
straight or straightisli, light-green or deep-olive, tranquil, not oscillating, but moving with a 
gliding motion ; ends somewhat attenuate, broadly rounded or subtruncatc, curved ; articles 
5-12 times shorter than broad, slightly contracted at the joints; cytioplasm homogeneous, 
olive-green ; sheaths firm, distinctly transversely grooved at the joints. 

Eemarls. — The strata of this species are often of great extent, and resemble 
more masses of spirogyra than of tlie ordinary oscillatoria. They are very loose in 
texture ajid are very slimy, whilst their edges are fringed by the long tranquil 
rays. In certain conditions of growth, the endochrome of the filaments is so dense 
as to render them very opaque and the articulations very obscure. The sheaths 
when emptied show the marks of the joints very distinctly ; but, at times, when 
gorged with cytioplasm, scarcely can the sheath itself be seen. The color of the 
filament is also affected by the state of the protoplasm, so that it varies from a 
lightish-green with an olive tint to a very decided dark olive. This species seems 
to be closely allied to the European 0. prlnceps, from which, however, it differs in 
its motion, which is always very slow and merely gliding, its color, the distance of 
the dissepiments, and the much longer curvature of the ends. It grows everywhere 
in the ditches around the city ; when mature, generally floating upon the surface 
with an adherent under-stratum of dirt, but, in its earlier history, often adhering 
to the bottom. 

Fig. 6a, pi. 1, is a drawing of the end of a filament; fig. 6?), represents a small 
fragment of a filament, showing the tendency to take a roundish or barrel shape ; 
much of the endochrome has been squeezed out by the injury which has broken 
the filaments. 

Genus CIITIIOXOBLxlSTUS, Ktz. 

Phormidii trichomata fasciatira congesta et vagina communi mucosa apice clausa vel aporta inclusa. 
Tales fasciculi numerosi in stratum (quasi thallum) gelatinosum, passim amoso-divisum aggrcgati. 
Vaginte communes achromatica;, sa^pe laraellosa;, plus minus ampliata;, rarius indistinct^ et subnulla', 
evacuatae, pleruraque valde intumescentes. Trichomata Phormidii mode oscillantia, articulata et 
vaginata, rigida, recta vel ])arum curvula, in fasciculos funifornics plus minus dense contorta, apice 
soluta et divaricata. Cellulas propagatorias observare mihi contigit. (II.) 

Filaments fasciately placed together and included in a common mucous sheath with open or shut 
apex. A number of these fasciculi aggregated in a gelatinous stratum (pseudothallus), whicli is 
gelatinous, and here and there ramosely divaricate. Common sheath colorless, often lamellate, more 
or less enlarged, rarely indistinct and nearly wanting, when empty mostly markedly intumescent. 
Filaments oscillating like to those of Phormidium, articulate and vaginate, rigid, straight, or a little 
curved, more or less densely entangled into cord-like fasciculi, with the apex dissolved and dis- 
severed. 

Cli. repens, Ktz. 

Ch. terrestris, strato plus minus expanso, saturate ajrugineo-chalybeo aut olivaceo-fuscescente, 
mucoso-membranaceo ; tricboniatibus fequalibus in fasciculos filiformes, soepo valde elon- 
gatos, e vagina; communis apertura pcnicillatim cxsertos congestis; articulis diametro iequali- 
bus dissppimentis granulatis, apicnlo obtuse recto. (R.) 
Species, mihi ignota. 



22 FRESHWATER A L G .E OF THE UNITED STATES. 

^a6.— Common on dan.|. .arlli. West Roint, New York ; Bingham, Massacbusetts ; Provi- 
dence, Rhode Ishmd; 13aily, Silliman's Juurn., N. S., vol. iii. 

Terrestrial, stratum more or less expanded, deep rerusinous chalybeate, or olivaceous fuscous, 
mucous membranaceous; filaments equal, in filiform fasciculi, which are often much elongate 
and penicillately exserted from the open common sheath ; joints as long as broad, the dissepi- 
ments granulate ; the ape.x obtuse, straight. 

Genus LYNGBYA, Agardh. 

Trichomata inarticulata vel breve articulata, cellulis pcrdurantibus instructa. Yaginre sa;pe colo- 
rata;, erassa;, sa>i)0 himellonaj. 

Filaments not articulate, or shortly so, furnished with heterocysts. Sheaths often colored, thick, 
often lamellate. 

"L. niiirnlis, Aa. 

Filaments somewhat rigid, thickish, tortuous, very long, interwoven in a bright, grass-green 
stratum; annuli strongly defined. Ag. Syst., p. 74 ; Earv. Man. Ed., p. IGO; Conf. vmralis. 
Dillw., tab. 7, E. Bot. t. 1554. jS. aquatica. 

Eah. — Yar. /3. in pools of fresh water, Whalefish Island, Davis Straits. Dr. Lyall. 

The specimens are mi.xed with turfy soil. E.xcept in the submerged habitat, this agrees with 
the ordinary form. Intermixed with threads of the usual size and structure are others 
cohering in pairs, as in L. copulata, Harv., which is obviously only a state of this widely 
dispersed species. I have not received specimens of the ordinary L. muralis from America; 
but no doubt it is common on damp walls, &c., as in Europe generally." 

I have never identified this species, and have simply copied Harvey's account 
of it from the Nereis Boreali Americana, pt. III. p. 104. 

I.(. bicolor, Wood. 

L. trichomatibus siraplicibus, in ciEspites nigro-virides vel coeruleo-viridos dense intricatis, varie 
curvatis, plerumque inartieulatis, interdum breviter articulatis et ad genicula coutraetis; cytio- 
plasmate dilute ca3ruleo-viride, plerumque eopiosc granulato, saspe interrupto; cellulis perdu- 
rautibus cylindricis, stepe elongatis, saturate brunuejs, sparsissimis; vaginis firmis, achrois, in 
trichomata matura modice crassis. 

Syn.—L. bicolor, Wood, Prodromus, Proc. Amer. Philos. Soc, 18G9, 124. 

Eah. — In flumine Schuylkill prope Philadelphia. 

L. with the filaments closely interwoven into a blackish or bluish-green mat; filaments variously 
curved, simple, mostly inarticulate, sometimes shortly articulate with the joints contracted; 
cndochrome light bluish-green, mostly very granulate, often interrupted ; heterocysts cylin- 
drical, often elongate, deep brown, very few; sheaths firm, transparent, in old filaments 
moderately thick. 

Remarhs.—T\n^ species is abundant in the shallow water of the Scluiylkiil 
River, near Spring Mills, where it forms dark waving tufts a half inch or more in 
height, which are adiierent either to the bottom of the stream or to some firm sup- 
port, such as large growing plants, sticks fixed in the mud, &c. When examined 
with the microscope, these tufts arc seen to be composed of innumerable, very long, 
motionless, greatly curved filaments. They do not seem to be attached to tlieir 
support, but in the denser parts are woven into a very tliick mat, which apparently 
adheres en masse to the fixed body. These filaments are very rarely articulate, 



FRESn-WATER ALG Ji F THE U i\ 1 TE D ST A TE S. 23 

but, when tliey are, the joints are shorter than broad. The endochrome is mostly 
very granulate ; sometimes, however, it is much more homogeneous. The sheaths 
in the old filaments are rather thick, and frequently partially empty ; the exterior 
of such sheaths has often a rough, ragged look. The larger cells are very few in 
number. They are elongated cylinders with concave ends. I have found this plant 
in the Schuylkill River, just above Fairmount dam, in a younger state, and appa- 
rently without heterocysts. The threads near their ends had their endochrome 
distinctly articulate, like an oscillatoria, but elsewhere the protoplasm was continu- 
ous. It often contains numerous large granules resembling minute starch grains, 
which however fail, to exhibit the reaction with iodine. 

Fig. 7, a, pi. 1, represents a portion of the filament slightly magnified; fig. 7, h, a 
heterocyst from the same specimen more magnified ; fig. 7, e and </, are drawings from 
another specimen from the same locality, each magnified 800 diameters ; fig. 8, 
pi. 1, represents the form alluded to in the text as having been found in the 
Schuylkill lliver just above the dam. 

Family NOSTOCFIACE^. 

Trichomata simplicia, o cellulis distinctis coraposita, intcrilum vaginata, articulata, in gelatina 
iramersa, cellulis perdurautibus, et intevdum sporis porro instructa. 

Filaments simple, composed of distinct cells, sometimes vaginate, imbedded in jelly ; furnished 
with heterocysts and .sometimes with spores also. 

Remarks. — The nostochacefe are plants of simple construction, consisting of a 
more or less firm jelly in which are imbedded serpentine filaments, composed of 
numerous cells. These cells are mostly more or less globose, especially in the true 
nostocs, so that the filament has a moniliform aspect. They have not distinct walls, 
or at least any that can be distinctly seen by ordinary powers of the microscope, 
and are sometimes closely connected, sometimes rather widely separated. No 
nuclei are usually discernible ; I have, however, seen in some instances central 
spots, which were possibly of that nature. The filaments themselves are of various 
length, almost always tortuous, sometimes widely separated, sometimes closely in- 
terwoven. The gelatinous portions of the fronds are of various consistence — some- 
times semifluid, sometimes very firm, almost cartilaginous. 

The order is divisible into two families — the Noslvcs proper and the Spermosireo'. 

In the former, the outer portion of the frond is condensed and firm, forming a 
sort of outer coat or epidermis, which is sometimes quite distinct, but in other 
instances can scarcely be said to exist. 

In the filaments of a true nostoc are placed at irregular intervals cells, which 
are mostly larger than the others, and have thick, distinct walls. These cells con- 
tain very little or no chlorophyllous protoplasm. They are often, but by no means 
always, provided with numerous exceedingly attenuated, hair-like processes, or 
quiescent cilia. These bodies were supposed by Kiitzing to have some sexual 
value, and received from him the name of Spermatia. But, as their functions are 
entirely unknown, the name of heterocysts, first applied by M. Allman, is prefera- 
ble. They are the " connecting cells" of Thwaites. No one has as yet demon- 



24 PRESU-WATER A L G .E OF THE UNITED STATES. 

stratcd the existence of anything indicating sexuality in the nostocs proper, or 
shown any body at all wortliy to be looked upon as a spore. 

Their ordinary method of reproduction is simply a slight modification of that of 
growth. If a fragment of an actively growing nostoc is placed under the micro- 
scope, the filaments of it are seen to be irregular and distorted, thicker in one 
place than another, the cells misshapen, and sometimes apparently lumped and 
fused together. The formation of new filaments is taking place in such cases by 
the simultaneous growth and longitudinal segmentation of the cells of the old, and 
this may occur through the whole or in only a portion of the length of the latter. 
(ri. 2, fig. 10.) 

The filament of a nostoc is, in other words, capable of a double growth or de- 
velopment, the result in one instance being increase in its length, in the other the 
production of a new form like itself The first of these is brought about by a 
transverse division of the cells, so that out of each single cell two are formed, 
placed end to end, each daughter-cell at first only half the size of their parent, but 
soon attaining to its full stature. In the other case great increase in the size of 
the cell occurs almost consentaneously with a longitudinal or lateral segmentation, 
the cell dividing in the direction of its length, instead of transversely, so as to form 
two cells lying side by side instead of end to end. The misshapen filaments alluded 
to simply represent difi"erent stages of this change, which goes on until two perfect 
filaments lie side by side, to be finally more or less widely separated by the jelly 
which they secrete around themselves. 

This process of growth continues until the plant has arrived at its mature size, 
when it ceases. During this time the inner portion of the frond has been be- 
coming more and more liquid, and finally the outer epidermis bursts and the 
thoroughly softened inner portion is discharged. In this way, innumerable filaments 
are set free, which are endowed with a power of motion similar to, but much less 
active than, the gliding of the oscillatoria, by means of wliicli they are diff"used in 
the water. Scattered in this way, carried hither and thither by currents, each 
minute thread, fixing itself to some object, at last becomes the centre from Avhich 
a new plant is formed in a manner similar to that already described. 

In the second division of the Nostochacea\ the jelly is always much less firm 
than in the true nostocs, and is not condensed in the outer portions. The fronds 
are therefore soft, almost diffluent, and entirely shapeless. The filaments them- 
selves also diff"er from those of the true nostocs. There are no fixed diff'erences 
in the vegetable cells or heterocysfs, however, although the former are apt to be- 
come more cylindrical and the filament consequently less moniliform. It is espe- 
cially in the possession of distinct reproductive sporangia! cells that the differences 
are to be found. These are much larger than the ordinary cells, from which, in 
their first appearance, they arc not distinguishable ; but, when the frond has attained 
a certain age, the spore-cells begin to enlarge both in diameter and length, and 
finally assume a form and size apparently fixed within narrow bounds for each 
species, and surround themselves with distinct, often quite thick coats. It is very 
possible that the production of new individuals may take place by a detachment of 
portions of the frond and subsequent growth, as described in the Nustocs proper, 



FRESH-WATER ALG^ OF THE UNITED STATES. 26 

but increase of the species does certainly occur by means of these so-called spores. 
The growth of the plant takes place in the same way as in the true nostocs. 
The filaments increase in length by transverse division and consequent multiplica- 
tion of the cells, whilst new filaments are formed by the consentaneous longitudinal 
division of all the cells of a filament. 

The spores of a CyUndrospennum have the power of germinating after prolonged 
desiccation, they having been successfully cultivated even from specimens long 
preserved in the herbarium. Their development has been carefully and success- 
fully studied by M. Thuret. According to this authority the first change consists 
in an elongation of the spore, which ruptures the wall of the sporangium, pushing 
a portion of it before it. Directly after this the spore undergoes division, so that 
out of it is formed a little torulose filament, composed of four or five cells. Growth 
takes place at both ends, but more rapidly at the free one. The new cells formed 
are smaller than those which arise directly from the spore, but, finally, all the arti- 
cles assimilate. The wall of the sporangium remains attached for a long time to 
the end of the filament forming a little cap to it. The heterocysts, according to 
Thuret, at first are indistinguishable from the ordinary cells, but after awhile the 
granules in them begin to disappear, the color to pale, the outer wall to become 
apparent and grow thicker, until at last a perfect " connecting cell" is educed. 
I have, myself, carefully watched the early development of the spores of a cylin- 
drospermum, and can confirm, in all essential particulars, the description Thuret 
has given of the process. Fig. 10, pi. 2, represents a partially formed filament, 
to which the empty sporangium is still attached. 

As no sexual reproduction has as yet been shown to exist among the Nostocha- 
cece^ it is very evident that their whole life-history is not comprised within the 
changes which have been detailed. It has long been known that the gonidia of 
many lichens have the power of independent existence, i. e. that when they are 
discharged from their thallus they can continue 'to live and multiply, if circum- 
stances favor them, without giving origin to a new thallus. This, and the great 
similarity of structure between the nostocs and the lichen genus CoUema, has 
suggested a possibly close relation between the two. The first observer, I believe, 
who asserted that they were difl"crcnt stages of the same plant was Dr. Hermann 
Itzigsohn. 

His observations are, however, rendered of so little value by his own statements 
that it is not necessary to review them here. Thus, he says, that after seven years' 
observation he had yet to ^ee a true one called algap, that the DesmkUce are, at 
least, two-celled, &c. &c. The most weighty observations upon this subject are 
those of Professor Julius Sachs and of J. Baranetzky — the former published in tlie 
Botanische Zeitung for 1855, the other in the Bulletin of the St. Petersburg 
Academy for 1867. 

Professor Sachs states that he watched a whole bed of Nostoc commttne deve- 
loping into ColJcma hulbosum. He says that the peculiar Collemoid threads first 
appeared as little lateral offshoots or prolongations from the cells of the nostoc 
filaraent, and rapidly developed into well-formed collemoid filaments. Every 
possible stage from the typical nostoc to the typical collema was seen repeatedly. 

4 February, 1872. 



26 



FKESn-WATER ALGJ^ OF THE UNITED STATES. 



The (Icvclopnicnt of the distinguisliing threads of the coUema out of the ordmary 
nostoc-ccll has never been confirmed by any other observer ; but it seems to me 
that it must be at least provisionally accepted, although De Bary expresses some 
doMbt of it. {Morphol. und Physiol, der Pdzc, FlecJdcn, &c., p. 290.) 

The researches of M. Baranetzky were directed to the developing of a nostoc 
out of a collema. Hicks and other observers had previously stated that they had 
seen this, but none of them had given sufficient details as to the method of their 
observations, to be fully convincing. 

M. Baranetzky placed sections of actively growing fronds of CoUema pidposum, 
Ach, upon smooth, damp earth, using all proper precautions to prevent external 
influence. After some days the sections became less transparent and intensely green 
from the crowding of the gonidia, which were noAV arranged in curved rows closely 
rolled together into balls. Upon the upper surface of the section appeared little 
gelatinous balls or warts, which contained gonidia in rows, and gradually developed 
tyincal nostoc forms, whilst on the edges of the sections appeared little colorless 
wart-like masses of jelly, in which, after some time, appeared gonidia, some of 
which developed into the typical nostoc form, others into true collemoid plants. 

Mr. Baranetzky further states that he watched the body of the section gradually 
change by the continual growth and increase of the rows of gonidia, before alluded 
to, and by the disappearance of the collemoid threads, until at last the whole 
mass of the tissue of the lichen had been converted into a true nostoc, which was 
finally identified as Nostoc vesicnrium, D. C* 

I have no observations of my own to offer upon this subject; but think enough 
has been done to show not only that the nostocs proper have very close relations 
with the collemoid lichens, but that they are probably a peculiar phase in their 
life-history. This being the case, it may seem a perfectly superfluous work to 
indicate species amongst the nostocs. To any one who has given much study to 
the fresh-water algfe, the reply t(? this Avill immediately suggest itself; namely, that 
in tlic present state of the science it seems impossible to avoid it; they are so 
commonly thrust at one by collectors, amateurs, &c., are so distinct, are so often 
the subject of tongue and pen, that tliey must have a name. The idea that at- 
taches to the term species is at present not a very definite one; that there are, 
however, amongst the nostocs fixed forms, which do not change into one another, 
and can readily be distinguished, I have no doubt. Such forms are herein de- 
scribed. If they be only life stages of lichens, I have no doubt that it will finally 
be found that each so-called species of nostoc has its own peculiar so-called species 
of lichen, from which it alone springs, and into which alone it can develop. It 
seems to me, then, that as yet no cause for abandoning the specific names of the 



* In order to aid any one desirous of going over tliis sulijcct more thoroughly, a list of papers is 
appended: — 

Yentenab und Cassini Opuscula Phytolog., 1817, vol. ii. p. 3G1. 

Dr. Hermann Itzigsohn. Botanische Zeitung, 18.54, p. .521. 

Prof. Julius Sachs. Botanische Zeitung, 18.55, p. 1. 

Bayrhoffcr. Botanische Zeitung, 1857. 

Hicks. Journal sf Microscopical Science, ISCl, ]). 90. 

Baranetzky. Bulletin de la Socicte des Sciences Xat., St. Petersburg, vol. xii. p. 418. 



FRESn-WATER ALG.E OF THE UNITED STATES. 27 

nostocs has been shown, but only reason to study also their relations with the vari- 
ous collema. 

In regard to the Sperm osirea', there is as yet no direct proof whatever connect- 
ing them with lichens. It is very possible that they are not so closely related to 
the true nostocs as is generally believed, so that the probabilities of their being 
lichens are at present £o remote, that for the systematist to refuse to take note of 
their distinct forms, seems to me most unwarrantable. 

Subfamily NOSTOCE.E. 

Thallus peridcrmate plus minus distineto instructus, sporis destitutus. 

Tballus provided with a more or less distinct integument, and destitute of spores. ' 

Genus NOSTOC, Vaucher, (1803.) 

Thallus gelatinosus, varie coloratus, aut globosus yel subglobosus aut foliaceo-mcmbranaceus et 
irregulariter expansus, sffipe bullatus. Trichomata plus minus monilifovmia. Cellulaj perdurantes 
exacte sphsericse vel rare oblougse. 

Thallus gelatinous, variously colored, either globose or subglobose, or foliaceously membranous 
and indefinitely e.xpanded, often a bulla. Filaments more or less mouiliforme. Heterocjsts exactly 
spherical or rarely oblong. 

a. niallus globo!<us vel subglobosus, vel disciformis. 
Tfiallus globose, subglobose or discoid. 

I¥. Anstinii, Wood, (sp. nov.) 

N. subglobosum, parvuni, plerumque niagnitudine ovorum piscium, rare ad 2", fuscescente, 
vel nigrcscente, interduni durum intordum submolle, superficie saepo corrugata ; tricho- 
matibus varie curvatis, dense intricatis vel distantibus et laxissime intrieatis, viridibus, 
fuscescentibus, subplumbeis vel luteo-brunneis, in thallis minoribus ssepe distincte vaginalis, 
in thallis majoribus hand vel indistiucte vaginalis ; articulis maturis globosis, stepe didvrais, 
crasse granulatis; cellulis perdiirantibus artieulorum diamctro ferpialibus vel paulo majoribus, 
globosis, interjectis vel terminalibus, plerumque sparsis. 

Diam.—CcW. Teg , t/jj/— t^|,jo" = .0020"— 00033"; cell. i>erduraut, .00033". 

Hab. — in rupibus irroratis, New Jersey. (Austin.) 

Subglobose, small, mostly the size of fish-eggs, Init reaching the diameter of nearly two lines 
fuscous or blackish, sometimes very hard, sometimes much softer; surface often corrugated* 
filaments variously curved, densely intricate or distantly and loosely interwoven, greenish, 
fuscous, subplumbeis or j-ellowish-brown, in the smaller fronds often distinct!}' vagiuate, in 
the larger indistinctly or not all vaginate; mature joints globose; often didymous, coarsely 
granulate; hetorocysts equal to the diameter of the other joints or a little larger, globose 
interspersed or terminal. 

Remarlcs. — The fronds of this distinct species vary greatly in appearance; the 
larger of them are often almost colorless, and, when viewed with the microscope, 
are seen to be composed of a transparent colorless jelly, with remarkably large 
filaments scattered through it. These filaments are generally without sheaths, 
though occasionally a sheath can be faintly traced. The smaller fronds are much 
firmer than the larger and are more decidedly colored. Some of them are entirely 
opaque, looking simply black when viewed by transmitted light under the micro- 
scope. In these the filaments are densely crowded together, often misshapen and 



2S FRESn-WATER A L G ,E OF THE UNITED STATES. 

provided with distinct broad browiiisli sheaths : every gradation exists between 
tlicsc forms and the tirst described fronds. The heterocysts are quite uniform iu 
size, agreeing in diameter with the largest vegetative cells, they are always single. 
This species is most nearly allied to N. ichthyoon, Kabenh. ; from which it is 
separated by the differences in the sheaths, the greater size of the filaments, and 
the m\"\e heterocysts. It gives me great pleasure to dedicate the species to Mr. 
Austin, by whom it was collected near Gloucester, New Jersey, growing amidst 
mosses on rocks. 

I¥. priiiiirorine, (Roth,) Agh. 

N. magnum, gregarium, noncohaerens, globosum, magnitudine pisi, pruni majoris et ultra, oliva- 
ceum vel saturate serugincum, rotate provecta fusco-nigrescens, baud raro cavum, lajvissiraum, 
iutus aquosum, peridermate eoriaceo subacbroo ; tricbomatibus subEequalibus, liic illic tumidis, 
lase iutricatis; articulis globosis, plerumque compressis, saspe didymis, arete connexis; cel- 
lulis perdurautibus articulis duplo majoribus, plerumque terminalibns, rarius iuterjcctis. R. 
Species mibi ignota. 

Z)/a??i.— Artie. 0.00024"— 0.0003" ; cell, perdur. 0.0003—0.00045". (R.) 

Syn. — N. pruniforme, (Roth,) Ag. Rabenhorst, Flora Europ. Algarum, Sect. II. p 108. 

Eab. — Maine. Leidy. 

Large, gregarious, not cobering, globose, varying from the size of a pea to a large plum, or 
even beyond this, olivaceous or deep serugineous, in old age blackish fuscous, often hollow, 
very smooth, within watery, periderm coriaceous, somewhat transparent; filaments subequal, 
here and there swollen, laxly intricate; articles globose, mostly compressed, often twofold, 
closely connected; heterocysts twice the size of the vegetative cells, mostly terminal, rarely 
interspersed. 

Bemarks. — 1 have never found this species ; but some years since some speci- 
mens, sent to the Academy of Natural Sciences of Philadelphia from Maine, were 
identified by Professor Joseph Leidy as belonging to it. 

IV. Temicosiiiu, (Linn.) Vauch. 

N. magnum, gregarium, bipollicare et ultra, subglobosum, soepe lobatum, verruculosum, irrora- 
tum, initio soliduni, postremo cavum, vesiciforme, saturate brunneo-viride ; peridermate mera- 
branaceo-coriaceo, olivaceo-fuscescente; tricbomatibus varie curvatis, centralibus parcioribus 
et laxissime intricatis, peripbericis densius intricatis; articulis oblongis, rare globosis, arete 
connexis, crassc granulatis ; cellulis perdurautibus interstitialibus vel terminalibus, sphajricis, 
articulorum diametro duplo majoribus. 

Diam.— Cell vegetativ. .000166"; cell, perdurant. .000233". 

Syn.~N. verrucosum, (Linn.) Vauch. Rabenhorst, Flora Europ. Algarum, Sect. IL p. 176. 

Eab. — In fonte. Centre County, Pennsylvania. 

Large, subglobose, often lobed, warty ; gregarious, two inches in diameter, growing under water, 
fixed, in the Ijcgiuning solid, afterwards hollow, bladder-shaped; periderm membranaceous, 
coriaceous, olivaceous-fuscous; filaments variously curved, centrally fewer, and laxly intricate, 
towards the outside much more close; articles oblong, rarely globose, closely connected, 
coarsely granulate; heterocysts interstitial or terminal, spherical, twice the size of the other 
joints. 

RemarJcs.—ln the summer of 1869, 1 found a nostoc growing in great abundance 
in a very cold, large, limestone spring in Centre County, Pennsylvania, which I 



FRESH-WATER ALG^ OF THE UNITED STATES 29 

have referred to N. verriicosum with some little hesitation. Some of the fronds 
were smoothish, others very decidedly warty. My specimens are old plants, 
which have become hollow by the discharge of their internal contents. It is pos- 
sibly on this account I have not been able to verify the minute description given 
by Professor liabcnhorst. As the latter may not be accessible to some of those 
who consult these pages, I append the latter part of it, which differs from that 
given by myself from the American plants. 

" Trichomatibus flexuoso-curvatis, quasi triplici ordinc ; centralibus parcioribus, 
laxissimc implicatis, apices versus plus minus attenuatis, articulis oblongis, sub- 
distantibus, periphericis densius sa?pe densissime intricatis, basi hand raro cellulis 
biseriatis, articulis globosis, arete connexis, extremis (nonnisi in thallo vctusto 
occurrunt) subflagelliformibus, articulis oblongis, cylindraceis sphtericisque simul 
immixtis, distantibus; cellulis perdurantibus spha?ricis intcrjectis terminalibusque, 
nonnunquam pluribus simul seriatis articulorum diametro duplo triplove majoribus." 

According to Professor Harvey (Nereis Bor. Amer., part iii. p. 114), this species 
has been collected by Dr. Lyall in pools of fresh water, Isle of Disco, and at 
Beechey Island, Arctic Regions; also by Mr. Fendler at Sante Fe, Xew Mexico. 

IV. alpinuni, Ktz. 

N. rupestre, immersum ; tballo suborbiculare, erecto, membranacco, ad ^=| unciam lato, ad 
lineas duas vel tres crasso, tenaci, saturate olivaceo-fusco, liEvi, stepe rugoso-plicato, cum mar- 
gine integro et plerumque incrassato; tricbomatibus varie curvatis, lase vel nonnihil dense 
implicatis; articulis fuscis vel dilute lerugineis plerumque globosis, ssepe subtiliter graiuilatis, 
arete connexis; cellulis perdurantibus spha;ricis plerumque articulorum diametro paulo ma- 
joribus, interdum subsqualibus, intcrjectis vel terminalibus. 

Z)ia?ji.— Artie, vegetativ. .00016"— 00023" ; cell. perd. .00026. 

Syn. — " N. alpinum, Ktz. Phycol. General., p. 206, No. 10." Rabenhorst, Flora Europ. 
Algarura, vol. ii. p. 174. 
" N. Sutherlandi, Dickie." Harvey, Nereis Boreali Americana, part iii. p. 114. 
" N. crisiatum, Bailey." Harvey, Nereis Boreali Americana, part iii., 1S51, p. 114. 
Growing attached by its margin to the- rocks in running water; thallus suborbicular, erect, 
membranaceous ^ — | an inch high and 1 — 3 lines thick, very tenacious, deep olive-green, 
smooth, often rugosely plicate especially at the base, with the margin entire, rounded, and 
mostly thickened; filaments variously curved, laxly or somewhat densely interwoven; arti- 
cles fu.scous or greenish, mostly globose, often finely granulate, closely connected; heterocysts 
spherical, generally a little larger than the ordinary cells, sometimes about ecjual to them, 
interspersed and terminal. 

Remarhs. — This interesting little plant was found in the mountain rivulets 
near West Point, New York, by the late Prof. Bailey, and received from him the 
specific name cristatum, first published in Harvey's work on the North American 
Alga?. I have myself seen it growing in very great abundance in rapid mountain 
streams in the central portions of this State. It is doubtless, therefore, an inhabi- 
tant of the whole Alleghany range. In the low country, east or west of these 
mountains and their outlying hills, I do not know of its having been found. I have 
very recently received specimens of a nostoc from Screno Watson, Esq., undoubt- 
edly belonging to this species, which were collected by himself, in cold streams in the 
Clover Mountains, Nevada, at an altitude of 11,000 feet. Under the name of M. 



30 



FRESlI-WATEll ALG^ OF THE UNITED STATES. 



SatlicrlamUl a iiostoc has been described by Mr. Dickie, which was collected in the 
neighborhood of Baffin's Bay, and must be referred to tliis species, although the 
description given of it is very imperfect. x\gain, N. alpinum, Ktz., appears to be in 
all respects similar to the North American forms. So that this cosmopolitan little 
plant seems only to ask for a cold shelter, and it flourishes. Tlie Alps, the Alle- 
ghanics, the Rocky Mountains, and the cold North are its homes. To those who 
believe in a single centre for a species, the suggestion that it has spread across 
the globe, through the arctic regions, and followed our mountain chains southward, 
will of course present itself. 

As I have seen it, tlie plant is very abundant where it grows, five, six, twelve, 
or more of the little fronds adhering to a single pebble. The frond is generally 
lono-er than broad, the margin sometimes sinuous but never, as I have seen it, 
lobate or incised. It appears finally to burst and discharge its inner portion, 
whilst the outer cortical portion, now a little vesicle containing a globule of air, is 
set free and floats down the stream. 

]\. depressuni, Wood, (sp. nov.) 

N. euoi-miter suborbicularc, minutura, gregarium et intcrdum aggregatum muscos iramersos 
adhsevens, raangitudine seminis sinapeos vel parvius, durum, elasticum, subnigris ; peridermate 
firme, achroo; trichomatibus plerumque laxe intricatis, baud vaginatis ; articulis globosis, 
plerumque modice arete coimcxis, rare distantibus ; ccUulis perdurautibus globosis, ceteris 
paulo majoribus. 

Diam. — Artie, veget. max; .0002"; cell, perdurant. max .00029. 

Eab. — In rivulis, New Jersey (Prof. Austin). 

Irregularly suborbicular, gregarious and sometimes aggregated, elastic, blackish, about the size 
of a mustard-seed, or smaller, adhering to immersed mosses ; periderm firm, translucent; fila- 
ments not vaginate, mostly loosely interwoven; joints globose, generally rather closely con- 
nected, rarely distant ; heterocysts rather larger than the other. 

Remarlcs. — This plant was found by Prof. Austin attached to a brook-moss 
{Dkhelyma), growing in a rapid rivulet in Northern New Jersey. 

The minute fronds sometimes are so thin and spread out as to be almost folia- 
ceous. The species I take to be most nearly allied to N. lichenoides of Europe, 
from which it is, however, apparently distinct. In the American plant the fila- 
ments and heterocysts are a little larger, and the frequent elliptical cells of the 
European plant arc wanting. The frond also apparently does not grow so large as 
the European, and is further distinguished by its flat, discoid form. In many of the 
specimens examined the filaments are very thick, irregular, and contorted, the cells 
being fused together. In other instances, a filament will be plainly double, and 
every grade between these conditions is present. This is plainly owing to a process 
of growth, to the cells enlarging and dividing laterally so as to form new filaments. 

I¥. ^ipliaci'iciiiu, (PoiRET,) Vauch. 

N. globosum, interdum oblongum vel ovale, gregarium, sa;pius aggregatum, raro tamen conflu- 
ente, durum, elasticum (in SEtate provecta iutus molie et subaquosum?), olivaceum, magnitudine 
seminis sinapeos, ad ccrasi parvi ; peridermate firrao, pellucido; trichomatibus intricatis, luten- 
lis, aut prasiuatis ant dilute cajruleis; articulis plerumque subquadratis, interdum transverse 



FRESH-WATER ALGiE OF TUE UNITED STATES. 31 

subovalibus, arete connexis; cytioplasmate graiiulato; ccllulis perdurantibus intcrjectia 
termiualibusque, sphiericis. 

Diam.—ATt\c. diam. loug. ^^Vs" = -000125" ; transv. jj^'^^g" = .00017"; cell, pcrdurant. 
„Vt" = -00029". 

Sr/71. — N. sphxricum, (Poiret ) Vadch. Rabenhorst, Flora Europ. Algarum, Sect. II. p. 161. 
Hab. — In fontibus, prope Philadelphia. 

Globose, sometimes oblong or oval, gregarious, but rarely confluent, hard, elastic (in advanced 
age within soft and watery?), olivaceous, varying from the size of a mustard-seed to that of 
a small cherry; periderm firm, pellucid; filaments intricate, yellowish, greenish or bluish; 
articles mostly subquadrate, sometimes transversely suboval, closely connected ; cytioplasni 
granular; heterocysts interspersed or terminal, spherical. 

Remarks. — The specimens from which the above diagnosis was prepared were 
found at Spring Mills, adhering to mosses and twigs in the water. The fronds 
were remarkable for their firmness and elasticity. The color was a didl, rather 
greenish, olive ; that of the filaments varied from a decided greenish to a marked 
yellowish, or sometimes an almost silvery bluish tint. The heterocysts Avere rather 
few in number, and were either terminal or interstitial, sometimes they were Avith- 
out, sometimes with evident endochrome. The length of the general articulations 
varied a good deal, it was, however, mostly less than their breadth, which seems 
quite constant. When kept in water in the house, this species softens, and the 
periderm as it were peels ofi", allowing the interior to disperse itself as it gradu- 
ally becomes more and more diffluent. Most of the fronds afforded ample evidence 
of their method of growth by the presence of filaments in every stnge of division. 

Fig. 10, pi. 2, represents filaments of this species. 

I¥. Cieriileiim, Ltngb. 

N, minimum, sajpe microscopicum, enormiter globosum vel subglobosum, affi.xum, grcgariuni, 
sejunctum vel aggregatum ; trichomatibus valde insequalibus ; articulis elongato-cylindrafci.';, 
vel acute ellipticis, vel perfecte ellipticis, vel globosis, vel subglobosis, vel subquadrangulis, 
sejunctis et nonnihil distantibus vel arete connectis aut confluentibus ; ccllulis perduranlibus 
globosis, passim intcrjectis termiualibusque, ceteris duplo vel subduplo majoribus. 

Biam.—CeW. perdurant, .000303; cell, vegetat. plerumque .00012— OOOIGG" ; rarius .0001— 
.00021. 

Syn. — N. cseruleum, Ltngb. Rabenhorst, Flora Europ. Algarum, Sect. II. p. ICV. 

Hah. — Inter muscos, New Jersey (Prof. Austin). 

Very small, often microscopic, irregularly globose or subglobose, affixed, gregarious, separate or 
aggregated ; filaments very unequal ; articles elongate-cylindrical, or acutely elliptical or 
perfectly so, or subglobose, or globose, or subquadrangnlar, .separate and somewhat distant 
or closely connected or, confluent ; heterocysts globose, interspersed or terminal, double or 
about double the size of the other cells. 

Remarks. — I am indebted to Mr. Austin for specimens of this species collected by 
him in Northern New Jersey. The fronds grow attached to moss and are very mi- 
nute, the largest I have seen being not more than half a line in diameter. The 
filaments are remarkable for their inequality, which is often very perceptible in 
diff'erent parts of the same filament. I have referred my specimens to N. ca:rulcum — 



32 FRESn-WATER ALGJ3 OF THE UNITED STATES. 

the only differences between them and the European plant are that they arc not so 
large, and do not agree in color, many of them being browner; but these are certainly 
insufficient grounds for separating them. Prof. Rabcnhorst speaks of observing 
the contents of lieterocysts dividing up so as to form a little colony of cells, which 
finally break through the maternal wall. I have only studied mounted specimens, 
but have seen very clearly heterocysts in which this process was taking place. 

Hf. piinctatiiiu, Wood, (sp. nov.) 

N. terrestre ; tliallo expaiiso orbiculare vcl nonniliil irregulare, tenuissimo, jerngineo, parvo 
niembrauaceo, pellucidulo; trichoiuatibus laxo intricatis, varie curvatis, articulis globosis vel 
swpius ellipticia, plcrumque medio pellucidulis, laxe connexis ; cellulis perduraiitibus termi- 
nalibus vel interjectis. 

Z)mm.— Cell, vegetat. tsbtjt" = -OOOIOG ; coll. pcrdur. j^J^s" = .00033. 

Hab. — In terrestre, New Jersey, (Prof. Austin.) 

Terrestrial ; thalliis expanded, irregular or orbicular, very thin, Ecruginous, small, membranous, 
pellucid ; filaments loo.sely interwoven, variously curved, joints globose or often elliptical, 
mostly pellucid iu the centre, loosely connected ; heterocysts terminal or interspersed. 

Remarks. — Mr. Austin has kindly sent mc the only specimens I have seen of this 
species; they are labelled "Damp Ground, Sept." The fronds, which are often 
aggregated, are very small and exceedingly thin, especially in their central por- 
tions, where they are quite translucent ; in form they are often circular, some- 
times quadrangular, sometimes quite irregular. As to size, most of them are not 
more than two lines in diameter, some three, or possibly five lines. The margins 
are often reflexed and thickened, especially in the smallest fronds. Two kinds 
of filaments are visible ; 1st, those which I take to be in a perfected quiescent 
state ; 2d, those which are in active growth. The former are composed of globose, 
or more commonly elliptical joints, which are remarkable for the possession of a 
central translucent, almost colorless spot, the endochrome apparently being arranged 
in a ring around the outer part of the cell. This is, however, occasionally want- 
ing. The filaments, which are in active growth, are very irregular in form, often 
much broader than the others; their cells very irregular and sometimes fused 
together into one mass. The measurements given in the diagnosis were taken 
from the filaments of the first kind. 

h. Thallus indefinite expansus. 
Thallus indefinitely expanded. 
I¥. Cesatii, Bals. 

N. terrestre ; thallo longe latcque oxpanso, gelatinoso-merabranacco, viridi-flaveseente ; tricho- 
matibus flexuoso-curvatis, sublaxe implicatis, pallida aerugineis ; articulis sphsericis, laxe vel 
arctius connexis ; cellulis perduraatibus sphoericis, et interjectis et terminalibus. 

Z>mm.— Artie. .00016— .0002; cell, perdur.— .00033". 

Syn.—N. Cesatii, Bals. Rabenhorst, Flora Europ. Sect. II. p. 175. 

Hab.— In terrestre, Kansas (Prof. Parry) ; Texas (Prof. Ravenol). 

Terrestrial; thallus broadly and indefinitely expanded, gelatinous-membranaceous, yellowish- 
green; filaments flexuously curved, rather laxly implicate, pale-greenish; articles spherical, 
laxly or more closely connected ; heterocysts sjjhcrical, both interstitial and terminalibus. 



FRESH-WATER ALG^ OF THE UNITED STATES. 33 

Remarlcs. — This plant was sent to me by Dr. C. C. Parry, from whose letter the 
following is extracted: " I send enclosed specimens of a singular land Alga? which 
I met with in tliis vicinity ; lightly attached to bare patches of soil interspersed 
with buffalo grass. In the adjoining bluflfs are cretaceous shales full of seams and 
layers of selenite, from the decomposition of which the bottom soil becomes 
strongly impregnated with various saline matters. The present season has been 
characterized by unusual quantities of rain, causing extensive floods over what is 
usually a dry, arid district." 

The agreement between the mature forms is essentially perfect. There can be 
scarcely any doubt as to the identification, although I have not seen the Ameri- 
can plant in its young state. The fronds appeared to be 1 — 2 lines in thickness, 
with its surface smooth, or sometimes with close subparallel ridges or wrinkles. 

According to Rabenhorst, the young European N. cesatii is in the beginning 
globose, and pale golden-yellow ; soon, however, bursting and spreading out into an 
indefinitely expanded thallus. 

Among the algse collected by Prof Ravenel in Texas is a Nostoc, labelled " On 
Mud Flats, Cedar Bayou, Harris Co.," which comes so close to N. cesatii^ that I 
think it must be referred to it. It differs only in being more olivaceous, some- 
what firmer and in the size of the heterocysts — the largest of the latter which I 
have examined, attaining the size only of .00027". The largest vegetative cells are 
.00017 in diameter. 

I¥. calcicola? Ao. 

N. tliallo irrogulariter expanse, enormiter siiblobato, tenue, membranaceo, cartilagiaeo, elastico, 
pellucido, aut laete viride, vel brunueo, vel dilute viride, irrogulariter undulato plicato vel 
buUatoo; peridermate pleruraque subaullo; trichomatibus cum filis leptothrichoidei-s ramosis 
intcrmixtis, flexuosis, plerumque distantibus, rarissinie e cellulis biseriatis compositis ; cellulis 
subglobosis, oblongis, ovalibus, cum ceteris ellipticis intermixtis, plerumque laxe connexis; 
cellulis perdurantibus spusericis, iaterjectis et terminalibus. 

Diam.—Xvi. 7A5"— loJW = .0001"4— .0001"; cell. V^rAn^: j^^i^-s"—s^W = .0003"— 
.0002". 

Syn. — N. calcicola, Aa. Rabenhorst, Flora Europ., Sect. II. p. 174. 

Hah. — In rupibu.s, Georgia. (Prof. Ravenel.) 

Thallus irregularly expanded, membranaceous, thin, cartilaginous, elastic, pellucid, bright green, 
pale green or brownish, thin, irregularly undulately plicate or bullate ; periderm mostly 
scarcely distinguishable ; filaments intermixed with branched leptothrix filaments, flexuous, 
mostly distant, very rarely composed of biseriate cells ; cells subglobose, oblong, oval, inter- 
mingled with elliptical ones, mostly loosely connected ; heterocysts spherical, interspersed or 
terminal. 

Eemm-ks. — This species is one of those sent me by Dr. Billings. It was collected 
near Catoosa Springs, Georgia, by Prof. H. W. Ravenel. In the dried state it is 
of a dirty olive-green, and very much wrinkled and irregular on its surface. The 
largest specimens are about an inch long. There is no very distinct periderm, 
although in some places the filaments are placed more closely together on the outer 
portions of the frond. This plant seems to agree with the descriptions of the 

o March, 1873. 



34 FRESn-WATER A L G vE OF THE UNITED STATES. 

European S. cakicola, from wliicli it differs somewhat, however, in having its hete' 
rocysts both terminal and among tlic cells, and also somewhat in their size. 

I¥. calidariiim, Wood. 

N. thallo maxinio, indefinite expanse, aut membranaceo-coriaceo vel raembranaceo-g-elatinoso 
vel mcnibraiiaceo, aut Irote virdi vel sordide olivaceo-viridi vel olivaceo-brunneo, irregulariter 
profunde laciniato-sinuato, ultimo eleganter laciniato; tricliomatibus intequalibus, interdum 
flexuoso-curvatis, plerumque subrectis et arete conjunctis, in forniis duabus occurrentibus : 
forma altera parva, viridi, artieulis eylindncis, cum cellulis perdurantibus hie illic interjectis, 
vaginis interdum obsoletis, sa;pius diffluentibus; forma altera maxima, artieulis globosls vel 
oblongis, aurautiaco-brunnca, cellulis perdurantibus ab artieulis ceteris baud diversis. 

Biarn.—Formoi prima; articuli maxiini jijj^^ unc. ; cellule perdurantis ^^jVu unc. FornitB 
secundre articuli long, s^^w to tsucu ""c., hit. jj^Vu to ^^\^, articuli globosi ^gVuto ^^Vir ""c. 
Syn. — N. calidariuni, Wood, American Journal of Science and Arts, 1869. 
Hab. — "Benton Springs, Owen's Valley, California" (Mrs. Partz). 

Thallus very large, indefinitely e.xpanded, either membrano-coriaceous or membrano-gelatinous 
or membranaceous, either bright green or dirty olive-green or olive-brown, irregularly pro- 
foundly lacinlately sinuate, finally elegantly laciniate ; filaments unequal, sometimes fiexu- 
ously curved, but mostly straightish and closely conjoined, occurring in two forms ; the 
one small, green, with cylindrical joints, the heterocysts scattered here and there, the sheaths 
sometimes absent, often diffluent; the other form very large, with globose or oblong articles, 
orange-brown, the heterocysts not different from the other cells. 

Remarks. — Numerous specimens of this species were received from Mrs. Partz, 
who collected them in Benton's Spring, a thermal water situated in the extreme 
northern point of Owen's Valley, California, sixty miles southwest from the town 
of xVurora. The following extract from a letter of Mrs. Partz describes the place 
and mode of their growth more minutely. 

" I send you a few samples of the singular vegetation developed in the hot springs 
of our valley. These springs rise from the earth in an area of about eighty square 
feet, which forms a basin or pond that ponrs its hot Avaters into a narrow creek. 
In the basin are produced the first forms, partly at a temperature of 12-4° — 135° 
Fahr. Gradually in the creek and to a distance of 100 yards from the springs are 
developed, at a temperature of 110° — 120° Fahr., the Algfe, some growing to a 
length of over two feet, and looking like biniches of waving hair of the most beau- 
tiful green. Below 100° Fahr., these plants cease to grow, and give way to a slimy 
fungus growth, though likewise of a beautiful green, which, finally, as the tempera- 
ture of the water decreases, also disappears. They are very difficult to preserve, 
being of so soft and pulpy a nature as not to bear the least handling, and must 
be carried in their native liot water to tlie house, very few at a time, and floated 
upon paper. After being taken from the water and allowed to cool they become 
a black pulpy mass. But more strange than the vegetable are the animal organ- 
izations, whose germs, probably througli modifications of successive generations, 
have finally become indigenous to these strange precincts. Mr. Partz and myself 
saw in the clear water of the basin a very sprightly spider-like creature running 
nimbly over the ground, where the water was 124° Fahr., and on another occasion 
dipped out two tiny red worms." 



FRESH-WATER A L G yE OF THE UNITED STATES. 35 

In rcijard to the temperatures given, and the observation as to the presence of 
animal life in the thermal -waters, Mr. William Gabb, of the State Geological 
Survey, states that he has visited the locality, knows Mrs. Partz very well, and that 
whatever she says may be relied on as accurate. 

The color of the dried specimen varies from a very elegant bluish-green to dirty- 
greenish and fuscous-brown. After somewhat prolonged soaking in liot water, tlie 
specimens regained apparently their original form and dimensions, and were found 
to be in very good condition for microscopical study. 

The plant in its earliest stages appears to consist simply of cylindrical filaments, 
which are so small that they are resolved with some difficulty into the component 
cells by a first-class one-fifth objective. Fronds composed entirely of filaments of 
this description were received. Some of these were marked as " first forms," and 
as having grown in Avatcr at a temperature of 160° Fahr. Probably these were 
collected immediately over the spot where the heated water bubbled up. At this 
temperature, if tlie collection made is to be relied on as the means of judging, the 
plant does not perfect itself To the naked eye these "first forms" Avcre simply 
membranous expansions, of a vivid green color and indefinite size and shape, 
scarcely as thick as writing-paper, with their edges very deeply cut and running 
out into a long, waving, hair-like fringe. Other specimens, which grew at a much 
lower temperature, exactly simulated those just described, both in general appear- 
ance and microscopical characters. These, I believe, were the immature plant. 

The matured fronds, as obtained by the method of soaking above described, were 
"gelatinous membranous," of a dirty-greenish or fuscous-brown at their bases, and 
bright green at their marginal portions, where they were deeply incised and finally 
split up into innumerable hair-like processes. Proximally they were one, or even 
two, lines in thickness, distally they were scarcely as thick as tissue paper. Their 
bases were especially gelatinous, sometimes somewhat translucent, and under the 
microscope were found to have in them only a few distant filaments. 

Two sets of filaments were very readily distinguished in the adult plant. The 
most abundant of these, and that especially found in the distal portions of the 
fronds, were composed of uniform cylindrical cells, often enclosed in a gelatinous 
sheath. The diameter of such filaments varies greatly; in tlie larger the sheaths 
are generally apparent, in the smaller they are frequently indistinguishable. 

In certain places these filaments are more or less parallel side by side, and are 
glued together in a sort of membrane. It is only in these cylindrical filaments 
that I have been able to detect heterocysts, which are not very different from the 
other cells; they are about one-tliird or one-half broader, and are not vesicular, but 
have contents similar to those of tlie other cells. In one instance only was I able 
to detect hairs upon these heterocysts. 

The larger filaments are found especially near the base and in the other older 
portions of the frond. Their cells are generally irregularly elliptical or globose, 
rarely are they cylindrical. They are mostly of an orange-brown color; and there 
exists a particular gelatinous coating to each cell rather than a common gelatinous 



36 



FRESH-WATER ALG^ OF THE UNITED STATES. 



sheath to the filament. These larger threads are apparently produced from the 
smaller filaments by a process of growth. 

Near the base and in the under portions of the fronds, these filaments are scat- 
tered in the homogeneous jelly in which they run infinitely diverse courses. In 
the upper portions of the frond, and at some little distance from the base, the ad- 
joining cells are very close to one another, and pursue more or less parallel courses, 
with enough firm jelly between to unite them into a sort of membrane. 

This plant certainly belongs to the NosfocJiacece, and seems a sort of connecting 
link between the genera Ilormosiplion of Kiitzing and Nostoc. 

The best algologists noAV refuse to recognize the former group as generically 
distinct; and the characters presented by this plant seem to corroborate that view. 

Adherent to, and often more or less imbedded in, the fronds of the Nostoc, were 
scattered frustules of several species of diatoms, none of which was I able to iden- 
tify. In some of the fronds there were numerous unicellular Algae, all of them 
representatives of a single species belonging to the genus Chroococcus, Niigeli. 
This genus contains the very lowest known organisms — simple cells without nuclei, 
multiplying, as far as known, only by cell-division. These cells are found single or 
associated in small families ; and in certain species these families are united to form 
a sort of indeterminate gelatinous stratum. In these species the families are com- 
posed of but very few cells, surrounded by a very large, more or less globular or 
elliptical mass of transparent, firm jelly. The species is very closely allied to 
Chroococcus turgidi(s,\av. thermalis, llabenh., from which it difiers in the outer 
jelly not being lamellated. 

The technical description of this plant will be found in the proper place. 

Fig. 2 a, pi. 2, represents the most mature and largest filament ; Fig. 2 ft, a small 
filament from the same frond, each magnified 800 diameters. Fig. 2 c, represents 
portions of the upper surfaces of fronds. 

IV. coinininiituiu, Kxz. 

N. thallo indefinite expanse, gelatinoso, natante, modo viridc, plernmque sordide ferrugineo; 
trichomatibus flexuosis, plerumque subdense intrieatis; articulis globosis (ante divisionem 
factam subcylindrieis), subtiliter granulatis, interdum Itete viridibus, plerumque ferrugineis 
aut luteo-fuscescentibus aut fuscis ; cellulis perdurantibus globosis, articulorum diametro 
duplo majoribus, interjectis aut termiualibus. 

Diam.—kxiic. ^^Vts"; cell, perdur. ^^Vtt"- 

Sijn—N. comminulum, Kxz. Rabenhokst, Flora Europ. Algarum, Sect. II. p. 119. 

Eab.—ln fossis natante, prope Philadelphia. 

Thallus indefinitely expanded, gelatinous, floating, mostly sordidly ferruginous, sometimes 
greenish; trichomata flexuous, mostly subdensely intricate; joints globose (before division 
subcylindrical), minutely granulate, sometimes bright green, sometimes ferruginous, yellow- 
ish-fuscous, or fuscous ; heterocysts globose, about twice as long as ordinary joints, both 
interspersed and terminal. 

RemarJcs.— This species is to be found floating on the surface of the ditches 
below the city in the latter part of August and September, forming a repulsive, 
ferruginous, slimy scum. The periderm is not very apparent, and indeed the sepa- 



FRESH-WATER ALG^ OF THE UNITED STATES. 37 

rate fronds are not distinct. The filaments arc very long, mostly closely intricate, 
very much curved; in some places they are more sparse. Their color is mostly a 
sort of yellowish ferruginous-green, sometimes they are, decidedly, almost purely 
ferruginous, more rarely a bright green. This plant agrees pretty well with the 
descriptions of the European Nostoc comvilnutum, and I believe is the same 
species; if, however, N. lacustre of Kiitzing is distinct from N. conimiuvfinn, this 
is also ; but I incline to the opinion that they are all different forms of one plant. 
Fig. 3, pi. 2, represents a single filameut magnified 800 diameters. 

1¥. commune, Yacch. 

N. terrcstre, tliallo irrcgulariter expanse, difformi, undulato-plicato, trcniulo, intus aquose gela- 
tinoso, ffitate provecta plerunique excavato, peridermate subcoriaceo firmo, olivaceo, luteo- 
fuscescente vel luteo-fusco cincto ; trichomatibus flexuoso-curvatis, pallide nenigiiieis, laxe 
implicatis, ffiqiialibus vel suba;qiialibus, baud raro a basi ad medium usque ecllulis biscriatis 
compositis; articulis sphaericis vel e mutua pressione subquadrangularibus, laxe conncxis, 
pas.sim distantibus, puncto central! turbato pra'ditis; celluli.s perdurantibu.s globosis, articu- 
lorum diametro duplo majoribus, intcrstialibus terminalibusque. 

Dmm.— Cell, vegetat. .00012"— .00016" ; cell, perdurant. .00025"— .00033". 

Syn. — N. commune, Vauch. Rabenhorst, Flora Europ. Algarum, Sect. II. p. 115. 

Bab. — In terrestre, New Jersey. (Austin.) " Rio Bravo. Schott." Harvey. 

Terrestrial ; thallus irregularly expanded, shapeless, undulate-plicate, tremulous, within of the 
consistence of thin jelly, in advanced age mostly hollow ; periderm subcoriaceous, firm, oliva- 
ceous, yellowish-fuscous; filaments flexuously curved, pale green, laxly implicate, equal or 
subequal, not rarely composed of a double series of cells from their base to their middle ; 
articles spherical or subquadrangular from mutual pressure, loosely connected, here and tliere 
distant, furnished with a central spot; heterocysts globose, twice as large as the vegetative 
articles, interstitial and terminal. 

Remarlcs. — The only specimens I have seen of this species are very old ones, 
which have burst and discharged their central portions. I have consequently pre- 
ferred to copy the diagnosis of Prof. Rabenhorst. My specimens agree pretty 
closely with it. The filaments, and also the single cells, are closer together than 
his words would seem to indicate. My measurements of the heterocysts, as given 
above, are larger than those of Prof. Rabenhorst. They agree, however, with his 
text, which his own measurements do not. I am indebted to Prof Austin for 
specimens of this species, wliich he collected in Northern New Jersey. According 
to Professor Harvey this plant was collected by Dr. Schott along the Rio Bravo, 
where it is common on dry flats after rains. 

Subfamily SPERMOSIRE.E. 

Thallus sine peridermate, interdum nullus. Trichoraata sporis instructa. 

Thallus without any periderm, sometimes absent. Filaments furnished with .spores. 

Genus ANAB^NA, Bory. 

Trichoraata moniliformia, evaginata ; sporis sphaericis, anreis vel aureo-fuscis, plerumque singulis, 
cum cellulis vegetativis vel perdurantibus conjunctis. 



38 FRESH-WATER AJ^QM OF THE UxNITED STATES. 

Filaments n.oiiilifor.n, witliowt sl.eatlis; spores spherical, yellow or yellowish-fuscous, mostly sin- 
gle, variously placed as to the licturocysts and ordinary cells. 

Remarks.—Thc characters which I have given arc somewhat different and less 
exacting than tliosc of Prof, llabenhorst, otherwise our American species would 
hardly be covered by the diagnosis. Professor Harvey in his Phycologia Britan- 
nica states that A. Jussicu liad preoccupied the name, Analana, by applying it to 
a <Tenus of Euphorbiacew. The date of Bory's name is, however, 1823, whilst that 
of Jussieu is 1824. Hence, it is the latter which must be changed. 

A. gelatinoxia, Wood. 

A. thallo mucoso gelatinoso, indefinite expanse, dilutissime brunneo, nonnihil pellucido ; tricho- 

matibus hand vao-jnatis, Icvitcr flexuoso-curvatis, nonnihil distaiitibus, baud intricatis, aut. 

dilute aureis aut dilute cseruleo-viridibus ; articulis globosis, homogcneis ; cellulis perdu- 

rantibus articuloruni diametro fere sequalibus, globosis, vel rare oblongis; sporis terminalibus, 

singulis, globosis (fusco-brunneis?). 

Syn. — A. gelatinosa, Wood, Prodroraus, Proc. Amcr. Philos. Soc, 1869, 126. 

JJab. — Prope Philadelphia. 

Thallus gelatinous, mucous, indefinitely expanded, somewhat pellucid, with a brownish tinge; 
filaments not vaginate, somewhat curved, rather distant, not intricate, either a light golden- 
yellovF or light bluish-green; joints globose, homogeneous; heterocysts about equal to the 
filaments in diameter, globose or rarely oblong ; spores terminal, globose. 

Remarks. — The color of the shapeless mass of jelly of which the frond is com- 
posed is a light.brown with, in places, a decided reddish or flesh-colored tint. The 
heterocysts are either interstitial or terminal, no hairs were detected on them ; 
they are mostly globose and only occasionally are they oblong. 

Fig. 4, pi. 2, represents a filament of this species magnified 750 diameters; the 
color of the endochrome of the large spore was possibly due to its being dead. 

A. flos aquae, (Lyngb.) Ktz. 

A libere natans, submembranacea, aeruginea; trichomatibus plus minus eurvatis, sa3pius circi- 
natis; articulis sphrericis vel e mutua pressione modo ellipticis modo oblongo-quadratis ; cel- 
lulis pcrdurantibus ellipticis singulis vel geminis; cytioplasmate pallide a;rugineo granulate 
turbato ; sporis exacte globosis aureo-fulvis lucidis, singulis interjectis, articulorum diametro 
subduplo majoribus. R. Species mihi ignota. 

D-Jam.— Artie. 0.00017"— 0,00025" ; diam. long cell. perd. 0.00018"— 0.00053"; spor. 
0.00032"— 0.0004". 

Syn.—A.flos aquae, (Lyngb.) Ktz. Rabenhorst, Flora Europ. Algarum, Sect. II. p. 182. 

i7a6.— "Round Pond, West Point, New York." Prof. Bailey. Silliman's Journal, N. S., vol. 
iii. 18 

Swimming free, submcmbranaceous, ajruginous; filaments more or less curved, very often eir- 
eiiinate; articles spherical, or, from mutual pressure, elliptical or oblong quadrate; heterocysts 
elliptical, single or geminate ; cytioplasm pale reruginous, granulate ; spores exactly globular, 
golden-fulvous, bright, singly interspersed, nearly twice the diameter of the joints. 

A. ^ig^antea, Wood. 

A. thallo nullo, trichomatibus singulis et numeroso-consociatis, natantibus, rectis, in retate 
juveni spiraliter eonvolutis ; articulis plerumque subglobosis, arete connexis, granulosis ; eel- 



FRESH-WATER ALQAi OF TUE UNITED STATES. 39 

lulls perdurantibus interjectis, articulis vegetativis subaequalibus, utroque polo puncliforme 
iucrassatis, subsphsericis; sporis subsphaericis. 

Syn. — A. gigantea, Wood, Prodromus, Proc. Amur. Philos. Soc, 18G9, 145. 

Eab. — In stagnis natante, prope Philadelphia. 

Diavi. — Artie, vegetat. max. ^^^^^. Utterocysts j^'j^ = .0005. Spor. lat. T^^Vuts = Loug. 
„Vtr = -001. 

Thallus wanting ; filaments oceurring floating singly on water or in great numbers, straight, 
but in the young state often spirally convolute ; articles mostly subglobose, closely connected, 
granular, heterocysts subspherical, interstitial, a very little larger than the vegetative cells, 
thickened at each end iu a punctiform manner; spore subspherical. 

Remarlis. — This plant was found by myself, late in the summer, floating upon a 
brick-pond below the city, forming a part of a thick, dirty-green, " pea-soup 
colored," almost pulverulent scum. The filaments, though occasionally in great 
numbers, were never, that I saw, joined together by any jelly so as to form a frond. 

Fig. 5, pi. 3, represents a short filament of this species magnified 750 diameters. 

Genus CYLINDROSPERMUM, Ktz. 

Sporae ante cellulam tcrminalem ortae. 

Spore developing from the next to the terminal cell. 

C. niiniitum, Wood. 

C. trichomatibus dilute terugineis, plerumque flexuoso-curvatis et intricatis, interdum subrectis ; 
articulis cylindricis, ad genicula plus minus constrictis, homogeneis vel granulatis; cellulis 
perdurantibus terminalibus, hirsutis, globosis; sporis cllipticis, diametro 2 — 3 plo longioribus, 
subtilissime granulatis. 

Syn. — C. minutum, Wood, Prodromus, Proc. Amcr. Philos. Soc, 18G9, 126. 

X>jam.— Artie. ^^VV ; spor. long. ^■^^■^" ; transv. j^Vo"- 

3ah. — In stagnis prope Philadelphia. 

Filaments light seruginous-green, generally curved and intricate, sometimes straightish ; articles 
cylindrical, more or less constricted at the joints, homogeneous or granulate; heterocysts 
terminal, hirsute, globose; spores elliptical, 2 — 3 times longer than broad, very minutely 
granulate. 

Remarlcs. — This species was found by myself at Spring Garden, New Jersey. 
With a number of other algae it formed a ferruginous-brown gelatinous mass, 
growing in a deep, shaded, very stagnant pool. In most instances the filaments 
were closely interwoven, and sometimes formed minute greenish balls, just large 
enough to be visible to the unassisted eye. In other instances they were mixed 
up with various algae in little indefinite masses. There is apparently a stage in 
the life of the plant, when it consists of a single filament enclosed in a little cap- 
sule, for mixed in with the rest of the gelatinous sctmi were little microscopic, sub- 
globose masses, with a firm outer periderm and a single filament coiled up in the 
centre. The color of the filaments was generally a faint bluish-green, sometimes, 
however, with a yellowish tint. The spores were decidedly yellowish. 

Fig. 6, pi. 2, represents a fragment of a filament with the spore magnified 800 
diameters. 



40 



FRESH-WATER AhGM OF THE UNITED STATES. 



C. flCXIIOSIIIM, (AG.) Rabenh. 

C. strato gelatiiioso, saturate viride, indeBnite expanse ; trichomatibus sequalibas, pallida vel 
saturate ca>ruleo-vindibus, plcrunique valde flexuosis et intricatis, sa?pius eircinatim vel 
fasciatim coiivulutis, inturdum subrectis, et fasciatim coutcstis; articuiis oblongis, ad geni- 
cula plus minus coutractis, homogeneis vel granulatis, distinctis ; cellulis perduraiitibus 
terminalibus, subglobosis, rare hirsutis, nonnunquam in trichomatis utroque fine ; sporis 
oblongo-cylindricis, diainetro 2 — 3 plo longioribus, distinutc granulatis. 

Diam—Spor. ^5^5/ == -000416" ; cell, veget. ^Au" = .000166". 

Srjn. — C. flcxuosum, (Ag.) Rabenhorst, Flora Europ. Algarum, Sect. II. p. 188. 

Ilab. — In locis irroratis, propo Philadelphia. 

Stratum gelatinous, deep green, indefinitely expanded ; filaments equal, pale or deep bluish- 
green, mostly very flexuous and interwoven, often circinuately or fasciately convolute ; some- 
times straiglitish and in bundles ; articles oblong, more or less contracted at the joints, homo- 
geneous or granulate, distinct; hetcrocysts terminal, subglobose, rarely hirsute, sometimes 
at both ends of the filament; spores oblong-cylindrical, 2 or 3 times longer than broad, dis- 
tinctly granulate. 

Remarlcs. — The color of the filaments in yovmg specimens is deeper than in the 
older, which, however, grew in a much darker locality. The young spores are a 
yellowish-green, afterwards they are of a sort of yellowish reddish-brown. In one 
instance two spores were seen closely conjoined together at the end of a filament. 
In some filaments one or more heterocysts occur interstitially. Often one or more 
filaments will be seen coiled together like a rope. On the banks of the Schuyl- 
kill River I have found this species in two localities in the latter part of Sep- 
tember. In the one instance it grew along the Reading Railroad, just above the 
Flat Rock tunnel, in a dark little grotto, formed by shelving rocks. In the other 
case, it was on wet ground by a horse-trough very near the west end of the upper 
bridge at Manayunk. 

Fig. la, pi. 3, represents a filament, magnified 450 diameters. 

Fig. 1Z», a portion of a filament, magnified 800 diameters. 

C. macrosperniuni, Ktz. 

C. trichomatibus curvatis vel subredtis, pallide ajrugineis; articuiis cylindricis vel subcylin- 
dricis (in forma Europcea " globosis vel ellipticis"), ad genicula plus minus constrictis, 
passim confluentibus ; cellulis terminalibus plerumque ellipticis vel ovatis, diametro paulo 
vel subduplo longioribus; sporis elliptico-oblongis vel oblongo-cylindraceis, viridibus (in 
formam Europaeam maturam '•' saturate fuscis"), subtiliter granulosis, diametro duplo lon- 
gioribus. 

Z>«a»i— Trich. cell, transv. ^^V/ = -OOOOS" ; spor. .00046"— .00054". 

Syn.— C. macrospermum, Ktz. Rabenhorst, Flora Europ. Algarum, Sect. II. p. 186. 

Eab.— In rivulis, South Carolina. (Prof. Ravenel.) 

Filaments curved or straightish, pale sernginous ; articles cylindrical or subcylindrical (in 
European species " globose or elliptical"), more or less constricted at the joints, here and 
there confluent; terminal cells mostly elliptical or ovate, a little longer or about twice as 
long as broad; spores elliptical-oblong or oblong cylindrical, greenish (in mature European 
specimens deep fuscous), finely granular, about twice as long as broad. 

Eemar7cs.—1 have received this species from Professor Ravenel, who collected 
it near Aiken, South Carolina, in the month of September ; with it was the follow- 



FRESU-WATER ALQJE OF THE UNITED STATES. 41 

ing note: "In bottom of shallow, slowly running streams, adhering to ground or 
fallen leaves, &c., gelatinous green." The specimens agree well with the descrip- 
tion of the European form, except that I have never seen the joints globose or ellip- 
tical, but always cylindrical, as they are said to be sometimes in the typical speci- 
mens. The color of the spores also is not " fuscous," but that probably depends 
upon their not being fully mature. 

Fig. 7, pi. 2, represents the spore of this species with the neighboring hetero- 
cyst, magnified 750 diameters. 

C. COmatllin, Wood (sp. nov.) 

C. terrestre, stratum gelatiuosum serugineum interduni brunneo tinctum, formans; triehomati- 
bus flexuosis, intricatis, baud spiralibus, sequalibus ; articulis breve cylindraceis, diametro 
aequalibus ad plus dupio lougioribus, plerumque sejunctis, pallide aerugineis, obscure granu- 
latis ; ccllulis terminalibus subglobosis ; sporis oblongo-eylindricis, diametro fere duplo lougi- 
oribus, granulatis, luteo-brunitcis ; membrana crassa, distincte granulata. 

Diam — Spor. transv. -r^Sijij" = .00042". Long. j^ViJcj" = .00092". Artie. .0001". 

Hab. — In terra uda ; Niagara, Canada. 

Growing on tbe ground, forming a gelatinous stratum of an seruginous color, sometimes tinged 
on edges with brown; filaments fle.xuous, equal, intricate, not spiral; joints shortly cylin- 
drical, equal to or more than twice as long as the diameter, mostly separated, pale ffiruginons, 
obscurely granulate, terminal cells subglobosc ; spores oblong-cylindrical, about twice aa 
long as broad, granulate, yellowish-brown ; membrane thick, distinctly granulate. 

Remarlis. — I found this Ci/Iindros^yenmitn growing upon the ground in the 
marshes which border the Niagara River just above the Canadian Falls. It formed 
a bright, a?ruginous, gelatinous, but firmish, almost membranous, stratum. 

The filaments are often quite long, and are composed of sliort, cylindrical cells, 
mostly placed rather far apart. The terminal cells are remarkable for being abun- 
dantly provided with long, flexible, hair-like processes, upon the cuds of which are 
minute lobular bodies (cells?). These appendages are so minute as to make it diffi- 
cult to determine their structure, and although I have studied them with a ^'^th 
immersion lens, giving a power of nearly 2500 diameters, there arc some points 
about them still inidetermincd. I do not know whctlier they or the little globules 
are hollow or not. I do feel pretty certain, however, that the little globules are 
distinct bodies, and that they finally drop off, leaving the naked hair behind. Is 
it possible that they have any sexual significance ? The spore-wall is thick, and 
under a high power is seen to be distinctly granulate. The granules are of course 
small, but in the perfected spore can plainly be seen with an eighth objective pro- 
jecting out from the margin. 

Fig. 8, pi. 2, represents the spore-end of a filament, magnified 1375 diameters. 

Genus DOLICHOSPEllMUM, Thwaites. 

Spora; cllipticae, oblongre vel cylindraccae, inter cellulas vegetativas ortse, ssepe in seriebus con- 
nexse, a cellulis perdurantibus disjunctae. 

Spores elliptical, oblong, or cylindrical, occurring amid.st the vegetative cells, often connected in 
series, separated from the hetcrocysts. 

6 April, 1872. 



42 FRESII-WATER ALG^ OF TUE UNITED STATES. 

Syn. — Sphaerozyga, (Auctores, partim.) 

Doiichospermum, Thwaite's MSS. Mr. J. Ralfs on the Nostochinem, Ann. Mag. 
Nat. Hist. 1850, p. 335. 

RemarTcs. — This genus differs from Sphcerozi/ga in that the spores have no rela- 
tion, in regard to position, with the heterocysts. Professor Rabenhorst, in his 
Flora, docs not acknowledge it ; but it is very evident that he has neither seen 
the original paper of Mr. Ilalfs, nor the species upon which the genus was founded, 
for he mentions none of the latter, either as good species or synonyms, and the 
memoir itself is not included in his bibliographical list. The generic characters 
given by myself are essentially those of the original description, with the excep- 
tion that the filaments in the latter are said to be aggregated into a stratum, which 
is not true of the American forms herein described. 

D. siibri^idiini, Wood. 

S. nutans; trichomatibus singulis, rectis ant subrectis, minimis, dilute viridibus; articulis 
cylindraceis aut subglobosis, distinctis ; sporis cyiindraceis, in medio gradatim nonnihil 
constrictis, singulis aut duplicis, sine cellulis perdurantibus inter se ; cellulis perdnrantibas 
breve cylindraceis, singulis, distinctis. 

Syn. — Sphxroziga subrigidum, Wood, Prodromns, Proc. Amer. Philos. Soc, 18C9, p. 123. 

X)tam._CelI. veg. trans. ^^Vir" = -00016"; spor. transv. :jgVty"—iAir" = •00023" — .00022"; 
long. -r5'5!j" = -00066"; cell. perd. transv. ^^Vis" = 00022". 

Sab. — In stagnis props Philadelphia. 

S. Floating; filaments single, straight or straightish, very small, light green; articles cylin- 
drical or subglobose, distinct; spores single or double, in the middle gradually a little con- 
stricted, not having a heterocyst between them ; heterocysts shortly cylindrical, single, 
distinct. 

Remarks. — I have found this species growing in the scum floating upon the 
ditches below the city. The filaments are always, as I have seen them, scattered. 
They seem always to be nearly straiglit, or entirely so, and indeed preserve their 
straightness so constantly as to suggest the name given the species. The spores are 
very distinct, and all that I have seen were greenish, cylindrical, and constricted in 
the middle, so that their sides are concave. Their position does not seem to be 
uniform, any further than that they are amongst the ordinary cells. The heterocysts 
are large, almost equalling the spores in diameter ; I have never detected hairs on 
them. This species appears to be most nearly allied to D. Thwaiiesii of Ralfs, from 
which it differs in not forming a stratum, and in the great proportionate diameter 
of the heterocysts. I have never seen any measurements of D. ThioaitesiL 

Fig. 2, pi. 3, is a filament, magnified 975 diameters. 

D. polyspernia, (Ktz.) 

S. trichomatibus plerumque subsolitariis, sed intcrdum consoeiatis et intricati-s dilute ca^ruleo- 
viridibus, subrectis aut varie curvatis et flexuosis; articulis aut subsphsericis aut breve cylin- 
dricis; cellnlis perdurantibus globosis aut latissime ellipticis, articulorura diametro paulo 
vel duplo majoribus; sporis plus minus elongatis, cylindraceis— in setate immatura, sparse 
granu alls, dilute ca^ruleo-viridibus, et cum membrana baud distincta,— in eetate matura dense 
granulatis et cum membrana subcrassa. 



FRESH-WATER ALG^ OF THE UNITED STATES. 43 

Diani.— Artie. 55*05" = -00016" ; spor. zstW—cAW = .00026"— .00033". 

Syn. — S. Carmichaelii, Harvey, Pliycol. Brittanica, T. cxiii. 

6'. jjclysperma, (Ktz.) Rabenuorst, Flora Europ. Algarum, Sect. 11. p. 192. 

Hab. — In stagnis, New Jersey. 

S. filaments mostly subsolitary, but sometimes associated and interwoven together, light bluish- 
green, straighti.sh, or variously curved and flexuous ; articles either subspberical or shortly 
cylindrical ; beterocysts globose or very broadly elliptic, a little larger to twice as large in 
diameter as the ordinary joints ; spores more or less elongate, cylindrical, in the uncertain 
condition sparsely granulate, light bluish-green, with the membrane not distinct, in the 
mature state densely granulate, and with a thickish membrane. 

Remarks. — I found this species growing in a brownish jelly, with various other 
algae, in a. pool east of Camden, New Jersey. The filaments were mostly scattered, 
but in some places numbers of them were collected in little masses. In some fila- 
ments almost all the cells were developed into spores, so that a single thread con- 
tained ten or even more spores. In by far the larger number of such cases there 
was between each pair of spores a heterocyst ; sometimes, however, the latter was 
wanting, and the spores would be attached to one another. 

My specimens differ somewhat from the European form, but are too close to 
separate from them. They equally resemble, however, S. Carmichcelii. Indeed, I 
cannot see any sufficient reason for separating the species. S. Carmichcelii is, to 
be sure, a salt-water plant. I have, however, received specimens collected by Dr. 
Lewis, near Stonington, which I believe grew in salt water, and which agree in 
every respect with my fresh-water specimens. 

Fig. 3, pi. 3, represents a portion of a filament, magnified 750 diameters. 

Family RIVULARIACE^. 

Thallus gelatinosus, mollis vel induratus, vel crustaceus, interdura calce impletus, subglobosus 
vel amorphus. Trichomata ad oscillarium raorem articulata, vaginata, sed interdum estate provecta 
cum vaginis in gelatinara matriealem confluentibus et hand visibilibus, siniplicia vel pseudoramosa, 
snperne attenuata, ssepius in ajiicem piliformem longe producta, parallela vel radiatim disposita, 
cellula basale hyaliua globosa et interdum cellulis inter.stialibus instructa. Sporae (maiiuhria, Ktz.), 
singula plerumque inter cellulam perdurantem basilarem et cellulas vegetativas posits, sffipe per- 
magnsB, c^lindricas, plerumque pachydermaticse. 

Vegetatio terminalis. Propogatio sporis tranquillis. 

Thallus gelatinous, soft, or indurated, or crustaceous, sometimes filled with lime, subglobose or 
amorphous. Trichomata. articulated like an oscillatoria, vaginate, but sometimes, when old, with 
the sheaths confluent in the maternal jelly and not visible, simple or pseudoraniose, attenuated 
above, often with the ape.x prolonged into a long hair, parallel or radiately disposed, furnished with 
globose hyaline, thick-walled basal cells, and sometimes with interstitial cells. Spores cylindrical, 
generally placed between the basal and vegetative cells, often very large, mostly with thick coats. 

Vegetation tranquil. Propagation by means of tranquil spores. 

Bemarlcs. — In the Bivul aria ceo; the thallus is always small ; but is most gene- 
rally in the various species somewhat definite in form and size. Its consistency in 
our North American forms varies from that of an exceedingly soft, formless jelly 
to that of a gristly mass. The maternal jelly is usually colorless, sometimes brown- 
ish or yellowish. There is never any condensation of the outer portion of the 



U FRESH-WATER A L G .E OF THE UNITED STATES. 

frond into a periderm. The filaments commonly radiate from the centre to the 
circumference ; sometimes, especially in the softer fronds, they are simply parallel 
with one another. The sheaths vary in their breadth, firmness, and distinctness. 
These little plants grow chiefly in the water ; some species are said to live in 
the air in exceedingly damp places, but I have not as yet met with any such. 
They appear to prefer cold climates, although I have received specimens from 
South Carolina. With us, I have only found them in the late autumn and winter 
months. As to their life-history very little appears to be known ; I have not been 
able to make any observations myself upon this point, nor to obtain access to the 
papers' by De Bary, almost the only sources of such information, and therefore 
pass by the subject. 

Genus NOSTOCIIOPSIS, Wood. 

Trichomata ramosa cum cellulis perdurantibus aut in latcribus sessilibus aut in ramulorum ))revissi- 
inorum apicibus dispositis. Yaginaj niillaj. Thallus defiuitus. 

Syn. — Nostochopsis, Wood, Prodromus, Proc. Amer. Philos. See, 18G9. 

Thallus definite ; filament branched ; heteroeysts sessile upon the sides of the filaments, or raised 
upon the apices of short branches ; sheaths none. 

Remarhs. — The curious plant upon which this genus is founded has the habit 
of a nostoc. The outer portion of the frond is condensed, so as to give the appear- 
ance of a periderm ; but there is, in reality, no true periderm. The consistence 
of the thallus is that of a firm, gelatinous mass. The trichomata or filaments 
radiate from the inner part of the frond towards the outer surface, but many of 
them take their origin in the outer portions of the thallus. In most places they 
are distinctly articulated, and, indeed, the joints being swollen and moniliform, in 
some parts they almost seem to be composed of globular cells, resembling some- 
what the filaments of a nostoc ; on the other hand, in certain portions they are not 
at all articulated, and this for long distances. No sheaths are anywhere visible. 
The heteroeysts are, strangely enough, never placed in the continuity of the fila- 
ments. Sometimes they are sessile immediately upon the latter, sometimes they 
are raised upon very short branches. They are globose, with rather thick walls. 
Possibly, however, I am mistaken in believing these bodies to be heteroeysts, for 
they may be rather of the nature of spores, as is somewhat indicated by their 
thick walls, and often apparently dense contents. Their round shape, and the 
absence of anything else representing heteroeysts, has induced me, however, so to 
consider them. In my Prodromus I placed this plant provisionally amongst the 
nostocs ; but the radiation of the filaments from within outwards, and especially 
their being branched, on second thought seem to me to indicate a closer relation 
with the ElvuJariacece. The genus appears to be a sort of connecting link be- 
tween the two families. 



Flora," 1863. 



FRESH-WATER ALQM OF THE UNITED STATES. 45 

KT. lobaf IIS, Wood. 

N. tballo vivide viritle aut luteo-viride, cave, enormiter lobato, uataute, modice ma^no, firrao 
gelatinoso ; tricboiuatibus plerumque longis, fle.xuosis, dilute viridibus, plerumque artieulatis, 
partim inarticulatis, cylindricis aut sub-moniliformibus, sparse granulatis. 

Z>iam.— Trichom. Tsi^/ = .00006"— t^l^j" =, .00013" ; cell perdum. ^^'j^" = .00026". 

Syn. — N. lohalus, Wood, Prodromus, Proc. Amer. Philos. See, 1869. 

Hub. — In Schuylkill Flumine, prope Philadelphia. 

Thallu.s bright green or yellowish-green, hollow, irregularly lobed, floating, moderately large, 
firm, gelatinous; filaments mostly long, flesuous, dilute green, mostly articulate, partly inar- 
ticulate, cylindrical or somewhat moniliform, sparsely granulate. 

Remarhs. — I found this plant floating upon the Schuylkill River just above 
Manayunk. The hollow frond was buoyed up by a bubble of gas contained within 
it. It was an irregular, flattened, somewhat globose mass, of a bright green color 
and about half an inch in diameter. It seems very probable that in its earlier 
condition, it was a solid attached frond. The long slender filaments are often very 
tortuous, but run a pretty direct general course towards the outer surface. 

Fig. 6 rt, pi. 3, represents a section of the frond slightly magnified ; a, h, c, por- 
tions of filaments magnified 800 diameters. 

Genus GLOIOTRICHIA, J. Ac. (1842.) 

Trichomata e planitie orta pseudoramosa, distincte vaginata ; vaginae amploe, basi plerumque 
saccata;, transverse undulato-plicatee, plus minus constrictae, apice apertae, uon laciniatae. SporaB 
magnse cylindrica9. 

Filaments springing from a plane, pseudoramose, distinctly vaginate ; sheath ample, mostly 
saccate at the base, transversely undulately plicate, more or less constricted, open at the apex, 
not laciniate. Spores large, cylindrical. 

Remarks. — This genus was, I believe, first indicated by Professor Agardh in 
his Algce Maris Mediterranei et Adriatiei, a work to which I have not access. 
On account of tliis, and also because I have not seen any of the typical species 
of the genus, I have preferred simply copying the generic characters given 
by Professor Rabenhorst. If my understanding of " e planitie orta" is cor- 
rect, I do not think it true. Professor Rabenhorst's own figure of Rivularia 
shows that the filaments do not all arise on one plane ; although he asserts the 
character equally for tliat genus. In our American species the filaments do not 
all arise on one plane, nor can they be spoken of as "^JsertcZoramosa." 

G. incrustata, Wood. 

G. globosa vel subovalis, firraa, solida, ad pisi minimi magnitudinem, dilute viridis, crystallo- 
phora; trichoraatibus rectis aut leviter curvatis, in pilum productis, viridibus aut flavcscen- 
tibus, SEepe infra Isete viridibus sed supra flavescentibus, hand ordinatira artieulatis; articulia 
inferioribus in trichomatibus maturis brevibus, plerumque eompressis ; pilo apicale recto aut 
leviter curvato, plerumque indistincte articulato. soepe interrupto; vaginis araplis, achrois, 
saccatis, interdum valde constrictis ; sporis cylindricis, saepe curvatis, diametro ad !) plo lon- 
gioribus ; cellulis perdurantibus sphaericis. 



46 FRESH-WATER ALG.E OF THE UNITED STATES. 

Diam.—TTidiom. cum vag. ^U^"—^i<i^"■, sporis max. ^^^g^"—^^^^"; cell. perd. xeooc"- 

Syn.—G. incrustata, Wood, Prodronius, Proc. Amor. PLilos. See, 1869, p. 128. 

£a6.— Schuylkill River, plantas aquaticas adhaerens. 

Frond globose or suboval, firm, solid, about the size of a very small pea, light green, crystal 
bearin<^- filaments straight or slightly curved, produced into long hairs, green or yellowish, 
sometimes bright green in their proximal portions but yellowish above, not regularly articu- 
late- lower articles iu the mature filament short, and generally compressed; apical seta 
strai"-ht or slightly curved, mostly indistinctly articulate, frequently interru])ted ; sheath 
ample, transparent, saccate, sometimes strongly constricted; spores cylindrical, frequently 
curved, about 9 times as long as broad. 

Remarlcs. — I found tliis species growing attached to some little plants, either in 
the Schuylkill near Spring Mills, or else iu the spring itself, I do not know which. 
The roundish fronds varied in size from a mustard-seed to that of a half-grown 
pea. They were of a decided green color, but appeared grayish from the amount 
of carbonate of lime in and upon them. The larger balls, when cut in two, were 
distinctly separable into a central and cortical part. The former was more gela- 
tinous and contained fewer of the filaments than the latter. The filaments mostly 
arose in sets together, i. e. there were one or more zones or planes in which the 
bases of the filaments were placed together. This, however, was not strictly the 
case, as there were almost always some scattered trichomata. The matured fila- 
ments are very distinct. Their sheaths are very large, and often saccate, with 
wavy, loose-looking margins ; sometimes they are suddenly transversely constricted, 
once or more in their length ; sometimes they look as if a tight spiral band were 
wound around ; sometimes they are entirely free from any constrictions. These 
sheaths are open above, appearing as though they had been melted away. The 
spore is long and cylindrical, and is highly granular. The endochrome is gene- 
rally articulated below, the joints are often so nearly globular in the lower portions 
as to give a moniliform appearance; sometimes the articles are compressed. The 
upper portion of the trichoma is frequently interrupted, and if at all articulated 
is very irregularly and indistinctly so. The younger filaments have their endo- 
chrome variously and irregularly interrupted. The basal cells are globular. I 
believe the formation of new filaments and the consequent growth of the frond 
take place by distal portions of the projecting endochrome separating from the 
parent filament, then forming a basal cell, and lastly a sheath. (See Plate 00.) 
The carbonate of lime does not exist as a definite incrustation, but in the form of 
semi-crystalline masses scattered through the frond. Tliis species seems to come 
closer to O. horyana than any described species, from the description of which it 
difi"ers, in the color of thallus, in the latter being always solid (at least so I have 
found it late in the fall, when the spores were fully perfected), in its habit of in- 
closing crystals of carbonate of lime, in the curved spores ; and, doubtless, a com- 
parison of the specimens would show still more important differences. 

Fig. 4 «, pi. 3, represents a section of a frond moderately magnified ; fig. 4 h, 
the basal end of a filament magnified 460 diameters ; fig. 8 c, filaments magnified 
260 diameters. 



FRESn-WATEll A L G .E OF TUE U ^■ 1 T E D STATES. 47 

Cr. angulosa, (Roth.) J. Aqh. 

G. globoso-angulosa, cava, viridi-fuscescens, ad cerasi magnitudinem ; trichomatibus strictis, 
torulosis, supenie leviter flexuosis, passim interruptis ; articulis inferioribus plus minus 
corapressis, diaraetro duplo triplove longioribus ; vaginis amplis, achrois hie illic leviter con- 
strictis; sporis plus minus elongatis, oblongo-ovatis vel ellipsoideo-cylindricis, diametro 3-fi- 
10 plo longioribus, ajrugineo-fuscescentibus, noununquam leviter curvatis, cytioplasmate sub- 
tillter granuloso, turbato. (R.) Species mihi ignota. 

Diam.—CtW. perd. 0.00036"— 0.0005". Spor. ma.x. 0.00059". (R.) 

Syn. — O. angulosa, (Rotii.), J. Agardh., Rabenuorst, Flora Europ. Algarum, Sect. II. p. 201. 

Hab. — Hudson River props West Point. (Bailey.) 

Globose angular, hollow, greenish-fuscous, attaining the size of a cherry ; filaments strict, toru- 
lose, above somewhat flexuose, here and there interrupted; inferior joints more or less com- 
pressed, 2-3 times longer than their diameter; sheath ample, colorless, here and there slightly 
constricted; spores more or less elongate, oblong-ovate or ellipsoidal-cylindrical, 3-6-10 
times longer than the diameter, airuginous-fuscous, sometimes slightly curved, cytioplasm 
very minutely granulate. 

Genus RIVULARIA, (Roth.) Agh. 

Thallus et trichomata cadem quae Gloiotricha, sed vagina: arctissimaj, sape in gelatinam matri- 
calem confluentes, quasi nullae. 

Thallus and filaments similar to those of Gloiotricha, but the sheaths very close, often confluent 
in the gelatinous matrix and apparently wanting. 

Remarks. — The characters given above are those of Professor Rabenhorst. 
Flora Europ. Algarum, Sect. II. p. 206 

R. cartilag^inea, Wood. 

R. subglobosa, parva, cartilaginea, saturate brunnea vel subatra, solitaria in plantis aquaticis: — 
trichomatibus maturis-sterilibus, rectis aut subrectis, cylindricis, elongatis, baud articnlatis ; 
cytioplasmate siEpe interrupto; vaginis arctis et distinctis; cellulis perdurantibus globosis, 
diametro subsqualibus : — trichomatibus fertilibus — rectis aut subrectis, supra spora cellulis 8-9 
instructis; sporis elongatis, rectis, cylindricis; vaginis nonnihil crassis, arctis: — trichomatibus 
immaturis breve articulatis; vaginis subamplis. 

i>ifflm.— Trieh. cum vag. ^^V??" ; spor ,^V/- 

Syn. — R cartilaginea, Wood, Proc. Am. Philos. Soc, 1869, p. 128. 

Hah. — In palude. Northern Michigan. 

Frond subglobose, small, cartilaginous, deep brown or blackish, solitary upon aquatic plants; 
mature sterile filaments, cylindrical, elongated, not articulated, their cytioplasm frequently 
interrupted, their sheaths close and distinct, their heterocysts globose and about equal to 
them in diameter; fertile filaments straight or nearly so, above the spores furnished with 8 or 
9 cells ; spores elongate, straight, cylindrical ; sheaths rather thick, close ; immature filaments 
shortly articulate, their sheaths rather large. 

Remarlcs. — The frgnd of this species grows attached to the leaves of water-plants, 
and has its under side markedly flattened so that it is somewhat semi-globose. The 
filaments which compose the mass of the very firm frond arc elongated, cylindrical, 
and of nearly or entirely uniform diameter throughout. The sheaths are close, 
distinct, rather thin, open above, and, in many instances, almost or even entirely 
empty. Scattered amongst such filaments are the fertile ones. These have at 
theit base an elongated cell, in which is the long cylindrical spore, which varies 



48 



FRESn-WATER ALG^ OF THE UNITED STATES. 



very greatly in length in the various filaments, but is almost always shorter than 
the cell containing it. Just beyond the spore is a series of distinct, variously 
shaped cells, about seven in number, which are, as I have seen them, empty. In 
the outer portions of the frond occur what I believe to be young filaments. These 
are distint^uishcd by their rapidly decreasing in diameter towards their distal end, 
by their being distinctly articulated, by their basal cell not being distinctly sepa- 
rated as in the older filaments, and by their sheaths being more ample. 

These various filaments composing the fronds do not arise from any one place, 
but commence at very difi"erent distances from the centre, and pursue a more or 
less straight course to the circumference of the frond, from which they often project. 

Fig. 9, pi. 2, represents a section of the frond moderately magnified ; fig. 9 6, is 
a drawing of the basal part of a filament magnified 800 diameters. 

Genus ZONOTRICHA. 

Tlialli pulvinato-lieniisphcerici, soepe confluentes, calce prsgnantes, plus minus indurati, basi plani 
affixa, a^tate provecta plerumque excavati, iutiis zonati; zonis concentricis, variegatis; trichomata 
pseudoramosa, gracilia, intequalia, apice liyalina et plus minus longe cuspidata vel in piluni producta. 
Vaginae firma;, homogeneas vel longitudinalitor plicato-fibrillosae, apice integraa vel dilatatoe et iu 
fibrillas soluta;. Sporse ignotee. 

Thalli pulvinately hemispherical, often confluent, impregnated with lime, and more or less indu- 
rated, fixed by the flattened base, in advanced age mostly excavated, zoned within ; zones concentric 
variegated ; filaments pseudoramose, slender, unequal, their apices hyaline and more or less cuspid- 
ate or prolonged into a hair ; sheaths firm, homogeneous, or longitudinally plicately fibrillose, their 
apices entire or dilated and dissolved in fibrillas. Spores unknow^n. 

Z. mollis, Wood (sp. nov.) 

Z. interdum subhsemispherica sed gregaria et in stratum nonnihil mammillosum confluens, 
submoUis, cinerea vel griseo-carnea, parcezonata ; trichoniatibus longissimis, angustis, 
flesuosis ; vaginis arctis, decoloratis, non fibrosis, firmis ; trichomatibus internis articulatis, 
saepe interruptis; articulis disjunctis, diametro sequalibus ad 4 plo longioribus ; cellulis 
perdurantibus singulis globosis. 

J>mm.— Tricb. c. v. T5§iyV' = .00011". Sine vag j^i^/' = .000084". 

Hab. — In saxis irroratis, "Cave of the Winds," Niagara, Wood. 

Z. sometimes subsemispherical but gregarious and confluent into a somewhat mammillate, rather 
soft stratum, ashy or grayish flesh-colored, sparsely distinctly zoned ; filaments very long, 
narrow, flexuous ; sheaths close, colorless, not fibrillose, firm ; internal filament articulated, 
often interrupted ; joints separated, equal to 4 times longer than the diameter ; heterocysts 
single globose. 

EemarJcs.— 'Every American tourist is familiar with that most wonderful spot, the 
so-called " Cave of the Winds," at Niagara. It is simply a place where it is possible 
to go underneath a portion of the great cataract, and then round upon the rocky 
debris outside of it. Growing upon these rocks, eternally wet and glistening with 
foam and spray, I found this and the following species. The present form was 
much the most abundant, making a slippery, grayish, or grayish flesh-colored coat- 
ing to many of the rocks, dotted here and there with the rigid, blackish fronds of 



FRESH -WATER ALG.E OF THE UNITED STATES. 49 

its fellow. This coating Avas not at all uniform, but was covered with mammillated 
masses, and consequently varied from two to six lines in thickness. Internally, it 
was striated or radiated, but not so evidently as the following species, and presented 
several distinct variegated zones. It was quite soft to the touch, as well as readily 
broken or crushed, and under the microscope was seen to contain very little lime 
salt. When dried it has a pronounced sebaceous appearance. The filaments com- 
posing it are remarkable for their great length, often apparently running from the 
bottom to the top of the frond. They are rarely if ever branched, and appear 
never to be furnished with any heterocysts save at their enlarged base. I have 
never seen any distinct hairs terminating them, their ends always appearing broken 
and open. They are often quite flexuous or even tortuous. The internal filament 
is remarkable for having its articles so distinctly separated. It is often very much 
interrupted, and in specimens preserved in carbolic-acid water is of an orange-brown 
color. 

Fig. 3, pi. 4, represents a single filament magnified 260 diameters. 

Z. pnrcezonnta, Wood, (sp. nov.) 

Z. nigro-viridis, enormiter semiovalis, ad 6'' longa, dura, lubrica, non fragilis, calce prsgnans, 
intus a basi distincte radiata, parce et saepc obsolete zonata ; trichomatibus luodice lougis, 
subrectis; trichomatibus internis cylindricis inarticulatis vel articulatis, et interdum mouili- 
formibus ; articulis longis et cylindricis vel brevibus et globosis ; vaginis amplis, fibrillosis ; 
cellulis perdurantibus basalibus et integectis, Lis oblougis vel cylindricis, illis globosis et 
ssepe gemiuis. 

Diajn.— Cell. perd. basal. 5i5Vi5"=000n"; trichom. cum vag. ju'jo"—5tf'ou"=- 00026"— .00037". 
Sine vag. .00006"— .00008". 

Hah. — In saxis irroratis. " Cave of the Winds," Niagara. • 

Var. — Z. cinerea. 

Blackish green, irregularly semioval, to 6 lines long, hard, slippery, not fragile, impregnated with 
lime, internally distinctly radiate, sparsely and often obsoletely zoned ; filaments moderately 
long, straightish ; internal filament cylindrical, not articulated or articulated, sometimes monili- 
form ; joints long and cylindrical, or short and subglobose ; sheath ample, fibrillose ; heterocysts 
basal and interposed in the body of the filament j the former globose, often geminate ; the 
latter oblong or cylindrical. 

Yar. — Cineritious in color. 

Remarks. — I found this plant growing on rocks as glossy, blackish, very hard and 
slippery fronds or masses, which varied in size from that of very small shot to 
nearly half an inch in length. The larger ones were not nearly so high as long, 
and presented irregular, almost bossellated upper surfaces. The filaments are 
often very evidently and frequently pseudoramose. The external surface of the 
broad sheath is covered with numerous fibrillte, which envelop and seem sometimes 
to wrap it round and round. The color of the frond internally, when broken, is 
mostly a dark chocolate, and the surface presents a radiated appearance, with but 
two or three zones at most, and, in the very dark specimens, even these are not 
evident. No signs of spores have been found. Certain specimens which I ob- 
tained growing with the others, instead of being blackish in color, are grayish, but 

7 April, 1872. 



60 FRESH-AVATER A L G .E OF THE UNITED STATES. 

a-rcc in all other respects with their fellows. This gray color depends, I believe, 
upon the deposit of an immense quantity of lime salts, which in such specimens 
constitute by far the larger portion of the frond. 

Fig. 4, pi. 4, represents a section of frond, slightly magnified. 

It Is citlicr this, or the preceding species, which is referred to by Professor 
Bailey in Silliman's Journal, vol. iii, nnder the name of Blvularia calcarea, Sm. 
The present form may possibly be that plant, but not having been able to find any 
description sufficiently well made out to make identification possible, I have de- 
scribed both species as new. 

Z iniiiiidila, Wood, (sp. nov.) 

Z. luiiiutissima, nii?ro-viridis, siibglobosa, hand distincte zonata, nonnihil mollis, muscicola, calce 
non prajgnans; trichomatiljiis iiitcruis, breve artioulatis, distinctissime fasciculatim pseudora- 
mosis; vaginis crassis, amplis, soepe dilute aurantiaco-brunneis, apice plerumque coloris 
expertibus fissis et apertis; cellulis perdurantibus ovato-globosis. 

Diam.—Tvich. intern. .00012"— .00021" ; cell. perd. .00025." 

^o6.— In lacu, " Clear Pond," muscis affixa, Adirondack Mountains. 

Yery small, blackish-green, subglobose, not distinctly zoned, rather soft, growing on mosses, not 
impregnated with lime ; internal filaments shortly articulate, very distinctly fasciculately pseu- 
doramose ; sheaths thick, ample, often pale orauge-brown, with their apices mostly colorless, 
torn and open ; heterocysts ovately globose. 

Remarks. — The locality in which I found this plant is in the heart pf the Adi- 
rondack wilderness. The little frond in none of my specimens is larger than a 
mustard-seed, and is not distinctly zoned. The plants were collected in the begin- 
ning of Juiy, and very possibly are not fully grown, as the season of general growth 
opens very late in its parent lake. Very possibly, later in the year, it may be found 
larger and distinctly zoned. The general appearance of the plant, the character 
of its sheath, and the marked branching habit of the filaments have caused me to 
place it in this genus. 

Genus DASYACTIS, Ktz. 

Thallus gelatinosus. mollis, non zonatus. Trichomata matura saspe hand vaginata. Sporse 
nuUaj. 

Thallus gelatinous, soft, homogeneous, not zoned. Mature filaments often not vaginate. Spores 
absent. 

D mollis, Wood. 

D. parva, ad magnitudinem pisi minimi, enorniiter snbglobosa, mollis, gelatinosa, dilute viridis; 
trichomatibus plerumque subrectis, partim distincte, partim indistincte articulatis; vaginis, 
in trichoraatibus maturis haud visibilibus, in trichomatibus juvenibus supra subamplis; cel- 
lulis perdurantibus sub-globosis, globosis, vel ellipticis, diametro duplo majoribus, plerumque 
singulis sed interdum bi vel triseriatis. 

Dm/7!.— Trich. j^Vo"— ^tsVr"; cell. perd. ^Vs"- 

Stjn.—D. mollis, Wood, Prodromus, Proc. Amer. Philos. Soc, 1869, p. 128. 

Hab. — In palude plantas aquaticas adha^rens, Northern Michigan. 



FRESH-WATER ALGiE OF THE UNITED STATES. 51 

Frond small, about the size of a small pea, irregularly subglobose, soft, gelatinous, light green, 
filaments generally slraightisli, partly distinctly, partly indistinctly articulate ; sheaths in the 
mature filament not perceptible ; in the young filaments rather large in the upper portion ; 
heterocysts subglobose or globose or elliptic, twice as large as the filament, generally single 
but sometimes bi or tri-seriale. 

Remarks. — I found this species growing attached to the little leaves of various 
minute cryptogamic and phanceroganiic water-plants, in a small bog, near the 
mouth of Carp River, in Northern Micliigan. The frond is somewhat translucent, 
with a slightly greenish tint, and lias a soft, gelatinous consistency. The matured 
trichoma or lilaments are more or less radiating, very long, generally nearly straight 
and parallel. Their joints or articles are long, mostly not very distinctly separated, 
and often are entirely wanting. The sheaths are entirely lost, no traces of them 
being perceptible. They seem to be altogether melted down into tlie homoge- 
neous jelly, in which the filaments are imbedded. The basal cell is hirge, mostly 
globular, and very prominent. On the edges of the frond may frequently be seen 
small, evidently immature filaments, which have no distinct basal cell. Around 
the basal portion of these young trichoma there is a well-marked close slieath, 
which near the apex is wanting. In tlieir immature filaments the joints are mostly 
very short, rather distinctly separated, almost globular. 

Fig. 5, pi. 4. 

Genus MASTIGOXEMA, Schwabe. 

Trichoraata articulata, sursum flagelliforraia vel subulata, simplicia vel pseudornmosa (nonnunquam 
fasciculatim pseudoramosa), procunibentia vel crecta, in thallo indistineto csspitoso-aggregata; 
vagince arctse et homogeueaj vel auiplaj et phis minus dislincte lamellosai, apiee plerumque apertse, 
interdum laciniataj. 

Filaments articulate, superiorly flagellifomi or subulate, simple, or falsely branched, sometimes 
faseieulately so, procumbent or erect, csspitosely aggregated into a sort of thallus ; sheaths close 
and homogeneous or ample, and more or less distinctly lamellate, the apex for the most part open, 
sometimes laciniate. 

M. fertile, Wood, (sp. nov.) 

M. ccespitosum, cum algis alteris intcrmixtum; triehomatibns simplicibns, clongatis, flexuoso- 
eurvatis, apice truncatis; trichomatibus interiiis viridibus, sa'iie iuterruptis, interdum dis- 
tincte articulatis interdum inarticulatis; articulis diametro 3-5 plo longioribus; vaginis modice 
arctis, firmis, achrois, crassis, colons expertibus, apice truncatis et apertis ; sporis cylindricis, 
sparsis, in filainento unico s»pe pluribus, in cellulis inclusis; ccllulis perduraiitibus globosis, 
interdum conipressis trichomatis diametro fere a;qualibus. 

Diam.— Filam. ^^'5/ ^ .00033" ; spor. ^^V/ = .00016G". 

Hah. — In stagnis. Alleghany Mountains, Centre County, Pennsylvania. 

Cffispitose, intermixed with other algaj ; filaments simple, elongate, flexuously curved, trun- 
cate at the apex ; internal filament green, often interrupted, sometimes articulated, some- 
times not articulate ; joints 2-3 times longer than their diameter ; sheath moderately close, 
thick, firm, transparent, and colorless, truncate and open at the apex ; spores cylindrical, 
scattered, each contained in a cell, frequently several in a filament; heterocysts globose, 
sometimes compressed, about equal in diameter to the filament. 



52 FRESH-WATER AhGJE OF THE UNITED STATES. 

Eemarks.—l found tiiis plant in a stagnant pool in " Bear Meadows," forming a 
iilanientous, felty uuiss with LEdoijoiiium echinutum and other alga;. The variously 
curved and interlaced flexible filaments are always simple and of uniform, or 
nearly uniform, diameter through their whole length ; excepting that in some 
instances there are small, local, bulbous enlargements of the sheath. Though the 
ends of the filaments in all the specimens I have seen are abruptly truncate, it is 
very possible that in the young trichoma the apex is prolonged into a long hair as 
in most of the Mastigonema. The inner filament is sometimes very distinctly arti- 
culated, often, however, it is not at all so. The sheaths are firm, not at all lamel- 
late, and generallv project beyond the inner trichoma. The spores are cylindrical, 
yellowish, with a pretty distinct, although very close coat. They are always in- 
closed in distinct cells, and are mostly several in a filament, placed at intervals in 
its length. 

This is the first instance, at least that I know of, in which a species of this 
genus has been found in fruit, and it is interesting to note the resemblance of the 
spores to those of the more commonly fruiting rivularias. At the same time the 
peculiar arrangement of the spores is remarkable, and if the other species of Mas- 
ligonema should be found to have the more common exclusively basal arrangement 
of spores, I think it would aftbrd good ground for considering M. fertile as the type 
of a new genus. Moreover, the filaments are not united into a distinct thallus, and 
also want the apical hair of Mast'ujothrix, so that it is very probable that they represent 
an undescribed genus. Until, however, the fructification of the European species 
is elucidated, it seems best to forbear multiplying names. 

Fig. 1, pi. -4, represents a single filament of this species. 

M. Iialos, Wood, (sp. nov.) 

M. CKspitulis ; triclioinatibus simplicibus, in Eetate niatura valJe elongatis et cum vaginis trun- 
catis et apertis, — in a^tate imnjatura niodice brevibus et in .setara niodice longam acliroam 
productis; trichomatibus intcrnis breve artieulatis, siibtiliter graiiulatis continuis vel varie 
juterruptis ; vaginis firrais, modice crassis, Siepe distincte lamellosis, coloris expertibus ; cel- 
lulis perdu rantibus subglobosis 

Diom.— Sine vag.= .0003" ; cum vag.= .0005". 

Hah. — In aBstuario, Stonington, Conn. (Dr. F. Lewis.) 

In little tufts; filaments simple, in mature state greatly elongate, and with the sheath truncate 
and open, — in the young condition shorter and often ending in a rather short seta; internal 
filament shortly articulate, minutely granular, continuous or variously interrupted ; sheath 
firm, rather thick, often distinctly lamellated, colorless ; beterocysts subglobose. 

Remarks. — This species is an inhabitant of salt, or at least brackish water, having 
been collected in Stonington Inlet by Dr. Frank Lewis. The filaments are very 
long and always simple ; forming apparent exceptions to this, I have seen once or 
twice a number of young filaments so united as to give the appearance of having 
been produced from one old one, and in other cases young filaments growing from 
the side of an old one ; but I believe those are always set free so soon as they 
attain a certain size. In one instance there were large, globular cells, with very 
thick walls, produced, and lying free, in the sheath. Are these spores] They are 



FRESn-WATER A L G yE O F T H E U N I T E D S T A T E S. 53 

well shown in figure 2 b, pi. 5. Associated with them were a number of similar cells 
which had not obtained as yet the outer thick Avail. The color of the filaments is 
in my specimens of a rich golden brown ; but, as they have been preserved in car- 
bolic acid water, I cannot speak positively as to the original tint. The heterocysts 
are subglobose, sometimes compressed, sometimes somewhat triangular. They 
about equal in diameter the internal filament. 

Fig. 2, pi. 5, represents a small cluster of youngish filaments of this species. 

M. sejiinctiiin, Wood, (sp. nov.) 

M. tliallo cespitulo, molle, piirasitico ; trichoraatibus siniplicibus, pleninique inartipulatis, Red, 
iuterilum breve, interdum longe, articulatis, coiitinuis, rariiis inti'rniptis, apiee attenuatis, 
flaTO-olivaceis aut viridibus, sparse grauulatis ; vaginis jikTunuiuf aniplis et distinctis, liya- 
linis, SGepius valde undulatis, apice plerumque valde amplilicatis et in fibrillas solutis ; cellulis 
perdurantibus dianietro subsequalibiis ; sporis nullis. 

7)(a„i.— Tnchoni ■^^^^" = .000 IG"; cum vag, jj,'^/ = .0005". 

Hah. — III plantiirum aquaticarura foliis. Carp River, Michigan. 

Tballiis somewhat ca;spitose, soft, parasitic; filaments simple, mostly inarticulate, but some- 
times shortly sometimes long articulate, continuous or more rarely interrupted, attenuate at 
the apex, yellowish-olive or greenish, sparsely granulate; sheaths mo.stly ample and distinct 
hyaline, often strongly undulate, the apex mostly much amplified and dissolved into fibrillar; 
heterocysts about equal to the filament in diameter; spores wanting. 

BemarJiS. — This species was found in the Carp River bog, growing on the edges 
of minute leaves, so as to form little prominences or thickenings of the margin. 
The trichomata are quite distinct from one another, and can scarcely be said to be 
united into a frond, although they all appear to radiate from the base, where they 
are consolidated into a dense mass. The sheaths are generally quite distinct, much 
broader than the cytioplasm, and are not sensibly dilated below. In most si)cci- 
mens they are very distinctly alternately dilated and contracted, or in other words, 
midulated. This is especially the case when the sheaths are quite wide. Above, 
they are rapidly and widely dilated, are distinctly fibrillose, and appear to gradu- 
ally melt away. The cytioplasm is rarely articulated, and, wlien it is so, the joints 
are scarcely longer than broad, and are most generally confined to the distal end of 
the filament. Thg species appears to be most nearly allied to M. Bauerlannw, 
Grun., from which, however, it is quite distinct. 

Fig. 2 a, pi. 4, represents this species magnified 250 diameters ; fig. 2 h, a single 
filament magnified 800 diameters. 

M. clongntiim, Wood. 

M. initio subglobosum, postea siepe nonnihil fusinnm, nigro-viride, liibricum, Crme ; triclioma- 

tibus aerugineis, valde elongatis, flagelliformibns, interdum inarticulatis sed siEpius breve 

articulatis, interdum ad genicula valde constricti.'i, apice interdum truncatis sed plerumque 

in pilum, longum, achroum, flexnosum, produetis; vaginis achrois, arctis, sa;pe apice trun- 

^ catis ; cellulis perdurantibus globosis vel subglobosis. 

Biam — j^ji-s" = .0002G." 

Syn. — M. elongatiim, Wood, Prodromus, Proc. Amer. Philos. Soc, 1800, p. 128. 

Hab. — In aquario. 



54 FRESn-WATER ALGJ3 OF THE UNITED STATES. 

Tliallus at first sul)globosp, afterwards frequently fusiform, blackibh-grcen, slippery, firm ; fila- 
ments SEruginous, very elongate, sometimes not articulated, but more generally shortly arti- 
ciihitcd, soiiictiiiic'S strongly contracted at the joints; apices sometimes truncate but generally 
produced iulo a long, flcxuous, translucent hair; sheath transparent, close, frequently trun- 
cate at the apex ; heterocysts globose or subglobose. 

Eemarks. This species grew in my aquarium on some brook-moss, which I 

obtained from a spring above Manayunk. It forms little nodules of the size of a 
pin's head upon the wire-like stems, or sometimes longer fusiform masses, which are 
apparently produced by the coalescence of a number of the little globes. The color 
of these fronds, wliich are very firm, is a blackish-green. The filaments radiate from 
the base in all directions, and at the apex are tipped with a very long hair-like flexu-' 
ous point, or they are truncate, apparently from the breaking off of this terminal 
seta. The cndochrome is not unfrequently interrupted within the sheath. When 
it is articulated, tlie joints are usually about as long as broad, and frequently are 
distinctly separated from one another. The sheath is sometimes quite apparent 
and distinctly truncate and open above, but in other instances is with difficulty 
perceived anywhere, and above is lost in the long hyaline point. At the points 
of attachment of the frond the filaments are so densely crowded as almost to 
appear to be coalescent, though I believe they are never really so ; yet it is often 
almost impossible to separate them one from another by pressure on the glass cover, 
without entirely mashing and distorting the filaments. 

Fig. 1 fl, pi. 5, represents a section of a frond of this species slightly magnified; 
fig. I h, a single filament magnified 460 diameters. 

Genus MASTIGOTHRIX, Ktz. 

Trichoniata singula, plerumque sparsa, parasitica intra thallum Chastophorarum aliarumque 
algarum, flagelliformia, in apicem piliformem achroum hyalinura cuspidata, distincte articulata, 
arete vaginata, basi cellula perdurante instructa. (R.) 

Filament single, mostly scattered, parasitic within the thallus of Chsetophora or other algae, 
flagelliform, with the apes produced in a. hyaline hair, distinctly vaginate, furnished with a basal 
heterocyst. 

Rcmarlcs. — I have simply copied the generic description of Prof. Rabenhorst, 
although it seems to me more than doubtful whether the place of growth is any 
generic character whatever. I have relied more on the long hyaline apical hair, 
although our American form does grow in a gelatinous palmella like jelly. 

M. fibrosa, AVood. 

M. dilute vel Cffiruleo-viridis, vel olivaceo-viridis, vel sub-a>rnginea, infra baud articulata, 
sursura sspo breve articulata, apicc in trichomata inntura in setam hyalinam, distincte 
articulatam, longam, producta; vaginis achroois — in filanicnto inimaturo, supra distinctis, 
latis, hyalinis, infra modice crassis, arctis,— in trichomata niatura infra arctis, indistinetis, 
supra in fibrillis dissolutis, apice absentibus ; cellulis perdurantibus globosis, interdura 
geminis. 

i)m7n._Trichone5,V/; cell, perdur. thJcs'-tt^^/. 

Syn.—M. fibrosa, Wood, Prodromus, Proc. Amer. Philos. Soc, 18G9, p. 129. 

flat.— Propo Philadelphia. 



FRESH-WAT-ER ALG^ OF THE UNITED STATES. 55 

Light bluish-green, or olivaccous-green, apex in the mature filament prolonged into a long, 
distinctly articulated hyaline seta ; sheath transparent — in the immature filament distally, 
broad, and distinct although hyaline, below rather thick and close ; in the mature filament 
below close, indistinct, above dissolved in fibrilla; and wanting at the apex; heterocysts 
globose, sometimes geminate. 

Remarhs. — This plant was found growing with other low algfe in a thick jelly, 
which clothed some wet, dripping rocks near Manayuuk. In the young filaments 
the sheath is produced above into a broad, thick, gelatinous-looking portion, the 
cavity of which is often scarcely apparent. The cytioplasm in such filaments is 
mostly of a light bluish-green color, is granular and not very apparent. In older 
filaments, the trichoma above is prolonged into a long, curved hyaline point, and the 
sheath just below the base of this is split into a number of fibrilla?. No spores 
were perceived. The increase of the species appears to take place in the follow- 
ing manner : Near the middle of the filament a tumid swelling forms, in the 
centre of which appears after awhile a constriction, and this increases until at last 
there are shaped out the bases of two filaments. Then the heterocysts appear, and 
finally the two halves of the original trichoma separate — each a perfect filament. 
(Fig. 3, pi. 5.) Sometimes, instead of a pair of filaments being thus formed, but 
a single base is shaped out at the place of swelling, and the original filaments split, 
as it were, thus giving origin to a second trichoma, which for awhile appears as a 
branch of the former, but is soon detached from it. In some specimens there are 
two heterocysts, unless the proximal of these, Avhich is a light orange-clay color, 
represents a spore. 

Fig. 3, pi. 5, represents difi"crent forms of this species. 

Family SCYTONEMACE^. 

Trichomata articulata, saspe moniliformia vel submoniliformia, vaginata, psendoramosa, cellulis 
limataneis, ad pseudoramulorum basin, vel interstitialibus, plerumque pachydermaticis instructa. 
Vaginae e stratis pluribus (etsi non semper distinctis) formitte, superGcie laves, corrugatoe vel 
esasperatae, ernstatfe, nonnmquam stratis exterioribus in fibrillas discedentibus, hand raro passim 
intumescentes vel ocreatffi. 

Vegetatio non terminalis ; cellularum vegetativarum divisio ad unam directioncm, initio in tricho- 
matibus medio, postea in utroque fine saepe alternans. CellulaB limitanea^ ad utrumque polum locello 
lucido instructse. 

Propagatio gonidiis plerumque exultima generatione ortis. Gonidia plerumque numerosa seriata 
e vagina se exserunt tumque in singula secedunt. (R.) 

Filaments equal, articulate, often moniliform or submoniliform, vaginate, pscudoramose, furnished 
with heterocysts which are either interstitial or at the base of the branches, and are mostly thick- 
walled. Sheaths formed of numerous strata (not always distinct), their surface smooth, corrugate, 
or roughened, the exterior stratum sometimes breaking up into fibrillie, not rarely inturaescent or 
ochreate. 

Vegetation not terminal; division of the cells occurring in one direction, in the beginning in the 
middle of the trichoma, afterwards often alternately at each end. Ueterocysts furnished with a trans- 
lucent spot at each end. 

Propagation mostly by gonidia arising from the last generation Gonidia mostly numerously 
seriate, passing out of the sheaths and then separating one from the other. 



oG 



FRESH-WATER ALGJi OF THE UNITED STATES. 



E marks.— The &'ci/toncmaccw are simple or branched filamentous plants, which 
grow in water, or in the air, upon tree-trunks, rocks, fences, &c., in moist localities. 
A number of individuals of one or more species are almost always associated to 
form on the ground little mats, or in the water attached or floating masses of vary- 
in" color and characters according to the species. The individual filaments are 
composed of two distinct parts, the inner the protoplasmic matter, the outer tlie 
cellulose sheath. The former of these is a long cylindrical mass, which is occa- 
sionally interrupted by a distinct thick-walled cell, spoken of in this memoir as 
the Ju'leroci/fif, or "«■//«?/« percZ«rfl?i//5MS-." The inner filament is composed of 
colored protoplasm, which is sometimes homogeneous, but in other cases is dis- 
tinctly granular. It is most generally articulated after the manner of an oscilla- 
toria, but occasionally it is continuous for a great portion of its length, and in one 
species, which is here described, although very possibly not belonging in the family, 
there are, at regular intervals, partitions running across from one side to the other of 
the sheath, so that the inner filament may be said to be made up of a number of cells. 

The heterocysts are of various shapes, globular, compreseed, cylindrical, oblong, 
&c. &c. They are mostly provided with a bright colorless spot at each end. Their 
number varies according to the species. Sometimes they are single, in other cases 
there are several of them arranged in series. They are placed either at the origin 
of the branches, or are scattered apparently without definite arrangement in the 
length of the filament. In the one case, they are known as " lasal" in the other 
as " interstitial." In any species, either of these methods, or both of them, may 
prevail; but a certain amount of specific value attaches to the situation of the 
heterocysts. Their function is totally unknown, although some have imagined 
them to have a sexual significance and even to be spermatozoids, but there is 
no proof whatever of the truth of such suppositions, and it is, I think, very certain 
that these heterocysts are not of the nature of spores. 

The sheath of the Scytonona is composed of one or more strata, which are 
often very distinct from one another, but are more often, perhaps, not so. It is 
opaque or translucent, and has its outer surface smooth, or tubercular, fibrillate or 
roughened in some way. 

The specific characters in this family can best be commented upon under two 
heads— namely, those which are discoverable with the unaided eye, and those 
which the microscope alone can reveal. The points to be observed under the first 
of these are as follows : The place of growth of the plant, whether in the air or in 
the water, and, if it live in the air, to what it is attached — whether to stones, dead 
wood, or living trees, and it is possible that in some cases it may be found that 
certain species of Scytomma inhabit only certain species of trees. If the plant 
be in water, it must be noted whether it be attached or floating. Then the habit 
of growth must be looked at, including in this the size and thickness of the masses 
of filaments, whether they be flocculent, turfy, crustaceous, membranous-gelatinous, 
&c., their softness or rigidity, their color, as well as the arrangement in them of 
the filaments. To discover the latter, it will generally be necessary to use a low 
power of the microscope, and at the same time the mode and profusion of branch- 
ing of the individual plant should be studied. 



FRESn-WATER A L G J<: OF THE UNITED STATES. 57 

The second class of characters are those discoverable only with the liiyhcr powers. 
They are divisible into two sets ; those afforded by the inner filament and tliose 
derived from the sheaths. In the first of these the points to be noted are, the 
diameter of the filament ; its color, whether it be or be not articulated, and if it 
be the length of the joints ; whether it is uniform or moniliform ; whether it be 
homogeneous or granulate ; then the heterocysts should be examined as to their 
size, position, arrangement, shape, number, and color. 

The diameter of the sheath, its homogencousness, its color, firmness, and the 
condition of its outer surface are to be included in the specific study. 



Genus SCYTONEMA. 

Triclioruata caespitoso-congregata vol fasciculata, plus minus pscudoramosa, cellulis interstitialibus 
instructa; vagina gelatinoso-membranacece, e stratis (interdum obsolutis) pluribus cylindraceis com- 
posite; cellulis perdurantibus singulis. 

Filaments csespitosely-eongregate or fasciculate, more or less pseudoramose ; furnished with in- 
terstitial cells ; sheaths gelatinous-membranaceous, composed of many cylindrical, sometimes ob- 
solete, strata; heterocysts single. 

a. Terrestres vel aquaticae. 
a. Terrestrial or aquatic. 

S. siinplice, Wood, (sp. nov.) 

S. iu strato modice crasso, subtomentoso, nigro-viride ; trichoraatibus valde elongatis, flexuoso- 
curvatis, parcissime pseudoramosis vel ssepe sine pseudoramulis; pseudoramulis geminis vel 
singulis, plerumque elongatis ; trichomatibus interiiis modo distincte articulatis, raodo inar- 
ticulatis, apicc interdum brevissime articulatis, granulosis, pallide viridibus, ad genicula siiepe 
nodosis Tel disjunctis, articulis plerumque diametro fequalibus ad 7 plo longioribus; vaginis 
plerumque supra truncatis et apertis, pellucidis, ssepc coloris cxpertibus, interdum dilute 
aureo-brunneis ; cellulis perdurantibus cyliudricis, interjcctis, diametro 2-5 plo longioribus. 

Z>iam._Trich. cum vag. 55'ij/— tsVts" = .0004"— .00066" ; sine vag. 75*0/— 75^55" = .00013" 
—.00026". 

Hab. — In lignis irroratis. South Carolina. (Ravenel.) 

S. in a moderately thick, somewhat tomentose, blackish-green stratum; trichomata very elongate, 
flexuously curved, very sparsely branched or frequently without branches ; branches geminate 
or single, mostly elongate ; internal filament partly distinctly articulate, partly inarticulate, 
granular, pale-greenish, in its apex sometimes very shortly articulate, sparsely granular, 
often nodose or disjoined at the joints ; articles mostly from equal to to 7 times longer than 
the diameter; sheaths thick, transparent, often colorless, sometimes pale yellowish-brown, 
mostly open and truncate at apex ; heterocysts cylindrical, interspersed, 2-5 times longer 
than their diameter. 

Remarhs. — I am indebted to Professor Ravenel for specimens of this species. 
They are preserved in solution of acetate of alumina and accompanied by the fol- 
lowing label : " Adhering to the wet sides of a wooden gutter, leading water from 
a spring, September 29, 1869: Aiken, South Carolina." The filaments are 
remarkable for the fewness of their branches. Generally, indeed, there are no 

8 May, 1872. 



58 FRESII-WATEK A L G .E OF THE U .N 1 T E D STATES. 

brandies whatever, and I have never seen more than a single pair, or, at most, 
tliree branches to a fihimcnt. The mass of fihinicnts is blackisli-grecn, somewhat 
tomentose and quite shiny in appearance. Tlie articles are often very long, and 
tlie internal filament is frequently in suck cases enlarged into a sort of globular 
node at the joint. Not at all rarely there is a very decided break in the endo- 
chrome at the joints. 

This species is very close to S. Anstinli, from which, however, I think it suffi- 
ci(Mitly distinct. The points of difference are in the much firmer, much more 
colored aiul opaque, and rougher sheath of that species; in the swollen ends of 
the internal filament of ^S'. Avstinii, and its shorter articles, with the absence of 
nodes or distinct interruption of the cndochrome at the joints. The heterocysts 
are also quite different in the two forms, whilst the filaments of S. simjjUce are 
nuich the longer. 

S. Aii!«li»ii, Wuup, (sp. iiov.) 

S. nipic'ola, strato tomentoso, csespitoso, crasso, fiisco-nigro ; trichomatibus adscendcntibus, 
curvatis, plcniniqiic siiiiplicibus ; trichomatibus intcniis itrugineis vel fuscescentibus, articu- 
latis Tcl iiiarticiilatis, fine sa>pe valde incrassatis ; articulis diametro plerumque multo bre- 
Tioribus, interdiiiu longioribus ; vaginis riibido- vel aureo-fuscescentibus, s»po sub-opacis, 
firmis, iiidistiiicte bimellosis, in apice plerumque achrois et coloris fere expertiljus, snperficie 
subnigosa et birta; eellulis pedrurantibus breviter cylindricis, vel subquadratis vel subglo- 
bosis, iiiterdum valde couipressis et diametro multo brevioribus. 

Biam.—FW. cum. vag. .OOOG"— .0008" ; sine vag. .00016"— .0004". 
Ilah. — lu rupibus, "Little Falls, Jsew Jersey." (Austin.) 

S. growing on roek.s, stratum tomentose, and somewhat turfy, brownish-black ; trichomata 
ascending, mostly simple, curved ; internal filament a;ruginous or fuscous, articulate or inar- 
ticulate, often very much thickened at the ends; articles much shorter to longer than tlieir 
diameter ; sheaths reddish or yellowish-fuscous, at the apex colorless and transparent, firm, 
indistinctly lamellate ; surface rough; heterocysts shortly cylindrical, subquadrate or sub- 
globose, sometimes strongly compressed and much shorter than broad. 

Be I narks. — This plant occurs as a blackish stratum of one or two lines in thick- 
ness, forming a sort of miniature turfy cushion upon the rock. When examined 
with the hand-glass, this layer is seen to be composed of a great number of ascend- 
ing curved filaments Avhose color, in some specimens, is a reddish-brown ; in 
others, apparently younger, yellowish-brown. Under the compound microscope 
the sheaths in the older filaments are seen to be much roughened externally and 
irregular in outline. The young sheaths are smooth. The filaments are mostly 
simple, since I have not seen more than a half dozen having even a single brancli. 

The heterocysts are scattered at irregular intervals, and are remarkably irregular 
in form — sometimes much shorter than broad, sometimes several times as long. 
As the ends of the filaments are approached the internal filament suddenly swells 
out and increases sometimes to twice the diameter it has in the central part of the 
filament. In the filament proper it rarely attains a diameter of more than .0003", 
and is commonly about .00025", whereas at the ends it very generally approaches 
the maximum .0004:2". 



FRESH-WATER ALG^ OF THE UNITED STATES. 59 

S. iniiuersiiiu, Wood, (sp. nov.) 

S. immersum cum algis altt-ris intermixtum et plantas aquaticas adliEerens ; trichomatibus 
elongatis ; pseudoramulis j)lus minus distantibus, plerumque gemiuis, et e basi divergeuter 
adseendentibus, brevibus aut elongatis; trichomatibus internis Isete aerugineis, interdum dis- 
tincte articulatis, iuterdum inarticulatis, apice obtuse rotuudato, ajrugiueo; articulis diamcti-o 
subffiqualibus vel brevioribus ; vaginid amplis, hyalinis, coloris expertibus ; cellulis pcrdu- 
rantibus distinctis, singulis, iuterjectis, subcylindricis, diameti-o iuterdum fere duplo breviori- 
bus, interdum duplo longioribus. 

Biam.— Sin. vag. yj^j,/ = .000415". Cum vag. tj§oj" = -00076". 

Hab. — In aquis quietis, Cumberland County, New Jersey. 

S. immersed, intermixed with other algae and adhering to aquatic jilaiits ; filaments elongate; 
branches mostly geminate, more or less distant, short or elongate ; iiiteriia! lilaniciits bright 
aeruginous, sometimes distinctly articulate, at others not so, apex obtusely rounded a:ruginous; 
joints about equal to the diameter or shorter; sheath ample hyaline, cohirle.-s; lieterocysts 
distinct, single, interjected, subcylindrical, sometimes about half as long as broad, sometimes 
nearly twice as long. 

Remarks. — I found tlii.s plant in September, 1869, in Shepherd's Mill Pond, near 
Greenwich, Cumberland County, New Jersey, forming, with other alga?, a floccu- 
lent, greenish-black, slimy coating to the stems and finely dissected leaves of 
Eaiiuiiculus aquatilis. The branches arc very few in number in most specimens, 
and when they are more plentiful are apt to be short and abortive. Their apices 
do not differ materially from their other portions. 

Fig. 9, pi. 2 a, represents a portion of a filament of this specimen magnified 750 
diameters ; fig. 2 & a whole filament magnified 2G0 diameters. 

S. l\a;gelii, Ktz. (?) 

S. csesptoso-floccosum, bryophilum, nigro-viride; trichomatibus, plerumque sparse pseudora- 
mosis, pseudoramulis(|ue elongatis et intricatis ; trichomatibus internis brevitor articulatis, sa?|ie 
interruptis, saspe nonnihil moniliformibus, viridibus aut in state provecta brunneis; articulis 
saepe sejunctis, diametro plerumque brevioribus, subtiliter granulatis; pseudoramulis plei'umque 
singulis ; vaginis modice arctis, interdum subamplis, hand distincte lainellosis, niodice crassis, 
hyalinis, coloris expertibus ant in aetate provecta dilute fusco-brunneis; cellulis perduranti- 
bus nonnihil reniformibus, plerumque nnllis, basilaribus. 

Diam. — Fil. cum vag. plerumque y/uu" — max. 5550" ; S'"c vag. T^^jyu'i *''■'"• pcrdurant. lab. 

T5(T?)T long. j^uiJTJ • 

Siin.- — S.Nxgelii (Ktz.), R.-VBExnORST, Flora Europ. Algarum, Sect. II. p. 2.52. 

Hah. — In fonte, prope Belvidere, Centre County, Pennsylvania. 

Growing in small, blackish-green woolly mats attached to mosses; filaments mostly sparsely 
branched, with the branches elongate and intricate ; internal filament shortly articulate, 
often somewhat nioniliform, often Interrupted, green, or, in mature state, brownish ; joints 
often disjoined, mostly shorter than the diameter, finely granulate; branches mostly single; 
sheaths moderately close, .sometimes ample, not distinctly lamellate, rather thick, hyaline, 
colorless, or, in old age, light fuscous brown ; heterocysts mostly wanting. 

Rcmarl-fi. — I found this plant in the large spring that supplies Bcllcfonte with 
water, growing attached to mosses, so as to form little dark-green mats around 



GO FRESII-WATER ALG^ OF THE UNITED STATES. 

their stems and branches. These mats never exceeded an inch in length in any 
specimens that came under my notice. The filaments themselves are apparently 
not much branched and are densely interwoven. The sheaths are close, rather 
thick, not lamellate, of uniform diameter, except in that they are occasionally 
locally swollen, and are truncate and open at the end. The internal filaments are 
frequently much interrupted, and in the younger plants are of a deep green. The 
joints are in many instances much separated, and in most cases very distinct. 
The filaments, indeed show a remarkable tendency to break up at the joints, so as 
to form a series of dish-like gonidia, so that the articles, or endochrome masses, 
may be generally described as strongly compressed spheres. In all the specimens 
that I have examined, I have seen but a single heterocyst. This was at the base 
of a branch, was somewhat rcniform, and about three-fifths as long as broad. I 
have referred this species, doubtfully, to S. Naegelii, Ktz., the only account of 
which that I have met with, or know of, is a brief diagnosis in Rabenhorst's Flora, 
in which many of the essential characters are omitted. 

Fig. 6, pi. 8, represents a portion of a filament of this species. 

S. thei'iuale, Ktz. 

S. strato tenue, nigrescente ; trichomatibus flexuoso-curvatis, intricatis, parce pseudoramosis, 
internls pallitle serugineis, SEepe coloris fere expertibus, passim interruptis, plerumque inar- 
ticulatis sed ssepe indistincte et interdum distincte articnlatis, granulosis ; articulis dianietro 
brevioribus vel subsqualibus ; pseudoramulis plerumque brevibus, geminis, iu dianietro tri- 
chomatibus aequalibus vel subaequalibus et interdum usque ad medium eonjunctis, basi coa- 
litis, ssepe e basi divergentibus; vagiuis crassis, indistincte lamellosis, vel luteo-fuscis vel 
fuscis, sed passim fere coloris expertibus, plerumque vix pellucidulis, in ramulorum apice 
ssepe hyalinis et coloris fere expertibus; cellulis perdurantibus, subquadratis vel cylindricis, 
singulis, interjectis. 

Diam.—i:v. cum vag. -r50(io"—T5B5(y" = -00042"— .00058 ; sine vag. ^oV?" = -000166"— 
5^/ = - 00025. 

Syn. — S thermale, Ktz., Rabenhorst, Flora Europ. Algarum, Sect II. p. 250. 

Hab. — In terra argillacea. South Carolina. (Ravenel.) 

Stratum thin, blackish; filaments flexuously curved, intricate, sparingly branched; internal 
filament pale-greenish, often almost colorless, here and there interrupted, mostly inarticulate, 
but often indistinctly and sometimes distinctly articulate, granular ; joints shorter or about as 
long as broad ; branches geminate, mostly short, equal or subequal to the filament in diameter, 
coalescent at the bases, rarely so even to their middle, mostly divergent from the base ; sheath 
thick, indistinctly lamellate, yellowish-fuscous, and scarcely semitransparent, but here and 
there nearly colorless and pellucid, generally so in the apices of the branches; heterocysts 
subquadrate or cylindrical, single, interspersed. 

Remarks.— I am indebted to Professor Ravenel for specimens of this species pre- 
served in solution of acetate of alumina. The label reads, "Damp surfoce of hard 
clay, Sept. 25, 1869." The sheaths are quite thick and scarcely translucent, so that 
the color of the inner filament seen through them is that of themselves. Curiously 
enough, one of these dark sheaths will for a space lose its color and be very trans- 
parent, in such places and in the apices of the branches, the inner filament is often 
a decided pale-green ; at other times it is almost colorless. The end of the sheaths 
are mostly closed, but I have seen them open, with the inner filament project- 



FRESH-WATER A L G J3 OP THE UNITED STATES. 61 

ing. The branches are nearly always short, and divergent from their united bases. 
The heterocysts have frequently one of their ends rounded ; and are quite 
numerous. This species corresponds too closely to liabenhorst's description of 
Scytoaema thermale to be separated, but it is possible a comparison of specimens 
might show decided differences — the description of the European form is not very 
full. The American plants seem to approximate most closely the Var. intextum. 
I have seen a single branch given off only in one instance. 

Fig. 1, pi. 6, represents a filament of this species magnified 260 diameters; fig. 
1 h, the outline of a heterocyst magnified 750 diameters. 

S. lUyocliroii)!), Aa. 

S. strato tenui, pannoso-tomentoso, obscure fusco (nonnunf|nani siibsericeo) ; trichoniatibus 
validissimis, fuscis, lucidis, leniter curvatis, adscetiflentibus, internis lErugineis, apice (articul. 
term. 5-6) rubellis, distiucte articulatis; pseudoraraulis plerumque geminis, sa;pe longissirais 
flaccido-erectis, trichomate dimidio circiter tenuoribus; trichomatis vaginis crassis, distincte 
lamellosis, firmis, pulchre luteo-fuscis, supcrficio l«vissimis, ramulorum semper pallidioribus 
(luteis, rarius aclirois), apice s»pc achrois, clausis et obtuso-rotundatis; cellulis perdu- 
rantibus obloiigis vel subcyliiidricis, achrois, trichomatis interni diametro subiequalibus. 
(R.) Strato-obscure olivaceo, trichoraatibus parce pseudoramosis, ad ^L"' crassis; pseiido- 
rannulis singulis, vagiuis achrois vel luteolis ; vag. trich. luteo-fuscis. (R.) Species mihi 
ignota. 

Z)m?)i.— Trichom 0.0011"— 0.0014" ; ramulorum ad 0.000G8". (R.) 

Syn. — S. Mijochrous, Agardii ; Yar. Contextum, Carmichael. Rabenhokst, Flora Europ. 
Algarum, Sect. II. p. 254. 

Hab. — " Foot of Crow's-nest, West Point." Bailey. Silliman's Journal, N. S. vol. iii. 

Strato thin, pannosely toraentose, obscurely fuscous (sometimes somewhat silky) ; filaments very 
strong, fuscous, bright, slightly curved, ascending; the internal [cruginous, distinctly arliru- 
late with the ape.x (terminal 5-G joints) reddish ; branches mostly geminate, often very long, ' 
flaccidly erect, about one-half thinner than the filament ; sheath of the filament thick, dis- 
tinctly lamellate, firm, beautifully yellowish-fuscous, surface very smooth ; sheath of the 
branches always paler (luteous or rarely colorless) with the apex colorless, short and obtusely 
rounded; heterocysts about equal in diameter to the internal filament. Stratum obscurely 
olivaceous, filaments sparsely branched, about ^^"' thick ; branches single, with the sheaths 
transparent or yellowish ; sheath of the trichoma luteo-fuscous. 

S. caloti*ichoide)!i. Kutzing(?). 

S. cajspitosum, mucosum, plerumque cum algis variis interraixtum ; trichoniatibus plus minus 
curvatis; pscudoramulis plerumque geminis, varie curvatis, siraplicibus, elongatis ; tricho- 
niatibus internis modo distincte articulatis, modo inartieulatis, inlerdum moniliformibus, 
luteo-viridibus vel serugineis, granulosis; articulis plerumque diametro brevioribus sed in- 
terdum permulto longioribus, baud rare vel subglobosis vel valde compressis ; cellulis per- 
durantibus .singulis, subcylindricis; vaginis plerumque pellucidulis, di.«tincte lamellosis, in 
trichoniatibus plerumque rubido-vel luteo brunneis sed interdum eoloris expcrtibus, in pscu- 
doramulis hyalinis, eoloris expertibus vel dilutissime luteis vel dilute luteo-brunneis. 

Z>iam.— Cum vag. max. ,^-\,^"=. 00015"; plerumque 55%/ =.00045"; sine vag. tsVt" — ?o'us"; 

pseudoram. ^^^ly" = -0005". 
Syn.S. calotrichoides, Ktz. Rabenhorst, Flora Europ. Algarum, Sect. II. p. 252. 
Hab. — South Carolina. (Ravenel.) 



02 FRESir-WATER AlAi Ai OF THE UNITED STATES. 

Caespitosc, niiicous, mnstly intermixed with various algre ; filaments more or less curved; 
branches mostly in i)aii-s, cdongate, simple, variously curved ; internal filament partly dis- 
tinctly articulate, partly not articulate, sometimes moniliforra, yellowish-green or rerugiuous, 
granular ; joints mostly shorter than the diameter, sometimes much longer, sometimes sub- 
globose or strongly compressed; heterocysts single, subcylindrical ; sheaths distinctly lamel- 
late, mostly reddish or yellowish-brown, but sometimes colorless, in branches hyaline, color- 
less, or with a very faint yellowish tint, or sometimes brownish. 

Remarlcs. — The specimens, from which the above description was drawn up, 
were sent me by Professor llavenel from Soutli Carolina. The extremities of the 
sheaths are either closed, or open. The branches are almost always in pairs, and 
sometimes three or four are given off together, but this is not common. They 
are often nearly or quite colorless; the main filament is generally a sort of 
brown — sometimes quite bright from the predominance of the yellow hue. 
Although my specimens do not precisely agree with the descriptions of the 
European S. calotriclioidcfi, yet the disagreement docs not seem sufficient or 
sufficiently constant to separate specifically the two forms; the most important of 
the differences is in the coloration of the sheaths and heterocysts, which in the 
American plant are commonly, but not universally, respectively bro^vnish and 
greenish. 

The label, which Professor Ravenel has attaclied to some of the specimens, 
reads, " In wet, boggy places, on rotten pine boards, Sept. 25, 1869." 

Pig. 2, pi. 6, represents a filament of this plant magnified 250 diameters. 

S. cataracta, Wood. 

S. rupicola, csespitosum, fusco-atrnm, longe et late expansum; trichomatibus flexuosis, flexili- 
bus, fere 0.25" longibus, vage pseudoramosissimis, superficic lajvibus; pseudoramis elongatis, 
singulis, rarissime geminis, liberis, interdum fuscis, saepius hyalinis, apice plerumque truncatis 
et rare nonnihil attenuatis et sa;pe barbais scd hand rubellis ; trichomatibus internis aerugi- 
neis, tenuissimis, plerumque distincte articulatis ; articulis diametro jilcrumque brevioribiis, 
sed interdum longioribus, saepe sejunctis, stepe subglobosis ; vaginis crassis et firmis; cellulis 
perdurantibus et basilaribus et interjectis, singulis, rarissime geminis. 

Z>ia)H. —Trich. cum vag. plerumque .00045" ; ma.x. .0011"; sine vag. max. .00013". 

Si/n.—S. cataracta, Wood, Prodrorau-s, Troc. Am. Phil. See, p. 129, 18G9. 

Hal). — In Qumine Niagara propc cataractam. 

S. forming on rocks an extended turf-like stratum of a brownish-black color ; filaments (lexnous, 
flexible, almost 0.25" long, irregularly branched, their surface smooth ; branches elongate, 
single, rarely in pairs, free, sometimes fuscous, frequently hyaline, their apices generally 
truncate, rarely somewhat attenuate, frequently provided with enlargements, never reddish ; 
cytioplasm aeruginous, very thin, generally distinctly articulate ; articles mostly shorter than 
broad, but sometimes longer, frequently disjoined, often subglobosc; sheaths thick and firm; 
heterocysts both basal and interjected, single, extremely rarely geminate. 

Remarlcfi.—'Y\n^ species grows abundantly in the Niagara Eiver, on the rocks 
below the great cataract. It is really in little tufts, but these are in many cases 
placed so closely as to form a broad turf-like coating to the stones. Often, however, 
the tufts are in smaller patches, and are of sufficient length to wave with the 
oddies and currents in the water. Tlie branches are ahuost alwavs given off 



FRESH-WATER A L G .E OP THE UXITED STATES. 63 

singly since I liave examined some hundreds of specimens, and have only in one 
instance detected them in pairs. The apices of the branches, and indeed of 
the main filaments, are beautifully colorless and hyaline, and not unfrequently a 
branch will have this hyaline sheath for a long distance. The extreme ends are 
mostly truncate and open, and, often near them, the sheaths will have marked 
swellings ; a condition which, for want of a better term, I have spoken of as being 
hurhate. Sometimes near the end of the filament the diameter of the sheath will 
be suddenly lessened. The large cells are both interstitial and placed at the bases 
of the brandies ; they are more or less oblong or quadrangular, sometimes being 
scarcely longer than broad, but in other cases several times longer. At their posi- 
tion there is very generally a sort of globular enlargement of the filament. The 
sheath is sometimes very obscurely lamellate. The color of the 'older filaments is 
a dark, almost chocolate-brown. This is apparently the species referred to by 
Professor Bailey as being Scytonema ocellatum of Harvey, in Silliman's Journal, vol. 
iii. N. S., although that plant, according to Professor Rabenhorst, belongs to the 
genus Slrosiphon. 

Fig. 1 a, pi. 7, represents a portion of a filament, magnified 280 diameters ; fig. 
1 5, a whole filament slightly magnified. 

S. diibitini, Wood (sp. nov.) 

S. immersum, in floccis mucoso-tomeutosis olivaceo-nigris plantas aquaticas adhaBrons, vel in 
strato mucoso et nonnihil tomeutoso dispositum; tricbomatibus valde elongatis et arete in- 
trieatis, varie curvatis, plerumque sparse pseudoramosis; pseudoranuilis pleriimque singulis, 
etplus minus distantibus et niodice brevibus, vel interdum brevissiniis et abortivis et nonnihil 
confertis; trichomatibus internis saepe in pseudocellulis distinctis contentis, interdum con- 
tinuis et indistincte articulatis vel inarticulatis, plerumque dilute creruleo-viridibus sed inter- 
dum Iffite ffirugineis, subtilit^r granulatis; vaginis arctis plerumque modice crassis et firniis, 
hyalinis, coloris expertibus; cellulis perdurantibus cylindricis, diametro 2-6 plo lougioribus. 
Z>wm.— Cum vag. ^^^^^" —^^^^^" =■. .00025"— .0004". 

Hah. — In aquis quietis, Cumberland County, New Jersey. 

Immersed, adhering to water plants in olive-black tomentose flocculent masses, or arranged 
in a mucous and .somewhat tomentose stratum ; trichoraata very long and closely interwoven, 
variously curved, mostly sparsely branched ; branches generally single, more or less distant, 
and moderately short, sometimes very short, abortive, and somewhat crowded ; internal fila- 
ment often contained in distinct cell-like apartments, sometimes continuous and indistinctly 
articulate, or not at all articulate, finely granulate, mostly a pale bluish-green, sometimes a 
bright aaruginous color; sheath close, mostly rather thick and firm, hyaline colorless; hetero- 
cysts cylindrical, 2-6 times longer than broad. 

Remarlcs. — I found this plant, September, 1869, in Shepherd's Mill Pond, near 
Greenwich, Cumberland County, New Jersey. It formed dark, ugly, somewhat 
slimy, tomentose flocculi adhering to, and binding together, the finely-dissected 
leaves of Ranunculus aquatilis. The filaments are very long, slender, and sparsely 
branched. The branches are given off at right angles, or nearly so, but are fre- 
quently sharply bent just above their origin. They are often, but not always, 
rather short. The most remarkable character that the plant possesses is that in 
many filaments there are very distinct regular partitions stretching across from 



64 FRESH-WATER ALG.E OF THE UNITED STATES. 

side to side, so that the interior is divided, as it were, into snccesstve cell-Hke 
chambers, in which the colored protoplasm is contained. This character seems 
almost to separate the plant from the genus Scytonema, but I have deemed it 
insufficient grounds for indicating a new genus. Since writing the preceding 
remarks, I have received specimens of this species from Professor Ravenel, who 
collected them in South Carolina, near the town of Aiken. They agree in all 
respects, except that they form a dark, mucous, somewhat tomentose coating to 
pieces of wood. 

Fig. 3 a represents the outline of a scries of the cells alluded to, magnified 750 
diameters, and figs. 3Z> and 3 c, portions of filaments magnified 460 diameters, 

b. Arboricolx. 

b. Growing on trees. 

S. cortex. Wood. 

S. rainutissiiuuni, stratum tenue subraembranaceum formante; trichomatibus sparse pseudoramu- 
losis, pseudoramulisque repentibus et plus minus concretis, viridibus aut dilute fuscis, varie 
curvatis, baud rigidis; cytioplasraate viride, articulate, rare distinctc granuloso; articulis 
diametro longioribus aut brevioribus; vagiuis aretis, nonnihil tenuibus, pleruraque coloris 
expertibus, sed interdum dilute fuscis; cellulis perdurantibus et singulis et gemiuis, ct basa- 
libus et interjectis, globosis vel subglobosis. 

I>ia>?i.— Trich. cum vag. 75W— tsW- 

Syn. — Scylonema cortex, Wood, Prodromus, Proc. Am. Philos. Sec, 1869, p. 130. 

Eab. — South Carolina. 

S. very minute, forming a thin, submembranaceous stratum ; filaments sparsely branched, toge- 
ther with the branches, creeping and more or less concreted together by their sides, green or 
light brown, variously curved, not rigid; cytioplasm (internal filament) articulate, rarely 
distinctly granulate; joints longer or shorter tlian broad; sheaths close, rather thin, trans- 
parent, generally colorless but sometimes light brown ; hcterocysts globular or subglobular, 
single or in pairs, basal or otherwise. 

RemarJcs. — I have specimens of this species collected in South Carolina by Pro- 
fessor Ravenel, who found it growing on the bark of Platanus occidentalis. The 
thin, almost membranous stratum which it forms, is of a dark olive-black, and has 
to the eye a sort of minutely warty appearance. The filaments are so involved 
and so adherent, one to the other, that I have not been able to separate any length 
of them, nor are the branches distinguishable from the main filaments. The sheaths 
are rather thin, and often not very apparent. 

Fig. 4, pi. 6, represents this species. 

S. Ravenelii, Wood. 

S. liguicola, breve cajspitosum, viride-nigrum; trichomatibus pleramque repentibus, vel fusco- 
olivaeeis vel aureo-fuscis, modice pseudoraraosis ; ramis ascendentibus, rigidis, flexuosis rare 
pscudoramulosis, vel fusco-olivaceis vel aureo-fuscis, rarissime cum apicibus subachrois ; tri- 
chomatibus internis coloris expertibus, granulosis, stepe vagina eriimpentibus, plerumque 
articulatis; articulis diametro longioribus aut brevioribus; vagiuis aretis, crassibus, fusco- 
olivaceis vel aureo-fuscis, plerumque supra truncatis et apertis, superficie nonnunquam irregn- 
lanbus; cellulis perdurantibus subquadratis vel subglobosis singulis aut rare geminis, inter- 
jectis ; in stato juvene trichomatibus internis airugincis, vaginis tenuibus. 

Dmm.-Trlch. cum vag. 7/55"— 7 eV ) ram cum vag. 75%^"— t/stt" ) trich. sine vag. j^Vir" 



FRESn-WATER A L G .E OF THE UNITED STATES. 65 

Syn. — S. Bavenelii.Woos, Prodromus, Proc. Am. Philos. Soc, 1869, p. 130. 

Sab. — In cortice, South Carolina. 

S. Forming little turfy spots of a greenish color, on bark ; filaments mostly creeping, either 
brownish-olive or yellowish-brown, moderately branched ; branches ascending, rigid, flexu- 
ous, very rarely provided with secondary braachlets, either brownish-olive or yellowish- 
brown, rarel}^ subtransparent at the apex; cytioplasm colorless, granular, often extending out 
beyond the sheaths, generally articulate ; joints longer or shorter than broad ; sheaths close, 
thick, brownish-olive or yellowish-brown, for the most part truncate at their ends and open, 
their surface sometimes irregular ; heterocysts subquadrate, single, interstitial. 

Remarhs. — I am indebted to Prof. H. W. RaA'enel for specimens of this very 
distinct species. Some of these are labelled as having grown on the twigs of a 
ccltis in South Carolina, other specimens are on the bark of a willow. The branches, 
which are mostly shortish, simple, and variously curved, are sent up in great 
numbers by the creeping stems, and, like the stems themselves, are mostly free, 
but not unfrequently are closely adherent by their edges. 

The internal trichoma or cytioplasm, owing to the great thickness of the sheaths, 
is not very apparent within these latter, but not unfrequently projects for a dis- 
tance beyond them, when it is seen to be colorless, very granular, and mostly, but 
not always, distinctly articulated. In the young plant the filaments are bright- 
green, often not more than ^gV o of an inch in thickness, and have the sheath very 
thin, or may be almost imperceptible. It affords me great pleasure to dedicate 
this species to Professor Ravenel, not as an acknowledgment merely of his aid in 
my studies of this hitherto neglected branch of the North American Flora, but 
rathe* of the great services he has rendered science in some of its kindred 
branches. 

Fig. 4, pi. 5, represents the end of a filament of this species magnified some 450 
diameters. 

Genus TOLYPOTHRIX, Ktz. 

Trichoma scytonemacea cum cellulis perdurantlbus seriatis. 

Filament similar to that of scytonema, but with the heterocysts seriate. 

T. distorta, (Mijller) Kotz. 

T. ciEspitoso-floccosa, Iste et pnlchre viridis ; trichomatibus intertextis, Isete viridibus, raodo 
distincte articulatis niodo inarticulatis; articulis diametro brevioribus siepe aut sub-nullis 
aut nullis ; pseudoramulis singulis; vaginis arctis, homogeneis, vltreis ; cellulis perdurantlbus 
basilaribus et interdum interjectis, pachydermaticis, plerumque in parallelogramma; enormis 
forma, plerumque 4-seriatis, subachrois, interdum sparsissime granulatis. 

Syn. — T. distorta, (MiJLLER) Ktz. Rabenhorst, Flora Europ., Algarum, Sect. II. p. 275. 

Eab. — In aquario, Philadelphia, Wood. Rhode Island (Olney) Thwaites. Warden's Pond, 
Rhode Island ; Reservoir Pond, West Point ; Fourth Lake, Madison, Wisconsin, Bailey. 

Flocculent caespitose, bright, beautiful green ; filaments interwoven, bright green, partly dis- 
tinctly articulate, partly continuous ; articles shorter than long, often very indistinct, some- 
times absent; branches single; sheaths close, homogeneous, glas.«y ; heterocysts basilar, 

9 May, 1872. 



66 



FUKSII-WATER ALGJ3 OF THE UNITED STATES. 

sometimes interspersed^ thick-walled, mostly irregularly parallelogrammatic, mostly 4-seriate, 
seiuitrausparcut, sometimes very sparsely granulate. 

Bejuarlcs.— This species grew spontaneously in the aquarium of my friend Dr. 
Fricko, to whom I am indebted for specimens of it, forming little, bright-green 
bulls adherent to the various aquatic plants. It approaches so very closely the 
European T. distorta, that I have considered it as a mere variety of it, although it 
differs in having the heterocysts mostly arranged in fours, and also apparently in 
their shape— they being in our plant mostly parallelogrammatic. 

Fio-. 1 a, pi. 8, represents a section of heterocysts magnified 800 diameters; fig. 
1 6, a portion of filament magnified 800 diameters. 

Genus PETALONEMA, Berk. (1833.) 

Scytonematis trichomata vagiuis crassissimis e stratis numerossissimis brevioribus, infundibuli- 
formi dilatatis, imbricatis et plerumque dilutissime coloratis compositis. (R.) 

Syn.—Arthrosiphon, Ktz. (1845.) 

" Filaments stratified, decumbent, free, simple, or branched. Tube or sheath very wide, flat- 
tened lon"-itudinally and transversely striate and crenulate at the edge ; endochrome oliva- 
ceous annulated, here and there interrupted by a heterocyst. Branches issuing in pairs, 
formed by the division and protrusion of the endochrome of the original filament. 

" When placed under the microscope the filaments present the appearance of a cylindrical cen- 
tral column, containing annulated, olive-colored endochrome, and a wide wiug-like border at 
each side of the column. This border or sheath is obliquely striate, the strioe running in an 
arch from the margin toward the centre, where they become parallel, and are then continued 
lon"-itudinally downward along the medullary column, till lost in the density. The margin 
of the wing is closely crenulate and in age transversely striate at the crenatures as though 
jointed. Such is the apparent structure ; the real structure seems to be, that an annu- 
lated central filament is inclosed within a number of compressed, trumpet-mouthed gelatino- 
membrauaceous tubular sheaths, one arising within the other, and successively developed as 
the growth proceeds. These sheaths, thus concentrically arranged, are indicated by arching 
longitudinal striae; and the mouths of the younger sheaths, projecting slightly beyond those 
of the older, form the crenatures of the margin." Harvey. 

P. alatiilil, Berk. 

A. pulvinato-crustaceus, rupicola, varie coloratus; trichoraatibus internis serugineis, curvatis, 
parce pseudoramosis, modo continuis, modo torulosis, submoniliformibus, apice plerumque 
paulum incrassatis, sDepe roseolis, rotundatis ; articulis distinctis, granulosis, diametro sul>- 
jequalibus vel paulo brevioribus ; vaginis stratis internis, aureis vel aureo-fuscentibus, 
externis achrois, vitreis; cellulis perdurantibus interjectis et ad pseudoramulorum basin, 
plerumque solitariis, subglobosis vel oblongis, dilute fuscis. (R.) Species mihi ignota. 

Dmm.— Trich. intern. 0.00016"— 0.00032" ; vag. O.OOSII". (R.) 

Syn. — Arlhrosiphon alaliis, (Grev.) Rabenh. Flora Europ. Algarum, Sect. II. p. 265. 

Petalonema alatum, Berkeley. Harvey, Nereis Boreis Americana, part iii. p. 99, 
Smithsonian Contributions, 1846. 

Eab. — " On dripping rocks under Biddle Stairs, Niagara Falls." (Harvey.) 

" This forms strata of a dark chestnut-brown color and of indefinite extent on the surface of 
rocks or soil exposed to the constant drip of water. The filaments are decumbent, lying 
without order in the gelatinous matrix in which they are developed, and which forms the 



FRESH-WATER A L G uE F THE UNITED STATES. 67 

w 

groundwork of the stratum. They appear to be unattached to the soil, and each filament 
may be about half an ineli in length ; but they ai'e eummonly found brukeu ott' at the inferior 
eud, or the lower part deeays whilst the upper continues to grow. They are slightly curved, 
in serpent-like fashion, never quite straight ; at first they are simple, but now and then emit 
lateral branches, which issue at considerable angles and generally in pairs. When a filament 
is about to branch, a rupture takes place in the side of the sheath, and the endoehrome issues 
in two portions, one connected with the upper, the other with the lower half of the filament; 
these form the nuclei or medullary portion of two new branches and become duly invested with 
a membranous sheath, and gradually put on the aspect of the adult filament. The endo- 
ehrome is granular, dark-brown, and annulated at short intervals, the transverse rings being 
placed very close together in the youngest portions, and less closely in the older, where they 
are distant from each other about twice the diameter of the column. Tliis annulated endo- 
ehrome is interrupted at certain fi.xcd places, where an ellipsoidal cell is formed, separating 
the endoehrome of the lower from that of the upper portions." Harvey. 

Reniarhs. — I have never seen either the genns or species, and therefore am 
forced to copy the descriptions of both from liabeuhorst and Harvey. 



Family SIEOSIPHONACE^. 

Thallus ramosus, e eellulis pachydermaticis aut uni vel pluri seratis et in vagina ampla inclusis 
formatus, interdum eellulis perdurantibus instructus. RaniiUcatio vera fit cellularum vcgetativaruni 
quaruudam divisinne in a.xis longitudinalis din-ctlonera, (|ua ex re cellula; dme sororias gignuntur; 
cellula inferior in trichomatis continuitate permauet, superior divisione continua rcpetita in eaudcm 
directionem se ad ramum e.xplicat. 

Propagatio adhuc ignota. 

Frond branched, formed of thick-walled cells in an ample shenth, sometimes furnished with liete- 
rocysts. Cells uni- or multi-seriate. Branches formed by a longitudinal division of certain 
cells, so as to form two sister cells; the inferior of which remains as part of the trichoma, whilst 
the other, by repeated divisions, grows into a branch. 

Propagation not known. 

Remarks. — The Sirosiplionaceos are the most complex in tlieir organization of 
all the Pliijf-ocliromophuceai, in so far as the protoplasm within the slicaths is every- 
where broken up into a number of distinct cells, each of which is provided with 
a thick coat or wall as well as in the circumstance of the frond having more perfect 
branching. The so-called pseudo-branches in tlie other families are more truly 
comparable to distinct fronds or thalli remaining attach(?d to the parent thallus 
than to distinct branches, whilst among the sirosiphons the branches really belong 
to the original thallus. The heterocysts are much more frequently absent than 
present, only one of the known American species being furnished with them. 
The sheaths are generally not so distinctly sheaths as among the oscillatoria, &c., 
for, instead of being distinct tubes, they appear rather in most cases as masses of 
firm jelly, the outer portion of which is hardened almost into a periderm, and in 
the inner part of which the cells are imbedded. Their color varies from the 
transparent colorlessness of glass to a dark opaque-brown. Their surface is per- 
haps most frequently smooth, but at times is tubercidate or otherwise roughened. 
I have never seen anything like spores about them. 



68 FRESn-WATER A L G .E OF THE UNITED STATES. 

These plants grow in the majority of cases in the air, in snch situation as on 
the face of dripping rocks, on the trunks and branches of trees, on moist ground, 
&c. ; but some of the species are found in the water, either attached or floating. 
They o-enerally form little mats of indefinite extent, but occasionally the filaments 
are united more closely into an almost membranaceous stratum. 

The species are, I think, in most instances readily distinguished, the characters 
being partly discoverable with the unaided eye and partly microscopic. The 
points to be attended to in the first category are the size, color, form, and 
consistency of the mats of fronds, and the place of growth. In the second are 
included the general shape of the frond and its size and method of branching ; 
the general shape, color, and size of the cells, the thickness of their walls and the 
method of their arrangement, both in the main thallus and the branches, also the 
form. Sec, of the end cells of the branches; the hotorocysts, their absence, or, if 
present, tlieir frequency, size, shape, color, and position; the sheaths, their color 
and firmness, and the character of their surface. 

Genus SIROSIPHON, Ktz. 

Trichomata torulosa, vaginata, plerumque ramossissima et aureo- vel olivaceo-fusca, e cellulis 
pachydermaticis 1-2-3 vel pluri-seriatis foniiata et celliilis iuterstitialibtis (siepe nullis) suljglobosis 
vel oblongis coloratis iiistriicta. Vagina plerumque crassissima, firuia, pulcbre aureo-fusea, lutea 
vel olivaeea, in apicem obtusuui plus minus attenuata. 

Filament torulose, sheathed, mostly very much branched, yellowish, or olivaceous-fuscous, formed 
of thick-walled 1-2-3 or many seriate cells and furnished with interstitial cells (often wanting) 
which are globose or oblong and colored. Sheaths mostly very thick, firm, beautiful golden fus- 
cous, clay-colored or olivaceous, more or less attenuate at the obtuse apex. 

a. Cellula in trichomalibus plerumque in serie simplice vel duplici ordinaia. 

a. Cells mostly arranged in a simpAe or double series in the filament. 

S. scytenematoides, Wood. 

S. strato submembranaceo, nigro-viride, sispe interrupto, cum superficie inoequale ; trichoma- 
libus soepe arete intricatis, flexuosis aut varie curvatis, baud rigidis, plerumque vis ramosis ; 
cellulis uniscriatis, interdum interruptis, arctis, irregulare quadrangulis, diametro sub»qua- 
libus aut 1-3 plo brevioriljus, baud distincte granulatis, cteruleo-viridibus; vaginis amplis, 
baud distincte lamellosis, superficie enormiter corrugatis et hirtis, plerumque coloris experti- 
bus sed interdum dilute brunneis. 

Diam.— Sine vag. max. jg%^" = .000(36" ; cum vag. max. ^ig^" = .0013". 

Syn.—S. scytenematoides, Wood, Prodromus, Proc. Amer. Philos. Soc, 1869, p. 134. 

Eab. — South Carolina. (Ravenel.) 

S. In a submembranaceous, blackish-green, frequently interrupted stratum, with an uneven 
surface ; filaments often closely intricate, flexuous or variously curved, not rigid, mostly 
sparsely branched ; cells uni-seriate, sometimes interrupted, close, irregularly quadrangular, 
about equal in length to their diameter, or about 1-3 times shorter, not distinctly granulate, 
blui.sh-green; sheaths ample, not distinctly lamellate, their surface rough and corrugate, 
transparent, mostly colorless, sometimes light-brown. 

Bemarks.— This species was collected in South Carolina by Prof. Ravenel, who 
found it in the month of February growing on the limbs of Mi/r!ca eeri/era. The 



FRESn-WATER A L G .E F T II E U x\ 1 T E D S T A T E S. 69 

blackish-green layer, which it makes upon the bark is very peculiar, being almost 
membranaceous, and especially in the dried state, presenting a rough, somewhat 
warty surface. The trichomata have the sheath more distinctly in the form of a 
hollow cylinder, or, in other words, more plainly a sheath, than any other species 
T have seen of the genus ; the cells are also without any apparent walls, and are 
placed very closely together, so that the whole filament looks very like a scylo- 
nema. 

Fig. 1, pi. 9, represents a portion of a frond magnified 260 diameters. 

S. pelliicidulu!^, Wood. 

S. immersus; trichomatibus ramossissimis, soJitariis vel subsolitariis ; ramis plerumque unila- 
teralibus, ramnlosis; ramulorum apicibus late rotundatis, baud attenuatis; cellulis in serie- 
bus simplicibus dispositis, in tricbomatibus nonnihil rotundatis, in raraulis sspe angularibus, 
plerumqne compressis, diametro ffiqualibus — 4 plo brevioribus ; termiualilms cylindrieis et 
obscure articulatis ; cellulis interstitialibus nullis; vaginis arctis, hyalinis, baud lamellosis; 
cytioplasmate aerugineo vel brunneo, minute granulato. 

Dfawi.— Tricb. cum vag. 7/55" = .00106" ; sine vag. = .0008". 

Syn. — S. jxllucidulus, Wood, Prodromus, Proc. Amer. Pbilos. Soc, 1869, p. 133. 

Hah. — In stagnis, prope Hibernia, Florida. (M. W. Canby.) 

S. immersed ; filaments very much branched, solitary or subsolitary ; branches mostly unilateral, 
branched; apices of the branches not attenuate, broadly rounded ; cells disposed in a simple 
series, in the trichoma somewhat rounded, in the branches frequently angular, mostly com- 
pressed, from equal to 4 times shorter than the diameter ; terminal cell cylindrical, obscurely 
articulate; interstitial cells none ; sheath close, hyaline, not lamellate; cytioplasm ajriigin- 
ous or brown, minutely granulate. 

Remarks. — This species was collected by Mr. Willi am Canby in a little marsh 
pool near Hibernia, Florida. The branches are given off in abundance, mostly in 
a unilateral manner, are often very long, and about equal in diameter to the main 
filament, and give origin to numerous branchlets. The sheaths are very trans- 
parent and very close. I have never seen them in any way lamellate or fibrous, 
or of any color. The cells do not have very apparent walls. In the main fila- 
ment and branches they are globose, or, more commonly, very much compressed, 
but in the newer branches, and sometimes in the older, they are very angular. 
The few cells near the end of the branches are so sliaped as to remind one of the 
phalanges of the fingers. The last cell is cylindrical and has a number of cells 
indicated in it. The color of the young cells varies from a deep bluish-green 
to a ferruginous-brown — that of the older from a light bluish-green to ferruginous- 
brown. 

Fig. 2 a, and 2 b, pi. 8, represent portions of filaments of tliis species. 

S. conipactus, (Ac.) Ktz. 

S. strato expanse, tomentoso, fuseo-nigro; trichomatibus elongatis ramulisquc adscendentibus, 
apice interdum paullum attenuatis sed sspe clavatis, obtusis ; trichomatibus iiiternis e cellu- 
larum serie simplici formatis, et plerumque moniliformibus ; cellulis diametro suba^qualibus 
vel brevioribus, subglobosis vel subquadratis, saepe compressis ; cytioplasmate dilute caeruleo- 
viride, subtiliter graiiulatis ; cellulis apicalibus cylindrieis et oscillarium niodo, si^pc indistinete. 



70 FRESn-WATER ALG. EOF THE UNITED STATES. 

articulatis ; vaginis Qrmis, aurco- vcl rulMdo-fuscis, in ramulis sspe subluteis, baud distincte 
lamellosis;' cellulis perdurantibus pkrumque modice uumerosis, singulis, subglobosis, siBpe 
valde compressis, dilute fuscentibus. 

i>mm._Ploru.nque T5'o':ja"-T5Vo/ = ■0008"-.001" ; max. 3,^,/ = .0013" ; cell, perdarant. 
TJ^a!T" = -00058". 

Syn.—Scrjlonema compactum, Agakdh. Syst. p. 38, N. 3. Harvey's Manual, p. 154. 
Jlassalia compacia, Hassal, Fresh-water Algoe, p. 232, t. l.xviii. f. 3. 
Sirosrphon compactus, (Ag.) Ktz. Rabenhorst, Flora Algarum, Sect. II. p. 281. 

Ilab.—ln rupibus calcareis. New Jersey. (Austin.) Prope Salera, Mass. (Russel.) 

Stratum expanded, tomentose, fuscous-bkick ; filaments and brandies ascending, with their 
obtuse ends sometimes slightly attenuate but often clavate; internal filaments composed of a 
single series of cells, mostly moniliform; cells shorter than or nearly as long as broad, 
subglobose or subquadrate, often compressed; apical cell cylindrical and articulate somewhat 
like an oscillatoria; cytioplasm light bluish-green, finely granulate ; sheath firm, reddish or 
yellowish-brown, yellowish in the branches and near the ends ; heterocysts mostly rather 
numerous, single, subglobose, brownish. 

Eemarl-s.— The specimens from which the above description was drawn up 
were received from Messrs. Austin and Russell, and have been considered as 
identical with the European *S'. compactus, although not in absolute agreement 
with the descriptions thereof. The most important of the differences are in the 
matter of size, the measurements given by Prof. Rabenhorst not equalling those 
attained to by the American plant. 

The differences, however, do not seem sufficient to separate the forms, and, 
in tlie absence of European specimens, the two have been considered one species. 
The sheaths in the older portions of the filaments are nearly opaque, but in the 
branches and younger portions they are quite translucent. The heterocysts some- 
times are truncate at one end. The internal cells are rarely arranged in a double 
series, such arrangement is, however, much more common in the specimens re- 
ceived from near Salem, than in those found in Northern New Jersey. Mr. Rus- 
sell's specimens are labelled as growing on shaded and moist rocks in patches two 
or three inches wide. 

Fig. 3 a, pi. 8, represents the end of a filament of this magnified 150 diameters; 
3 i, a fragment magnified 250 diameters ; 3 c, a heterocyst magnified 860 dia- 
meters. 

S. Craineri., BRiJGG. 

S. csespitibus, tomentosis, spatiose espansis, fusco-nigris ; trichomatibus yage ramosis ; rami." 
plerumque singulis, saepe elongatis, ssepe clavatis ; cellulis internis uniseriatis, diametro sub- 
lequalibus vel brevioribus, interdum subglobosis, scepe subquadratis, in aetate provecta ssepe 
e pressione mutua valde compressis et transverse oblongis, aureo-fulvis vel in astate juvene 
interdum ferugineis; cellulis terminalibus in massam subcylindricam coalesccntibus ; cellulis 
perdurantibus nullis; vaginis auroo-fuseis in aetate provecta plus minus subopacis et distincte 
lamellosis, in aetate juvene plus minus pellucidis et saepe coloris e.xpertibus. 

Z)/am— Trich. cum vag. max plerumque .002"; interdum .00225"; ram. .0015"— .0025" ; trich. 
sine vag. .00083". 

Syn.—S. Grameri, Brugg. Rabenhorst, Flora Europ. Algar., Sect. II. p. 288. 



FRESH-WATER A L G .^ OP THE UNITED STATES. 71 

Eah. — In rupibus irroratis inter muscis minutis. Mount Tahawus (vulgo Mount Marcy),' alt. 
5000 feet. 

Forming a blackish, widely expanded, tomentose turfy covering to rocks ; filament with scat- 
tered branches ; branches mostly single, often elongate and clavate ; cells uniseriate, about 
equal, or shorter than long, sometimes subglobose, often subquadrate ; in advanced age often 
strongly compressed iind transversely oblong from mutual pressure, yellowish, or sometimes, 
when young, greenish ; the apical cells coalescent into an irregularly cylindrical mass ; hete- 
rocysts wanting ; sheaths yellowish-brown ; at maturity more or less subopaque, and distinctly 
lamellate; in youth more or less transparent, and sometimes colorless. 

Remarhs. — Near the top of Mount Tahawus, in the Adirondack Mountains, 
tliere is, at an altitude of aboiit five thousand feet, a steep slope of bare rock, 
the bed of an old landslide, over portions of which water is continually drip- 
ping. In such places the plant luidcr consideration flourishes, forming with 
some very minute mosses a blackish, turfy coating to tlie rock of many feet, 
or even yards, in extent. The specimens agree well with the descriptions of tlie 
European plant, which also grows at about the same altitude as the American. 
They have, however, one pecidiarity not noted in description of the European 
form, namely, that oftentimes the slieath of a branch Avidens out until it is actually 
much larger than the main filament. The color of the cells in the European form 
is said to be seruginous ; but I conceive this depends somewhat upon the age of 
the specimens and is scarcely of primary value. Tlie only other difference wortli 
noticing is that my measurements exceed somewhat those given of the European 
plant. I do not think, however, there is any good ground for separating the forms 
as distinct species. 

The finding of an Alpine plant growing on a mountain half way across the world 
from its first discovered home, at practically the same altittidc, is a matter worth 
noting as a fact in Botanical Geography. 

S. neg^Iectiis, Wood. 

S. immersus; trichomatibus subsolitariis, longis usque ad lineas quatuor, cylindricis, raraossis- 
simis ; ramulis singulis; cytioplasmate interdum ajrugineo, plerumque aureo-brunneo; cellulis 
uniseriatis rarissime biseriatis, subglobosis, interdum sejunctis sed plerumque arete connectis 
et moniliformibus, modo conflucntibus, hand distincte pachydermaticis ; cellulis terminalibus 
elongato-cylindricis, sa^pe nonnihil oscilatorium modo articulatis ; cellulis interstitialibus nullis ; 
Taginis interdum brunneis, plerumque coloris cxpertibus. 

Dmm.— Trichom. cum vag. ■^\^" = .0017" ; sine vag. y^Vu" = OOl"- 

Syn. — S. ncglectus, Wood, Prodromus, Proc. Amer. I'hilos. Soc, 1SG9, p. 133. 

Hab. — In stagnis, New Jersey. 

S. immersed, subsolitary, attaining a length of 4 lines, cylindrical, very much branched ; branches 
single ; cytioplasm seruginous, mostly yellowish-brown ; cells uniseriate, very rarely biseriate, 
subglobose, sometimes separate but more frequently closely united and moniliform ; terniinal 
cell an elongated cylinder, often articulate somewhat like an oscillatoria ; interstitial cells 
■wanting ; sheaths transparent, sometimes brown, mostly colorless. 

' " Tahawus" cloud splitter. The Indian names of the American mountains ought to be retained, 
in spite of the fact that some vulgar land surveyor has defiled the Adirondacks with the names of 
politicians, through whose influence he hoped for patronage. 



14 



FRESH-WATER ALG.E OF THE UNITED STATES. 



Rejnarks.— This plant was found in a very stagnant pool, forming, with various 
other species of algte, a gelatinous, a>ruginous-brown stratum, through which the 
single plants were thickly scattered, without anywhere forming the major portion 
of the mass. The plants themselves are large enough to be distinguished by the 
iinaided eye. Under the microscope the sheaths are seen to be exceedingly trans- 
parent and colorless, except in the older part of the filament, where they are often 
dark brown and opaque; but even in such case, the edges are translucent and 
lighter colored. 

The internal cells or globose masses rarely have distinct coats, and even when 
such were apparent, as in the older portions of the plants, there appeared to be a 
communication between the cells. The original main stem is rather short, shorter 
often than numerous branches into which it breaks up. Very often the apices of 
the branches are colorless and entirely empty, consisting simply of sheath ; often, 
however, they are occupied by a cylinder of protoplasm, which is sometimes arti- 
culated more or less distinctly like an oscillatoria. 
' Fig. 4, pi. 8, represents a fragment of a filament with a small branch. 

S. lignicola, Wood. 

S. stvato expanse, tomentoso, atro ; tricUomatibus ramossissimis, arete intertextis ; ramulis ab- 
breviatis vel elongatis, subreetis aut varie curvatis, apicibus obtuse rotundatis vel subacumi- 
natis ; trichomatura et ramulorum cellulis uiii- vel biseriatis, rare in trichomatibus matnris mul- 
tiseriatis, plerum(iue paebydermatieis, dilute vel saturate terugineis, euormibus, plerumque 
homogeneis ; cellulis terminalibus in trichomatibus immaturis elongatis, cylindricis, saepius 
nonnihil oscillatorium modo articulatis, granulosis; vaginis sat amplis, baud aclirois, vel 
luteo-brunneis vel fusccntibus vel ferrugineis. 

Diam.—Tvich. cum vag. max. ^sVu" = 00066". 

Si/n. — S. lignicola, Wood, Prodromus, Proc. Aracr. Philos. Soc, 1SG9, p. 133. 

Hah. — South Carolina. (Ravenel.) 

Occurring in an expanded, tomentose, black stratum ; filaments very much branched, closely 
interwoven, branches abbreviate or elongate, nearly straight or variously curved, their apices 
obtusely rounded or subacuminate ; cells 1-2 seriate, mostly thick-walled, light or deep 
ceruginous, irregular, mostly homogeneous ; terminal cells elongate, cylindrical, frequently 
articulate somewhat like an oscillatoria, granulate ; sheaths somewhat ample, not transparent, 
light bright, fuscous or ferruginous. 

Remarks. — I have seen dried specimens only of this plant, which were collected 
by Prof. H. W, Ravenel, in South Carolina. It is said to grow on old boards, 
and appears to be a very distinct species. There are frequently two or three 
very short, stubby branches arising together. The apices of the filaments and 
branches are in some cases filled with endochrome to the end, and are broadly 
rounded at the apex. In other cases the sheath of the filament extends a distance 
beyond the endochrome, and is finally rapidly diminished to a point. The cells 
withm the filaments are of various shapes, sometimes globular, sometimes quad- 
rangidar, more often irregular. The original specimens from which this descrip- 
tion was written were collected in April. I do not know whether they grew 
immersed, or merely on boards exposed to the weather. I have since received 



FRESH-WATER A L G J3 OF THE UNITED STATES. 73 

w 

specimens collected in the month of August, wliicli grew on boards over which 
spring water was constantly running. These specimens agree perfectly with the 
others, except that the filaments are larger and the elongated apical cell is wanting; 
differences which I believe to be due to the specimens collected in August being 
older than those first received. 

Fig. 2 a and 2 b, pi. 9, were taken from the types, whilst fig. 2 c, pi. 1), from the 
August specimens. 

a. Ccllulse plerumque in serie duiMci vel muUiplici. 

a. Cells generally in double series, or multiple series. 
S. argillaceiis, Wood, (sp. nov.) 

S. strato tenui, expanse, subnigro, subinembranacoo ; trichomatibus brevibus, dense intricatis 
et saepe nonnihil concretis, ramosis, irregiilaribus; pseudorauiulis brevilm.s, varie ciirvatis, 
nonniliil rigiilis, plerumque asceudeutibus, apice nonnihil attenuatis; cellulis subglobo.sis, 
saepe compressis, plerumque in serie simplici sed interdum in serie duplici, vel rai-e multipliei ; 
cellulis apicalibus valde elongatis, cylindricis, scytonemoe trichomatibus internis siniilibus; 
vaginis crassis, firmis, in trichomatibus maturis saturate rubido-brunneis, in ramulis sajpe luteo- 
bruuneis et in apice hyaliiiis et fere coloris expertibus; cellulis perdurautibus nullis. 

Zfiarn.— 5/50" = .000833". 

Sab. — In palude argillacea. South Carolina. (Ravenel.) 

Stratum thin, expanded, blackish, submembranaceous; filaments short, densely intricate, and 
frequently somewhat concreted, giving origin to numerous branches, irregular ; branches short, 
variously curved, somewhat rigid, mostly ascending, apex somewhat attenuate; cells suIj- 
globose, often compressed, mostly in simple series, sometimes in double, rarely even in multi- 
ple ; apical cells elongate, cylindrical, resembling the inner filament of a scytonema; sheath 
thick, firm, in the mature filament deep reddish-brown, iu the branches yellowish-brown, at the 
apices of the branches nearly colorless and transparent ; hetcrocysts absent. 

Remarhs. — I am indebted to Prof. Ravenel for this plant, which was found by 
him on a moist clay bank near Aiken, South Carolina, August, 1869. It forms a 
thin, somewhat membranous, dark stratum, the filaments of which are so closely 
united that it is almost impossible to tease them apart with needles. Neighboring 
filaments are often united at the edges so as to form distinct bundles, and even 
the branches are sometimes concreted, although, generally, as seen under the 
microscope, they project from the mass in all directions. The surface of the fila- 
ments is mostly rough and ragged with fibrillte and membranous projections. In 
the older filaments the cells are often entirely absent. They are mostly single, 
but sometimes multiple in the filaments ; in the branches they are often partially 
double. The ends of the older branches are often broken and empty, Avhilst those 
of the younger are rounded. The color of the cells, as I have seen it, does not 
strikingly differ from that of the sheaths. 

Fig. 3 fl, pi. 9, represents a portion of an old frond magnified -4(50 diameters, 
and fig. 3 b, the end of a younger branch. No. 79. Collection of Ravenel, Aug. 
1869. 

S. giittiiln, Wood. 

S. in maculis subnigris, parvis, tenuibus, plerumque rotundatis, interdum enormibns, dispositus; 
trichomatibus arete intertexti.s. ramossissimis, rigidis, insequalibus, subcylindricis, nonnihil 

10 May, 1872. 



74 FRESH-WATER AhGAi OF THE UNITED STATES. 

coutortis; rauiulis abbreviatis vel noiinihil elongatis, apice obtuse rotundatis; ramulorum et 
trichoiuatuiu cellulis tri-multiseriatis, plerumque pachydermaticis, ferrugineo-fuscis, enormiter 
globosis, liomogeneis; cellulis apicalibus interduni breve cylindricis, baud articulatis; vaginis 
sat aiiiplis, lutco-bruiiiieis vel dilute ferrugiueo-brunneis. 

Biam. — Max. trich. cum vag. ^l^" =.0013". 

Sijti. S. gutlula, Wood, Prodromus, Proc. Amer. Philos. Soc, 1869, p. 132. 

Zfo&.— South Carolina, in Tasodium distichum. (Prof. Ravenel.) 

Arranged in small, thin, black spots, which are generally round, but sometimes irregular : fila- 
ments closely interwoven, very much branched, rigid, unequal, subcylindrical, somewhat con- 
torted ; branches abbreviate or somewhat elongate, apex obtusely rounded ; cells of the 
trichoma and branches 3 to many seriate, mostly with thick coats, ferruginous-fuscous, irregu- 
larly globose, homogeneous ; apical cells sometimes shortly cylindrical, not articulate, sheaths 
ample, yellowish-brown. 

Remarks. — This species was found growing on the bark of Taxodmm distichum, 
by Prof. H. W. Ilavenel, in South Carolina, and by him given to Dr. Billings, 
U. S. A., to whom I am indebted for specimens. It forms on the bark minute 
roundish, blackish, dot-like spots of about a line in diameter, or sometimes, appa- 
rently, by the coalescence of two or more of these spots, larger irregular patches. 
The habit of the plant is a rigid one. The main stem is often irregular in size, 
variously bent and rebent, and mostly gives off a number of branches, which fre- 
quently nearly equal the main filament in size, and like it are bent in various 
directions. They also frequently give origin to numerous short branches. In 
some instances, there is a distinct apical cell, which is cylindrical, but only two or 
three times longer than broad ; in many cases, however, this cylinder being want- 
ing, the ordinary cells extend to the extreme apex. 

Fig. 4 rt, pi. 8, represents a filament, and fig. 4 h, the end of a branch magnified 
460 diameters. 

S. acervatiis, Wood. 

S. in guttulis minutissimis, subernstaceis, nigris, in strato subcontinno sfepe aggregatis; tricho- 
matibus parvis et brevibus, rigidis, adraodum imequalibus, prostratis, tuberculis, arete et dense 
ramossissimis, viridibus aut aureis aut brunneis ; ramulis brevibus, plerumque baud ramnlosis, 
erectis aut ascendentibus, sspe abbreviatis et papilliformibus, obtusis, sa?pe lateraliter connatis ; 
cellularum scrie in trichomatibus multiplici in ramulis plerumque simplici ; cellulis subglobosis 
vel subangularibns, viridibus, hand distincte granulosis, in ramulorum apice ssepe breve cylin- 
dricis et iuterdum obsolete articulatis ; vaginis aureis, nonnihil hyalinis. 

i?mm.— Trich. max. ^ig/ ; ram. teV'-tsV- 

Syn.—S. acervatug, Wood, Prodromus, Proc. Araer. Philos. Soc, 1869, p. 132. 

fla6.— South Carolina, in corttce (Ilex opaca). (Prof. H. W. Ravenel.) 

Arranged in drops, which are very minute, subcrustaceous, black, and frequently aggregate into 
a subcontinuous stratum ; filaments small and short, prostrate, rigid, somewhat unequal, tuber- 
culate, densely and closely branched, green or golden or brown ; branches short, for the most 
part not branched, erect or ascending, frequently abbreviate, and papilliform, obtuse; series of 
cell multiple in trichoma, mostly simple in the branches; cells subsrlobose or subangular, 
green, not distinctly granulate, in the apices of the branches frequently shortly cylindrical and 
sometimes obsoletely articulate; sheaths- golden, somewhat hyaline. 



FRESH-WATER A L G .E F T II E U N I T E D S T A T E S. 75 

Remarks. ~~'['hk species was found in winter by Prof. II. W. Ravenel in South 
Carolina, growing upon tlie bark of Ile^v o/.aca, forming minute, firm, crustaceous, 
roundish dots or masses, much smaller than a mustard-seed, but in some cases so 
closely aggregated as almost to make a continuous stratum. When one of these 
dots is placed under the microscope, the branches are seen presenting their ends 
upon all sides, reminding one of some varieties of coral, and between these are 
blackish matters, which prevent the whole dot from being seen. These branches 
are frequently placed very close to one another, and cohere by their edges so as to 
make a sort of membrane or a solid mass. The filaments themselves are mostly 
obscured in the dense mass of branches which clothe them. This species seems 
to be closely allied to S. coraUoides, and I am not certain whether it is distinct or 
not. It is certainly very much smaller. 

$. piilvinatii!!!, Breb. 

S. pulvinatus, humectatns, saturate olivaceo-iiig^er, ad trcs linoas crassus; triclioniatibus crassis- 
siuiis, ramossissiniis, fusceticentibiis, fiioriuitui' curvatis; raniulis polyinorpliis pro ffitate cras- 
sitie magnitudincque variis, apicc pleiumque obtuse rotundatis ; triehomatum celliilarum serie 
multiplici, ramulorum 2-4 plici ; vaginis crassis, luteo-fuscis ad saturate-fuscis, vcl pellucidis 
vel noil pellucidis, intcrdum rugcso-tuberculis. 

Diam. — Tricli. cum. vag. max. .0042". 

Syn. — S. pulvinatus, (Breb.) Rabenhorst, Flora Europ. Algar. , Sect. II. p. 290. 

JIab. — In rupibus prope Philadelphia. Wood. 

In moist, deep olive-black cu.shion-like masses of two or three line.s thick ; filaments verv thick, 
much branched, brownish, irregularly curved ; branches polymorphous, varying in thickness 
and size, mostly with their apices obtuse ; cells of the filament many seriate, of the branches 
two to four seriate; sheaths thick, yellowish-fuscous to deep fuscous, pellucid or opaque, 
sometimes rugose-tuberculate. 

EemarJiS. — I have received specimens of this species found by Mr. Austin in 
Northern New Jersey, growing on the exposed face of rocks. 

The size attained to exceeds that given by Mr. Rabenhorst for the European 
form. The color of the cytioplasm varies from an almost verdigris-green to 
fuscous. 

Besides these specimens. Dr. I. Gibbons Hunt has given me fresh ones of a 
Sirosl])hon which he found growing on the face of dripping rocks along the 
Wissahickon Creek, near this city. These are much smaller in every Avay than 
their more northern brethren, and differ in other respects, I think, sufficiently for 
a distinct variety. The filaments and branches are much flatter than in Mr. 
Austin's specimens. I append a description. 

(Far. parriis.) 

S. trichoraatibus in caBspite saturate olivaceo-nigro arete intertextis; trichomatibus cra,ssissinjis, 
enormiter ramosissimis, luteo-fuscescentibns, varie curvatis; ramulis polymorphis, apiee 
plerumque obtuse rotundatis; triehomatum cellularum serie multiplici, ramulorum 1-4 plici; 
cytioplasmate granulato, plerumque saturate fuscescente, intcrdunj Uetc viride; vagiuis crassis, 
dilute luteo fuscescentibus, interdura achrois. 

Diam. — Trichom. cum. vag. max. .^\^" = .QZ" 



7G FRESII-WATEll A L G ^E OF THE UNITED STATES. 

Filaments closely interwoven into a deep olive-blaek turfy mass, very thick, irregularly anil fre- 
(luently bniuched, yellowish-fuscous, variously curved ; branches polymorphous, their apices 
mostly obtusely rounded ; series of cell in iilament multifold, in branches 1-4 fold ; cytio- 
plasm granulate, mostly deep brown, sometimes bright green ; sheaths thick, light yellowish- 
brown, sometimes transparent. 

Remarks.— The frouds are very irregular in form and size, much branched, and 
so closely interwoven that they mostly cannot be separated without breaking. 
The branches are sometimes short and stumpy, sometimes they are very long. 
The color of the cells approaches somewhat to a chocolate, at times with a little 
red in it so as to give something of a maliogany tint. The walls of the cells are 
mostly very thick, but they arc often lost in the general mass of the frond. In the 
branches, the cells are often so closely crowded as to almost obliterate their walls. 
In a few specimens I have found the cells to be of a bright green color, instead 
of that just mentioned. The exact meaning of this I do not know; it would 
scarcely seem to indicate immaturity, for I have found it in the oldest portion of 
large fronds, whose other parts were of the normal color. 

Fig. 1, pi. 10 represents a filament of tliis variety magnified 160 diameters. 

I have received from Prof, llavenel certain dried algoc, labelled St'ujonema 
RavenelU, Berkeley, which appear to me to belong to this genus. In what place 
Berkeley described them, if ever, I do not know, nor why he placed them in the 
genus Stigonema. The following is a description of the species: — 

S. stralo sub-nigro; trichoraatibus arete intertextis, ramossissimis, cnormibus, varie curvatis; 
ramulis brevibus et sublongis, varie curvatis, latis, apice nonnihil attcnuatis et obtusis ; tri- 
chomatum et ramulorum cellulis arctis, cnormibus, in serie duo-multiplici enormitcr dispositis; 
ej^tio-plasmate bomogenco, Isetc viride ; vaginis aureis, lucidis. 

Diani. — Mas. trieh. cum vug. jioo"- 

When dried blackish ; fdameuts closely interwoven, very'rauch branched, irregular', and variously 
curved ; branches short or largish, variously curved, broad, their apices somewhat attenuated 
and obtuse; cells of the filament and its branches very close, irregular, irregularly arranged 
in a twofold or multiple series; endochromc homogeneous, bright green; sheath yellow, 
semitranshieent. 

Remarks. — This plant was collected by Prof. Ravenel on the now famous Look- 
out Mountain. It is of a thick, bushy habit, and appears to form turf-like mats 
of a line or two in thickness and of a blackish color. The filaments throw off in 
all directions very numerous branches, some of which are short and stumpy, others 
quite long, and are themselves the parents of numerous secondary branches. The 
longer branches often rival the main filament in size, and like it vary continually, 
in being irregularly expanded and contracted. There is never a long, articulated 
cell, not even in the apices of the branches. The apices are often somcAvhat 
attenuated, and are always more or less obtuse. The cells are of a bright green 
color, are very irregular in form, and are often very irregularly arranged in rows 
of from two to five, both on the main filament and branches. The base of the 
filament often gives origin to several small, cylindrical, root-like processes. 



FRESH-WATER ALG.E OF THE UNITED STATES. 77 

Fig. 4 a, pi. 9, reproscnts a frond of this plant magnified 125 diameters; fig. 4 h, 
a fragment magnified 460 diameters. 

Professor Bailey, in American Journal of Sciences, vol. iii., new series, states 
that he has found two species of the genus Sthjonema, namely, St. afroviren-f, Ag. 
and St. mammillosum , Ag. ; the former growing on wet rocks at Indian Falls, 
Putnam County, New York ; the latter at liound Pond, near West Point. I have 
no personal knowledge of the genus, but, according to authorities, it belongs to 
the lichens rather than the algae, apothecia having been detected in various 
species. 

Class CIII.OKOPIIYLLACE^.^ 

Plantidce aqnaticiE vel aerea?, luii-, bi-, vol multicelliilai'cs, aut singula3 
aiit consociata^', faniilias forniantes. 

Vegctatio terminalis vel non terminalis. 

Ramificatio aut nulla aut vera, sed ccllularum non divisione, potius 
proliticatione. 

Cytioderma non siliceum, combustibile, sa^pius e stratis successivis 
compositura, substantiam gelatinosam plerunique liquidam exsudans. 

Ciltiophsma cliloropliyllosum, cblornphylli loco nonnunquam erythrino 
vel substantia oleosa coccinea, carnea aut rufescente coloratum, luieleo 
(eentrali vel lateral!) plerumque prjijditum, granulis amylaceis rarissime 
carens. 

MuUiplicafio fit cellularum divisione vegetativa. Foecundatio j^le- 
I'umque sexualis. 

Propagatlo fit aut oosporis vel zygosporis aut gonidiis tranquillis vel 
agilibus. 

Aquatic or aerial wax-, bi-, or multicellidar i)lants occurring singly, or 
consociated in fiimilies. 

Vegetation terminal or not so. 

Brandies either wanting, or if present, true branches, although formed 
rather by a process of proliferation tlian division of the cells. 

Cytioderm not siliceous, combustible, often composed of successive 
strata. 

Cytioplasm chlorophyllous, sometimes colored by an oily crimson, flesh- 
colored or yellowish-red substance, in the place of the chlorophyl, gene- 
rally fm-nished with a nucleus (either lateral or central), very rarely 
without starch granules. Growth occm'ring by the division of the cells. 
Fecundation generally sexual. 

Propagation taking place by oospores or zygospores, or by tranquil or 
motile gonidias. 

' The description of this Class and Order is that of Prof. Italindiorst. 



78 FllESir-WATKR A L G .E OF TUE UNITED STATES. 

Order Coccophyceac. 

Algie unicellulares. Celliilae aut singulas (plcrumque jierfecte scgregatse) ant plurcs in familias 
consociataj, teo-unientis involutoe vel nudae, aut raiuificationc aut vegetatioue termiuali destitute, 
rropagalio Gt aut cellularuiu divisione aut zoogouidiis. 

Unicellular alg£e. Cells either single (mostly entirely segregate), or mostly consociated in fami- 
lies, walled or clothed with teguments, destitute of branches or terminal vegetation. Propagation 
by means of zoospores, or by the division of the cells. 

Family PALMELLACE^. 

AlgiE unieelliihu'cs sensu latiori. Cellulse aut singulae aut numerosae, familias constituentes, in 
muco matricali plus minus firmo, stratum gclatinosum amorphum, sa»pius figuratum, tuliulosum 
(Ilormospora) varie divisum et perforatum (Tetraspora), quasi ramificatum (Ilydrurus) formante 
nidulantes, vel nullo (Rhaphidium, Dactylococcus). Cytioderma plerumque tenue, ssepius tegumento 
gelatinoso aut homogeneo aut lamelloso pranlituni. Cytioijlasma homogeneum, aitate provecta ple- 
rumque distiiicte granulosum, viride, aut rubescens aut fuscescens, vesicula chlorophyllosa semper 
instructum (exeepto Rhaphidio). 

Multiplicatio fit cellularum divisione vegetativa, propagatio gonidiis ex ultima eellularum gene- 
ratione transitoria cytioplasmatis divisione varia ortis. Gonidia tcgunientis liberata, polo autico ciliis 
vulgo binis plerumque iustructa et alacriter circumvagantia. (R.) 

Algai unicellular in a broad sense. Cells either single or numerous, constituting families, imbedded 
in a jelly to form a gelatinous stratum which is amorphous or shaped, as tubular (Hormospora), 
variously divided and perforate (Tetraspora), falsely branched (Hydrurus), or sometimes is wanting 
(Rhaj>hidium, Dactylococcus). Cytioderm mostly thin, often furnished with a gelatinous or homo- 
geneous or lamellate tegument. Cytioplasm homogeneous, mostly at maturity distinctly granular, 
green-reddish or fuscous, always furnished with a chlorophyllous vesicle (except Rhaphidium). 

Multiplication taking place by a vegetative division of the cells, propagation by transitory gonidia 
arising by various divisions of the protoplasm from the last vegetative generation. Gonidia with- 
out integument, mostly furnished with two cilia at the anterior end, and moving about actively. 

Genus PLEUROCOCCUS, Mengh. (Rabenh.) 

Cellulse globosoe vel e niutua pressionc angulosae, plerumque nucleo instructae, turn singulae turn 
in familias consociatae. Cytioderma firmum, Siepe crassum, laeve, hyalinum ; cytioplasma homoge- 
neum viride vel oleosum rubrum. Multiplicatio cellularum vegetativarum divisione in directiouem 
ad omnes dimensiones altcrnantem. Propagatio fit gonidiis intra sporangia ortis. 

Cells globose or angular from mutual pressure, mostly furnished with a nucleus, sometimes single, 
sometimes aggregated into families. Cytioderm firm, often thick, smooth, hyaline ; cytioplasm 
homogeneous-green or oleaginous-red. Multiplication occurring by a vegetative division of the 
cells alternately in three directions. Propagation by means of gonidia, formed within sporangia. 

P. seriatus, Wood, (sp. nov.) 

P. corticolus, strata pulvenila, rubido-brunnea, nonnihil Crustacea formans ; cellulis enormiter 
subglobosis, vel ovalibus, hctc aurantiacis, interdum viride tinctis, haud distincte nucleatis, in 
seriebus singulis rectis vel curvatis conjunctis ; tegumentis crassis, haud lamellosis, coloris 
expertibus. 

Diam.—^^%^"—j^%^" = .00053"— .0012". 
Eab.— In palude. New Jersey. (Austin.) 

Growing on bark, forming a reddish-brown, somewhat crustaceous powdery mass; cells irregu- 
larly subglobose, or oval, bright orange, sometimes tinged with green, not evidently nucleated, 
conjoined in single straight or curved series; tegument thick, lamellate, or not so, colorless. 



FRESH-WATER ALG^ OF THE UNITED STATES. 79 

Remarhs. — I am indebted to Mr. Austin for specimens of this little plant, which 
he found growing in a swamp near Closter, Northern New Jersey, on a young 
pin oak. It forms a sort of crustaceous powder, with little aggregations here and 
tliere, of a dull reddish-brown color. When these little masses are broken up, 
they are found to be composed of little series of very closely joined cells, generally 
a half dozen to a dozen in the row. I believe that at certain states of their growth 
these cells are green, as many of them have a very decided green tint on their 
edges, and I have seen one or two of them quite green. 

Fig. 2, pi. 10, represents this species magnified 460 diameters. 

P. piilvereiis^ Wood, (sp. nov.) 

P. cellulis minimis, cseruleo-viridibus, enormiter subglobosis, vel angulosis, in familias nume- 
rosas consociatis ; familiis e cellulis numerossissiinis et dense eonfertis compositis, irregii- 
laribus, interdum confluentibus, plerumque pseudotegumcntis byalinis involutis, iu strato 
pulvereo laete viridi aggregatis. 

Diam.—^l^Ts"—rz%^" = .00004"— .00013". 

Hah. — In fonte. " Boiling Springs," prope Bellefonte, Pennsylvania. 

Cells very small, bluish-green, irregularly subglobose, oval, or angular, associated in numerous 
famdies ; families composed of very numerous and densely crowded cells, irregular, sometimes 
confluent, mostly surrounded by a false hyaline tegument, aggregated into a bright green 
pulverulent stratum. 

Remarks. — In Centre County, Pennsylvania, two miles from Bellefonte, there is 
a very large and beautiful limestone spring, which is a favorite roadside watering 
place, and is laid down on the maps as " Boiling Springs." Forming a stratum 
over most of the bottom of this spring is the little plant here described. The 
stratum is in places nearly an inch in thickness, and when lifted by the hand is 
found to be dry and crumbly, instead of mucous and tenacious. Under the micro- 
scope it is seen to be composed of vast numbers of irregular masses or families of 
cells imbedded in a firm jelly, which projects so as to form a sort of transparent 
coat to the whole mass ; this cast I have spoken of in the description as a false 
tegument. The cells themselves are exceedingly small and furnished with an 
excentric point, which is probably a nucleus. 

Genus PALMELLA. 

Cellulae globosae vel ovales vel oblongae, tegunientis plus minus crassis in niucum gelatinosum, 
Sffipius mox confluentibus involutes, thallum ditforme elficientes. Cellularum divisio directione in 
omnes dimensiones alternante. 

Cells globose, oval, or oblong, surrounded with a more or less thick integument generally very 
soon confluent into a firm or soft jelly. Thallus shapeless. Division of the cells alternately in all 
directions. 

P. Jesenii, Wood. 

P. thallo indefinite expanso, initio dilute ant Isete viride, molle, pellueidulo; setate provecta 
firmo, tuberculoso, saturate olivaceo-viride; cellulis globosis vel ellipticis, — in thalli a;tale 
immaturo, plerumque singulis autgeminis, sfepe distantibus, — in setate provecta saepe in fami- 
lias connexis, plerumque eonfertis; tegumentis in thalli setate immaturo plerumque diffluenti- 
bns, aetate provecta plerumque distiuctis. 



80 FRESn-WATER ALG.E OF TUE UNITED STATES. 

Diam.— Cell, glob. mas. ^sVu" = ■00028"; cell, oblong, long. max. 55V/ = -0004". 

Syn.—P. Jesenii, Wood, Prodromus, Proc. Am. Philos. Soc, 18C9, p. 134. 

Hab.—h\ rupibus irroratis, prope Philadelphia. 

Thallus indefiuitely expanded, in the beginning soft and pellucid, afterwards firm, tubercular, 
deep olive-green; cells globose or elliptical; in the immature thallus, single or geminate, fre- 
quently scattered; in the mature thallus often closely conjoined into families, mostly crowded ; 
iu the voung thallus the teguments of the cells are mostly diffluent, afterwards distinct. 

Remarks. — This little plant was found along the banks of the Schuylkill River, 
just above Flat Rock tunnel, near Manayunk, forming in the early winter a gela- 
tinous mass of two to three lines in thickness, irregularly and. interruptedly spread 
over the face of wet, dripping rocks. In what appeared to be the younger per- 
tions, the jelly was often quite soft and almost colorless, and had the cells scat- 
tered rather sparsely and distantly through it. The cells were but partially filled 
with chlorophyl, the vacuole left containing often numerous granules, and had 
distinct walls, being, as it were, merely immersed in the general maternal jelly. 
In the older fronds the texture is more firm, the color a deep green, and the bright 
green cells are mostly surrounded by a thick, very distinct tegument. They are 
also largely arranged in little families of two, four, or even eight cells, stu'rounded 
by a common integument. The oldest fronds are of a deep olive, almost blackish 
color, markedly tuberculate upon their upper surface and very firm in texture. 
They are surrounded by very distinct, firm, dark brown coats (a simple coat often 
involving two or more cells), and arranged in groups or families. As shown by 
the microscope in the superficial portion of such fronds, the jelly is of a yellowish- 
fuscous color, and the cells are themselves of a dark bro^vn tint. The number of 
cells in the individual families varies from two to a dozen or more. Even in these 
old, firm fronds, the interior portions are frequently composed of greenish cells, 
withoiit any distinct teguments or coat. Iir such cases the cells are mostly oblong 
or elliptical, and very much crowded together. This species appears to come 
closest to P. BreUssonii, Ktz., from which it difi'ers, however, in its habit of 
growth and the size of its cells. 

Fig. 3 rt, pi. 10, represents a fragment of the upper surface of an old frond 
magnified 750 diameters; fig. 3 5, when taken from the inner jelly of similar 
fronds. 

P. (liira, Wood, (sp. nov.) 

P. thallo enormitcr subgloboso, enormiter minute lobato vel verrncoso, cseruleo-nigro, nonnihil 
crustaceo, minuto ; cellulis arctissime coufertis, plerumqne enormiter oljlongis, siepe in serie- 
bus irregulare dispositis, ca;ruleo-viridibus vel luteo-bruuneis ; tegumentis baud distinctis; 
sporis globosis vel ovalibus. 

Diam.-Gell. t^W=.00008"—j^V/ = .00010" ; spor. ^5ij^" = .00058"— ^^W' = .0008" 
Hah.— In fonte prope Philadelphia. 

Thallus irregularly subglobose, irregularly minutely lobate or warty, bluish-black, somewhat 
crustaceous, minute; cells densely crowded, mostly irregularly oblong, often arranged irre- 
gularly in series, bluish-green or yellowish-brown; coats not apparent; spores globose or 
oval. 



FRESHWATER A L G -E OF THE UNITED STATES. gl 

Remarhs. — I found this plant growing in the large spring at Spring Mills in 
March or April. The fronds were in the form of little blackish balls attached to 
the stems of mosses in the water. They varied in size from the minutest speck, 
scarcely \isible to the naked eye, up to ten lines in diameter ; they are globose, 
very firm and hard, and the larger look almost as if they were aggregations of 
smaller ones. They are gregarious. The spores are mostly borne on the edges 
of the frond, sometimes they appear to be imbedded in its substance. At first 
they are of an intense bluish-green, but afterwards they appear to be yellowish- 
brown. None of the cells, as I have seen them, have their contents granulate. 

Fig. 5 a, pi. 10, represents a section of a frond magnified 460 diameters; fig. 
5 h, a section of the edge of an old frond, developing spores. 

P. hyalina, Lysgb. 

" Fronds from a quarter of an inch to an inch in diameter, somewhat globose, but at length fre- 
quently more or less elongated into an ovate or even cylindrical form. Substance gelatinous 
and very tender, of a pellucid, watery appearance. Grannies numerous, globose, green. 
The fronds are produced at first on rocks and stones at the bottom of streams, and afterwards 
become disengaged and float on the surface." 

RemarTcs. — Professor Bailey states that he has found this species from Rhode 
Island to Wisconsin. Whether it is identical with the P. hyalina of Brebisson, or 
not, I cannot say. 

Genus PAGEROGALA,' Wood. 

Thallus solidns, gelatinosns, iadefinitus, exalbidus, nonnihil pellucidalus, nodulis dense aggregatis 
et saepe confluentibus formatus. Cellulae globosse, confertae, in familias consociatas. Familiae tegu- 
mentis tenuibus et membranaceis involntse, in nodulorum centro positse. 

Thallus solid, indefinite, gelatinous, whitish, somewhat pellucid, composed of closely aggregated 
nodules which are often indistinct. Cells globose, crowded in families. Families surrounded by a 
thin membranaceous coat and placed in the centra of the gelatinous nodule. 

Remarks. — This curious plant was foiand by myself floating as indefinite masses 
of milk-white jeUy on a mountain spring near Bear Meadow, Centre County, Penn- 
sylvania. The largest of these gelatinous masses was six inches long. On taking 
them out of the water they were seen to be composed of somewhat irregular 
nodules, which in some portions of the mass were very distinct one from the other, 
but in other parts were confluent into an almost uniform jelly. When the nodules 
were separated it was discovered that each contained a membranous verj^ delicate 
sack of a pale green color, which the microscope showed to be reaUy a cell family. 
Their interior was hoUow, or at least only partially fiUed with a transparent fluid, 
and they contained aU round their exterior portion a layer of round, closely placed 
cells. In some instances the outer membrane was ruptured, and the sac only con- 
tained a few cells, which could often be seen to be moving freely in the inner 
liquid. The sac membrane is thin and delicate, colorless, and marked with curious, 
regular wrinkles or folds. In those portions of the common gelatinous mass, where 
the nodules were lost, I could not find any of these sacs. 

* noyfpoj, frozen ; yaxa, milk. 

11 May, 1873. 



82 FRESII-WATER A L G J3 OF THE U iNI T E D STATES. 

No opportunity was afforded to study the development of this plant; but there 
can be but little doubt that the globular, thickish-walled cells are finally dis- 
charged by a rupture of the membrane and escape from the softening jelly into the 
water, eacli to be a possible starting point for a new frond. 

1 have given this curious plant the name of Pagerogcda, from its milky white- 
ness. Floating in the water it offered so close a resemblance to the spawn of frogs, 
though more opaque, that my companion, a most excellent naturalist, insisted, 
until its true nature Avas absolutely demonstrated, that I was simply wasting my 
time collecting the spawn of an amphibian. 

P. stellio, Csp- nov. ) 

Diam. — Froud ^ incb ; cells jt^so" — 5TsViy"- 

Genus TETRASPORA, Link. 

Thallus gdatinosus, membranaceus vel subraembranacens, initio saccato-clausns, state prorectiori 
vel postea esplanatus. Cellulffi globosse (vel anguloso-rotundatae) pins minus distantes sed in familias 
magnas unistratas consociatfe ; tegumentis crassis in mucum homogenenm cito diffluentibus. Cel- 
lularum divisio in planitiei duas directiones alteruans. 

Propagatio fit gonidiis mobilibus. 

Thallus gelatinous, membranous or submerabranons, in the beginning a short sack, afterward 
expanded. Cells globose, or angularly so, more or less distant but consociated in a single stratum 
into large families. Tegument thick, very rapidly difiluent into a homogeneous mucus. Division 
occurring in two directions in the one plane. 

Propagation by means of zoospores. 

T. lubrica ? (Roth) Aa. 

T. thallo gelatinoso-membranaceo, lubrico, dilutissime viride, tubuloso sed ssepe postea explanato, 
siraplice vel ramoso, undulato-sinuoso, SKpe laeunis munerosis perforate ; cellulis globosis 
vel clliiiticis, Iste viridibus, interdum singulis sed plerumque quaternis vel gemiiiis, locello 
achroo hyalino parietali s«pe prseditis ; cytiodermate tenuissimo, baud distincte visibile. 

Dinm.—QcW. ^^Vir"— ttjV/ = 0.00025"— 0.0005". 

Syn. — T perforata, Harvey. Bailey, Silliman's Journal, N. S. vol. iii. 

T. lubrica, (Roth) Ag. Rabenhoest, Flora Europ. Algarum, Sect III. p. 41. 

Hab. — Northern Atlantic States. 

Thallus gelatinoso-membranaceous, slippery, very dilute green^ tubular, but often finally ex- 
panded, simple or branched, undulately-sinuate, often perforated with numerous holes ; cells 
globose or elliptical, bright green, sometimes single but mostly in pairs or fours, furnished 
with a parietal transparent hyaline space; cytioderm very thin, not distinctly visible. 

Remarlcs. — This little plant is very common around this city, growing usually 
in limpid, quiet water, such as springs, little rushy pools, and clean ditches. The 
frond is a translucent, light green or scarcely greenish, very slippery jelly, with 
the edges often very markedly undulate. It is very rarely simple, but on the con- 
trary is often very much and very irregularly branched, frequently indeed consist- 
ing of several broad portions united by narrow necks. It is an irregular sack, 
generally profusely perforate, and often with large imperfect portions. " I think it 
finally in many instances becomes expanded and open. It is sometimes found 
lying'on the bottom, but more frequently floats on the surface of the water. The 
breadth of the frond varies from two or three lines to an inch. The length often 
reaches several inches. The cells are mostly globular ; but, immediately after 



FRESn-WATER A L G ^E OF THE UNITED STATES. 83 

division, they are elliptical. They are of a bright green color and almost always 
have a conspicuous rounded granule within them; sometimes, but not commonly, at 
one end there is a hyaline space or vesicle, similar to that seen in zoospores. I 
have watched the production of zoospores in a plant gathered late in November. 
The outer wall of the cell is always so thin as to be scarcely perceptible, and when 
the zoospore is beginning to move, it looks as though the whole cell were rocking, 
the thin outer coating being lost to sight. After a considerable period of vain 
effort the zoospore escapes from the thick gelatinous mass which surrounds it. It 
is biciliated, roundish, and furnished with a hyaline space at the end. 

I have observed a Tetraspora growing in rapidly running water, which some 
would no doubt consider distinct, but which seems to me rather a variety. The 
saccate frond was of a very vivid green, erect, buoyed up by an air-bubble con- 
tained in its upper end. Its shape was that of a long sack widened very much 
above, and below constricted into a fine point, by which it was firmly attached. 
In some instances it attained a length of seven or eight inches. In all other 
respects these plants agreed with the others found in quiet water. 

The species of this genus are to me not at all well-defined in any work which I 
have had access to. The plant now under consideration abounds everywhere in 
this neighborhood, and is without doubt the one identified by Prof. Bailey as T. 
(jekdinosa (Vauch), of which, however, he afterwards states that Prof Harvey, to 
whom he had sent specimens, writes that it is a distinct species, and proposes to 
call it perforata. In my Prodromus I referred the plant to T. lubrica (Roth). 
INIy reasons for doing this were that the size of the cells corresponds very closely 
with the measurements of that species as given by Prof Eabenhorst, and the 
absence of anything that seemed to me definite in the descriptions of the two 
species. Moreover, if the possession of a parietal hyaline spot be not simply an 
accident of growth, it would indicate that the plant belongs to P. lubrica. I do 
not think, however, that any importance is to be attached to this, as the vacuole 
is often absent, and, although Prof Rabenhorst makes no mention of it, is, in all 
probability, present in certain states or stages of T. gelatinosa. My own convic- 
tion is, at present, that T. gelatinosa and T. hibrica are very probably synonyms. 
If they be distinct, the plant from which the above description was taken is refer- 
rible to T. perforata (Harvey), which, if not new, is a form of T. hibrica rather 
than T. gelatinosa. If T. lubrica and T. gelatinosa be united, no grounds are left 
for sustaining the separateness of T. perforata. 

Whilst botanizing in a primeval glade and forest, known as Bear Meadows, in 
this State, I came across a spring, covered with a TeirasjMra, which appears to 
represent the T. gelatinosa type. It formed great masses half an inch in thickness, 
at first attached, afterwards floating and covering the surface of the pool for several 
feet each way. When young these masses were elongated and were formed of 
numerous lobes attached often by very slender pedicles, and having their margins 
thickened and undulated so as to give a beautiful waved appearance to the light 
green mass. Under the microscope the structure was similar to that of the other 
form, except that the cells varied more and attained a greater size. Their diame- 
ters ranged from ^^'5/ = 0-00027" to ^J^^''^ 000066". 



84 



FRESH-WATER AhQJE OF THE UNITED STATES. 



I have also received from Prof. Kavenel specimens of a Teiraspora, which may 
be the young of a variety of this species, but which is very possibly distinct. If 
the specimens are adult, it certainly is. They consist of numerous little fronds not 
more than a third of an inch in length, often composed of several subcylindrical 
arras, as it were, radiating from a central portion, and attaining a length of a third 
of an inch or so. These fronds are irregularly perforate, and are composed of 
cells agreeing perfectly iu form, size, and arrangement with the more ordinary 
forms of T. luhrica. 

T. bullosa, (Roth) Ag. 

T. thallo membranaceo-saccato, obovato, sinuoso-bulloso, nnciam usque palmam longo, postea 
explanato, dilacerato, saturate viridi, plus minus verrucoso; cellulis subsphericis (post divi- 
sionem factam hemisphaericis vel angulosis) geminis vel quateruis, confertis, granulosis. 
(R.) Species mild ignola. 

Diam.—Cen. ante divis. 0.00032"— 0.00049" ; post divis. 0.00022"— 0.00029". (R.) 

Syn. — T. bullosa, (RoTii) Ao. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 39. 

JJab. — " Salem, North Carolina. Schweinitz, Newburgh, New York." Bailey, Silliman's 
Journal, New Series, vol. iii. 

Thallus membranaceous saccate, obovate, sinuosely-bullose, from one to six inches in length, 
afterwards expanded, torn, deep green, more or less verrucose ; cells subspherical (after divi- 
, sion hemispherical or angular) in twos or fours, crowded, granular. 

Genus DICTYOSPH^RIUM, N^G. 

Thallus gelatinosus plus minus liquidus, libere natans, saepe quasi nullus. Cellulae vesicula ehlo- 
ropbyllosa unica et locello achroo parietali prjeditae, tegumentis crassis in gelatinam homogeneam 
coufluentibus involutse, fills propriis subtilibus dichotome divisis, e familiarum centro ad peripheriam 
radiantibus connexoe. Cellularum divisio ad omnes directiones. 

Propagatio fit gonidiis mobilibus 

Thallus gelatinous, more or less liquid, swimming free, often almost wanting. Cells furnished 
with a single ehlorophyllous vesicle and a lateral transparent spot, surrounded with thick coats, 
which are confluent into a homogeneous jelly and united by very fine filaments, which are dichoto- 
mously divided and radiate from the centre to the peripheral families. Division of the cells occur- 
ring in all directions. 

Propagation by motile gonidia. 

D. pulchelliiiii, Wood, (sp. nov.) 

D. thallo subgloboso vel subovale, interdum subnullo, interdum indistincte lobato ; cellulis 
globosis plerumque sparsis sed interdum nonnihil confertis. 

Diam.—CeW. ^^\^" = 0.00025" ; thalle plerumque g^^" = 0.0033" ; interdum x^/ = 0.0054." 
Hab. — In stagnis prope Philadelphia. 

Thallus subglobose or suboval, sometimes indistinctly lobate, sometimes almost wanting; cells 
globose, mostly scattered, but sometimes rather crowded. 

RemarJcs.—l found this little plant, one August day, floating, in company with 
CIoRterium aceromm, in a brick-pond below the city. The little fronds are mostly 
roundish, or longer than broad, with a distinct outline, sometimes, however, the con- 
stituent jelly seems to fade into the surrounding water. There is never a distinct 



FRESH-WATER A L G yE OF THE UNITED STATES. 85 

outer coat. The lateral transparent spot in the cells is mostly very evident, some- 
times it is wanting, however. Occasionally there is a very distinct blackish " eye 
spot." The threads which join the cells are very delicate, and I have never been 
able to absolutely demonstrate their meeting in the centre of the frond, although 
I believe they do so. In mounted specimens, even when preserved in carbolic 
acid water, they disappear after a time. I have never seen zoospores or any other 
reproductive bodies. 

Genus RHAPHIDIUM, Ktz. 

Cellulae fasiformes vel cylindracefe, ntrinque (plerumque) sensim sensimque cuspidatae vel acunii- 
natce, rarius obtusatae, rectse vel varie curvatae, singulis, geminse vel fasciculatim aggrcgatae, medio 
decussatim vel radiatim coujunetae, rarius binae sub polls lateraliter connesae, ceterum liberse. 
Cytioderma tenue, laeve. Cytioplasma viride, subtiliter granulosum, locello pallidiori vel acliroo, 
centrali, rarius lateral!, praeditum. Cellularum divisio ad unam directionem. (R.) 

Cells fusiform or cylindrical, generally very gradually cuspidate or acuminate at the ends, rarely 
obtuse, straight or variously curved, single, geminate, or fasciculately aggregate, decussate in the 
centre or radiately conjoined, rarely two laterally united at the end, other cells free. Cytioderm 
thin, smooth. Cytioplasm green, very finely granular, furnished with a central or rarely lateral 
transparent vacuole. Division of the cells occurring only in one direction. 

R. polj'inorphiiin, Fresen. 

R. cellulis rectis vel varie curvatis, singulis, vel 2-4-8-16 fasciculatim collocatis, gracilibus, 
saepe graeiliimis, nonnunquara medio paulium turgidis, subventricosis, nonnunquam paullum 
constrictis, apices versis, sensim atteuuatis, acutissimis. 

Z)iam.— 7 jVo" =-00013". 

Syn.—B. polymorphum, Fresen., Rabenhorst, Flora Europ. Algarum, Sect. III. p. 44. 

Jjab. — Prope Philadelphia, Wood. 

Cells straight or variously curved, single or 2-4-8-16 fasciculately joined together, slender, 
often exceedingly so ; sometimes slightly turgid in the centre, subventricose, sometimes 
slightly constricted ; the apices gradually attenuate, very acute. 

Var. falcatiim. 
Cellulis fusifurmibus, gracillibus, utroque fine acutissime cuspidatis, curvatis vel semilunaribus, 
4-16 fasciculatim cougregatis. 

Syn. Ankisirodesmys falcatus. (Corda.) Rabenhorst, Flora Europ. Algarum, Sect. III. 

p. 45. 
Hah. — South Carolina, Georgia, Florida, Rhode Island. (Bailey.) 

Cells fusiform, slender, at each end very acutely cuspidate, cijrved or semilunar, 4-16 fascicu- 
lately congregate 

Remark. — Fig. 3, pi. 7, represents different forms of E. polymorphum. 

Family PROTOCOCCACE^. 

Algae unicellulares sensu strictissirao, chlorophyllosae, et vegetatione terminali et ramificatione 
vera carentes, sine cellularum generatione vegetativa. Vivnnt aut singulae, segregatae aut in fami- 
lias consociatae. Harum familiarnm cellulae nuraero aut indefinitae .semper ,se angente.s (turn sensu 
vero familiffi nonien ferunt), aut definitoe, se non augentes (quae coenobiura dicuntur). 



86 PRESII-WATER A L G /E OF THE UNITED STATES. 

Propagatio fit goniiliis, quaj intra cellulara matrit-alcm cytiogenesi libera oriuntur et dnplicis iudolis 
sunt; altera majora, qua3 niacrogonidia, altera minora quae microgouidia dicuutur ; ilia oblonga, polo 
antioo plenimquo rostellifornii-produtta, pallidiora, ciliis vibratoriis prtedita, polo postico truncato- 
rotundata, obscure viridia, iudividuuni propagaut ; La3c forma siiuilii, ilidem mobilia, brevi postea 
in statum quiescentem transeuut, druique in sporas perdurantes (Hypnosporas, Bkaun) transmu- 
tautur. (R.) 

Unicellular algiB, in the strictest sense of the word, chlorophyllous, without terminal growth or 
true branching, without a vegetative generation of cells. They live either single, segregate, or con- 
sociated into families. The cells of these families, either indefinitely increasing in number (then 
families in the true sense of the term), or of definite number (then forming a ccenobium). 

Propagation by means of gonidia arising within the mother-cell by free cell-formation ; gonidia of 
two kinds; the one larger, niacrogonidia — the other smaller, microgonidia ; the former oblong, 
mostly produced into a pale bicilate beak anteriorly, rounded and greenish at their hinder end, 
developing into the individual plant ; the microgonidia similar to these and also motile, but passing 
after a short time into a quiescent state, and at last into resting spores or hypnospores. 

Genus PROTOCOCCUS, Ac. 1824. 

Cellulae sphseroidece, scgregata;, cytiodermate tcnui, hyalino, absque teguraentis, libere natantes 
vel e.xtra aquam in stratum tenue pulvereum cumulatse. Cytioplasma initio bomogeneum, deuique 
granulosum, viride vel rubellum. 

Spheroidal cells, segregate, cytioderm thin, hyaline, without integument, swimming free or col- 
lected out of water into a thin pulverulent stratum. Cytioplasm in the beginning homogeneous, 
finally granular, green, or reddish. 

Remarks. — I have introduced this genus as given by Professor Rabenhorst in 
his Flora Europtea Algarum for the purpose of describing a little plant, upon which 
I have made some observations. As the notes were originally drawn up as a de- 
scription of a species, I leave them in that form. I believe it has never before 
been described. 

Pl'OtOCOCCUS, (sp. nov. ?) 

P. aquaticus ; cellulis globosis vel angulis, viridibus in stratum pulvereum euraulatis vel in fami- 
lias arete coiijunctis; cytiodermate plerumque distincto; sporis rotundatis, tegumentis duobus 
vel tribus protectis; tegumentis externis, crassibus; zoogonidiis ovalibus, vel subrotundatis, 
vel subellipticis, ciliis duobus instructis. 

Diam—Max. spor. perdurant. 7/5/ = .00093" ; microg. 73*55" = .00053". 

Aquatic ; cells green, globose or angular, accumulated in a green pulverulent stratum, often 
closely united into families; cytioderm mostly not distinct; resting spores round with two or 
three thick coats ; zoospores oval or roundish, or somewhat elliptical, furnished with two 
cilia. 

Remarks. — I found this species growing in a spring near Hestonville, West 
Philadelphia, in the month of March. The large winter spores are round, with 
thick coats. Except in one instance, in which the color was a decided reddish- 
brown, all that I have seen have been green. How they are produced I do not 
know. The history of their development into the plant appears to be as follows : 
The first change is the rupture of their outer thick coat (fig. 4 h, pi. 7) from which 
the spore finally escapes still clothed with a coat of moderate thickness. The 
green contents next divide into a number of oval bodies (fig. 6 b, pi. 7) which 



FRESH-WATER ALG^ OF THE UNITED STATES. 87 

grow, and, at the same time, separate from one another. Whilst these changes 
have been taking place the spore coat has been becoming gelatinous and enlarging, 
so that it continues to enclose its progeny. In this way a family of oval cells is 
formed (fig. 4 b, pi. 7). So far, I think, is positive. The next step I have never 
actually seen, but believe to be the escape of these oval bodies as zoospores (fig. 
4 c, pi. 7) which are of very various sizes and are elliptical, globose, or oval. They 
have a tolerably well-marked bright vacuole at their beak, and after swimming 
about actively for a time finally settle down, lose their cilia, and undergo division. 
They seem often to cluster together before thus becoming quiescent, so as to make 
little colonies (fig. 5, pi. 7). 

Genus CHLOROCOCCUM, Fries. 

Cellulffi sphffiroideae, aut singulae, liberce, vesicula chlorophyllosa et locello lateral! pallidiori cavo? 
instructs, limbo hyalino et tegumentis saspe amplissimis ciuctee, aut plures in stratum vel acervulos 
cumulatse. 

I'ropagatio fit zoogonidiis cytioplasmatis divisione ortis, e cytiodermatis abavise (intellige tegu- 
mcutum extremum) rupturis escedentibus. 

Cells spheroidal, cither single, free, furnished with a ehlorophyllous vesicle and a paler lateral 
(hollow ?) spot, with a hyaline nimbus and surrounded by a wide coat ; mostly accumulated together 
into strata or little heaps. Propagation by means of zoospores, which are formed by a division of 
cytioplasm and escape from their general tegument (the cytioderm of the original cell). 

Remarks. — But a few weeks after the commencement of my study of fresh- 
water algse, a friend, a young microscopist, asked me to look at his aquarium, as 
the water of it had become stagnant, opaque, and green. On examining a little 
of the water with the microscope it was found to be fidl of what I now know to 
have been either one of the forms already described under this genus, or else one 
undescribed, but still embraced within its limits. There were two sets of bodies, 
the one motile the other at rest. The motile forms (Fig, 5, pi. 3) were globular or 
pyriform, and generally contained a large, roundish, green, distinct mass. They were 
of course provided with cilia, although at that time I was not able to demonstrate 
their presence. These bodies, even when moving, appeared to have a distinct 
wall. After a time they settled down and assumed the quiescent state. The 
outer coat now rapidly enlarged so as to leave a considerable space between it and 
the green endochrome, which rapidly underwent division, forming two or more 
new cells which were still surrounded by the enlarged maternal coat. The num- 
ber of daughter-cells enclosed in the parent cell varied. A considerable quantity 
of the water was allowed to stand in a glass jar, exposed to the light. In a very 
few days all the motile forms had disappeared. The contents of the vessel wore 
allowed slowly to evaporate. The jar being tall and narrow it was some weeks now 
before this process was completed, before which consummation hcvmaiococcus forms 
were abundantly developed. 

Instead of being green, and surrounded by a distant, almost sac-like wall, the cells 
had acquired a dark brownish-red color, were very opaque, and were protected by 
a thick wall, whose surface was quite rough. Unfortunately, I did not measure 
either the active gonidia or their progeny, the quiet cells, but I found the general 



88 



FRESH-WATER ALG^ OP THE UNITED STATES. 



diaiiK'tcr of these hsematococcus cells to be one twelve-hundredth of an inch 

(.0008;}"). 

MM. Famnitzin and Boranetzky, in a recent paper (" Zur Entwickelungsgeschichte 
dcr Gonidien und Zoosporcnbildung der Flechten," Mem. de L'Academie Imperiale 
des Sciences dc St. Petersbourg, 1868, Annals and Mag. Nat. History, Feb. 1869),. 
state as the result of direct observation that this genus of algse, so called, is really 
a stao-e in the life history of the gonidia of lichens. These gentlemen took thin 
slices of lichen thalli containing gonidia, and placed them upon pieces of fir and 
linden bark, which had been previously boiled to kill any plants that might be 
growin"- on them. These were then put in a glass jar inserted over a vessel con- 
taining water, in such way that they would be constantly exposed to a very damp 
atmosphere, and at the same time communication with the external air would be 
impossible. In another set of experiments, pieces of the lichens were allowed to 
lie for a long time in water, until the component filaments were decomposed into 
a gelatinous mass, in which the still green vigorous gonidia were imbedded. These 
pap-like (breiige) masses were then washed with pure Avater and smeared upon 
pieces of linden bark. The results obtained were identical in the two cases. The 
gonidia were at first provided each with a distinct nucleus and a well-marked 
lateral vacuole, and resembled closely the first form of cystococcus. The next 
change was a division of their contents into a large number of roundish masses, 
with the disappearance both of the vacuole and of the central nucleus. The cell- 
membranes were next ruptured, and the endochrome, protruding through the open- 
ing, formed a little ball sitting upon the parent cell. In doing this it doubled 
in size, so that the part without was as large as the part within, although the latter 
still filled the cell. The contents finally escaped, but were yet surrounded by a 
very thin membrane, which soon, however, ruptured, and freed the biciliated 
zoospores into which the endochrome had in the mean time resolved itself. These 
zoospores remained a long time in the motile state, but finally settled doAvn, drop, 
ping their cilia, and became little round cells, which grew to three or four times 
their original size. Further development was not made out. 

Certain of the gonidia, belonging to a lichen of the genus PJtr/scia, failed to 
produce zoospores, but their endochrome, divided so as to form a number of 
quiescent cells, which either ruptured very early the original cell-membrane and 
became free in the water, or else remained bound together by it into a family for a 
longer period. In these researches MM. Famnitzin and Boranetzky employed 
lichens of three genera, namely Pkijscia, Cladonia, and Eveinna, and claim, as 
above stated, that their investigations prove that they developed the alga; genus 
Cystococcus of Naegeli (Chlorococcum, Fries), from the gonidia. 

Genus POLYEDRIUM, N^geli, (1849.) 
Cellulae singuloe, segregatoa, liberc natantcs, compress®, 3-4-8 angulares, angulis plus minus pro- 
ductae, nonnunquara radiatim elongatas, aut integraj aut bifidie, plerumque armats, a latere oblongo- 
ellipticffi, utroque polo rotundatK vel subtruncata!. Cytioderraa tenue, teve. Massa cblorophyl- 
lacea plerumque granulosa, per cellule lumen squaliter distributa, nonnunquam guttulis oleosis 
rubris 1-4 mixta. 

I'ropagatio adhuc igaota. (R.) Genus mihi ignotum. 



FRESH- WATER ALGJ^; OF THE UNITED STATES. 89 

Cells single, segregate, swimming free, compressed, 3-4— 8-anglecl, more or less produced as to their 
angles, sometimes radiately elongate, either entire or bifid; mostly armed, oljlong-ellii)tical when 
viewed laterally, at each end rounded or subtrnncate. Cytioderm thin, smooth ; chloropiiyi mostly 
granular, equally distributed through the cell, sometimes mixed with reddish oil-drops. 

Propagation unknown. 

Remarks. — This genus was described by Naegeli in his " Gattungen EinzeUiger 
Algen," and, although I have never seen any specimen of it, it chiiins a place here, 
because one species has been found in this country by Prof. Bailey. 

P. enorme, (Ralfs) De B.\ky. 

P. tetraediicum, angulis productis achrois profunde bilobis, nonnunquam repetito-bilobis, lobis 
mucronatis. (R.) 

X>mm._0.0011"— 0.0016". (R.) 

Syn. — P. enorme, (Ralfs) De Bary. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 62. 
Slaurastruvi enorme, Ralfs, British DesmidieiB. 

Eah. — Florida. Bailey. 

"Frond irregular or quadrate, spinous; end view three or four-lobed ; lobes broad, more or 
less emargiuate or bifid, and terminated by spines, which are either simple or branched. 
Sometimes the front view differs but little from the end one, usually, however, there is a 
slight constriction or sinus at the junction of the segments, but I have never observed any 
diifcrence in the endochrome at that part. The spines, which are almost confined to the 
angles, are irregular, some simple and some branched. The end view has three or four broad 
and very irregular lobes ; these are spinous and more or less emargiuate, and frequeutly one 
lobe is much broader and more spinous than the others. The spines on such lobe form two 
groups, separated by the notch; they vary much in size and are either simple and subulate, 
or else forked; sometimes the forked spines are again divided at the apes." — Malfs' British 
Desmidieae, p. 141. 

Genus SCENEDESMUS, Meten. 

Cellule polymorphaj, utroque polo jpquales vel intequales, seepe in cornu spiniforme productse,' in 
ffitate perfecto 2-16 aut in seriem simplicem aut parenchymatice arete coiijuncta3 et coenobium cou- 
stituentes ; cytioplasniate initio homogeneo, postea grauuloso, vesicula cliloropliyllosa centrali vel 
sublaterali et siepe loccllo achroo laterali instructo. 

Propagatio fit eytioplasmatis divisione succedanea, unde gonidia oriuntur, qua; intra eelhiliiin 
matricalem jam iu ccenobium planum sese conjungunt et membran;e matricalis ruptura vel dissolu- 
tione prodeunt. 

Cells polymorphous, equal or unequal at the ends, often produced into a spine-like horn, in the 
perfect state 2-16 closely conjoined, either as a simple series or in a parenchyma-like manner so as to 
form, a ccenobium. Cytioplasm in the beginning homogeneous, afterwards granular, furnished with 
a central or sulilateral chlorophyllous vesicle, and often with a lateral transparent spot. 

Propagation occurring as a succedaneum to the division in the cells, whence arise gonidia, which, 
already within the mother-cell, join themselves into a coenobium, and are finally set free by the rupture 
and dissolution of the maternal cell-wall. 

Remarlis. — According to Unger, in the genus Scenedesmus the cells never exist 
singly, but always in families. 

Two of the species here described as representatives of tlie genus certainly do 
not conform to this, for I have frequently seen them both separate and in coenobia 

12 May, 1S73. 



90 FRESII-WATER ALG^ OP THE UNITED STATES. 

or ftunilics. The latter were exactly like those of the European forms, at least 
in one of the two species, and I do not therefore think it justifiable to indicate a 
new genus. Moreover, I have certainly seen single cells, belonging to a species 
Avhich agrees precisely in its characters with a European form, save only in the 
occasional existence of these single cells. 

I have never studied the method of propagation, but it is said to occur by the 
division of the cytioplasm of a large cell into a minute ccenobium composed of 
two or more cells, which remains for some time within the walls of the mother- 
cell, but is finally set free by the solution of the latter. 

The cells are mostly much longer than broad, cylindrical, elliptical, or oval, but 
in one species herein described they are habitually globular. 

a. CelluliE inermes. 

a. Cells nuarmed. 

S. obtnsiis, Meten. 

S. cellulis oblongis vel ovatis, utroqne polo obtusis, 4-6-8 mode arcte modo laxe in seriem 
simplicem aut rectam aut duplicem obliqaam conjunctis, diametro 3-5 plo longioribus. (R.) 

Diam.—TTansv. max. 0.00023"— 0.00028". (R.) 

Syn. — S. ohtusus, Meyen. RABENnoRST, Flora Europ., Algarnm, Sect. III. p. 63. 

Hah. — Georgia: Rhode Island, Bailcj. 

Cells oblong or ovate, obtnse at eacli end, 4-6-8, partly closely partly laxly conjoined into a 
simple series eitber straight or oblique and double, 3-5 times longer than broad. 

Remark. — I have never met with this species, 

S. aciitu!^, Meyen. 

S. cellulis fusiforraibus, vol ovato-fusiformibus vel ovatis, ntrinqne acutis sed inermibus, inter- 
dum singulis sed plernmque in seriem aut simplicem rectam aut duplicem inordinate alter- 
nantem dispositis, arcte concretis, diametro 2-4 (6?) -plo longioribus. 

2)tam.— Trans, vag. max. ? .00016". 

Syn. — S. acutus, Meyen. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 64. 

Hab. — Prope Philadelphia, Wood. Rhode Island, Bailey. 

Cells fusiform, or ovate-fusiform or ovate, acute at each end but unarmed ; sometimes single 
but mostly conjoined into a single straight series or into an irregularly alternate double series, 
2-4 times longer than broad. 

Remarks. — This species is common around Philadelphia. Our specimens agree 
very well with the descriptions and figures of the European, excepting that occa- 
sionally a cell is single, and that none which I have measured have attained the 
siz,e given by Prof Rabenhorst as the maximum, namely, 0.00023". According 
to Rabenhorst, S. obh'qinis, Ktz., is only a variety of S. acidns, Meyen. It has 
been found by Prof Bailey in South Carolina, Georgia, and Rhode Island, 

b. Cellulee armatee. 
b. Cells armed. 



FRESn-WATER A L .E OF THE UMTED STATES. 91 

S. poIyiuorphii<$, Wood. 

S. cellulis fusifurmibus, aut ovalibus aut ellipticis aut globosis, singulis aut 2-8 conjunctis, 
plerunique utroque polo aculeo unico, iiiterdum aculcis duobu.Si, instructis: apicibus obtusis, 
acutis, vel acutissimis ; aculeis gracilliinis, rectis, modice clougatis, inclinatis. 

Dza?n.— 55V'— TfiW ; plerumque 3-0V5". 

Syn. — S. polymotyhuit. Wood, Prodromus, Proc. Am. Philos. See, 1869, p. 135. 

Hab. — In aquis quietis prope Caiudeu, New Jersey. 

S. cells fusiform, or oval, or elliptic, or globose, single or 2-7 conjoined, furnished in most 
cases with a single spiue, sometimes 2, at each end ; ends obtu,se, acute, or very acute; spines 
exceedingly slender aud acute, straight, moderately lung, inclined. 

Remarks. — This plant was found in a quiet pool, filling the water in such num- 
bers as to make it opaque and very green. The color of the cells, as first obtained, 
under the microscope, was a vivid green, biit, the water containing them having 
been placed in a dish, during the slow desiccation which followed the color of tiie 
cells changed to a golden yellow. 

Fig. 1, pi. 11, represents different forms of this species magnified 450 diameters. 

S. qiiadi'icauda, (Tlrpin) Breb. 

S. cellulis oblongo-cylindricis, utroque polo obtuse rotundatis, 2-4-8 aretissime conjunctis, 
ordine aut simplici recto aut duplice alternante, omnibus rectis, medianis inermibus vel his 
illisve apice uno altcrove aculeo curvato instructis, extimis utroque apice sapius item dorso 
armatis. 

Z)iaw?._0.00035"— 0.00039"; long. 0.00091". 

Syn. — S. quadricauda, (Ttjrpin) Breb. Rabenhorst, Flora Europ. Algar., Sect. III. p. 65. 

Hab. — Rhode Island, Bailey. Pennsylvania, Wood. 

Cells oblong-cylindrical, obtusely rounded at each end, 2-4-8 very closely conjoined either in a 
single straight series or a double alternating one, all straight, the median unarmed or some of 
them with the apex furnished with a curved spine, the external with both apices and some- 
times the dorsum thus armed. 

Remark. — Fig. 2, pi. 11, represents this species magnified 750 diameters. 

S. rotiindatus, Wood, (sp. nov.) 

S. cellulis globosis vel subglobosis, spinulis longissimis, rectis, gracillimis, acutissimis, 3-6 
armatis, aut singulis aut geminis aut 3-4 arete duplice conjunctis. 

Diam..—^^\-s" to ^^Vtt"- 

Hab. — In aquis quietis prope Philadelphia. (Dr. Chapman.) 

Cells globose or subglobose, armed with three to five very long, slender, acute, straight spines, 
single or in pairs, or three to four closely conjoined in a twofold rank. 

Remarks. — The cells of this species are globular, and, when more than two, 
they are arranged in two rows placed at right angles one to the other. The con- 
tents of the cells are markedly granular, and the endochrome a bluish-green, and 
from the surface of the walls project outwards, very long and fine, rigid hair-like 
spines. 

It seems scarcely correct to place this plant in the genus Scenesdesmus, but I do 



92 FRESHWATER A L G .E OF THE UNITED STATES. 

not know any other genus to which it is more closely allied, and do not feel dis- 
posed to indicate a new one for it. 

Fi^'. 3, pi. 11, represents a cell-family magnified 250 diameters. 

Genus HYDIIODICTYON, Roth. (1800.) 

CelluliE oblongo-cylindricse, in coeuobium reticulato-saccatum conucxoe, omnes fertiles; alise 
procreant macrogoniilia, qiia3 jam intra cellulam matricalem iu coenobium tiliale se connectunt; alise 
microgonidia, quie multo minora, celluliE matricalis membranam perrumpunt, polo antico ciliis vibra- 
toriis binis et puiicto rubro laterali prasdita sunt, brevi postea in globulos protococcoideos tranquillos 
trausformata sporas perdurantes eificiunt. 

Cells oblong-cylindrical, joined into a reticulated saccate coenobium, all fertile; some producing 
macrogonidia, which join themselves into a coenobium within the parent cell; the others producing 
microgonidia, which are furnished with two vibratile cilia and a lateral red spot, and which, escaping 
from the parent cell, are, after a brief period of motile life, transformed into protococcoid thick-walled 
spores. 

Remarks. — The genus Hijdrodlcti/on comprises, as far as known, but a single 
species, which is common to North America and Europe. It grows in great 
abundance in the neighborhood of Philadelphia, especially in the ditches and 
stagnant brick-ponds in the low grounds below the city known as the "Neck." 
There it very frequently forms floating masses several inches in thickness and 
many feet in extent, so that with the aid of a rake it could be gathered by the 
bushel. When thus in mass the color is very generally dingy and yellowish, 
although tlic fronds, when in active vegetative life, are mostly of a bright, beauti- 
ful green. The plant is in greatest profusion in June and July, after which time 
it gradually disappears, until in the autumn it is scarcely to be found, but early 
in the spring it reappears. The very young fronds are minute, oval, cylindrical, 
filmy-looking, closed nets, with the meshes not appreciable to the eye ; when growth 
takes place, tlie fronds enlarge until finally they form beautiful cylindrical nets 
two to six inches in length, with their meshes very distinct and their ends closed. 
In the bright sunlight they, of course, by virtue of the life-functions of their chlo- 
rophyl, liberate oxygen, which being set free in the interior of the net, and its 
exit barred by the fine meshes, collects as a bubble in one end of the cylinder and 
buoys it up, so that, the heavier end sinking, the net is suspended, as it were, ver- 
tically in the water. I know of few things of the kind more beautiful than a jar 
of limpid water with masses of these little nets hanging from the surface like cur- 
tains of sheen in the bright sunlight. A few cells collected in the fall or early 
spring, if put into a preserving-jar and the water occasionally changed, will multi- 
ply, and in a little while become a source of frequent pleasure to the watcher. 

As the fronds increase in size they are always in some way or other broken up, 
so that, instead of being closed cylinders, they appear as simple open networks of 
less or greater extent. The extreme length to which the frond attains is, I think, 
very rarely over twelve inches, with meshes of about a third of an inch in length. 
The construction of the frond is always the same. It is composed of cylindrical 
cells united end to end in such a way as to form polygonal, and mostly pentagonal 



FRESn-WATER A L G .E OF THE U^UTED STATES. 93 

meshes, the size of which varies with the age of tlie phint. These cells, 
which are closely conjoined but have no passage-ways between them, are capable 
of independent life, so that the hydrodictyon may be looked upon as an elaborate 
type of a cell-family, one in which cells are conjoined in accordance with a defi- 
nite plan, so as to make a body of definite shape and size, yet in which each cell 
is an independent being, drawing nothing from its neighbors. The cells them- 
selves are cylindrical, with a thickish cellulose wall, and have no nuclei. Their 
chlorophyllous protoplasm is granular, and is placed in the exterior portion of the 
cell, forming thus, within the outer wall, a hollow cylinder, in which are imbedded 
starch granules, and whose interior is occupied with watery contents. The hydro- 
dictyon cell, when once formed, is capable of growth, but not of going through the 
usual process of cell multiplication by division, so that the adult frond is com- 
posed of just as many and indeed the same cells, as it had in its earliest infancy. 

No true sexual reproduction has as yet been discovered in the water-nets. There 
have been described, however, two forms or methods in which the species multi- 
plies, both of them occurring by means of motile zoosporoid bodies. In the one 
case these develop immediately into the new plant, whilst in the other before 
doing so they pass through a resting stage. Of the life-history of the latter, the 
micro'jonidia, I have no personal knowledge. 

The investigation' of the production and development of the macrogonidki, how- 
ever, has occupied considerable of the time devoted by myself to tlie microscope, 
and I have seen large numbers of specimens in almost all the stages of develop- 
ment. I have never been able to detect, however, any decided motion in the 
iriacrogoniilia. 

They are formed in the protoplasmic stratum, already alluded to as occupying 
the outer portion of the interior of the hydrodictyon cell. The first alteration in 
this, presaging their formation, is a disappearance of the starch granules, and a 
loss of the beautiful, transparent green color. Shortly after this, even before all 
traces of the starch-grain are gone, there appear in the protoplasm numerous 
bright spots placed at regular intervals; these are the centres of development 
around which the new bodies are to form. As the process goes on, the clilorophyl 
granules draw more and more closely around these points, and at the same time 
the mass becomes more and more opaque, dull, and yellowish-brown in color. This 
condensation continues until at last the little masses are resolved into dark hexa- 
gonal or polygonal plates, distinctly separated by light, sharply defined lines. In 
some, the original bright central spot is still perceptible, but in others it is entirely 
obscured by the dark crowded chlorophyl. The separation of these plates now 
becomes more and more positive, and they begin to become convex, then lenticular, 
and are at last converted into free, oval, or globular bodies. "Wlien these are fully 
formed, they are said to exhibit a peculiar trembling motion, mutually crowding 
and pushing one another, compared by M. Braun to the restli^ss, imeasy movcnumt 
seen in a dense crowd of people in which no one is able to leave his place. AMiilst 
the process just described has been going on, the outer cellulose wall of the hydro- 
dictyon cell has been undergoing changes, becoming thicker and softer and more 



94 FRES II -WATERALGiE OF THE UNITED STATES. 

ami more capable of solution, and by the time the gonidia are formed it is enlarged 
and cracked, so that room is afforded them to separate a little distance from one 
anotlier witliin the parent cell. Now the movements are said to become more 

active a tremblins? jerking which has been compared to the ebullition of boiling 

water. Tliere is, however, witli this a very slight change of space, and in a very 
short time the gonidia arrange themselves so as to form a little net within the 
parent cell, a miniature in all important particulars of the adult hydrodictyon. 
The primary cell-wall now becomes more and more gelatinous, and soon undergoes 
complete solution, so that the new frond is set free in its native element. As pre- 
viously stated, in my investigations I have never seen the peculiar motion above 
described, the newly formed gonidia simply separating and arranging themselves 
without my being able to perceive any motion, or exactly how they fell into posi- 
tion. 

It is evident that when the species is multiplied in the way just described, the 
birth of the new frond is consentaneous with the death of the old cell. But when 
the hydrodictyon disappear in the fall, it is months before they reappear in the 
spring. It is, therefore, evident there must be some other method of reproduction. 
This slow development of new fronds takes place, according to Pringsheim, by 
means of little motile bodies which he calls '■'■ Dauerschwarmer," which has been 
translated into English chronispores {statospores. Hicks). M. Braun stated already 
some years since that sometimes, instead of the hydrodictyon producing the ordi- 
nary reproductive bodies {macrogoniclta), there are formed in the cells much smaller 
and more active bodies, the microgonidia. The changes which occur in the pro- 
duction of these are very similar to those already described as happening when 
the macrogonidia are formed. When the clironispores are once formed, however, 
they, instead of uniting together escape in a free distinct condition into the water. 
They are now small ovate bodies, with a large anterior transparent space, to which 
are attached a pair of cilia, and their life and history, according to Pringsheim, is 
as follows : For a few hours they move about very actively in the water, and then, 
dropping their cilia, and acquiring an outer cellulose wall, pass into a quiescent 
stage, in which they closely resemble protococcus granules. They are capable of 
living in this state for a long time, if kept in water. They can also endure desic- 
cation if the light be excluded during the process, but, if it be present, they wither 
and die, and cannot be revivified. 

After a longer or shorter period, but never shorter than three months, according 
to Pringsheim, they recommence their life, provided they be in water. For four 
or five months after this the chief change consists simply in an increase in size. 
The dark-green protoplasm is arranged around the exterior of the cell, within are 
the more fluid colorless contents, the whole body still looking like a protococcus 
cell. After a size of about f ^ mm. is attained, the endochrome divides succes- 
sively into several portions. The external layers of tlie surrounding wall now 
give way in some spot and allow the inner layers to protrude and form a sort of 
hernial sac, into wliich the several endochrome masses soon pass, at tlie same time 
assuming the well-known characters of true zoospores. From two to five of these 



FRESH-WATER A L G .G O F T II E U N I T E D STATES. 95 

bodies are thus produced out of each original microgonidium. They are laro'e 
ovate, biciliate, and, generally, soon escaping from tlie hernial sac, move about 
actively in the water for a few minutes. Sometimes, however, they settle down 
within the generative utricle. In either case, after a little time, they become 
motionless, lose their cilia, and develop into polyhedral cells, which are structurally 
remarkable for having their angles prolonged into long horn-like appenda<'es. Under 
favorable circumstances, at the end of a few days, the briglit green endochrome of 
these undergoes similar changes to those described as presaging the production of 
the microgonidia, and is finally formed into zoospores, which, in from twenty to forty 
minutes, unite, within the polyhedron or large cell, into a Hijdrodictyon, which is 
finally set free by a solution of the cellulose coat of the polyhedron. The network 
thus formed differs in no essential way from that wliich arises in the better known 
way, except that it is composed of much fewer cells. It is generally a closed 
sac ; but when the polyhedron, out of which it is developed, is small, it is some- 
times merely an open network. Its after-history appears to be identical with that 
of the ordinary hydrodictyon frond, 

H. uti'iculatiiui, Roth. 
Species unica. 
Syn. — E. utriculalum, Roth. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 06. 

Hah. — In aquis quietis. West Point, Bailey. Weebavvken, (Mr. Walters.) "Waterholes 
between Van Horn's Mills and Mueote on the Mexican boundary, Dr. Bigelow. Pennsyl- 
vania, Wood. 

Genus PEDIASTEUM, Meten, (1829.) 

Coenobiam planum, disciforme, libere natans, e celluarum strato unico, rarius centre entro duplicato, 
continuo vel perforato formatum. Cellute polygoniEe, periphericae sa;pe bilobae, lobis cuneatis et 
simplicibus et bidentatis, nonuunquam in cornua productis. 

Coenobium plain, discoid, swimming free, formed of cells in a single, rarely in the centre double 
stratum, which is continuous or perforate ; cells polj-gonal, the peripheral often bilobed, the lobes 
cuneate, either simple or bidentate, sometimes produced into a horn. 

Remarks. — The coenobium or cell-family, or colony, in the genus Ped'iastrum is 
always discoid, and has generally a more or less truly circular outline. The cells 
are mostly in a single stratum, but in some species there are two, more or less, 
complete strata superimposed one upon the other. The arrangement of the cells 
in this stratum, or these strata, varies greatly, as does also their number. They 
are mostly more or less polyhedral, and often have their margins scooped out or 
their angles prolonged. This may occur in such a way that the projecting point 
of one cell fits into the hollow in its neighbor, and the coenobium be rendered 
entire, or, no such relation existing between the parts of adjacent cells, the coeno- 
bium nviy be perforated with regular or irregular openings. The outer or mar- 
ginal cells are often deeply notched externally, nnd frequently are prolonged into 
acute or obtuse lobe-like processes. The walls of the cells are, in adult specimens, 
quite thick. The contents consist of chlorophyl, protoplasm, starch granules, &c. 



96 PRESU-WATER ALG^E OF THE UNITED STATES, 

There arc generally one or more hyaline spaces, besides a distinct chlorophyl 
vesicle, but no distinct nuclei. 

At certain periods of their existence the Pediastrums produce both macrogonidia 
and wicrogoiddia. The life-history of the former is very similar to that of the 
same bodies in the water-nets. The ultimate fate of the microgonidia has not as 
yet been determined, but in all probability they go through cycles of change 
similar to those seen in the lives of the corresponding bodies in the Hydrodictyon 
utriculatum. I have not had an opportunity of watching the development of 
either of these reproductive forms, but, according to MM. Braun, Pringsheim, &c., 
their life-history, as far as known, is as follows: In most cases, all the cells of a 
pediastrum produce their macrogonidia simultaneously, or within a very short 
period of time, so that the coenobium will be left emptied of its contents as a mere 
shell, the outer skeleton of its former self. When a cell is about to give birth to 
these reproductive bodies, the endochrome divides into two parts ; each of which 
then undergoes a similar binary division. This is repeated once, twice, thrice, or 
oftener, until the endochrome is divided into 8-16-32-64 gonidial masses, the 
number of which, generally, but not always, corresponds to the number of cells in 
the colony, to wliicli the parent-cell belongs. After the division of the endochrome 
is completed, a slit occurs in the outer strata of the wall of the mother-cell through 
wliich a hernial protrusion of the inmost stratum occurs. The protruded part 
now rapidly enlarges until at last there is formed a sort of hourglass-shaped sac, 
one portion of which is within, the other part without, the old paa'ent-cell. 
Whilst this has been going on a portion of the gonidia have escaped from the 
parent-cell into the outer free portion of the sac, and each end of tho hourglass, 
therefore, contains some of them. The sac with its contents now gradually 
withdraws itself more and more from the parent-cell until at last it lies a free 
globose vesicle in the water. The gonidia occupy the centre, and M. Braun states, 
that, although he has never been able to demonstrate any cilia upon them, yet 
they have an active swarming motion. At first, they are irregularly heaped toge- 
ther in the nearly filled sac ; but the latter rapidly enlarges and elongates, and the 
gonidia in a little while arrange themselves in a flat, tabular group within it, and 
cease to move. Then the several individuals of this group begin to develop, 
becoming emarginate and assuming the form of the parent-cell, until, finally, they 
have all grown into the shape which is peculiar to the adult cells of the species, 
and after a few hours have closely cohered to form a young camobium. 

The microgonidia are formed in a very similar way by the dividing of the endo- 
chrome, the cracking of the outer membrane, and the protrusion and final escape 
of the inner. They are, however, much smaller and more numerous than the 
macrogonidia. When the parent vesicle first escapes into the water, they are 
crowded in its centre, and are nearly globose. As it enlarges, however, they elon- 
gate more and more, and finally become distinctly bi- or, more rarely, uni-ciliate. 
The cilia are much longer than the body, and are attached to the smaller end, 
which is prolonged into a pointed, transparent beak, about equal to the green por- 
tion in length. The microgonidia now become more and more restless, they, moving 
about very actively, and after awhile bursting the parent sac, escape into the water. 



FRESH-WATER ALG^ OF THE UNITED STATES 97 

What becomes of them after this, as has been stated, is a mere matter of conjec- 
ture. M. Braun' and others have described unicelkxlar forms of several of the 
multicellular species of Pediastrum, and Pringsheim suggests that these are really 
polyhedrons developed out of these microgonidia, as is seen ui the water-nets. 
This, of course, may or may not be the case. 

P. Boryauiiiu, (Turpin) Mengh. 

P. coenobio orbicular!, oblongo vel elliptico, magnitudine vario, continue, laste viridi, c cellulis 
4-8-16-32-64 (rarissinie 128) composite (cellulanim strato simplici, nonnunquam uicdio 
duplicate); cellulis periphericis plus minus profunde emarginatis vel bilobis, lobis cornutis, 
cornibus achrois hyalinis, abbreviatis vel elongatis, teretibus, obtusis vel subobtusis, intenlum 
capitellato-incrassatis, centralibus arctissime coucretis, polygonis (4-6 angularibus), in autica 
parte mode angulo prominulo mode plane truncatis, mode leviter repandis, omnium mem- 
brana decussatim punctata. (R.) 

Z>m??i.— Transv. cell 0.000T95" ; rarius 0.0008S"— 0.00094". (R.) 

Syn. — P. Boryanum, (Turpin,) Menghini. Rabenhorst, Flora Europ. Algarum, Sect. III. 

p. 74. 
Hah. — Georgia, Florida, Rhode Island, Bailey ; Pennsylvania, Wood. 
Cells arranged in one or more circles round one or two central cells ; the inner variable, generally 

concave at one side, the outer tapering into tvro long subulate points, the notch narrow. 
L. 1-2083" to 1-1C33"; B. 1-2733" to 1-2222". (Archer.) 

P. Selejiaea, Kxz. 

P. coenobio orbicular!, integro, e cellulis 8-16 (rarius 31 = 1 -f 5 -f 10 + 15, Ktz.) formato ; 
cellulis periphericis 'angustis, lunatis, acute lobatis, disci cellulis leviter excisis, central! unica 
5-angulari, omnium membrana firma, subcra.ssa, aetate provecta rubescente. (R.) 

Diam.—Ccenobii 0.00124"— 0.003.5"; cell, (distantia; interlobos) 0.00026"— 0.00069". (R.) 
Syn. — P.Selensea, Ktz. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 73. 
Eab. — Rhode Island, Bailey. 

Cells crescent-shaped, arranged in one or more circles round one or two central ones, connecting 
medium colored. (A.)' 

P. pertiisiiin, Ktz. 

P. coenobio orbicular!, lacunis pertuso, magnitudine vario, e cellulis pleruraque l-f5-t- 10-fl5 
(in formis quibusdam ad 64) composite ; cellulis periphericis basi tantum laxe connexis, ad 
medium usque bilobis, lobis rectis, in cornua hyalina mode subaeuta mode obtusa vel trun- 
cata plus minus productis, centralibus plus minus exacte quadrangularibus, et in autica parte 
et utrinque emaginatis, omnibus laevibus, locellis pallieribus finis instructis. (R.) 

Di'am. —Transv. cell, perfecte evolut. circiter 0.00065"— 0.00089". (R.) 
Syn. — P. pertusum, Ktz. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 75. 
Cells arranged in circles round one or two central ones ; inner cells quadrangular, sides concave 
and leaving angular vacant intervals; the outer cells with square bases, externally triangu- 
larly notched, the subdivisions tapering to an acute point. L. 1-2266" ; B. 1-3268". (A.) 

P. constrictiiin, Hassal. 

P. coenobio orljicular! vel suborbiculari, laete viridi, continue, laevi ?, e cellulis 16 (ad 1 -f 5 -f- 
10) vel 32 (ad 1 -f 6 -f 10 -f- 15) formato; cellulis periphericis irregulariter bilobis, sinn 



' The best exposition of this genus is to be found in Braun's Unicellular Algoe. 
^ The letter A used here signifies that the description is copied from Mr. Archer in Pilchard's Infu- 
soria. 

13 June, 1872. 



98 F R E S H- W A T E R A L G J-J OF THE UNITED STATES. 

aii-riisto, lobis iiia?fiualibns, basi plcruniqiie constrictis, in cornua subcrassa obtusa productis, 

centralibiis polygoiiis, in antica parto repaiidis. (R.) 
Si/n.—F. ellqilirum, Hassal. Rabenhorst, Hora Europ. Algarum, Sect. Ill, p. 77. 
Hub. — South Carolina, Georgia, Rhode Island, Bailey. 
Cells varying in number and arrangement; outer cells suddenly contracted into two short, 

cylindrical, obtuse processes. L. 1-1764" to 1-90G"; R. 1-1515" to 1-1020". 
(3, Trotesses of Hie lobes truncately emargiuate. (A.) 

P. Ehrenbei'g'ii, (Corda) Braun. 

P. coenobio et orbicular! ct oblongo, perfecte clause, e ccllulis 8 vel 16 composito et quadrate, 
e cellulis 4, late cuncatis, profunde lobatis, e.xacte cruciatim dispositis formato ; cellulis peri- 
phericis cuneatis a basi truneata ad apiccni usque concretis, profunde bilobis sinu angusto, 
lobi.s sajpe oblique truiicatis, plus minus sinuato-excisis, angulis interioribus ad duplum lon- 
gioribus, omnibus acutis vel breviter appendiculatis; cellulis centralibus aut singulis aut 
pluribus (2-5-6 v. 8), omnibus flavo-viridibus, polygouis, uno latere repandis vel profunde 
ineisis. (R.) 

Syn. — P. Ehrenbcrgii, (CoRDA,) Braun. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 77. 

Hah. — South Carolina, Georgia, Florida, Rhode Island, Bailey. 

Frond minute ; cells eight (seven disposed in a single series round a central one), bilobed, 
angular. L. 1-2900" ; B. 1-2500". (A.) 

P. simples, Meyen. 

P. cellulis peripherieis ovato-cuspidatis, 8-10-16 basi tantum concretis, circulum simplicem 
• constituentibus, centralibus siB|)e nullis. (R.) 

Syn. — P. simplex, Meyen. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 71. 

Monactiinis octonariux, Bailey, Smithsonian Contributions. 
Sab. — South Carolina, Rhode Island, Bailey. 
Var. — dtiodenni'ius. 
Coenobio dathrato, cellulis peripherieis 12, centralibus 4, regulariter cruciatum dispositis. (R.) 
S>/n. — Monactinus duodenarius, Bailey. 

Inner cells four, somewhat triangular, enclosing a central, quadrate vacant interval, and four 
broadly lanceolate vacant intervals between them and the outer series, to which they are 
united by their terminal angles, outer cells twelve, subovate, truncate below, much attenuated, 
acuminate. (A.) 

Famly VOLVOCINEtE. 

Coenobia mobilia, globosa, subglobosa vel quadrangulo-tabulata, e cellulis viridibus cilia bina 
agilia gerentibus, intus vesica duplici contractibili prsditis coiaposita, membraua (tegumento, 
chlamyde) communi achroa hyalina plus minus ampliata involuta. 

Propagatio aut se.xualis, monoica vel dioica (adhuc in paucis tantum generibus probata) ; cellulis 
coenobii aut omnibus aut quibusdam genus masculinum vel feminnm exhibentibus, illis in fascienlos 
spermatozoideorum (autheridia), has in oosporas episporio inclu.^as, non mobiles commutatis, aut 
non sexualis, gonidiis agilibus, (et niacrogonidiis et niicrogonidiis— etiam zoogonidia vocantur). 
Macro- et microgonidia (celluliB primordialcs) cytioplasraatis divisione simultanea et multiplici orta; 
priora nuraero definita (2-4-8-16, &c.), majora oblonga vel rotundata, polo antico plus minus rostri- 
formi producta, ciliis binis per vesica; racmbranam exsertis, puncto (ocello Ehrberg. stigma) sanguineo 
centrali vel parietal! et locellis (vacuolis) saepe binis contraetibilibus instructa; ultima numero indefi- 
nita, multo minora, pallide vel sordide viridia vel luteola, apice ciliis instructa, plernmque jam intra 
cellulam matncalem vivide vacillantia, postea membranie ruptura libcre erumpentia, examinantia. (R.) 



FRESn-WATER A L G .E OF THE UNITED STATES. 99 

Coenobiura mobile, globose, subglobose or in square tables, composed of green colls which have 
two motile cilia and a double contractile vesicle. The common tegument surrounding the cocnobium 
hyaline, and more or less amplified. 

Propagation either se.xnal or non-sexual. The sexual monaseious or dia3cious; either all or some 
of the cells of the coenobium exhibiting male and female characters. The male cells containitig 
spermatozoids, the female finally converted into a quiet oospore. Non-sexual propagation taking 
place l)y means of motile gonidia (both niarrogonidia and niicrogonidia, by some called zoogonidia). 
Macro- and micro-gonidia arising by the simultaneous and repeated division of the cytioplasm ; the 
first definite in number (2-4-8-1 G, &c ), the larger, oblong or rounded, with the anterior end more 
or less rostellate, with two cilia exsertod through the membrane of the vesicle, furnished with a cen- 
tral or parietal red spot, and often with two contractile vacuoles; the niicrogonidia indefinite in 
number, much the smaller, pale or dirty green or luteolous, furnished at the apex with cilia, mostly 
even within the mother-cell, moving rapidly, and finally escaping on the rupture of tlie membrane. 

Genus CHLAMYDOCOCCUS, A. Braun. 

Cellulse globosiE, vel subglobosae (4—8 in coenobium fugacissimnm conjuncta;), cytiodermate sub- 
crasso firmo, cytioplasmate granuloso, fusco-rubro vel puniceo (in evolutionis gradibus quilmsdam 
in colorem viridem mutato). Macrogonidia 2-4-8, rotundata, polo antico rostrifornii producta, duo 
cilia longissima gerentia, nucleo centrali rubro, globulis amylaceis 4-6, non semper visibilibus 
instructa, tegumeato amplissimo hyalino plerumque ovoideo vestita. Microgonidia niulto minora, 
numerosa, luteola vel sordide viridia, apice rubella, ciliis binis instructa, intra tegumentum matri- 
cali alacriter vacillantia, denique membranae ruptura elabentia. (R.) 

Cells globose, or subglobose (4-8 conjoined in a very fugitive coenobium), cytioderm thickish, 
firm, cytioplasm granular, brownish-red or puniceus, in certain stages of evolution ciiangid into 
^reen. Macrogonidia 2-4-8, rounded, the frond end bearing very long cilia, furnisljid with a 
central reddish nuclei and with four to six, not always perceptible, starch granules, clothed with a 
very ample, hyaline, mostly ovoidal tegument. Microgonidia much the smaller, numerous, luteolous 
or sordid green, the apex reddish, furnished with two cilia, moving actively within the maternal 
'.egument, and at last escaping by the rupture of the membrane. 

Ch. nivalis (Bauer, Ag.). A. Braun. 

Ch. globulis, 0.004"— 0.00135". (R.) 

Hab. — In nive aitcrna, Greenland. Rocky Mountains. 

Syn. — Ch. nivalis (Baur, Ag.). A. Braun. Rabenhorst, Flora Europ. Algarum, Sect. III. 
p. 97. 

Globules, 0.004"— 0.00135" in diameter. 

Remarks. — I have never seen any good specimens of tliis plant, merely some 
cells mounted in Canada balsam, and therefore ruined for scientitic study, whicli 
had been collected by Dr. Kane in one of his Arctic voyages. I have also had 
some indications of plants in a little parcel sent me by Mr. Sereno Watson, who 
informs me he has seen the red snow very abundant in the higher peaks of the 
Rocky Mountains. It is a matter of presumption rather than determination, there- 
fore, that the snecies is identical with the European. 

Genus VOLVOX, Ehkb. 

Coenobium exacte sphasricnm, continuo rotatum et agitatum, globum cavnra qnasi fingens, e cel- 
lulis numerossissimis SBquali distantia peripherice dispositis, gelatina matricali connexis, ])uncto 
rubro laterali, locellis (vacuolis) binis contractibilibus necnon ciliis binis longe exsertis instructis, 
vesica communi hyalina eircumcinctis compositum. 



100 FRESH-WATER ALG^ OF THE UNITED STATES. 

Propagatio duplex ist, aiit non sexualis aut sexualis; ilia fit ci-llulis quibusdam certa distantia 
iutumescentibs, nmUipartitis, iu cojiiobia filialia iutra coeiiol)ium niatricale evolutis, postea lihere 
erumpentibus- lioec cellulis masculis multipartitis in fascicules spermatozoideorum mobilium, con- 
tractiliuui, pyriformium, ciliis binis instructorum, postea liberorum evolutis; cellulis femineis intu- 
mesceiitibus, nou divisis, sed post foecundationem in oosporas immobiles episporio duplici tircum- 
datas postremo rubras evolutis. (R.) 

Coenobium exactly spherical, continually rotating and agitated, looking like a hollow globe, 
composed of very numerous cells, which are arranged on the periphery at equal distances, and are 
connected by the maternal jelly, and surrounded by a common hyaline bladder; they are also fur- 
nished with a lateral red point, with two contractile vacuoles, as well as two long exserted cilia. 

The propagation is both sexual and non-sexual. In the latter, certain distant cells enlarge greatly, 
divide into numerous parts, and evolve within the parent coenobium daughter-ccenobia, which are 
finally set free. In the sexual propagation certain molecular cells undergo a multipartite division 
into fasciculi of spermatozoids, which are motile, contractile, pyriform, and furnished with two 
cilia; the feminine cells are enlarged, and do not undergo division, but after fecundation develop into 
immovable oospores, which are finally red, and are surrounded by a double episporium or coat. 

V. $!^lobator, (Linn.) Ehrb. 

V. coenobiis majoribus ad ^"', cellulis numerossissimis (ad 12,000); ccenobiis filialibus semper 
octo intra matricale fructificatione non sexuali evolutis ; fructificatione dioica ; coenubiis 
masculis fasciculos spermatozoideorum numerosos rubescentes foventibus (^ Sphxronira 
volvox, Ehrb.); cffinobiis femineis cellulas sexuales (oogonia) 20-40 post fcecuudationem in 
totidem oosporas globosas rubras episporio hyaliuo stellato circumdatas foventibus (= Yol- 
vox stellatus, Ehrb.). (R.) 

Syn. — F. globalor, (Linne,) Ehrb. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 91. 

Hah. — In stagnis. United States. 

Larger coenobium, about ^" in diameter, composed of very numerous (about 12,000) daughter- 
ccenobia, always 8 within the maternal one, evolved without sexuality; fructification dioe- 
cious ; male coenobium giving origin to numerous reddish spermatozoids (= Sphffirospliaera 
Volvox, Ehrb.); female coenobium, giving origin to from 20-40 sexual cells, which, after 
fecundation, develop juto the same number of globose red oospores surrounded by a stellate 
hyaline episporium. 

Remarks. — Some of my friends tell me they have found this species abundantly 
around Philadelphia. I have not been so fortunate, and have seen but a few 
scattered specimens, which have afforded no opportunity of studying their deve- 
lopment and life-history. 

Order Zy^Topliyceae. 

Alga; aut uni- aut pseudomulti-cellulares, sine vegetatione terminali et ramificatione vera. Cellulse 
singula aut geminatae aut seriatim conjunctaj. Multiplicatio fit cellularum divisione in unam direc- 
tionem. 

Propagatio fit zygosporis conjugatione cellularum similium binarum ortis. 

Algae either uni- or pscudomulti-cellular, without terminal growth or true branches. Cells segre- 
gate or geminate, or arranged in a single row. Multiplication taking place by a division of the 
cells in one direction. 

Propagation by zygospores, formed by the conjugation of two similar cells. 

Family DESMDIACE^. 

Alga; uniccllulares, sine ramificatione vel vegetatione terminali. Cellulaj forma admodum varia, 
plerunique iu medio plus minus profunde constrictie et in duas semici^llulas svmuietrica.s Cm>-v^. 



rKESH-WATER ALG^ OF THE UNITED STATES. 101 

libersB vel in fascias filifcrmes aut tseniiformes arete conjunctae aut in muco matricali nidulaiites et 
in lamilias indeliuitas cousociatie. Cytioderma non siliceuin, plus minus firmum, liuve aut varie 
asperatum (striatum, costatum, aculeatum, &c.). Massa uldorophjllacea iu laminales axiles vel 
parietales, sajpe e centre radiaiiles, distributa. 

Propagatio non sexualis per divi.sione transversa iu eaudeiu directionem repetita ; sexualis per 
zygosporas, quse per cellularura Ijiuaruui coujugationem oriuutur. 

Unicellular algaj, wilbout branches or terminal growth. Cells of very various forms, mostly more 
or less profoundly constricted in the middle and divided into two symmetrical semicells, free or con- 
joined in filiform or taaniform fascia, or involved in the maternal jelly so as to form indefinite fami- 
lies. Cytioderm not siliceous, more or less firm, smooth, or variously roughened (striate, costate 
aculeate, &c.) C'hloropliyl masses iu axillary or parietal lamina, which often radiate from the 
centre. 

Non-sexual propagation by repeated transverse division in one direction ; sexual by zygospores 
which are formed by the conjugation of two cells. 

Remarhs. — Of all the fresh-water algse, with the exception of the diatoms, this 
family has attracted most attention, owing, not only to the beauty and variety of 
its forms, but also to their universal presence and abundance, and the case with 
which their most wonderful life-histories are observed. They are exclusively, as 
far as known, denizens of fresh-water, and preferably that which is pure and limpid. 
Altliough Mr. Ralfs states that they never grow in stagnant water, I have often 
found them in great abundance in such, yet never in that which was actually putrid. 
The same authority is also too sweeping, at least as far as this country is concerned, 
in stating they are never found in woods, although they are really most abundant 
in the open country. My experience has taught me to look for them in brick- 
ponds, small mountain lakes, springy fens, ditches, and, in the fall, growing among 
mosses and in the thick jelly composed of unicellular algae on the face of dri[> 
ping rocks, or, to sum up in a word, they dwell in quiet, shallow waters, for I have 
never found them in rapidly moving or very deep water. 

The single cell, of which a desmid is composed, is mostly divided into two very 
marked similar portions, the exact counterj)arts one of the other, which by some 
have been asserted to be distinct cells. Their close union and connection, and their 
inherent oneness are, however, so apparent that it is needless here to spend time 
in demonstrating that they really are halves of one individual cell. They contain 
together all the parts found in the typical vegetable cell ; an outer cellulose wall, 
chlorophyllous protoplasm, a nucleus, starch granules and semiliquid contents. 
The cell-wall, or cytioderm, as it is called in this memoir, varies in thickness 
and firmness. During life it is mostly, if not always, colorless ; but in certain 
species in the dead empty frond is of a reddish-yellow. The markings upon it are 
various, and are not infrequently altogether absent; they are such as fine or coarse 
punctations, granulations of various size, striae, furrows or elevated ribs, tuber- 
cles, obtuse or sharp simple or forked spines, hair-like processes, umbonations, &c. 
&c. These markings are within narrow limits constant in each species, and 
more or less peculiar, so that they afford valuable characters to the systematist. 
The cytioderm itself is mostly composed of cellulose free from appreciable inor- 
ganic matters, but iu certain species contains a large amount of silex. Thus, 



102 



FRESH -WATER ALG.'E OF TUE UNITED STATES. 



accoi-diiii^- to Ue Barry, if Closterinm. Ivmda be carefully burnt upon a slide, a per- 
fect hyaline silex cast of the cells is left. 

The chlorophyl is variously placed in the cell, sometimes it is arranged in 
lamina, sometimes in spirals, sometimes in the form of radii from a central mass. 
These different methods afford good generic characters, and will be dwelt upon 
more in detail under the various genera. The color of the chlorophyl during 
active life is a vivid green, which, as the vital forces lessen, changes to a faded 
yellowish tint. 

Na?gcli and others affirm that there is always a central nucleus in the desmid, 
and probably do so with truth, although in many instances I have found it impos- 
sible to demonstrate its presence from the size and opaqueness of the frond, 
crowded with endochrome, &c. In a large number of cases, however, it is very 
apparent. 

As ordinarily viewed under the microscope the two most striking peculiarities 
presented by these little plants are the motion of the whole desmid in the water 
and the various movements exhibited within the fronds. The general movement 
is most apparent in the larger species, which exist free and distinct in the water, 
especially in the boat-shape closteria. It mostly consists of a steady, stately, 
slow onward movement, with sometimes backward oscillations. By virtue of it, 
desmids in a bottle will often congregate in such positions as are most exposed to 
light. There have been various theories advanced as to the cause of this motion. 
Ehrenberg believed that he had found foot-like processes protruding from the end 
of the frond and giving the motile power. Others, such as Rev. Mr. Osborne and 
Mr. Jabez Hogg, have attributed the movements to the presence of cilia, but I 
think have failed so entirely to establish this that their views are more than pro- 
blematical. That the motion is due to vital actions, taking place especially under 
the action of light, is as much as can be at present affirmed with any certainty, though 
it is probable that the immediate agents are endosmotic currents of gas or water. 

The movements of the contents within the cells are chiefly of two kinds. • Tak- 
ing Closterium lunula as an illustrative example, there will be found on ex- 
amination with an |th objective, a narrow, very transparent, and therefore 
often not very apparent layer or zone lying immediately within the cell- 
wall, between it and tlie endochrome, and dipping inward in the middle of the 
frond so as to communicate with the nucleus. In this zone are protoplasm, 
watery fluid, and scattered granules. In the ends of the fronds the difi'erent por- 
tions of this zone, meeting and widening, fill np the whole of the cavity, and within 
the space thus occupied by them, there is a globular, sharply defined, still more 
transparent vacuole.' This, some have thought to be a closed sac, with a distinct 
wall, but it seems really to be a vacuole lying in the midst of the inner protoplasm, 
which with a few granules occupies more or less completely the transparent zone 
already described. Sometimes the chlorophyl encroaches upon this zone at the 
ends so as to more or less completely surround the vacuole, within which are always 
found watery fluid and granules. In the protoplasmic zone and its vacuole active 
movements are probably always present during active life. Streams of protoplasnt 
appear to be constantly passing to and fro between the nucleus and the ends of 



FRESn-WATER A L G .E OF THE UNITED STATES. 103 

the cell, along the outer zone, and granules can be always seen passing backwards 
and forwards with an unsteady motion. 

When the streams of protoplasm are setting very actively from the centre to- 
wards one end, there will often be an accumulation of the protoplasm there, and a 
consequent decided lessening in the size of the vacuole, which Avill again expand 
as the return currents arouse themselves. Within the vacuoles are seen more 
or less numerous smaller or larger granules in active busy motion, swarming over 
and about one another with an unsteady hurrying to and fro. 

A form of motion, similar in appearance to this, but probably of different signi- 
ficance, is seen in most desmids when in an unhealthy feeble condition. I 
have seen it most marked in Cosviarium margaritaceum. In such fronds the endo- 
chrome has lost its deep green color, and become shrunken, and lying within it is 
a great space containing myriads of minute blackish particles swarming about 
actively. This peculiar state and appearance is by no means confined to the 
desmids, for I have seen it very highly developed both in species of Spirogijra and 
(Edogonium. It appears to be connected with decay. Is it possible tliat these 
minute particles are foreign to the plant, vibrionic in nature] 

In regard to the nature of the movements seen within a healthy desmid, some 
have viewed them as exceedingly mysterious, the result of the presence of 
cilia, &c. ; but these views have been so thoroughly exploded that it is scarcely 
necessary even to mention them here. The movements are, in truth, precisely 
parallel to the so-called cyclosis of the higher plants. Protoplasmic germinal mat- 
ter, wherever it exists, be it in animal or vegetable, has as one of its distinguish- 
ing characters the power of active, spontaneous, apparently causeless movements, 
and it is simply the carrying out of this power or attribute which has attracted so 
much attention in the desmids, because it is in them so readily seen. 

There are, in this family, two distinct methods in which the species are multiplied 
one with, the other without, the intervention of anything like sexuality. The 
non-sexual method of increase is really a modification of an ordinary vegetative 
process, a peculiar cell multiplication by division. In such fronds as tliose of the 
genus Cosmarium, which are composed of two evident halves connected by a 
longer or shorter isthmus, the first step in the process is an elongation of this neck. 
In a very short time there appears around the centre of this a constriction, and I 
believe an actual rupture of the outer coat. By this time a new wall has formed 
inside each Jialf of the isthmus, and stretches also across its cavity, forming witli 
its fellow a double partition wall, separating the two halves of the old frond. 
Rapid growth of the newly formed parts now takes place, the central ends become 
more and more bulging as they enlarge, and in a little time two miniature lobules 
have shaped themselves at the position of the old isthmus. These are at first 
small, colorless, and destitute of all markings, looking, as Mr. Ealfs says, like con- 
densed gelatine. They, however, rapidly increase in size and firmness, their con- 
tents assuming a green color and their walls taking on the peculiar markings of 
the species. At last, the parts thus formed having assumed the shape and appear- 
ance of the original lobules, the two fronds, which have been developed out of one, 
separate, mostly before the new semicells have acquired their full size. 



104 FRESH -WATERALG.E OF THE UNITED STATES. 

AMiat part the nucleus has in the process just described I have never actually 
demonstrated, but have little doubt but that it undergoes a division in the very 
commencement, so that the new nucleus of each secondary frond is formed out of 
one-luilf of the old one. 

In proportion as the form of the desniid becomes simpler, so do the peculiarities 
of its cell multiplication become less. In those species which are simple cylindri- 
cal cells, there appears to be nothing peculiar in the method of dividing, which, 
however, always takes place through the centre of the cell, and subsequent growth 
occurs, generally, only in the newly formed part. 

True sexual reproduction apparently does not take place as freely in this family 
as the former process, for whilst I have seen hundreds of cells undergoing the 
latter, it has not been my good fortune to meet with conjugating specimens on 
more than two or three occasions. 

The process has, however, been studied very closely by De Bary, Braun, Hof- 
meister, and others, and appears to consist generally in a rupture of the outer wall 
of two cells and the protrusion of delicate processes from an inner, often newly 
formed coat, with subsequent union of these, and consequently of the two cells, 
and afterwards a condensation of the contents in the enlarged connecting passage. 
The connecting passage between the fronds is really a sporangium in which the 
spore is perfected, the contents of the cells finally condensing it into a firm globe 
and secreting around themselves a thick coat. 

The after-history of this spore has been very successfully studied by M. Hof- 
meister, whose observations were made upon Cos7nar!uni teiraojihiJialmum, which. 
he watched conjugating and forming a sort of resting spore which was perfected 
early in the month of July. This Avas composed of a thick outer coat and green 
endochrome lying within as a distinct ball, nowhere in contact with the invest- 
ing membranes. In three Aveeks' time this chloroi)hyllous protoplasm had divided 
into ellipsoidal masses, or primordial cells, which soon surrounded themselves Avith 
cellulose Avails and became distinct free cells in the granular fluid Avhich filled the 
cavity of the original spore. In August, each of these masses Avas divided into two 
and in the month of September the process was repeated, so that out of the original 
endochrome eight strongly flattened primordial cells Avere produced. Division in 
some specimens ceased here, and in others took place once more, so that by the fol- 
lowing spring all of the living Sporangia contained eight or sixteen green daughter- 
cells, each of them discoid in outline Avith a strongly marked central notch. 
These daughter-cells Averc finally set free by the solution of the spore Avail, as Cos- 
maria of minute size, but agreeing in all other characters Avith the specific form to 
which they belonged. 

According to Braun, in the larger, more or less lunate Closteria, conjugation 
occurs in the folloAving method : Two fronds approach one another in such a Avay 
that they lie back to back. In the middle of each of them, there then appears an 
annular line or trench reaching through the cell Avail, and accompanied by a dis- 
tinct separation of the endochrome into tAvo halves. Whilst these changes have 
been progressing there has also formed a noAv double Avail at the position of the 
trench, so that out of the two Closferia two pairs of separate equal cells have been 



FRESH-WATER A L G .E OP THE UNITED STATES. 105 

formed. Near to the larger or central end of each of these now appears a pouting 
transparent nipple-like process. The corresponding opposing processes enlarging 
and meeting coalesce, so that the upper half of one closterium, in the form of a 
daughter-cell, is finally united with the upper half of the other closterium, and the 
two lower halves are also joined together. Thus from a single pair of fronds arise 
two conjugating pairs of cells, and finally two sporangia, in each of which a spore 
is perfected. 

This process does not seem, however, to be universal amidst the Closteria, for 
in many, if not all, of the smaller species, a pair of fronds produces a single spo- 
rangium. 

In the genus Palmogloea, in which I have had an opportunity to study the devel- 
opment of the spores, the process closely simulates that seen in certain of the 
Spirogyra. The contents of the cells first became broken up and confused, and 
almost simultaneoijsly the nucleus disappeared (fig. 4, pi. 11) the cells became 
swollen at one side and slightly bent backward so as to form jutting processes, 
which meeting grew together, became confluent and developed into a sporangium 
much larger than cither of the parent cells. Into this sporangium the contents of 
the latter passed and soon became converted into a thick-walled spore (fig. 00, pi. 
00) often completely filling the cavity, and apparently with its wall adherent to that 
of the latter. 

Genus PALMOGLCEA, Ktz. (1843). 

Cellulse oblongae, ellipticiB vel cylindricas, utroque polo rotundatae, medio non constricte, plerum(|ue 
in muco gelatinoso nidulantes, liberae, singulse vel in familias consociatse, lamina eliloropbyllaeea 
aAili vel exeentrica, state provecta medio constricta, denique divisa prroditJE. (R.) 

Syn. — Mesolaenium, NjEOELI. 

Cell oblong, elliptical or cylindrical, rounded at each end, not constricted in the middle, mostly 
swimming in a gelatinous mucus, free, single or associated in families, chlorophyl lamina axillary 
or cxcentric, in the early state constricted, and at length divided in the middle 

Remarks. — The above diagnosis of the genus is that given by Prof. Rabenhorst, 
and agrees essentially with that of Dc Bary, Na^gcli, &c. In the species herein 
described however, the axillary lamina of chlorophyl were not so pronounced, for 
the green coloring matter seemed often to surround the cavity of the cell, and in 
other specimens was broken up and diff"used through it. 

P. clepsydra, Wood. 

P. sasicola et bryophila, in gelatina achroa interdum dilute viride nidulans ; cellulis cylindricis, 
cum polls obtuse truucato-rotundatis, diaraetro 2-3 plo longioribus ; lamina chloropbyllacea 
axili, plernmquc indistincte, s»pe nulla; plasmate dilute viride; nucleo plerumque distincto; 
zygosporis subfuscis aut subglobosis aut enormiter in clepsydrffi forma; membraua externa 
enormiter excavata et sulcata. 

Diam.—^\%^". 

Syn. — P. clepsydra, Wood, Prodromus, Proc. Amer. Philosophical Soc. 1869. 

Hab. — In rupibus et in muscis irroratis ad Chelten Hills, prope Philadelphia. 

14 June, 1872. 



106 FRESH-WATER A L G .E OF THE U i\ 1 T E D STATES. 

P. liviiij^ on rocks and mosses, swimming in a transparent, sometimes light-green jelly; cells 
obtusily truncated, rounded at the ends, 2-3 times longer than broad ; chlorophyl lamina 
axillary, mostly indistinct, often wanting; endochrome light-greeu ; nucleus generally distinct; 
zygospore subfuseous, either globose or of an irregular form, somewhat resembling that of an 
hour-glass ; external coat irregularly excavated and sulcate. 

Remarhs. — This species was found along the North Pennsylvania Railroad, near 
Chelten Hills, growing amid mosses on tlie rocky jiittings over which the water 
was dripping. It occurs as a rather firm, transparent jelly, mostly of a light 
greenish tint, in whicli the cells are often placed quite thickly. They are cylin- 
drical, mostly straight, but sometimes slightly curved, and often completely filled 
with a light greenish endochrome. The central lamina is irregular, and mostly 
not at all pronounced. In some cells the endochrome is much broken up, so that 
the interior is filled with little green masses with light spaces between them. In 
these cells the nucleus is generally not perceptible, whilst in the others it is very 
weU marked. The zygospore is often globular, sometimes it is irregularly elliptical, 
with a constriction in the centre, so as to give it somewhat of an hour-glass shape. 
The outer coat mostly fits pretty closely on the inner contents, and is very often 
distinctly marked with little pits, some round, some irregular in shape; in otlier 
cases, instead of being thus pitted, the spores seem to be marked with deep curved 
furrows. 

Fig. 4, pi. 11, represents this plant in different stages of growth. (See Expla- 
nation of Plates.) 

Genus PENIUM, Breb. (1848.) 

Cellulae cylindricse vel fusiformes, rectoe, ntroque polo rotundatoe vcl trnncato-rotundatfe (nee emar- 
gioatie nee excisas), medio saspius constrictte. Lamina chlorophyllaceaaxilis, ex transverse conspccta 
radiatim-divcrgens, radii scepe furcati, granula amylacca plerumque longitudinaliter seriata includens. 
Individua in aqua libere natantia, singula, sparsa vel in massa gelatinosa consociata. Cellulae mem- 
brana tevis vel granulata, achroa vel fuscesceus vel rubicunda, saepius longitudinaliter striata. (R.) 

Syn. — Ndriiivi, Nveqeli. 

CylindrocystLs, Mengh. 
Closlerium, jMrlim, Ehrenberg. 

Cells cylindrical or fusiform, straight, rounded at each end, or truncately rounded (not emarginate 
or excised), medianly often constricted. Chlorophyl lamina axillary, when seen transversely radi- 
ately divergent, arms often forked, and containing starch granules, mostly longitudinally striate. 
Individuals swimming free in the water, scattered and single, or associated in gelatinous masses. 
Cell membranes smooth or granulate, transparent or fuscous or reddish, often longitudinally striate. 

a. Lamina chlorophyllacea peripherice lobala vel radiatim expansa. 
a. Chlorophyl lamina, lobate on the periphery or radiately exjmnded. 

P.Dig;itii!!i, (Ehrb.) Breb. 

P. cellulis ovato-cylindricis, diametro 3-5 plo longioribus, utroqne polo parum attenuatis, snb- 

truncato-rotundatis ; laminis chlorophyllaceis peripherice lobatis, medio interruptis. 
Diam.—jl^^" = .00173"— 7|§/ = .0029". 

Syn.— P. Digitus, (Ehrb.) Br£b. Rabenhorst, Flora Enrop. Algar., Sect. III. p. 118. 
Cells ovately cylindrical, 3-5 times as long as broad, at each end slightly attenuate, snbtrun- 

cately rounded; chlorophyl lamina lobate on the periphery, interrupted in the middle. 



FRESn-WATER A L G .E OF THE UNITED STATES. 107 

Remarks. — This species is probably widely diffused through the temperate por- 
tions of North America. I have found it abundantly near Philadelphia, as well as 
among the AUcghanies, and have received specimens from Dr. Lewis, collected in 
Saco Lake, Northern New York ; Prof. Bailey also notes it as occurring in Georgia. 
There is one form of it which resembles somewhat in outline the modem coffin, 
one end being much broader and much more rapidly narrowed than the other. 
There is no distinct vacuole at the end, at least in any specimen I remember to 
have seen, although frequently large numbers of moving granules can be detected 
in that portion of the frond. 

Fig. 6, pi. 20, represents the outline of a frond of this species. 

P. laiuelloi^uni, Breb. 

P. cellulis oblongo- vel fusiformi-cylindricis, diametro 5-6 plo longioribus, medio sa;pe leviter 
coustrictis, utroque polo magis atteuuatis, obtuso rotundatis. (R.) 

Kiam— 0023"— 0.0029". (R.) 

Syn. — P. lamellosum, Breb. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 118. 

Hab. — Rhode Island. (Olney) Thwaites. 

Cells oblong or fusiform cylindrical, 5-6 times longer than broad, often slightly constricted in 
the centre, more attenuate at the ends, obtusely rounded. 

Remarhs. — I have never recognized this species, but it is one of those sent over 
by Mr. Olney, and identified by Prof. Thwaites. 

b. Lamina chlorophyllacea integer rinia. 
b. Chloropli ijl lamina entire. 

* CeUulae in medio plus minus constrictae. 

* Cells more or less constricted in the middle. 

P. mar^ai'itacenin, Ehrb. 

P. elongato cyliudricum, diametro 8-9 plo longius, medio plernmqne leviter constrictum, utroque 
polo rotundato-truncatum ; cellulae uiembraua noduiis seriatis quasi margaritacea ; locellus 
in medio (circiter) utriusque cruris corpusculis mobilibus in more Closteriorum repietus. (R.) 

Diam.— 0.00098"— 0.0011". (R.) 

Eah. — Rhode Island. (Olney) Thwaites ; Bailey. Florida. Bailey. 

Elongate cylindrical, 8-9 times longer than broad, in the centre generally slightly constricted, 
at each end roundly truncate ; membrane of the cells somewhat pearly with seriate granules ; 
vacuole about in the centre of each crus, filled with moving granules, as in closterium. 

Remarks. — I have not seen this desmid, but it is in Prof. Bailey's list; it was 
also among those sent by Mr. Olney to Prof. Thwaites. 

P. miniitiini, Cleve. 

P. cylindricum, gracile, diametro 5-7 plo longius, Iseve, ad polos obtusissimos (latissime rotun- 
datos) parum attenuatum, medio leviter constrictum. (R.) Species mihi ignota. 

i>jam.— 0.00044"— 0.000G3". (R.) 

Syn. — Docidium viinutum, R.^lf's British Desmid. 

P. minulum, Cleve. Rabenuorst, Flora Europ. Algarum, Sect. III. p. 122. 



108 FRESH-WATER ALG^ OP TEE UNITED STATES. 

Hab.—Souih Carolina; Florida. Bailey. Rhode Island. (S. T. Oluey) Thwaites. 

Froud .slender, .snture nut i)riiminent; segments four to six times longer than broad, somewhat 
tapering, inlialiou obsolete, sides straight, ends entire; e. f. without puncture. L. ^jj''; 
ii- izW- (Areher.) 

b. Cellulx in medio non constrictae. 

b. Cells not constricted in the middle. 

P. interriiptum, Breb. 

"P. eellulis late lineari-cylindricis, diametro 5-C plo longioribus, utroque polo subito euneato- 
acutatis, apicibus obtuso-rotundatis; laminis chlorophjllaceis longitudinalibus saturate viridi- 
bus, oetate provccta fasciis transversis tribus pallidis iuterruptis. " (R.) Species mihi ignota. 

X>iani.-0.0()147"— 0.001(7". (R.) 

Sijn. — P. inlerruptum, Bueb. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 119. 

Hab. — In fossis. South Carolina, prope Grahamsville. Prof. Bailey. 

Cells broadly linearly cylindrical, 5-6 times longer than broad, at each end suddenly cuneately 
sharpened, the apex obtusely rounded ; longitudinal chlorophyl lamina deep green, in ad- 
vanced age interrupted by three transverse pale fascia. 

P. Jeiiiieri, Ralfs. 

P. ab P. Brebissonii vix discernendum, eellulis cylindricis, utroque polo rotundatis, Isevibus, dia- 
metro 2i-5 plo longioribus ; zygosporis plerumque globosis, membrana fuscesceute subgranu- 
lata. (R.) Species mihi ignota. 

Z)mwi.—0.0005T"— 0.0006". (R.) 

Syn. — P. Jcnneri, R.alfs. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 120. 

Bab. — In fossis, Florida. Prof Bailey. 

Scarcely distinguishable from P. Brel)issonii, cells cylindrical, rounded at each end, smooth, 
2^-5 times longer than broad ; zygospores Tuostly globose, membrane somewhat fuscous, sub- 
granulate. 

P. Brebissonii, (Mengh.) Ralfs. 

P. in massa mucosa indefinite expansa saepe cum algis alteris intermixtis; eellulis perfecte 
cylindricis, interdum nonnihil curvatis sed pleruraque rectis, diametro 2i-4 plo longioribus, 
utroque polo late rotundatis, in medio non coustrictis ; " zygosporis angularibus vel rotundatis, 
membrana fuscente, .subtiliter granulata." 

.Viam.—jj%^" = .00066". 

Syn. — P. Brebissonii, (Mengh.) Ralfs. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 
120. 

Hob. — In fossis. South Carolina. (Prof Ravenel.) 

In an indefinitely expanded mucous mass, intermixed with other algte ; cells perfectly cylindri- 
cal, sometimes slightly curved, but generally straight, at each end broadly rounded, not con- 
stricted in the middle ; " zygospores angular or rounded, membrane fuscous, finely granu- 
late." 

Remarks. — Among the numerous desmids which I have received from Prof. 
Ravenel are some which, I think, must be referred to P. Brebissonii, although they 
do not nearly equal the size of tlic European form, nor even the diameter given 
above, which is almost the lowest limit of the mature foreign plant. I believe, 
however, Prof Ravencl's specimens are immature, 



F R E S II -W A T E R A L G yE OF THE UX T EI D ST AT E S. 109 

Mr. Ralfs' description of the conjugation is as follows : The process of tlio con- 
jugation in this species diifers from that in the rest of this genus; for, as in ////«- 
lotheca (lissiliens, the conjugation cells enter into the formation of the containing 
cell and are permanently attached to the sporangium, instead of being detached, 
as commonly happens, in the Desmids. The sporangium is at first cruciform, then 
quadrate, and finally orbicular. 

P. closterioides, Ralfs. 

P. cellulis anguste lauceolatis, diametro inaximo 5-6 plo longioribus, a medio in apices subtran- 
cato-rotundatos sensim attenuatis; laniinis chlorophyll, saturate viridibus, medio fascia trans- 
versa pallida interruptis. (R.) Species mihi ignota. 

Dmw!.— 0.00159"— 0.00175". (R.) 

Syn. — P. closterioides, Ralfs. Rabeniiorst, Flora Europ. Algarum, Sect. III. p. 121. 

Hab. — Prope Grahamsville, South Carolina. Prof. Bailey. 

Cells narrowly lanceolate, 5-6 times longer than the greatest diameter, sensibly attenuate from 
the middle into the subtruucate apices; chloruphyl lamina deep green, interrupted by a median 
pale band. 

Genus CLOSTERIUM, Nitsch. 

Cellulae interdum cylindricae sed saepius fusiformes et utroque polo attennatas, plus minus lunula- 
tim curvatfe, in medio hand constrictae sed stria transversa uniea vel 2-5 impresste. Cytioderma 
tenue, sat firmum, \seve vel plus minus distincte striatum et interdum longitudinaliter costatum. 
Cytioplasma chlorophyllosa plerumque in lamiuis longitudinalibus disposita, et sub cellulae polis 
loeello achroo, plerumque globoso et corpusculis plus minus numerosis se vivide movcntibus inipjeto 
iustructa. 

Cells sometimes cylindrical, but more often fusiform and attenuate at each end, more or less 
Innately curved, in the centre not constricted but marked with from 1-5 transverse striaj. Cytiodcrm 
tliin, moderately firm, smooth or more or less distinctly striate, and sometimes longitudinally costate. 
Chlorophyllous cytioplasra mostly arranged in longitudinal lamina, and furnished at each end with a 
clear space, which is mostly globose, and contains more or less numerous actively moving cori)uscles. 

a. Zijgosporae globosx, rarissime angulares ; cellulae crura aut non aut minus producfa. 
a. Zygospores globose, very rarely angular; crura of the cells not at all, or only slightly, pro- 
duced. 

1. Cellulse cylindricse, ad utrumque polum vix vel paulluvi attenuate, rectae vel leviler curvalae, 
apic'ibus rotundatis vel truncalis. 

1. Cells cylindrical, not at all or but slightly attenuated at the ends, straight or slightly 
curved, the apex rounded or truncate. 

C striolatuin, Ehrb. 

C. anguste lanccolato-fusiforme, leviter arcnatnm, 8-12 plo fere longius qnam latum, utroqne 
polo paulum sensimqne attenuatum, apicibus truncatis saepo fuscescentibus ; mcmbrana dis- 
tinctissime striata, vacuata fusceseente; vesiculis chlorophyllaceis 5-7 (in quoque crure) ; 
loeello apices versus sito, submagno, corpuscula 12-20 includentc. (R.) 

Dia7n._J5"— 5V' = 0.00152"— 0.00187". (R.) 

Syn. — C. striolatum, Ehrb. Rabenhorst, Flora Europ. Algarum, Sect III. p. 125. 

Hab. — In aquis quietis. Centre County, Pennsylvania. Wood. Saeo Pond, New Ilampshire. 

(Lewis) . 
Narrowly lanceolately-fusiform, slightly bent, 8-12 times longer than broad, .sensibly attenuated 



110 FRESH-W^ATER A L G il'] OF THE UNITED STATES. 

at the ends, which are truncate and often somewhat fuscous ; membrane very distinctly striate, 
when empty somewhat fuscous; chlorophy! globules 5-7 (in each limb); vacuole placed in 
the beut iii)ex, moderately large, including 12-20 corpuscles. 

Remarks. — The measurements given are those of Prof. Rabenhorst. Our Ame- 
rican forms agree well with them. 

C. aiisii!!>lafiiiii, Ktz. 

C. gracile, sublineare, diametro 16-18 plo longius, ad polos levissimo attenuatum, apicibus late 
truncatis; costis longitudinalibus paullulum prominulis 4-5, iuterstitiis eirciter jj^'" latis; 
vesiculis chlorophyllaceis in quoque cruro 6-7 ; locello ab apice subremoto mediocri, corpus- 
culis 12-20 impleto. (R.) 

Ztiam.—T^T"— A" = 0-00081"— 0.0010". (R.) 

Syn. — C. angustatum, Ktz. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 126. 

Hab. — In aquis quietis, prope Philadelphia, Peunsylvauia. Wood. Rhode Island. Bailey. 
New Hampshire. (Lewis) 

C. slender, snblinear, 16-18 times longer than broad, very slightly attenuate at the ends, which 
are broadly truncate ; with from 4-5 somewhat prominent longitudinal ribs, the interstices 
about 555"' broad ; chlorophyl globules in each limb G-7 ; vesiclo subremoto from the apex, 
moderate, containing from 12-20 corpuscles. 

C. jiincidiini, Ralfs. 

C. elongatum, anguste lineare, diametro 20-35 plo longins, leviter arcuatura, utroque polo vix 
attenuatum ; apicibus truncatis ; cy tiodermate luteolo, interdum longitudinaliter striate. 

Diam.—^-i^-s" = .0004". 

Syn. — C. juncidiim, Ralfs. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 127. 

Hab. — In fossis. South Carolina. (Ravenel) In lacu Saeo, New Hampshire. (Lewis) 

Elongate, narrowly linear, 20-35 longer than broad, slightly bent, scarcely narrowed at the 
ends ; apices truncate ; cytioderm yellowish-brown, sometimes longitudinally striate. 

Remarks. — I am indebted to Prof. Ravenel for specimens of this species, by 
whom they were found on the slimy surface of a half dried-up ditch, associated 
with numerous other desraids. The specimens are all smaller than the measure- 
ments of Rabenhorst, but much larger than those given by Mr. Ralfs. None of 
the plants have any chlorophyl granules — a circumstance probably simply depen- 
dent upon the stage of their development. The longitudinal stria; are in none of 
the specimens very distinct, and in many cannot be demonstrated. 

Since writing the above I have seen specimens collected by Dr. Lewis in " Saco 
Pond," near the Crawford House, New Hampshire. 

Mr. Archer (Pritchard's Infus., p. 749) lays stress upon the fronds being straight 
in the middle, with the ends curved downwards ; but I have seen numerous speci- 
mens in which the curve was through the whole lensth. 

Fig. 2o, pi. 12, represents one of the specimens collected by Prof. Ravenel in 
South Carolina. 

2. Cellulae cylindricx, dorso pZws minus convexw, venire subplanw, nunquam ventricoso 
— injlalx. ' 



FRESH-WATER ALG^ OF THE UNITED STATES. HI 

2. Cells cylindrical, with the dorsum more or less convex, the belli/ straightish, 7iever ventri- 
cosely inflated. 

C lilinilla, (MiJLLEK) Ehrb. 

C. permagrium, sublseve ^striae subtilissimse vel indistinctae), semilunare, dorso alte convesum, 
ventre subplanura, apicibus attenuatis rotundatis ; vesiculis chlorophyllaceis numerosis spar- 
sis; locello distiucto subapicali eorpuscula uuraerosa includente. (R.) 

Z»ia?7i.— jV'— jV" = 0- 00032"— 0.0045". (R.) 

Syn. — G. Lunula, (Muller,) Ehrb. Rabenoorst, Flora Europ. Algaruni, Sect. III. p. 127. 

Bob. — South Carolina, Georgia, Florida. Prof. Bailey. Pennsylvania. Wood. 

Very large, smoothish (striae very fine or indistinct), semilunar, dorsum strongly convex, belly 
straightish, the ends attenuate and rounded; chloropliyl globules numerous, scattered; vesi- 
cle distinct, subapical, including numerous corpuscles. 

C acerosuin, (Scurank) Ehrb. 
( Var. nov. maxiniuiii.) 

C. lineare-fusiforme, sub-rectum aut leve curvatum, ntroque fine sensim et paullulum atten- 
uatuui, diametro 16-24 plo longiore; apicibus angustissime truncatis, achrois; meml)raiia 
hand striata; vesiculis chlorophyllaceis 11-14 in quoque crure, in serie axilli simplici collo- 
catis; locello apicali parvo, eorpuscula uumerosa includente; zygosporis globosis. 

J»ia?n.— Transv. max. -^11-^" =■■ .OOlt" ; zygosp. ^H^" = .0027". 

Syn. — C. acerosum, (Schrank) Ehrb. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 
128. 

Hah. — Pennsylvania; Wood. South Carolina, Georgia, Florida; Bailey. 

Linear, fusiform, straightish, or slightly curved, at each end sensibly little by little attenuate, 
15-24 times longer than broad; apices narrowly truncate, transparent; membrane not striate; 
chlorophyl globules 11-14 in each limb placed in a simple axillary series; apical vesicle 
small, containing numerous corpuscles ; zygospores globose. 

Remarhs. — The desmid, described above, was found in New Jersey, near Cam- 
den. It differs from the typical form of C. acerosum in its size, proportionate 
len<Tth to breadth, -and in not being striate. The European '■'■ forma major" 
(Rabenh.) appears, however, to exxeed it in transverse diameter, and, according 
to some authors, certain fronds of the species are not striate, and all authorities 
agree that at times the striae are exceedingly delicate. For these reasons, I think, 
our American form must be regarded simply as a variety. As far as can be judged 
from the rude figure, it is this species which Prof Bailey identifies as C. ienue, 
Ktz., in Silliman's Journal for 1841. 

Fig. 5, and 5 a, pi. 11, represent this species magnified 250 diameters; 5 b 
represents the sporangium with portions of the dead fertile fronds still attached. 

C. areolatiiui, Wood, (sp. nov.) 

C. fuslforme, subrectum vel notfnihil curvatum, lateris ventralis medio ssepe paullulum concavum, 
diametro 9-10 plo longius, utrinque niodice attenuatum; apicibus truncato-rotundatis ; mem- 
brana crassa, et firma, rubido-brunnea, profunde distante striata, et minutissime sed distincte 
granulata vel areolata; suturis medianis distinctissimis 4-10. 

Diam. — 0.0024". 

Hob. — In aquis puris quietis ; Northumberland Co., Pennsylvania. 



112 FRESHWATER A L G vE OF THE UNITED STATES 

Fusiform, stfixi.irlilish, or very slightly curved, the ventral side often a little concave in the 
middle, 1)-10 times longer than broad, moderately attenuated at each end; the apices trun- 
cately rounded ; celi-menilirane reddish-brown, thick and firm, distantly profoundly striate, 
and very minutely but distinctly granulate or areolate; median sutures very distinct, 
4-10 ill number. 

Remarks. — I found this species growing in a quiet pool of pure water, in a wild, 
d(H'ply wooded ravine, near Danville, Central Pennsylvania. It was iu great 
abundance, forming a translucent greenish jelly, one or two gills of Avhich might 
have been readily gathered. Unfortunately, I had no microscope with me and 
cannot, therefore, determine at all as to the arrangement of the endochrome, the 
carbolic acid, used as preservative, having entirely disarranged this by the time I 
got the fronds upon a slide. The empty frond is of a reddish-brown color. Tlie 
membrane is (piitc thick and firm, and is marked with very prominent broad striae 
or grooves. In a number of cases I have counted these and always found nine 
present upon one face of the frond. There are also upon the surface numerous 
minute markings not fairly visible with a lower power than a ^^th. objective. 
Under this glass tliey appear as minute punctations. An eighth resolves them 
into granules mostly of an oblong shape, arranged more or less regularly in longi- 
tudinal rows. Very generally, each side of the stria or groove has a close row of 
larger and more distinct granules forming a sort of border to it. In truth, the 
surface of the frond is covered with broad longitudinal bands of these granidcs, 
and the narrow smooth spaces between them constitute the stria spoken of This 
species is very closely allied to C. turgidum, Ehrb., agreeing pretty well with it in 
general outline and size. I think, however, the peculiar markings upon the 
membrane are sufficient to separate it, and do not doubt that if fresh specimens 
were at hand, differences would be found to exist also in the arrangement of the 
cell-contents. The turning up of the ends, generally so marked in C. turgidum, 
is mostly entirely absent in this species, rarely there is some tendency to it. 

Fig. 6, pi. 11, represents in outline a frond magnified 160 diameters; Fig. 6 a, 
the end of an empty cell, magnified 1375 diameters; the color of this is, perhaps, 
a little too dark. 

C lineatiiin, Ehrb. 

C. valde elongatum, gracile, quater vieies-tricies longius qnam latum, distinete striatum, e 
medio recto cyliudrico utrinque valde attenuatum, apices versus leviter incurvum, ol)tiiso- 
truncatum; vesiculis chlorophyllaceis in quoque crure 20-21, in seriem unicam axilem dis- 
tributis; locello parvo, ab apicc remoto, corpusculis 10-12 impleto. (R.) 

ij/am.— 55V' = .0015". 

Syn.— C. lincalum, Ehrb. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 130. 

Hub. — Pennsylvania, Wood. 

Very much elongate, slender, distinctly striate, from the centre straight and cylindrical, at each 
end very greatly attenuate, apex bent, slightly incurved, obtusely truncate; chlorophyl glo- 
bules 20-21 in each limb, placed in a simple axillary series; vacuole small, remote from the 
ape.x, containing from 10-12 corpuscles. 

Remarks.— ']:h.e American forms agree well with the above description ; some 



FRESH-WATER ALG^ OP THE UNITED STATES. 113 

of them, however, are a little more curved in the central portion than it would 
imply. 

Fig. 1, pi. 12, is a drawing of an American plant, magnified 160 diameters. 

CCiicuiuis, Ehrb. 

C. oblougum, turgidum, leviter curvum, laeve, diametro 4-7 plo longius, apicibus obtusis. (R.) 

Syn. — C.Cucumis, Eiirenberq, Verbreit. b. 28, IV. F. 28. Rabenhorst, Flora Europ. Alga- 
rum, Sect. III. p^38. 

■*' Hab. — Xew York ; Ehrenberg. 

Oblong, turgid, slightly curved, smooth, 4-7 times longer than broad, the apex obtuse. 

Remarhs. — I have no knowledge of this species other than that in the above 
short description, which has been copied from Rabenhorst's works. 

3. Celliilse semilunares, plerumque magis curvatx quam in Sect. 1 et 2, ventre semper linnidse, 
ventricoso-infiatae. 

3. Cells semilunar, mostly more curved than in Sect. 1 and 2, with the belly always tumid, 

ventricosely inflated. 

C Ehrenbei'gii, Mengh. 

C. fusoideo-semilunare, ventre iuflato, ceterum ut in C. Lunula. (R.) 

Diam.—Lau jif/ = .0029". Long. ,1^/ = .0042." 

Syn. — G. Ehrenbergii, M-EtiQU. Rabexuorst, Flora Europ. Sect. III. p. 131. 

Hab. — Prope Philadelphia. 

" Frond large, stout, about five or six times as long as broad, lunately curved, extremities taper- 
ing; upper margin very convex, lower concave with a cons2}icuous central inflation; ends 
broadly rounded ; large granules, numerous, scattered ; fillets several ; e. f. colorless, without 
striae, central suture not evident. Sporangia orbicular, smooth, placed between the but- 
slighlly-colinected empty conjugated fronds, the endochrome during the process of conjuga- 
tion emerging from the opened apex of a short conical extension from each under side of each 
younger segment (or shorter cone) of each pair of recently divided fronds, the conjugating 
fronds being produced immediately previously by the self-division of a pair of old fronds — two 
sporangia being thus the ultimate produce of the two original fronds. L. j'g" ; B. jjg". 
Archer." Pritchard's Infusoria, p. 748. 

Remark. — Fig. 2, pi. 12, represents a plant of this species magnified 160 dia- 
meters. 

C. moniliferiim, (Bory) Ehrb. 

C. semilunare, plus minus curvatum, diametro maximo 6-9 plo longius, ventre inflato, utroque 
polo sensim attenuatum, apicibus achrois obtusis, vesiculis chlorophyllaceis in serie unica 
longitudinali axili dispositis, in quoque crure 7-10; locello apicali submagno, corpuscula 
numerosa includente (corpusculum in quoque locello unicum mobile ellipsoideum, magnitudiue 
linese partem millesimam a;quans, cetera mobilia per totum corporis distributa observavit cl. 
Perty.) (R.) Species mihiignota. 

i)iam.— 0.0019"— 0.0022". (R.) 

Syn. — C. moniliferum, Rabenhorst, Flora Europ. Algarum, Sect. III. p. 131. 

Hab. — Georgia ; Rhode Island ; Bailey. 
15 June, 1872. 



lU I r. KSU-WATER ALG.E OF THE UNITED STATES. 

" Frond sniallci- tliaii V. Elircnbcrgii, stout, five or six limes as lon.!^ as broad, lunately curved, 
cxtreiiiilies tapering, uiijier margin convex, lower coucave, witli a central injlation, ends 
rounded; large grauules, conspicuous, in a single longitudinal series; e. f. colorless, without 
stria;, suture not evident. L. A"— bo"- K. sh"— ?Jf"- Archer." Pritchard's Infmorm, 
p. 748. 

C. Leiblesnii, Ktz. 

C. priore minus, seuiilunare, magis incurvum, ventre inflate, ad utrumque polum largius attenn- 
atuni, apicibus achrois acutis; vesiculis chloropliyll in quoqae crure 5-6, in serie simplici 
axillari dispositis; locello magno, apices versus sito, corpuscula numerosa iucludente. (11.) 

Diam.—^\l^". 

Syn.—G. Leihleiini, Kutzing. Rabeniiorst, Flora Europ. Algarum, Sect. III. p. 132. 

£a6.— Georgia; Rhode Island ; Bailey. Pennsylvania; Wood. 

" Frond somewhat stout, distance between the extremities six or eight times the breadth, 
crescent-shaped, much curved, rapidly attenuated, upper margin very convex, lower very con- 
cave, often with a slight central inflation; ends subacute ; large granules, in a single series; 
fillets few or indistinct; e. f. somewhat straw-colored, without strife; suture evident. Spo- 
rangium orbicular." Archer. 

Remarh. Fig. 6, pi. 12, represents this plant, magnified 260 diameters. 

4. Cellulse maxime curvalse, ventre non tmnidae. 
4. Cells most curved, the belly not tumid. 

C. Diniiac, Ehrb. 

C. anguste fusiforme, semilunare, utroque polo valde attenuatnra, apicibus subacntis ; cytioder. 
mate achroo (vel dilutissime umbriuo), striis subtilissiuiis medio interruptis praidito, in media 
parte striis transversalibus 3-5; vesiculis in quoque crure 6-7, in serie unica axili dispositis; 
laminis chlorophyllaceis pluribus, saepe flexuosis; locello indistincto, corpusculis pluribus 
yivide mobilibus. (R.) 

i)wm.— Lat. 75V' =-00053". Long, ^ff/ = .00082". 

Syn. — C. Dianse, EnRENBERG. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 133. 

Hah. — Georgia ; Florida ; Rhode Island ; Bailey. Pennsylvania ; Wood. 

Frond crescent-shaped, six or eight times as long as broad, much curved, rapidly attcnnated; 
upper margin very convex, lower very concave without a central inflation ; ends subacute 
with a very slight emargination at the upper outer extremity; large granules in a single 
series; empty frond, somewhat straw-colored, or faintly reddish, without striae, suture evident. 
(A.) 

Remarks. — Mr. Archer marks C. Venus, Ktz., as a doubtful synonym of this 
species ; not having Prof. Kiitzing's work at hand, I do not know whetlier G. 
Venus, Ktz. is really the following species or not. The two forms here hiown as G. 
Dianer, Ehrb. and C. Venus, Ktz. are, however, I think sufficiently distinguished. 

Fig. 4, pi. 12, represents this species of desmid. 

C. Yeniis, Ktz. 

C. parvura, plus minus gracile, semicirculare, oetiess-duodecies longins qnam latum, in apices 
subacutos ffiqualiter sensimque attenuatuin ; cytiodcrmate tenui.'^lffive ; laminis chlorophylla- 
ceis obliteratis ; vesiculis in quoque crure 3-4 ; locello distincto corpusculis 4-6 replete. (R.) 

Diam.— .0004". 



FRESII-WATER ALG.E OP THE UNITED STATES. 115 

Syn. — C. Venus, Kutzing. Rabenhoest, Flora Europ. Algarum, Sect. III. p. 134. 

Sab. — South Carolina. (Raveael.) 

Small, more or les.s slender, semicircular, eight to twelve times longer than broad, equall}' and 
very perceptibly attenuate at both apices; cytioderm thin, smooth; chloropliyllous lamina 
obliterated; vesicles in each crus 3-4; vacuole distinct, containing 4-C corpuscles. 

Remark. — Fig. 7, pi. 11, represents in outline a frond magnified 450 diameters. 

C. parTiiliim, N^g. 

C. parvuin, seniicireulare, medio non tumidum, gracile, angu.ste lanccolatura, sexies-octies lon- 
gius quam latum, apicibus acutis; cytiodcrniate tentii, lievLssinio, vacnato nonnunquam luteolo- 
fuscescente et subtiliter striato; vesiculis uuiseriatis, in quoque crure 2-4, varius 1-7 ; lamiuis 
chlorophyllaceis 4-5. (R.) 

Z»iam.— Max. 0.0002C"— .00062" (R.) (.0008" W.) 

Syn. — C. parvulum, N^geli. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 134. 

Bah. — Frope Philadelphia, Wood. 

Small, semicircular, not swollen in the middle, slender, narrowly lanceolate, six to eight times 
longer than broad, with the apices acute; cytioderm thin, very smooth, when empty some- 
what yellowish-fuscous and finely striate; vesicles uniseriate, in each crus 2-4, rarely I-T; 
chloroi)hyllous lamina 4-5. 

Bemarhs. — I have referred to this species a desmid which T have found about 
Philadelphia, and which agrees in all respects with the description of Prof. Itaben- 
horst except in attaining a larger size. 

Fig. 5, pi. 12, represents this plant magnified 450 diameters. 

C. Jennerii, Ralps. 

C. cylindraceo-fusiforme, serailunare, teve, utrinque modiee attenuatum, sexies-octies longius 
quara latum, apicibus obtuse rotnndatis; vesiculis in quoque crure 5-7, in serie unica axili 
dispositis; lamiuis chlorophyllaceis 2-3; locelio subaquali magno, corpusculis numerosis 
impleto. (R.) 

Z)m7«._0.00057". (R.) 

Syn. — C. Jennerii, Ralfs. Rabendorst, Flora Europ. Algarum, Sect. III. p. 134. 

Hah. — Rhode Island, Bailey. 

Frond small, distance between the extremities six or seven times the breadth, crescent-shaped, 
much curved, gradually tapering (sometimes with an obscure central constriction); upper 
margin very convex, lower very concave without a central inflation ; ends obtuse, rounded ; 
large granules in a single series; e. f. colorless without striae. L. ^J/'. R- 1735"- Archer. 
Pritchard's Infusoria. 

b. Zygospores plerumque quadrangulares, cellularum crura longc vel longissime producla, 

saepe setiformia. 
h. Zygospiores mostly quadrangular, crura of the cells greatly produced, often sctiform. 

C rostratiini. Ehrb. 

C. corpore lanceolato-fusiformi, utrinque valde et longe attenuato, leviter curvato, striato ; cor- 
nibus setaceis singulis corpus vis £e(|uantibus, saepius longe brevioribus ; cytiodermate dilute 
umbrino vel luteolo, dense striato : vesiculis uniseriatis, in quocpie erure 5-0; locelio oblongo, 
ssepius indistincto, corpusculis 12-15 vivide se moveutibus. (R.) 



116 FRESHWATER ALGJE OF THE UNITED STATES. 

Diam.—Q.OOOS". (0.0li09"-0.0016." R.) 

Sijn.—C. rostralum, Ehrenberg. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 135. 

Hab. In fossis, prope Philadelphia ; Wood. 

Bodv lanceolate-fusiform, at each end greatly and for a long distance attenuated, slightly curved, 
striate; crura setaceous and scarcely as long as the body and sometimes much shorter; eytio- 
derm li"-htor luteolous, densely striate, vesicles uniscriate, 5-6 in each crus ; vacuoles oblong, 
often indistinct, containing from 12-15 actively moving granules. 

Remark. Fig. 3, pi. 12, is a drawing of this species, magnified 260 diameters. 

C. setaceiini, Eiirb. 

C. corpore anguste lanceolato, recto vel subrecto, distincte striato, utrinque in rostrum setaceum, 
levissime incurvum, obtusura, longissirae porrecto; singulo rostro corpore 3-4 plo longiore; 
et vesiculis et locello indistinctis. (R.) 

Diam.—M&x. (plerumque) 0.0004"— 0.00044." (R.) 

Sijn. — C. setaceum, Ehrenberg, Flora Europ. Algarum, Sect. III. p. 136. 

Eab. — Stonington. (Lewis) Pennsylvania; Wood. Georgia; Florida; Providence, Rhode 
Island ; Bailey. 

Frond very slender, from twenty to twenty-five times as long as broad, narrow-lanceolate; 
upper ai\d loiuer margins nearly equally and but slightly convex; each e.xtreraity tapering 
into a very long and slender setaceous colorless beak, longer than the body, ultimately curved 
downwards, ends obtuse; e. f. colorless, striw close, faint, central suture solitary. Sporangium 
cruciform. L. txs "• ^ 53st "• Archer. Pritchard's Infusoria. 

CAmblyonema, Ehrb. 

C. filiforme, cylindricum, laeve, utroque fine parum attenuatum, apice rotundum. (R.) 

Syn. — C. lineatum, Ehrb. Bailey, American Journal of Science and Arts, 1841, p. 303. 

G. Amblyonema, Ehrb. Verbreit. p. 123. Rabenhorst, Flora Europ. Algarum, Sect. 
III. p. 138. 

ffab. — West Point, New York ; Providence, Rhode Island, Bailey. 

Filiform, cylindrical, smooth, gradually attenuated at each end ; the apex rounded. 

Remarks. — I have never recognized a specimen of this species, nor have I had 
access to the original description of Ehrenberg. 

Genus TETMEMORUS. 

Cellulae cylindricse vel fusiformes, rectoe, medio distincte constrictae, utroque polo anguste incisse 
cytioderma sat firmum, plerumque granulatura vel punctatura. 

Cells cylindrical or fusiform, straight, distinctly constricted in the middle, narrowly incised at 
each end. Cytioderm firm, mostly punctate or granulate. 

T. Brebissonii., (Mengh.) Ralfs. 

T. diametro 4-6 plo longior ; a fronte cylindricus, utroque polo non attenuatus sed rotundato- 
truncatus ; a latere fusiformis et a medio in apices rotundatos sensim attenuatus; cytiodermate 

striato-punctato. 

Diam.— 7|§/' = .0016". 

Syn.— T. Bribissonii, Menoheini, Rabenhorst, Flora Europ. Algarum, Sect. III. p. 139. 



FRESH-WATER ALGJE OF THE UNITED STATES. 117 

Ilab. — In fossis, Atlantic States. 

Four to si.x times longer than broad; from the front cylindrical, not attenuate at the truncately 
rounded ends ; viewed laterally fusiform, attenuated from tbe middle to the rounded ends ; 
cytioderm striately punctate. 

Remarks. — The central constriction is more apparent in the lateral than front 
view. When the frond is full of endochrome the punctae on the outer wall are 
not apparent, hut vvlien it is empty they are seen to be small, and closely arranged 
in stria-like rows. This species extends through all the Atlantic sea-board States. 
Prof Bailey has found it in South Carolina and Florida, as well as in llhode Island. 
I have collected it in Centre County, of this State. 

Fig. 3, pi. 21, represents an empty half frond of this species; 3 a the outline of 
the frond. 

T. g^raniilatus, (Breb.) Ralfs. 

T. habitu Tetm. Brebissonii, sed major et cytiodermate irregulariter granulato-punctato. (R.) 
Diam.—^\-s" = mU". (.00155". R.) 

Syn. — T. granulalus, (Brebisson.) Ralfs. Rabenhorst, Flora Europ. Algarum, Sect. III. 
p. 140. 

Hab.—Pvo\w. Philadelpbia ; "Wood. Rhode Island; (S. T. Olney.) Thwaites. South Caro- 
lina ; Bailey. 

Frond somewhat longer than T. Brebissonii, about five or six times longer than broad ; in both 
f. V. and s. v. fusiform, the constriction a very shallow groove, ends with a hyaline lip-like 
projection extending beyond the notch ; endochrome with a longitudinal series of large 
granules; e. f. punctate, the puncta scattered, except near the constriction; where they are 
disposed iu two transverse rows. Sporangium orbicular, smooth, margin finely striated, jilaced 
between the deciduous empty fronds. L. -j-^iy"- B. ■^\^". Archer. Pritchard's Infusoria. 

Remark. — Fig. 8, pi. 12, represents this species magnified 450 diameters. 

T. g^iganteiis, Wood. 

T. maximus, oblongus, diametro 3 plo longior ; apicibus hand attenuatis, late rotuudatis; suturis 
profundis, linearibus; cytiodermate irregulariter granulato-punctato. 

Diam.—^IW = .0031". 

Syn. — T. giganleus, Wood. Proc. Acad. Nat. Sci., 18G9. 

Ilab. — In stagnis, Centre County, Pennsylvania. 

Very large, oblong. 3 times longer than broad ; with the ends not attenuate but broadly rounded ; 
suture profound, linear ; cytioderm irregularly granulately punctate. 

Remarks. — I found this beautiful desmid in a stagnant pool in Bear Meadows, 
Centre County, in the month of August. It is very different in its outline from 
its nearest ally, T. (jranulatus. The diameter is preserved uniform until near the 
end, where there is an alteration in the line of the margin, so as to cause 
some contraction, which is, however, wanting in some specimens. The ends are 
therefore broad and obtuse. The size is also double that of T. gramdatus. 

Fig. 7, pi. 12, represents a frond of this species magnified 260 diameters. 



118 FRESH-AVATEll AL(J.E OF THE UNITED STATES. 

T. levis, (KuTZ.) Ralfs. 

T. Bivbissouii forrais similis sed parvior, 3-4 i)Io longior quam latiis ; cytiodermate plerumque 

levissimo, interdum iudistiuclissiiue juiuetato. 
D/am.—x5V/ = . 00066". 

Syn. T. levis, Kutzing. Ralfs. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 140. 

ffah. — In aqui.s quietis, propo Philadelphia. 

Similar in form to T. Br^bissonii, but smaller, 3-4 times longer than broad ; cytioderm mostly 
very smooth, sometimes iiulistiiictly punctate. 

Remarks. — Prof. Kabeiihorst states that the cytioderm of tliis species is very 
smooth, and Mr. Ralfs says that he has failed to detect any punctations, but also 
states that " Mr. Jenner and Mr. Ross assure me that they (punctae) are scattered 
as in T. grcmnlaius." I have no doubt of their existence in certain individuals, 
whilst in other cases they appear to be absent. 

Genus PLEUROT^NIUM, N^geli (1849). 

Cellulte singuliE in aqua natantes, rectoe vel subrectae, eylindricse vel fusiformes, valde elongataB, 
utroque polo rotundatas vel truncatoe, medio leviter constriotse, ex transverso circulares. Cytio- 
plasma chlorophyllaccum in laniinis longitudinalibus pluribus dispositum, et sub utroque polo locello 
rotundato corpuseulis se vivide moventibus impleto instructum. 

Cells single, swimming in water, straight or nearly so, cylindrical or fusiform, very much elongate, 
rounded or truncate at each end, in the end view with a circular outline. Chlorophyllous protoplasm 
arranged in longitudinal lamince and furnished at each end with a round vacuole containing actively 
moving corpuscles. 

EemarTcs. — This genus appears to include the main portion of the species, which 
have been described under the name of Docid'mm ; the remainder being represen- 
tatives of a number of genera. I have not had access to the original description 
of Docidium, and do not know in what year it was published ; but, according to 
De Bary, Docidium is much the older name ("Ucber de Conjugat.," p. 75). M. 
De Bary states, however, that he prefers the name of Ntegeli, because that autho- 
rity first defined the genus and his name expresses very clearly the character 
of it, as well as from the circumstance that the name Docidium having been 
made to cover a lietcrogcncous mass of species, its retention might cause confu- 
sion. I confess to thiidving that this action of De Bary is not in accordance with 
the recognized laws of priority, but, in the absence of the original description, 
have thought best to follow it. 

P. trabeciila, (Ehrb.) Njegeli. 

P. ssepe valde clongatum, octies vicies-longius quam latum, cylindraceum, utroque fine h-evissimo 
attenuatum aut incrassatum, juxta medium constrictum ssepius bigibbum (quasi biundatuin), 
apicibus late truncatum ; cytiodermate tenui loevi, achroo. (R.) 

X)ja?H.— 7^/ = .0013". 

Syn. — " Docidium Ehrenbergii. Ralfs." Bailey, Microscopical Ob.servations. Smithsonian 
Contributions. 

Pleurotamium (rabecula, (Ehr.) N^oeli. Rabenhorst, Flora Europ. Algarum, Se^t. 
III. p. 141. 

.ffa&.— South Carolina, Georgia, Florida ; Bailey. Pennsylvania ; Wood. 



FRESH-WATER ALG.E OP THE UNITED STATES. HQ 

(Docidiuvi Ehrenbergii. Ralfs.) Frond slender, linear; suture forming a very sbarply 
defined rim; segments 8-12 times longer than broad, basal inflation having another suialler 
one above it, sides otherwise straight, parallel; ends crenate, owing to a number of emar"-iiia- 
tions on the edge of the truncate extremities, from three to five of the crenations being 
usually visible; e. f. punctate or rough with minute granules. Sporangium suborbicular or 
elliptic, or slightly angular, smooth, placed between the deciduous empty fronds. Ciliated 
zoospores formed by segmentation of the cell contents, and their emission effected through 
the opened apex of each one, two or three, especially, formed lateral tubes arising from be- 
-neath the base of one of the segments. Archer. 

Remarlcs. — This species is quite common around Philadelphia ; but I do not 
remember ever to have seen one with the cell-wall granulate. The smaller of the 
two umbonations near the centre is often wanting or exceedingly small, and the 
crenulations in the ends are very often obsolete. 

Fig. 9, pi. 12, represents a cell of this species magnified 160 diameters. 

P. Baciiluiu, (Breb.) Pe Bary. 

P. priori simile, sed gracilius, angustius et plerumque longius, medio tantum serael constrictum • 

cytiodermate laavi. (R.) Species mihiignota. 
Djam.— 0.00054"— O.OOOy". (R.) 

Syn. — P.Baculum, {^KEB.) DeBary. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 141 

Hab. — Georgia ; Bailey. 

Frond slender, suture not prominent; segments very many times longer than broad, basal in- 
flation very conspicuous, solitary, sides otherwise straight, very nearly parallel, large gran- 
ules of the endochrome in a single series; ends entire; e. f. without puncta. L. -rjy"- B. 



1 " 



p. breve, Wood. 

P. robustum, diametro 4-8 plo longius, in medio distincte constrictum sed baud undulatuin, 
utroque polo nonnlhil attenuatum ; apicibus truncatis et nonnihil rotundatis ; cytiodermate 
crassissimo, dense granulato-punctato; marginibus vel rectis, vel breve undulatis. 

i)M(m.— .00.38"— .00095". 

Syn. — P. breve, Wood. Proc. Acad. Xat. Sciences, 1809. 

Hab. — District of Columbia. (Billings.) 

Robust, 4-8 times longer than broad, distinctly constricted but not undulated in the middle, 
slightly attenuated towards the ends; apex truncate and somewhat rounded ; cytioderm very 
thick, densely minutely granulate ; margins either straight or shortly undulate. 

Remarhs. — This species was sent to me by Dr. Billings, who obtained it near 
Washington, D. C. The margins are sometimes straightish, but in other fronds there 
are three or more distinct short undulations, or rounded projections in each half 
margin. The cell-wall is excessively thick, especially at the end — in many cases 
much thicker than the drawing. 

Fig. 2, pi. 21, represents an empty frond of this plant magnified 750 diameters. 

P. crcniilntiiiii, (Ehrb.) Rabenhorst. 

P. robustum, cylindraceo-subclavatum, octies-duodecies longius quam latum, medio undulato- 
nodulosum, strictura3 mediae margine tumido, apicibus late truncatis, altero sajpe creuulalo ; 
cytiodermate granulato-punctato. (R.) Species mihi ignota. 

Diam.— 0.0023". (R.) 

Syn. — P. crenulatum, (Ehrb.) Rabenhorst, Flora Europ. Algarum, Sect. III. p. 142. 



120 FRESH-WATER A L G.E F T H E U N I TE I) S T A T E S. 

Docidium nodulosum, Breb. Ralfs. British Desmidiie, p. 155. 
Closteriuni trabecula, Bailey. American Journal of Science, 1841. 

jjab. In nqiiis quiotis, South Carolina; Georgia; Florida; Rhode Island; Bailey. Pennsyl- 

vauia ; New Jer.sey ; Wood. 

(^Docidium nodulosum.) Frond very stout, the thickened sutures forming a projecting rim; 
segments four to six times as long as broad, scarcely attenuated, regularly inflated at intervals 
so as to form an undulated margin, the basal inflation the most prominent, the others, as they 
approach the ends, less so, where they are indistinct or wanting; ends entire; e. f. coarsely 
punctate. L. jV ". B. ^J^". Archer. Pritchard's Infusoria. 

RemarJcs. — I have found this species in " Shepherd's Mill Pond," near Greenwich, 
Cumberland County, New Jersey, and also in a Spring in the Philadelphia Park, 
near Columbia bridge. 

Fig. 1, pi. 21, represents the outline of a frond of this species magnified 160 
diameters. 

P. claTatiim, (Ktz.) De Bary. 

P. subcylindraceum, multoties (16-24) longius quam latum, ad utrunique polum sensim incras- 
satum, subclavatum, apicibus late truncatis ; cy tiodermate firmo achroo, dense et irregulariter 
granulato-punctato. (R.) Species mihi ignota. 

Diam.— Max. 0.00165"— 0.00147" ; min. = 0.0010"— 0.00092". (R.) 

Syn. — P. davalum, (Ktz.) De Bary. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 141. 
Docidium davatum,'K^VT:zmQ. Ralfs, British Desmidiae. Archer. Pritchard's /n/wsoria. 
Hah. — South Carolina ; Georgia ; Bailey. 

Frond slender, suture scarcely prominent, segments eight to ten times as long as broad, slightly 
clavate near the ends, and ultimately somewhat attenuated, basal inflation sometimes solitary, 
sometimes having another slight one above it; ends entire; e. f. punctate. L. gJg". B. ^yj". 

P. lindulatuin, (Bailey ) 

D. Ifeve, gracile cylindricum, undulatum, latitudine 18-20 plo longius, medio modice constrictum; 

cruribus et basi et apice truncatis et crenatis. (R.) Species mihi ignota. 
Syn. — Docidium undulatum, Bailey. Micros. Observ. p. 36. 
Hah. — Florida, Bailey. 
"Segments eight to ten times longer than broad, constricted six to eight times at regular intervals 

throughout their entire length, with the base and ends crenate, smaller than D. nodulosum, 

Breb., with more frequent and deeper constrictions. The same characters distinguish it from 

D. nodosum and D. constrictum." 

P. nodosum, (Bailey.) 

D. validissimum, undulatum, spinulis sparsis hirsutum, medio valde constrictum, diametro 8-10 
plo longius; cruribus e basi dilatata leviter attenuatis 4-undati8, apicibus quasi productis, 
latissime truncatis; locello apicali ratione parvo, rotundo, corpusculis paucis (ut videtur) 
repleto. (R.) (Sjjecies mihi ignota.') 

Syn. — Docidium nodosum, Bailey. Micr. Observ., pi. 1, fig. 4. Ralfs, British Desmids, 
p 218. 

Hah. — United States ; Bailey. 

"Frond stout; segments with four prominent nodes separated by constrictions; end view 
crenate. An end view shows that each node is not a simple swelling, but really formed by 
whorls of tubercles. ' This species is easily recognized by the deep indentations in its out- 
line, corresponding to the constrictions which separate the transverse rows of knob-like pro- 
jections. It is one of the largest species in the genus,' Bailey." Ralfs. 



FRESH-WATER ALGvE OF THE UNITED STATES. 121 

P. con!!)tric(iim, (Bailey) 

D. subvalidum, laBve, latitudine 10-12 plo longius, medio valde constrictum, stricturae margine 
noil prominente ; cruribus a basi tumida in apicem late truncatum uon attenuatis, i uudu- 
latis. (R.) {Species mihi ignoia.) 

Syn. — Docidium constrictum, Bailey. Ralfs, British Desmids, p. 218. 

Hab. — Rhode Island, Bailey. 

" Frond stout, segment.? with moderately deep constrictions, which separate four equal, gently 
curYing prominences ; end view entire. ' This species is at once distinguished from D. nodosum 
by the cross section of the nodes being a simple circle instead of an indented one,' Bailey." 
Ralfs. 

P. Terriicosiim, (Bailey) 

D. validum, granuloso-verrucosum, latitudine 10-12 plo longius, undulatum, apicibus integris 
truncatis. (R.) {Species mihi ignota.) 

Syn. — Gosmarium verrucosum, Bailey, Araer. Journ. Sci. and Arts, 1846. 

Docidium verrucosum, Ralfs, Brit. Desm. p. 218. Bailey, Micr. Observ. p. 28. 

Hab. — Rhode Island; Bailey. 

" Segments, with numerous whorls of small prominences, which give the margins an undulated 
appearance, all the undulations are equal. ' This is a very pretty species with a waved out- 
line, caused by the slight projections, which are arranged in numerous transverse rings,' 
Bailey." Ralfs. 

P. hirtmitum, (Bailey) 

D. spinuloso-hirsutum, medio valde constrictum, diametro 10-12 plo longius; cruribus et basi 
et apice subdilatatis, truncatis. (R.) {Species mihi ignoia.) 

Syn. — Docidium hirsutum, Bailey, Micr. Observ. p. 36. 

Hab. — Florida; Bailey. 

" Segments many times longer than broad, slightly inflated at the base, surface hirsute. A 
. small species resembling D. Ehrenbergii in its form, but strongly hirsute on its outer sur- 
face." Bailey. 

Genus TRIPLOCERAS, Bailey. 

Cellulse singulas, rectte, valde elongatae, processus magnorum seriebus transversis armata;, utroque 
polo trilobatae, lobis acute bidentatis. 

. Syn. — Triploceras, Bailey, Microscopical Observations, p. 37, Smithsonian Contributions, 1850. 

Cells single, straight, very much elongate, armed with transverse series of large processes, trilo- 
bate at each end, lobes acutely bidentate. 

T. Terticillatiim, Bailey. 

T. cellulis subcylindricis, sed utroque fine leviter angustatis et nonnihil fusiformibus, modice 
robustis, diametro 12-20 plo longioribus; processibus lateralibus robustis, magnis, apice 
emarginatis. 
Diam. — Cum process. ^^Jo" = -00146" ; sine process, -r^'/jo" = .00113". 

Syn. — T. verticinatum,BAii,T^Y. Microscopic Observations. Smithsonian Contributions, 1850. 
Docidium verticillatum, Ralfs, British Desmids, p. 218. 
Pleurotaenium verticillatum, Rabenhorst, Flora Enrop. Algar., Sect. III. p. 148. 

5a&.— Rhode Island, New Jersey, Georgia, Florida; Bailey. Saco Lake, (Dr. Lewis) Wood. 

Subcylindrical.but slightly narrowed at each end, and therefore somewhat fusiform, moderately 
robust, 12-20 times longer than broad; lateral processes large, robust, with their apices 
emarginate. 

16 June, 1872. 



122 FUESU-WATEll A L G .E OF THE UNITED STATES. 

T. g:r»cilEc, Bailet. 

T. fcllulis subcylindrieis, utroque fine vix angustatis, graeillimis, diametro 25-30 plo longi-. 
oribus ; processibus lateralibus brevibus, couiuis. 

Diam.—Cnm process. 7/5 j" = -008" ; sine proc. TSouTr" = -0006". 

;S'ytt — T. gracille, Bailey, Smithsonian Contributions. 

Vucidium prididse, Hobson, Magazine Natural History, v. p. 168. 
Pleurolsenium gracile, Rabenhorst, Flora Europ. Algar., Sect. III. p. 144. 

JJah. — In iisdcm cum autccedente locis. 

Subcylindrical, scarcely narrowed at the ends, 25-30 times longer than broad ; lateral processes, 
short, conical. 

Genus SPIROT^NIA, Breb. 

CelluliE rectas, cylindricce vel suljfusiforracs, ssepe in mueo golatinoso aggregate, medio haud con- 
strictae, utroque polo rotundatiB vel acuminatoe. Cytioplasma chlorophyllaceum in laminis spiralibus 
dispositum. 

Cells straight, cylindrical or subfusiform, often aggregated in a gelatinous mucus, not constricted 
in the middle, rounded or acuminate at each end. Chlorophyllous cytioplasm arranged in spiral 
lamina. 

Sp. bryopliila, (Bkeb.) Rabenhorst. 

Sp. mimina, bryophila; cellulis in gelatiiia niatricali consociatis, oblongo-cylindricis, rectis Tel 
subcnrvatis, bis vel ter longioribus quam latis, utroque polo rotundatis ; lamina chlorophyl- 
lacea singula anfractu 1-2|^. 

Z)iom.—^ijV/ = -00033" (0.00024"— .00029". R.) 

Syn. — Spirotsenia hryophila, (Breb.) Rabenhorst, Flora Europ. Algarnm, Sect. III. p. 146. 

Hah. — Propc Philadelphia ; Wood. 

" (S. muscicola (De Bary)) Frond cylindrical two to four times as long as broad, ends rounded; 
endochrome a single, broad, smoothly defined, widely wound spiral band, its revolutions very 
few (one or two)." (A.) 

Remarl-s. — I found this beautiful little dcsmicl on the North Pennsylvania Rail- 
road, near Clielten Hills, growing amongst some mosses which were kept con- 
stantly wet by overhanging dripping rocks. It formed little transparent masses of 
almost colorless jelly looking much like drops of dew. It agrees well with the 
descriptions of the European form, except that there were generally from 2-2^ 
turns of the spiral, and the cells exceed somewhat the measurements of Prof 
Rabenhorst. The cells are closely placed in the jelly. 

Fig. 10, pi. 12, represents some plants of this species. 

Sp. condensata, (Breb.) Rabenhorst. 

Sp. cellulis cylindraceis, rectis (vel leviter curvatis) octies vel decies longioribus quam latis, 
utroque polo rotundatis; laminis chlorophyll, singulis, anfractibus subarctis (plerumque 8-12). 

Dzam.— 0.00075". 

Syn.—Sp. condcnsata, (Breb.) Rabenhorst, Flora Europ. Algarum, Sect. III. p. 146. 

Eab. — Florida ; Rhode Island ; Bailey. Pennsylvania ; Wood. 

Frond cylindrical, two to four times as long as broad, ends rounded ; endochrome a single, 
broad, closely wound .^spiral band, its revolutions numerous. L. 5J5". Br. txj??"- Archer. 
Fritchard's Infusoria. 



FRESH-WATER AJjQJE OF THE UNITKD STATES. 



123 



Eemarks.— The only specimens tliat I have seen of this species were found in a 
spring in the Phihxdelphia City Park, near Columbia bridge, 
lig- 11' pl- 12, was drawn from one of these specimens. 

Genus SPH^ROZOSMA, Corda. 

Celluloe compressas, medio transversim profunde incisie, itaque bilobatjB, in quoque lobo massa 
clilorophyllosa quadriradiata iiufleum amylaceura involvcnte prteditaj, in filum planum tseuiiformum 
literaliter isthmis conjunct*. ZjgospoiiB globosse vel ovules, glabras. (R.) 

Syn. — Isthmoxira, Ktz. 

Odontellee, spec, Ehrb. 
Idhmiae, spec, Men EG. 
Spondylosium, Bkeb. 

Cells compressed, transversely very deeply incised in the centre and therefore bilobate, furnished 
in each lobe with a quadriradiate mass of cliloropbyl surrounding a starch grain, conjoined laterally 
by isthmuses in a tasniform fascia. 

Remarhs. — I have never found any species of this genus in America. Professor 
Bailey has, however, detected the following: — 

Spli. excaTatiiui, Rat-fs. 

Sjth. plerumque nudum (sine tubo nnieo.so) sph. vertebratnm nnilto minus ; cellulis diametro 
duplo-longioribus, medio e.xcavato-constrictis, a latere ellipticis utroque polo rotundatis; lobis 
brevibus truncato-rotundatis, Ifevibus vel granulato-denticulatis ; isthmis biuis parvis verru- 
eiformibus; zygosporis pleruraque ovatis. (R ) 

Lata, filer. 0.00047"— 00032". (R.) 

Syn. — Sph. excavaium, Ralfs, British Desraids, p. fiT. 

Eah. — Florida; Georgia; South Carolina ; Rliode Island ; Bailey. 

"Joints longer than broad, having a deep sinus on both sides and two sessile glands at each 
margin at their junction, very minute, seldom more than twenty-five joints in the filament, 
which is fragile, and finally separates into single joints ; at their junction, in the front view 
are two minute glands or processes, situated one near each angle, and nearly invisible before 
the escape of the endochrome. The joints are nearly twice as long as broad and much con- 
stricted in the middle ; the constriction is like an excavation or broad sinus on each side, so 
that the margins of the filaments appear sinuated. The endochrome is pale bluish-green 
with minute scattered granules. The transverse view is oblong with four .Sessile glands, two 
on each side and situated near the ends." — Ralfs' Brit. Dcsm., p G7. 

Sph. piilchi'iim, Bailey. 

Sph. cellulis oblongo-quadrangularibus, diametro duplo-brevioribus, acute incisis, arete con- 
nexis; lobis oblongis rectis, apice rotundatis; isthmis nullis, vagina mucosa ampla dis- 
ncta. (R.) 

Syn. — S. pulchrum, Bailey. Ralfs, British Desmid., p. 209 (Cum icone). 

Eab. — West Point, New Tork ; Princeton, New Jersey ; Bailey. 

" Joints twice as broad as long, deeply incised on each side ; junction margins straight, con- 
nected by short bauds." 

RemarJc.- — " Prof. Bailey informs me that this species is twice as large as Sph. 
vertebratum" Ralfs. 



124 FRESII-WATER A L G yE OF THE UNITED STATES. 

Spli. serratiini, Bailey. 

Spli. cL'lluli.s diauietro duplo brevioribus, profuiule ct acute exeisis, arete conjunctis; lobis 
utrinqae cuspidatis, paulum conniventibus ; istbmis nullis ; vagina crassa. (R.) 

Syn, Sph. serralum, Bailey, Micros. Observation. Smitbsonian Contributions, 1850. Cum 

icone. 
jga6.— South Carolina ; Georgia ; Florida ; Bailey. 

"Joints broader tban long, deeply notebed or divided into two transverse portions with acute 
projecting ends, wliicb give a serrated outline to the cbaiu." Bailey. 

Genus HYALOTHECA. 

CelluliE brevffi, cylindricaj, medio non profnnde con.strictfe, a latere disciformes, in fila confervacea 
sine istbmis arete conjuuctoe et vagina mucosa ampla acbroa inclusae. Massa cbloropbyllosa in 
quaque seraicellula 4-8, 5-10 radiata. 

Cells sbort, cylindrical, not profoundly constricted in the middle, disciform in the end view, 
closely united without intervening isthmuses into a confervoid filament, which is inclosed in an 
ample mucous sheath. Chlorophyl masses in each cell 4-8, 5-10 radiates. 

H. disilliens, (Smith) Breb. 

H. fasciis prselongis ; cellulis oblongo-quadrangularibus, diametro sub-dnplo brevioribus, inter- 
dum ante divisionem sul)8equalibus, angulis nonnihil rotundatis, plerumquc medio obsolete 
constrictis, sffipe baud constrictis. 

Z>iam— 0.00089"— 0.00008". (R.) 

Syn. — U. disilliens, (Smith) Breb. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 152. 

Uab. — South Carolina; Florida; Rhode Island; Bailey. Rhode Island (S. T. Oluey), 
Thwaites. Pennsylvania ; Wood. 

Filament very long, cells oblong, quadrangular, about one-half as long as broad, sometimes before 
division as long as broad, angles somewhat rounded, mostly obsoletely constricted in the 
middle, often not constricted. 

Remarhs. — The specimens which I have identified as i?. c^mZZtms, agree with 
the various figures and descriptions of the European form, in every thing except 
that in many cases there is no constriction whatever in the centre of the cell, and 
when the constriction docs exist, it is never so pronounced, as some of the descrip- 
tions indicated. The plant is very common about Philadelphia, growing in springs 
and ditches. 

Fig. 12, pi. 12, represents this part of a filament of this species. 

H. miicoiiia, (Mert.) Ehrb. 

H. fasciis confervaceis, minus fragilibus ; cellulis quadrangularibus, diametro nequalibus vel 
suba;qualibus, medio non constrictis, ad utrumque fiuem (auuuliformi-bicarinatis) bideutatis. 
(R.) Species mihi ignota. 

Z)iam.— 0.00073"— 0.0008". (R.) 

Syn. — Gloeoiorium miicosum, Hassal, Fresh "Water Algte, p. 346. 

H. mucosa, (Mert.) Eiirb. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 132. 

//»6._Rhode Island ; (S. T. Olney) Thwaites. 

Filament scarcely fragile, mucous sheath very broad ; joints about as broad as long, not con- 
stricted, but having at one of the ends a minute bideutate projection on each margin, the 



FRESH-WATER ALG^E OF THE UNITED STATES. 125 

adjoining ends of the next joint being similar, tliese projeetions being produced ]>y an annular 
grooved rim. L. t.^l/_GOO". B. •^^\^"—^^\^". (Archer) 

Genus BAMBUSINA. 

Cellulffi oblongo-orculiformes, in filamenta articulata nodosa dense conjunctse, medio vitta trans- 
versa carinis duabus annuliformibus liniitata instrueta;, itaque superne et interne bidentatie, i'ruute 
circulares, supra et infra dente unieo pronunente. (R.) 

Cells oblong-oreuliform, densely united into an articulate uodose filament, surrounded by two 
median bands. 

B. Brebis§onii, Ktz. 

B. filameutis nodoso-articulatis ; cellulis diametro duplo longioribus. (R.) 

Diam.—O.OOOTr'— 0.00092". (R.) 

Syn. — B. Brebissonii, KiJTZiNa. Rabenhorst, Flora Europ., Algarum, Sect. III. p. 152. 

Bab. — South Carolina. (Ravenel) Wood. South Carolina; Georgia ; Florida ; Rhode Island. 
Biiiley. 

(Didymoprium Borreri, (Ralfs)) Joints inflated, barrel-shaped, longer than broad, without a 

thickened border at their junction ; angles bicrenate, crenatures rounded ; transverse view 

circular ; sporangium elliptic, formed within the (for some time) persistent extensions from 

the conjugating joints, which do not previously break up into single joints, but couple, still 

united in the filament, in a confused or zigzag manner, some of the joints remaining unchantred. 
1 " 



L. TsW- B. — '- 



Remarhs. — Tlie specimens which I have seen agree well with the descriptions, 
except in regard to size ; some of the cells which I measured were more than 
TiVo of ^^1 "^*^^^ "^ diameter. 

Genus DIDYMOPRIUM. 

Cellulse oblongo-ellipticae, modice compress^, ancipites, angulis porrectis inciso-bidcntatis, in fila- 
menta articulata biconvexa et torta sine isthnio arete conjunct^, ct in vagina mucosa inclu.s;p. 
Cytioplasma chlorophyllosa cellulas a fronte cruciatim disposita, cujus crura e laminis duabus jiarie- 
talibus divergentibus granum amylaceum unicum involventibus formantur. 

Cells oblong-elliptical, moderately compressed, two-edged, with the produced angles incisely-biden- 
tate, closely united into a biconvex and twisted filament, which is inclosed in a mucoid sheath, cj'tio- 
plasm so placed as to be cruciate when viewed from the front (end), each erus composed of two 
parietal divergent lamina, eacli of which contains a single starch granule. 

D. Grevillii, Ktz. 

D. cellulis obloDgis diametro duplo brevioribus, saturate viridibus. (R.) 
Z)iam.0.0024"— 0.0031." (R.) 

Syn. — D. Grevillii, KCtzing. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 153. 
Eab. — Georgia, South Carolina ; Bailey. Pennsylvania ; Wood. 

Sheath distinct ; joints broader than long, with a thickened border at their junction ; angles 
bidentate ; teeth angular; transverse view broadly elliptic. Sporangium orbicular, funned 
within one of the two conjugating joints, the endochrorae passing over from one by a narrow 
connecting tube produced between the otherwise, but little altered, broken-up single joints. (A.) 

Remarh. — Fig. 13, pi. 12, represents the end view of a broken filament of this 
species. 



126 FRESIl-WATER AhGM OF THE UNITED STATES. 

Genus DESMIDIUM. 

CellultD obloiigo-tabulares, medio inciso-bilobae, lobis iiitegris vel irregulariter dentatis, a fronte 
tri- vel quadrangulares, aiigulis obtuse rotuudatis, in fila angulosa, proelonga, torta, fragiles arete 
conuexa;. Massa chlorophyllosa (a cellulae fronte visa) 3-4 radiata ; quisque radius e lamiuis 
duabus lateralibus divergeutibus compositus. Zygospore globose vel oblonga;, glabrae. 

Cells oblong-tabular, mcdianly incisely bilobate, with the lobes entire or irregularly dentate, aa 
seen from tliu front tri- or quadrangular, and having the angles obtusely rounded, closely conjoined 
into an angular, fragile, twisted filament. Chlorophyl (as seen from the front) 3-4 radiate; each 
radius composed of two lateral divergent lamina ; zygospores globose or oblong, smooth. 

D. Swarlzii, Ao. 

D. cellulis a fronte triangularibus, diametro 2-3 plo brcvioribus. (R.) 

Dmm.— 0.00096"— 0.00189". (R.) 

Si/n. D. Sv:artzii, Agardii. Rabeniiorst, Flora Europ. Algarura, Sect. III. p. 154. 

Uab. In iiquis quietis, Atlantic States. Florida; Georgia; South Carolina ; Rhode Island; 

Railey. Kew York ; Edwards. Pennsylvania ; Wood. 

Filament triangular, equal, with a single longitudinal waved, dark line, formed by the third 
angle; joints in front view somewhat quadrangular, broader than long, with two slightly 
angular crenatures on each lateral margin, united at the whole of their end margins by a 
thickened border, end view triangular ; .eudochrome three-rayed. Archer. Pritchard's /h/u- 
sona. 
D. qiiadrangulaf iiin, Ktz. 

D. quadrangulare, cellulis oblongo-quadrangularibus, diametro 2-3 plo brevioribus, lobis denti- 
formibus obtusis, a fronte sinuato-quadrangularibus, augulis late rotuudatis, lateralibus exca- 
vatis. (R.) Species mihi ignota. 

X»iam.— 0.0021"— 0.0029". 

Syn. — D. quadrangulatum, Kutzinq. Rabenhorst, Flora Europ. Algarum, Sect. Ill, p. 155. 

Filament quadrangular, varying in breadth from its twisting, having two longitudinal waved 
lines ; joints in f v. broader than long, with two somewhat rounded crenatures on each lateral 
margin, united by the whole of their end margins; e. v. quadrangular; eudochrome four 
rayed. L. ^.\^". B. ^J,"-,!^". (Archer) 

D. aptogoniuin, Breb. 

D. fasciis plerumque subbrevibns, nudis, perforatis; cellulis quadrangularibns, inciso-bilobis, 
lateralibus concavis, lobis crenatis, a fronte triangularibus (nonnunquain biangularibus), centre 
concavo, angulis rotuudatis protensis isthmum brevissimum triplicem effieientibus. (R.) 
Species niihi ignota. 

Dmm.— 0.00089"— 0.001 47". (R.) 

Syn. — Aptogomiim desmidium, Ralfs, British Desmids. 

D. aidogonium, Brebisson. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 155. 

HaJ). — Georgia ; South Carolina ; Bailey. 

Joints in f v. quadrangular, broader than long, with two ronndod crenatures on each lateral 
margin, united at the outer portion only of each end margin by mutual projections, thus yvo- 
ducing intervening central oval foramina. Archer. 

Genus APTOGONIUM, Ralfs. 

Cclluhe 3-4 angulares vel compressse, non constrietae ; uiargiue laterali plana; vel crenatse, ip 
fascias peiforato-artieulatas, angulares conjunctae. (R.) 



FRESH-WATER A L G vE OF THE UNITED STATES. 127 

Cells 3-4 angular or compressed, not constricted, tbeir lateral margins plain or crenate, conjoined 
into angular perforately articulate fascia. 

A. Baileyi, Ralfs. 

" Filament not crenated ; joints about equal in length and breadth. 

Si/n. — Odontella? tridentata, Bailey. In lit. cum icone (184G). 

Jjab. — Worden's Pond, Rhode Island; near Princeton, New Jersey, with sporangia," Bailey. 

" Filament triangular; joints excavated at their junction like those of Aptogouum desmidiuiii- 
The joints are not bicrenate, hence the margins of the filament are entire, a character which 
distinguishes it from that species. The end view is triangular, with rounded angles." Ralfs, 
British Desmidiese, p. 208. 

Genus COSMARIUM, (Coeda) 

Cellulse oblongaB, oblougo-cylindricse, ellipticce, vel orbiculares, medio transverse plus minus con- 
striciE, utroque polo obtusai vel rotundatse et Integra!, a vertice ellipticaj. Zygospora; muricata; vel 
verrucosse. 

Cells oblong cylindrical, elliptical or orbicular, more or less transversely constricted in the middle, 
obtuse or rounded, and entire at each end, viewed from the end elliptical. Zygospore warty or 
muricate. 

1. Cellules sejunctee. 

1. Cells seijarate. 

a. Cellulae ellipticse, vel suhellipticse ; semicellulse medio nonvenlricosae. 

a. Cells elliptical or subellipitical ; semicells medianly not ventricose. 

* Gytiodermate granidoso vel verrucidoso. 

* Cytioderra granular or warty. 

C inni'grarifireriiin, (Turp.) Mengh. 

C. paulo longius quam latum, profunde constrictnm ; sinu amplo, vel modice angusto, interdum 
intra e.xcavato; semicellulis semiorbicularibus, vel reniformibus vel nonnihil quadrangulis 
dorso plerumque late rotundatis ; cytiodermate verruculoso. 

Z>w?Ji.— Max. ^5V = .0006" (0.00073"— 0.0012". R.) 

Syn. — Euastrum margaritiferum, I^hrb. Bailey, Silliman's Journal, 1841. 

Cosmarium margaritiferum (Turpin), Meneghini. R.\isenuorst, Flora Europ. Algar., 
Sect. III. p. 157. 

Eab. — In aqnis quietis, South Carolina ; Florida ; Mexico ; Bailey. Pennsylvania, Wood. 

A little longer than broad, profoundly constricted ; sinus ample or moderately narrow, some- 
times widened on the inside; semicells seniiorbicular, reniform or somewhat quadrangular ; 
dorsum mostly broadly rounded ; cytioderm warty. 

Remarhs. — I have found a form of this species growing in the vicinity of this 
city, which I at first was disposed to look upon as distinct, but which, in truth, 
grades into the typical form. In it the cells are almost quadrangular, often with 
their basal angles acute. The margin of the frond in C. mar<jar'diferum, as it 
occurs with us, is sometimes distinctly serrate or, more correctly, crenulate from 
the presence of the granulations. The granules are larger than in C. hoirytis, but 
smaller than in C. tetroi>htltalmvm. When viewed laterally the semi-cells are 
roundish, or nearly so (according to Ralfs' elliptical), and closely connected by 



128 FRESH-WATER ALG^ OF THE UNITED STATES, 

a verv brotul neck. I have never seen the sporangia, but, according to Mr. Ealfs, 
they are orbicular and inclosed in a granulated cell. 

Fio-. 8, pi. 21, represents half of an empty frond of this species magnified 750 
diameters; and fig. 21, pi. xii., a frond densely filled with living endochrome 

C Bofrylis, (Bory) Mengh. 

C. late ovale, profiinde constrictum, diametro plerumque 1^ — 2 plo longius ; sinu angusto, 
liueare- scmicellulis noimibil triaugularibus, apice iuterduui truncatis, interduni late rotun- 
datis ; cytiodermatc miuute granulato. 
Z>iawi.—5Jf" = 0.0019" (O.OOU"— 0.0023"). (R.) 

Syn, C. Botrytis, (Boey) Menegheni. RABENnoBST, Flora Europ. Algarum, Sect. III. p. 

158. • 

Ifab. — Pennsylvania, Wood. 

C. broadly oval, profoundly constricted, 1^-2 times longer than broad; sinus narrow, linear; 
semicells soraewluit triangular, with the apex sometimes truncate, sometimes broadly rounded; 
cytioderm minutely granulate. 

Remarls. — In this species the semicells, as viewed transversely, are broadly 
elliptic in outline. The end view presents a longer narrower ellipse. Their out- 
line, wlien seen from the front, varies remarkably from that of a very broad semi- 
oval to distinctly triangular with a truncate apex. The grannies are small and 
arranged regularly, sometimes they are very obscure. I have often seen the endo- 
chrome so arranged as to leave a large pyriform central vacuole in each cell, com- 
municatinor with the narrow marjjin between it and the cell-wall. This vacuole 
was apparently filled with a transparent fluid, in which were minute granules in 
immense numbers, in constant active motion circling among one another and pass- 
ing out, into and along the marginal connecting space. According to Ralfs, the 
sporangia of this species are large {j^^"), with branched spines. 

Fig. 5, pi. 21, represents an empty frond of this species; 5 a, outlines of semi- 
cells to show the variations, and fig. 14, pi. 12, represents a frond crowded Avith 
endochrome, magnified 460 diameters. 

C. ovale, PvALFs. 

C. magnum, ovale, compressnm, profunde constrietum, diametro subduplo longius, ambitu inte- 
gcrrimuni vel crenatura, a vertice late ellipticum ; semicellulis basi paulo latioribus quam 
longis, triangulo-rotundatis, disco punctatis, margine verrucis margaritaceis achrois hyaliuis 
in series 4 ordiuatis. (R.) 

iJt'am.— Long. 0.0053"— COOGt". Lat. plcrumque 0.0041". (R.) 

Sijn.— C. ovale, Ralfs, British Desmidieoe, p. 98. 

/7a6.— South Carolina ; Rhode Island ; Bailey. Cobble Mountain, Pa. (Lewis) Wood. 

Frond very large, elliptic, nearly twice as long as broad, constriction very deep, linear; seg- 
ments somewhat broader than long, somewhat triangular, rounded at ends, rough near the 
margin, with a band of large pearly granules, producing a dentate appearance, the disc punc- 
tate ; e. V. elliptic. (A.) 

C Brcbii^sonii, Menegh. 

C. paulo longius quam latum ; semicellulis semicircularibus, diametro paulo longioribus, angulis 
infenonbus obtusis approximatis, ventre modice concavis subplanis, dorso latissime rotun- 
datis; cytiodermatc muricato, muricibu.s conicis in ordinibu.s regularibus collocatis. (R.) 



FRESII-WATER ALG^ OF THE UNITED STATES. 129 

Z)/flm.— Semicell, 0.0019"— 0.0022". (R.) 

Sijn. — C. Brebissonii, Menegheni. Rabenhorst, Flora Europ. Algarum, Sect. III. [). 158 

Hah. — White Mountains, New Hampshire, (Dr. F. W. Lewis) Wood. 

Frond somewhat longer than broad, constriction deep, linear; segments semiorl)ieular, rough 
all over, with somewhat elongate conical scattered pearly granules ; e. v. elliptic. (A ) 

Rcmarlc. — Fig. 6, pi. 21, represents an empty frond of this species, magnified 
750 diameters. 

C suborbiciilare, Wood. 

C. parvuni, suborljiculare, paulo longius quam latum, cum margine euormiter crenato vel 
crenato-undulato; semieollulis a latere orbicularibus, a vertice ellipticis; sinu e.xtrorsum 
angustissimo sed iiitrorsum nounihil excavato ; cytiodermate crasso, sparse vcrruculoso ; 
granulis in seniicellulis singulis subdistantibus et in seriebus elongatis, duabus (iuterdum 
unica) esternis curvatis, et in seriebus duabus interni.s brevibus ct rectis. 

Diam.—Lat. t^Vsu" = -0012" ; lat. tij'/us" = -0013". 

8yn. — C. orbiculare, Wood, Proceed. Acad. Nat. Sc. 18Y0. 

Hab. — In lacu "Saco," New Hampshire, (Lewis.) 

Small, suborbicular, a very little longer than broad, with the margin irregularly crcnate, or 
creuate undulate ; semicells from the side orbicular, from the vertex elliptical ; sinus very 
narrow, but within somewhat excavated ; cytioderm thick, sparsely coarsely granulated ; 
granules subdistant, in each cell arranged in one or two curved marginal series and in a cen- 
tral group of two or three short rows. 

Een-arks. — The arrangement of the granules in this desmid is peculiar, one, or 
sometimes two rows of large obtuse pearly granules are placed at rather wide in- 
tervals along the whole outer margin, and then in the centre of each semiccll is a 
group of two or three, or even more short straight rows of three or four similar 
but rather smaller granules. The isthmus is rather broad and short; sometimes it 
las on it one or two granules. 

Fig. 9, pi. 21, represents an empty frond of this species, magnified 750 diame- 
ters ; 9 a, the outline of the end view of the same. 

C. tetrophthalniiim, (Ktz.) Breb 

C. tcrtiam partem circa longius quam latum, profundc constrictura ; sinu angusto, plcrumquc 
sublineare ; ambitu obtuse crenato; semicellulis nonnihil semicircularibus, ventre subplauis, 
dorso rotundatis; cytiodermate verruculoso ; verruculis maguis, obtusis, subordinatim dispo- 

sitis. 

Syn. — C. tetrophthahnum, (Kcitzing), Br^bisson. Rabenhorst, Flora Europ. Algarum, Sect. 
III. p. L59. 

Hah. — New Jersey ; Wood. 

About one-third longer than broad, deeply constricted ; sinus narrow, mostly sublinear; margin 
obtusely erenated ; semicells somewhat semicircular, belly nearly even, dorsum rounded; 
cytioderm warty ; prominences large, obtuse, arranged somewhat regularly. 

Remarlcs. — The only specimens I have seen, and I believe the only ones hitherto 

17 July, 1872. 



130 1' i: !•; S II - W A T K Fv A L G Ai O F T II E U N 1 T K D ST A T E S. 

found on tlie continent, v,'crc. collected by myself iu " Shepherd's Mill Tond," near 
Bridgeton, Cumberland County, New Jersey. 

Fio-. 7 a, pi. 21, represents the outUne of a frond magnified 460 diameters. 



C. ainoeniiin, Bugb. 

C. mi'ilinci-f, (ibli)iigum cyliiidricnm, IcvitcT comprcssnni, diamctro duplo fere triplove longins, 
utruquc polo rotuiidatiiii), iiitMliu jirofunde constrictmn, sinu angusto, lincari, amiiitu graiiulis 
luargaritacL'is achrois ob.sessuni, a vertice fllipticum ; scmicellulis obloiigo-rotundatis, dorso 
alto convexis, lateribus vero rcctis parallelis, angidis inferioribus rectiS et Rul)afulis; cytio- 
dermate granuloso-verrucoso, vurrucis Iiyaliuis in scrius rcgularcs dispositis. (K.) Sjjecies 
viihi ifjnota. 

Long. 0.0017"— O.IOIG"; lat. 0.00087". (R.) 

Syn — C. auumum, Brebisson. Rabenhorst, Flora Europ. Algar., Sect. III. p. 159. 

//a6.— Florida; Bailey. Rhode Lslaiul (S. T. Olncy); Tlnvaitcs. 

Frond twice as long as broad, sides parallel, ends rounded, constriction deep, linear; segments 
rough with crowded obtuse j)apilla-like pearly granules; s. v. much compressed, about thrice 
as long as broad ; e. v. elliptic. (A.) 

** Cyliodermate glahro. 

** Cytioderm smooth. 

C. t'HCUlllis, C'URD.V. 

C. ovale ellipticuni, utroqnc polo late rotundatum, tertiam partem vel duplo longius quam latum, 
profundc constrictuni ; sinu lineari ; seniicellulis augulis inferioribus rotuudatis, cytiodermate 
glabro, hand punctuto. 

Diam.—M&x. long. ^U" = 0.002G" ; hit. ^l^-' = .0019". 

iS'yn. — C. C'ucumis, C'orda. Rabenhorst, Flora Europ. Algarura, Sect. III. p. 161. 

Hab. — South Carolina; Georgia; Florida; Bailey. Pennsylvania; Wood. Saco Lake, (Lewis.) 

Oval or elliptic, at each end broadly rounded, one-third to twice as long as broad, profoundly 
constricted; sinus linear; semicells with their inferior angles rounded ; cytioderm smooth, 
not punctate. 

Remarks. — This species is very abundant arounil Philadelphia. The semioells 
generally each contain two large globidar masses placed near the median line, 
which are sometimes hidden by the crowded endochrome. 

Figs. 15, 15 a, pi. 12, represent this species with their endochrome in different 
conditions; 15 Z>, represents a monstrous frond, which had attem-pted to divide, hut 
had not succeeded in so doinir. 

C depreitiisiini, Bailey. 

" Ellii)tical, binatc, division in the plane of the longest a.\is. Segments entire, nearly twice as 

long as broad, ronndcd above, very mucli flattened at baae. 
Hab. — Lakes in Florida. 

This species resembles C. bioculnlum, Breb. ; but the segments are much closer together, and 
are angular, not rounded at the basal extremities." Bailey. Microscopical Observations. 
Smithsonian Contributions. 

€. pyrniiiidadiiii, Breb. 

C. mediocre, ovale vel subovale, ntroqne polo truncatum, medio profunde constrictum, duplo 



FRESII-WATEU A LG.E OF THE UNITED STATES. 131 

fere long! us quain latum; sciiiiccllulis brt'vitrr pviviiiiidatis, nngulis iiifci-ioribus ro(iiii<l:ilis, 
apice (dorso) inodo truiicatis uiodo rotuiidutis, a vcilire late cllijiticis ; cytiodermati' |)inic- 
tato vel subtilissiuie grauulato. (R.) 

Long. 0.0021"— 0.0037". Lat. nuix. 0.0026". 

Syii. — C. pyramidatum, Brebisson. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 102. 

Hab. — Georgia; Florida; Bailey. Pennsylvania; "Wood. 

Frond scareely twice as long as broad, suljoval ; constriction deep, linear; segments pyramidal, 
rounded at basal angles, somewhat truueate at the ends, punctate ; c. v. broadly elliptic. (A.) 

Remarli. — Fig. 14, pi. 13, is a drawing of this species. 

C biociilatiiin, Breb. 

C. parviter, circitcr tam longum quam latum vel paulo longius, ]irofunde constrictuni, .sinu e.x- 
trorsum ampliato ; semicellulis diainetro duplo latioribus, elliptico-prope he.xagonis angulis 
obtuse rotundatis, integerrimis aut levis.simc crenulatis; cytiodermate kcvi vel subtilissiuie 
punctate. (R.) Species niihi ignola. 

Long. 0.000G9". Lat. 0.000G6". (R.) 

Syn. — C. biociilatum, Brebisso.v. R.\beniiorst, Flora Europ. Algarum, Sect. III. p. 1G3. 

Hub— Tihodc Island, (S. T. Olncy) Thwaites. 

Frond minute, about as long as broad, constriction deep, producing a gaping notch at each 
side; segments about twice as broad as long, elliptic, smooth; s. v. comjiressed s. v. elliptic. 
Sporangium orbi'cular with conical spines L. -j^'j^" ; B. -ttts"- C^) 

C. ineneg:heuii, Breb. 

C. parvum, tam longum qnam latum, modo paulo-longius, modo paulo-brevius, pmfunile cun- 
strictum, sinu lineari, e.xtrorsum nou ampliato; semicellulis subquadratis, leviter .sinuato- 
he.\agonis ; angulis rotundatis, cytiodermate la;vi vel subtillis.sime punctato. (R.) 

Long. J/'— jV" = 0.00103"— 0.0013"; lat. rl/'—rl/' = 0.00081"— 0.00089". (R.) 

Syn. — C. Meneghenii, Brebisso.v. Rabenhorst, Flora Europ. Algar., Sect. III. p. 103. 

nab. — Pennsylvania ; Wood. 

Frond very minute, rather longer than broad, constriction linear; segments subquadrale, bicre- 
uate at the sides and ends, smooth ; e. v. elliptic. (A.) 

Reinarh.—Y\g. 18, pi. 12, represents a frond of this species, magnilied 750 
diameters. 

C crenatiiiii, Ralfs. 

C. oblongum, tertiam partem circa longius quam latum, profunde constriefum, sinu lineari an- 
gusto ; semicellulis e basi lata subsemicircularibus, dorso plus minus depressis vel truncatis, 
ambitu crenatis vel regularitcr undulato crunatis, crcuis 10-14; cytiodermate punctato. (R.) 
Species mihi ignola. 

Long. 0.0021"— 0.0023"; lat. O.OOln". (R.) 

Syn. — C. crenalum, Ralfs, British Desmidiea;, p. 96. 

Sa6.— Rhode Island; (S. T. Olney) Thwaites. 

Frond .slightly longer than broad, constriction linear ; segments semiorbicular, cnd.s and .«idcs 
broadly rounded, crcnate or minutely undulate at margin ; e. v. elliptic. Sporangium orbi- 
cular, spinous ; spines elongate, slender, swollen at the base and divided at the ape.\. L. ,{ j ; 

Bi " 
• 5TT • 



l;3-2 FRESH -WATER A L G .E OF THE UNITED STATES. 

C. iindiilatiiin, Corda. 

C. submediucrt', obloiigum, diamutro subdiipli) lungius, utroque polo late rotundatum, aiiibitu 
leviter sinuato-undulaliim, prol'uiidi! constrictuin, siiiu liueari extrorsum paulluni ampliato; 
seniicellulis scmiorbicularibus, et dorse et latcribus late rotundatis, margine undulato-creuatis, 
crenis 9, sublatis ; cytiodermate liBvi ; zygosporis spliaericis spinis elougatis, apice bi- tri-fidis 
obsitis. (R.) Species inilii ignota. 

Long. 0.0024". Lat. 0.0017". (R.) 

^yn. — C. undulatum, Corda. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 165. 

Hab. — South Carolina ; Rhode Island ; Bailey. 

Frond rather larger than that of C. crenatum, slightly longer than broad, constrictions linear; 
segments semiorbicular, ends and sides broadly rounded, crenate or minutely undulate at the 
margin ; e. v. elliptic. Sporangium orbicular, spinous ; spines elongate, slender, swollen at 
the base and divided at the apex. (A.) 

b. Semicellidse medio-venlricoso injlalx. 

b. Semicells mcdianbj venlr'icose. 

* Cyliodermale leevi. 

* Gyiiuderm smooth. 

C Sllblobntiiiii, (Breb.) Archer. 

C parvum, oblongo subquadratum, diaraetro subduplo longius, sinu angusto linoari; seniicel- 
lulis subquadratis, e basi dilatata ad verticem sensim angustatis, angulis et iuferioribus et 
superioribus rotundatis, dorso late truncatis lateribusque leviter sinuatis ; cytiodermate 
Isevissimo. (R.) 

Long. 0.00119"— 0.00196". Lat. max. 0.0015"— 0.00157". (R.) 

Syn. — G. sublobatum, (Brebisson) Archer. Pritchard's Infusoria, p. 731. 

Hab. — Georgia; Florida; Rhode Island ; Bailey. 

Frond scarcely twice as long as broad, oblong ; constriction linear, segments subquadrate, 
somewhat wider at the base, lateral and end margins slightly concave, smooth and trans- 
verse vein cruciform. (A.) 

* * Cytiodermale granulate. 

* * Gylioderm granulate. 

C. ornatiiin, Ralfs. 

C. parvum, plerumque tam longum quam latum ; semicellulis reniformibus, diametro duple 
longioribus, angulis inferioribus una cum lateribus rotundatis; dorso sub-producto late trun- 
catis; cytiodermate granulato-verruculoso ; zygosporis longc spinosis, spinis elongatis apice 
furcatis. (R.) Species inihi ignola. 

Long. 0.0016"— 0.0015". Lat. 0.0010". (R.) 

Sijn. — C. ornatum, Ralps, British Desmidiea3, p. 104. 

Hab.— Rhoda Island; (S. T. Olney) Thwaites. 

Frond in f. v. about as long as broad, constriction deep, linear; segments semiorbicular or 
subreniform, with a central truncate projection at the ends produced by the continuation of a 
central inflation, rough towards the margin and on the inflation with pearly granules; e. v. 
with a rounded lobe on each side. Sporangium orbicular, spinous; spines elongated, dilated 
at the base and slightly divided at the e.xtremity, 5J3". (Archer.) 

C. coinnii!$!i«iiraIe, (Breb.) 

C. minutum, fere dimidio latins qnani longum, profundi.ssime constrictum, sinu amplo basi ex- 
cavato; seniicollnlis angusto renifcn-milius, diametro jiaene trijilo longioribu.s, leviter inciuvis, 



FRESH-WATER A L G .E OF THE UNITED STATES. 133 

angulis rotundatis, dorso truncato-rotundatis, margine crenulato-dentatis, a dorso oblongis, 
medio veutricosis, utroque polo plus minus tumidis ; cyliodermate graimlato margaritiferu. 
(R.) 

Long. 0.0010"— 0.0012." Lat. 0.0013"— 0.0015". (R.) 

Si/n. — C. commissurale, Bueblsson. Rabeniiorst, Flora Europ. Algarum, Sect. III. j). 170. 

Hab — In lacu. White Mountain.'?, New Hampshire ; (Dr. P. W. Lewis) 

Frond small, in f. v. one-third broader than long; constriction very deep, rounded ; segments 
narrow-reuiform, with a central, somewhat truncate projection, produced by the continuation 
of the central inflation, rough on the inflation and on the extremities, with somewhat large 
pearly granules, e. v. three times longer than broad, constricted between the central inflation 
and the rounded extremities. Sporangium as in 6'. ornalum. (A.) 

Remarks. — I have seen but a single specimen of this species which differed from 
the typical form, in having tlie sinus very narrow in its outer portion, and in being 
shorter. 

Fig. 16, pi. 13, represents the frond of this specimen, magnified 750 diameters. 

C caelatiiiii, Ralfs. 

C. suborbiculare, profunde constrictum ; sinu angustissimo linear! ; semicellulis inciso-crenatis, 
angulis rotundatis, a vertice medio nonnihil inflatis; cyliodermate granulato, granulis in 
series regulariter cireulares positis. 

Z»mm.— Long. -^^^V' = -00 U". Lat. t^Vstj" = -0014". 

Syn. — C. caelalum, Ralfs, British Desmidieie, p. 103. 

Hab. — In stagnis prope Aiken, South Carolina. (Ravenel.) 

Suborbicular, profoundly constricted; sinus very narrow, linear; seraicells inciso-crenate, 
angles rounded, when seen from the end somewhat inflated in the middle ; cytioderm granu- 
late, granules placed in circular series. 

Remarks. — This species was collected by Prof Ravenel in a quiet ditch near 
Aiken, South Carolina, sparsely scattered amidst innumerable diatoms and desmids. 
The number of the crenations appears to vary. In the few individuals I have seen 
there were six end ones besides the two very broad basal ones, if the latter can be 
called crenatures. Ilalfs gives six as the total number,, and yet every one of his 
figures has many more. So I think the number a character of but little import- 
ance. The circular arrangement of the granules is not so positive and regular in 
the specimens I have seen, as is represented in the figure of llalfs, otherwise the 
agreement is perfect. 

C. Brooinei, Thwaites. 

C. subparvuni, plcrumque tam longum quam latum, nonnunquara paulo longius, obtuse quad- 
rangulare, profunde constrictum, sinu angustissimo lineari ; semicellulis oblongo-quadrangulls, 
diametro duplo longioribus, angulis et inferioribus et superioribus ol)tuse rotundatis, ventre 
subplanis, dorso latissime truncatis et saepius leniter retusis vel plane convexis; cytioder- 
mate granulato-margaritaceo, granulis in seriebus subrectis collocatis. (R.) 

Long, 0.00194"— 0.0022". Lat. max. .002", thick .0015". 

Syn. — C. Broomei, Thwaites. Ralfs, British Desmidie*, p. 103. 

Eab. — Georgia; Bailey. Prope Philadelphia ; Wood. 



l;}4 FllESn-WATER ALGiEOr THE UNITED STATES. 

Froiul ill f. V. about as long as broad, constriction deep, linear; segments quadrilateral, ends 
straigiit, angles rounded, rough all over with minute granules ; e. v. twice as long as broad, 
sli'i-htly iiiihited at the middle and rounded at the ends. Sporangium orbicular, smooth. (A.) 

Remarks. — Tlie only specimens which I have seen were found in a brick-pond 
below the city in the month of June. They agree well with the descriptions, ex- 
cepting in that I should descril)e their central inflation as pronounced. The sinuses 
also are ampliate or hollowed out within. The granulations are quite large, and 
are arranged somewhat irregularly in rows. 

Fi". 15, pi. 13, is a view of the front of the frond magnified 460 diameters; 
fig. 10, pi. 21, the outline of the lateral view. 

c. Ccllula; f US/formes, cylindricse vel ovales, in medio leviter constrictse. 

c. Cells fusi for in, cylindrical, or oval, liijhlly constricted in the middle. 

C. Tliw.TiJesii, T.alfs. 

C. mediocre, diametro bi-triplo longius, fusiforrai-cylindraceura, medio leviter constrictura, am- 
bitu integerrimum, utruque polo ri.itundatuin ; sfmicellulis e cylindraceu subconicis, e medio 
in apicem sensim sensimque (sed modice) attenuatum; cytiodermate laevi vel indistincte punc- 
tate. (R.) Species inihi ignota. 

Long. 0.0026t"— 0.00287". Lat. mas. 0.0012". (R.) 

Syn. — C. Tliwaitesii, Ralfs, British Desraidiese, p. 109. 

Ilah. — Florida ; Bailey. 

Frond in f. v. two or three times longer than broad ; constriction a very shallow groove ; seg- 
ments subcylindrical, with vouuded ends ; endochrome scattered ; e v. circular, or very slightly 
compressed ; e. f. not punctate, or puncta very indistinct. (A.) 

€. connatiim, Breb. 

C. validum, sulimagnum, leviter eompressura, diametro duple circa longius, subpandnriforme, 
plus minus constrictum, utroque polo late rotundatum, a vertiee lato ellipticum; semicellnlis 
subhemisphasricis, ambitu sequabiJiter rotundatis, integcrrimis ; cytiodermate punctate. (R.) 
Species mihi ignota. 

Long. 0.0035". Lat. ma.x. 0.00165"— 0.0019". (R.) 

Sf/n. — -C. connatiim, Brebisson. Ralfs, British Desmidicfe, p. 108. 
Ilab. — Florida; Bailey. 

Frond large, in f. v. about one-half longer than broad ; constriction shallow ; segments about 
two-thirds of a circle, coarsely punctate, and with a distinct, sometimes striated, border; e. v. 
circular. (A ) 

d. Gellulae in familias connexse. 
d. Cells united into families. 

C. <(llillil>yii, Wood. (sp. nov.) 

C. cellulis parvis, sub-ellipticis, medio profunde constrictis, in familias eopulis hyalinis con- 
nexis; scmicellulis a fronte ellipticis et diametro subduplo longioribus, a vertiee ellipticis, a 
latere rotundatis; sinu lato; marsis chlore-phyllaceis in quaque semicellula singulis; cytio- 
dermate tenue, glabre. 

/)iani._Long. „>^" = 0.001". Lat. a fronte ^i^^" = 0.00075" ; a latere jj-J^/ = 0.00042". 
Hab. — In aquis puris, New Jersey. 



I FRESH-WATER ALG^ OF TUE UNITED STATES. I35 

Cells small, subelliptical, profoundly constricted in the middle, joined by translucent bands into 
families; semicells seen from the front elliptical, and nearly twice as long as broad, from the 
vertex elliptical, from the side roundish; sinus broad ; clilorophyl masses single in eucli cell • 
cytioderm thin, smooth. 

I Remarks. — This plant was found by my friend Mr. Quimby growing in a beau- 
tiful spring above Camden, upon whose bottom it formed a gelatinous, trans- 
lucent, greenish mass. The cells resemble in sliape those of C. ciicumis, although 
much smaller. They arc joined by bands into little families, in which the original 
parent-cell is generally very distinct, it, or rather the two cells into which it first 
divides, remaining in the centre of the group. The bands are so hyaline that their 
edges can alone be distinctly seen, and hence the latter often look as tliough they 
were threads — there appearing to be two parallel threads, or two threads crossing 
one another, or a single thread, according as the band is fiat, twisted, or on edge. 

It gives me great pleasure to dedicate the species to my friend Mr. Quimby, by 
whom it was collected. 

Fig. 9, pi. 1, represents one of the family groups of this plant. 

Genus EUASTRUM, Ehrb. 

Cellulae vel oblongiB vel ellipticiB, medio profunde incisoe, symmctrice siimatte, vel lobatae, tumori- 
bus inflatis circularibus (rare obsoletis) instructae, utroque polo sinuato-emarginatse vel intiso-bilo- 
batiE, a vertice ellipticae. 

Cells either oblong or elliptic, profoundly incised in the middle, symmetrically sinuate or lobcd, 
provided with circular inflated protuberances (which are rarely absent), at each end sinuately emar- 
ginale or iucisely-bilobate, from the vertex elliptic. 

A. Lobo polares in apice late sinualoexcisi. 

A. Polar lobe with its apex broadly sinuately excised. 

E. multilobatiiin, Wood. 

E. magnum, fere duplo longius quam latum, medio profunde constrietum, et cum siuu modice 
amplo ; a latere medio ventricosum et duplo biumbonatum, ad verticem dilatatum et emar- 
ginatum ; semicellulis a fronte trilobatis, lobis sinus amplissimis inter se sejunctis ; lobi basale 
distincte late emarginato, lobo eentrale obtuso, lobo polare late leviter sinuato-cmargiuato ; 
semicellulis a vertice quinque lobulatis; cytiodermate loevi. 

2)iam.— Long. ^^V^^" = -00475". Lat. ^/fV = 0025". 

Syn.—E. mullilobalum, Wood, Proc. A. N. S., 1869. 

Hob. — In lacu "Saco;" New Hampshire ; (Lewis.) 

E. large, about twice as long as broad, in the centre profoundly constricted, with the sinus 
moderately large ; from the lateral view somewhat enlarged and doubly biumbonate in the 
middle ; semicells from the front trilobate, the lobes separated by very wide sinuses, the basal 
lobe broadly emarginate, the central lobe obtuse, the end lobe broadly and shallowly sinuately 
emarginate ; semicells from the vertex five-lobed ; cytioderm smooth. 

Remarl's. — The basal lobes of this beautiful desmid are distinctly five lobulate, 

the lateral lobules being longer and broader than the others, which, instead of 

i being emarginate, are obtuse. The sinuses, separating lobes and lobules, are very 

! broad, with very obtuse angles. When the desmid is viewed from two-thirds 

I round, so as to show the anterior and posterior lobides especially, it presents an 



136 FRESn-WATER A L G ^E OP THE UNITED STATES. 

outliue in which all the sinuses are of similar form, and the central and basal lobes 
are about equal size; whereas, when viewed from the front, the basal lobe is much 
tlie broader. When the desmid is viewed from the side it is seen to be enlarged 
in the centre, and provided with two distinct umbonations each side of the com- 
paratively narrow central sinus. 

Fig. 10, pi. 12, represents tjic front view of a frond of this plant; fig. 5, pi, 20, 
the outline of a two-thirds view, and tig. 5 a, the outline of a lateral view, all mag- 
nified 450 diameters. 

E. Terrucosiini, Eiirb. 

E. maginira, late ovatum, vix longius quam latum, medio profundo constrictum, sinu extrorsum 
dilatato; souiicellulis trilobatis, lobis triangularibus, divergeutibus, apice late et profunde 
sinuatis ; a latere ovato-oblongum, siiiuato-lobatum, lobis octo in apice rotuudatis, polaribus 
singulis porrectis, latcralibus teruis ; cytiodermate granulato-verrucoso. (R.) Species mihi 
iijnota. 

Long. 0.0036"— 0039". (R.) 

Syn. — E. verrucosum, Eheenbero. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 119. 

JJab. — South Carolina ; Georgia ; Florida ; Rhode Island ; Bailey. 

Frond somewhat longer than broad, rough all oyer with conic granules ; segments 3-lobed, 
somewhat divergent, all the lobes broad, euneate, with a. very broad, shallow, or external 
sinus. Empty frond; f. v. segments with one large circular basal inflation on surface, one 
smaller on each side, and two others on the end lobe ; s. v. segments inflated at the base, 
narrowed into a short neck, end dilated with a central sinus ; e. v. oblong, with three infla- 
tions at each side, one at each end, end lobe having 4 divergent lobelets. (A.) 

E. ^e IIS 111 a til 111, Breb. 

E. mediocre, diametro duplo longius, profunde constrictum, sinu angusto lineari, a vertice ovato- 
oblongum, ambitu sinuato-lobatum, lobis 8 couforraibus, rotuudatis ; semicellulis trilobatis, 
basi tumoribus 3 in seriem dispositis, lobis in apice profunde emarginatis, lobulis rotundatis, 
lobo polari dilatato et paulum producto; cytiodermate in tumoribus et lobulis granulato- 
punctato, ca;teruin laivi. (R.) Species mihi ignota. 

Long. 0.00224"— 0.0029". Lat. 0.00157'- 0.001*7". (R.) 

Syn. — E. gemmatum, Brebisson. Rabenhorst, Flora Europ. Algar., Sect. III. p. 180. 

Hab. — Rhode Island ; Bailey. 

Frond scarcely twice as long as broad; segments 3-lobed, lateral lobes horizontal, deeply emar- 
ginate, the protuberances minutely granulate ; end lobe dilated, its dilatations inclined 
upwards, and minutely granulate ; ends with a deep rounded emargination. Empty frond 
slightly punctate ; f. v. segments with three granulate inflations near the base ; fr. v. broadly 
elliptic, with three granulate inflations at each side and one at each end ; e. v. end lobe cruci- 
form, lobelets rounded, granulate. (A.) 

E. obloiig^iiin, (Grev.) Ralfs. 

E. magnum, diametro duplo triplove longius, oblongum, profunde constrictum, sinu angnsto, 
a latere oblongo-lanceolatum, utroque polo truncato leniter retusura, ambitu undulato- 
sinuatum ; semicellulis (fronte) sinuato-quinquelobis, basi et in quoque lobo tumore instrnctis, 
lobis lateralibus in apice dilatato sinuato-retusis, inferioribus latioribus quam superior., lobo 
polari late euneato in apice profunde inciso, angulis omnibus rotundatis, cytiodermate la;vi ; 
zygosporis globosis verrucosis, verrucis obtuse conicis achrois hyalinis. (R.) Species mihi 
ignota. 



FRESH-WATER ALG.E OF THE UNITED STATES. 137 

Long. 0057"— 0.0065". Lat. max. 0.00346". 

Syn. — E. oblongum, (Greville) Ralfs' British Desmidiese, p. 80. 

Hab. — Rhode Island ; Bailej. 

Frond rather more than twice as long as broad, smooth, oblong; segments 5-lobed; lobes nearly 
equal, cuneate ; lateral lobes, or the Ijasal only, with a broad, shallow, marginal concavity, 
all their angles rounded, terminal noteli linear. 

Empty frond; f. v. seg. punctate, with three large inflations, on surface near the base, two 
others above and two on terminal lobe; tr. v. three times as long as broad, with three sul- 
distant marginal inflations at each side, and one at each end, in /3, broader in proportion, 
more elliptic, and inflations close; e. r. end lobe notched at opposite external margins. 
Sporangium orbicular, beset with numerous conical tubercles. (A.) 

B. Lohi polares evidenter discreti ct in apice anguste incisi. 

B. End lobes evidently separated and narrowly incised in the centre. 

E. crassuni, (Breb.) Ktz. 

E. oblongum, dianietro subtriplo longius, profuude constrictum, sinu angusto lineari, e vertice 
subquadrangulare, utroque polo profunde e.xcisum, angulis rotundatis ; seuiicellulis (fronte) 
trilobis, basi et in quoque angulo tuniore instruetis, lobis lateraliljus latissimis unisinuatis, 
lobo polari panllum prominente, in apice bifido, segmentis late rotundatis; cytiodermate dis- 
tincte punctato, punctis in series transversas ordinatis. (R.) 

Long. 0.0051"— 0073". Lat. mas. 0.0041". (R.) 

Syn. — E. crassum, (Brebisson) Kltzing Rabenhorst, Flora Europ. Algarura, Sect. III. 

p. 181. 
Uab. — United States. 

Frond about twice as long as broad, subquadrilateral, smooth; segments 3-lobed ; basal lobes 
very broad, with a very broad, shallow marginal sinus, in which there is sometimes a slight 
intermediate rounded projection ; end lobe creueate, rounded, terminal notch linear. 

Empty frond ; f. v. punctate, segments with three inflations below and two above ; tr. v. two or 
three times longer than broad, with three lobes or inflations at each side and one at each end ; 
e. V. end lobe sinuate at opposite external margins. (A.) 

E. oi'iiatiiBii, Wood. 

E. oblongum, diamctro duplo longius, profunde constrictum, sinu angusto lineari ; semiccllulis 
a fronte trilobatis; lobis basalibus latissimis, nonniliil sinuato-emarginatis, angulis plus minus 
productis ot rotundatis; lobo polari medio profunde lineare iiiciso, segmentis late rotundatis; 
semicellulis a latere bilobatis, lobis basalibus profunde emargiuatis et cum angulis plus minus 
acutis ; cytiodermate distincte ordinatim punctato. 

Diam.—jJ'^^js" = .00029". 

Syn.—E. ornatum, Wood, Proc. A. N. S., 1869. 

Hab. — Saco Lake ; Xew Hampshire. Lewis. 

E. oblong, twice as long as broad, profoundly constricted ; semicells from the front trilobate ; 
basal lobe very broad, slightly sinuately-emarginate, angles more or less produced and 
rounded ; polar lobe mediauly profoundly linearly incised, segments broadly rounded ; semi- 
cells bilobate at the sides, basal lobes profoundly emarginate and with the angles more or 
less acute ; cytioderm distinctly regularly punctate. 

Remarl-s. — This species is close to E. crasswn, from Avhicli it differs in the pro- 
portionate lenpjth, being only twice instead of three times as long as broad ; in the 
size being only three-fourths as large ; and especially in the peculiar lateral split- 
ting, as it were, of the basal lobes. 

IS July, 1872. 



138 



FRESH-WATER ALG.E OF THE UNITED STATES. 



1m-'. ri, 1)1. 21, rrprescnts tlio front view oi' an empty half frond of this species, 
raasnificd'iJO diameters; fig. 12 a, the side view of au empty frond. 



E. alliiii', Kalfs. 

E. E. liumcTosum affine, paulo minus ; semicellulae quinquelobae ; lobi basales quales in E. hume- 
rosum scd tumores quataor iu serieui trausversam siinplicuin dispositi, lulii iiiterniedii valde 
abbreviati eoi-umquc basi tumoribus duobus instructi, lobus polaris magis porrectus et in 
apice minus dilatatus; cytiodema subtilissime punctatum sublaive. (R.) 

Long. 0.003S"— 0.U041". (K.) 

Syn.—E. offiiic, IIalfs, British Desmidecc, p. 82. 

Bah. — South Carolina; Georgia; Bailey. 

Frond aljout twice as long as broad; segments 3-lobed ; basal lobes slightly eraarginate, 
havin"'- intermediate between tliem and tlie end lobe on caeli side a tubercle representing 
middle lobes, the upper margin of wliieb is horizontal ; end lobe exsertcd, dilated, its notch 
linear. 

Emiity frond ; f v. minutely punctate ; the segments with four basal inflations, two above and 
two on end lobe ; tr. v. elli])tic, with four inflations on each side and one at each end; e. v. 
end lobe emargiuate at opposite ; e. v. end lobe emarginate at opposite external margins, 
producing four shallow lobulets. (A.) 

E.Didelta, (Turpin) Ralfs. 

E. robustum, diametro duplo longius etiara supra, in sectione transversa ellipticam, ambitu un- 

dulato-crenatum, in utroijue latere crenis quaternis ; seraicellulis pyramidal ibus, quinqueluhis, 
tumoribus 9 in series tres alternantibua oi'dinatis, lobis inferioribus oblique truncato-rotundatis 
nonnunquam leuiter retusis, intermcdiis subadscendentibus, rotundatis, lodo polari minus 
dilatato, bifido, scgmentis rotundato-truncatis, eoniiiventibus, in apiee tumidis ; cytiodermate 
distincte jtunctato, punctis modo irregulariler sparsis modo io scriebus reclis collocatis. (K.) 

Long. O.OO.'JS". Lat. 0.00279". 

Syn. — E.Didelta, (Turpin) Ralfs, British Desmideae, p. 84. 

Hah. — South Carolina ; Georgia ; Rhode Island ; Bailey. Pennsylvania; Wood. 

Frond rather more than twice as long as broad; segments pyramidal, inflated at the base and 

again at the middle, cud scarcely dilated, rounded, its notch linear. 
Empty frond punctate ; f v. segments with several inflations in lines and two at the end ; tr. v. 

elliptic with four inflations at each side and one at each end ; e. v. end lobe entire at margin. 

Sporangium orbicular, with subulate spines. (A.) 

Eemarh. — Fig. 13, pi. 21, represents this species. 

E. ainiiiillac'cuiii, Ralfs. 

E. diametro duplo longius ; seraicellulis trilobis, ad basin tumidis, e basi lati.ssiraa subito in lobi 
polaris collum attenuatiS; !o!)is liasalilnis maximis integris, loco loborum intermedioniiu pro- 
cessu deutiformi, lobo polari cuncato, in apice bifido, segmentis late truncato-rotuudatis; 
cytiodermate subtiliter punctate. (R.) 

Long. 0.0035"— 0.0038". Lat. max. .0026"; lat. in colli (lobi polar.) 0.00085". (R.) 

Syn. — E. ampuUacciim, Ralfs, British Desmideae, p. 83. 

Eab. — South Carolina ; Florida ; Bailey. 

Frond rather more than one-half longer than broad ; segments obscurely 3-lobed, short, with 
broad inflated base ; basal lobes not emarginate, having on each upper side a small inter- 
mediate tubercle between each and the end lobe ; cud lube exserted and dilated, its notch 



FRESn-WATEIl ALG^ OF THE UNITED STATES. I39 

linear. Empty frond minutely punctate ; f. v. narrow elliptic, with several inflated protube- 
rances, ends scarcely dilated, rounded; tr. v. with four inflations at sides and one at each 
end. (A.) 

circiilare, IIassal. 

E. mediocre, diametro duplo longius; seniicellulis trilobis (at non semper distincte), ad basin 
versus tumoribus qiiini.s aut pluribus iu series dua.s v. tres alternantes aut singulo central!, 
quaternis semicircularitcr ordinatis instructis, lobis basalibus siuuato-eniarginatii^, subitu in 
lobum polarem apice paullum dilatatum attenuatis; cytiodermate subtilitcr punctato. (R.) 

Syn. — E. circulare, Uassal, Fresh-Water Algaj, p. 383. 

llab. — Providence, Rhode Island ; Bailey. 

"Frond about twice as long as broad, tapering upwards into a nock, end not dilated, its notch 
an acute incision. Empty frond, segments with live Iiasal inflations, four iu a half circle 
around the fifth and two others at the e.\tremity." Archer. 

(Tar. Kalfsii) 

Semicellula tumoribus minimis 11 in series tres alternantes ordinalis. 

Eab. — Saco Lake, New Hampshire ; (F. W. Lewis) Wood. 

E. Jenneri, nobis. Frond scarcely twice as long as broad; segments 3-lobcd, basal portions 
subqnadrate, eniarginate at the sides ; end lobe, its notch linear. Empty frond punctate, 
segments with several inflations arranged in alternate lines. (Arelior.) 

E. iiisig^ne, Hassall. 

E. subgracile, diametro duplo-triplove longius, a vertice fere quadratum, lateribus eoncavis, 
angulis rotundatis; seniicellulis basi iiiflatis, integris,e basi subreniformi in colluin elongatuni 
citius attenuatis, lobo polari dilatato bifido truncato ; cytiodermate subtiliter punctato. (Pi.) 

Long. 0.0039"— 0.0043". Lat. mas. 0.00230". (R.) 

Syn. — E. insigne, Hassall, Fresh- Water AlgEe, p. 21. 

Hub. — Florida; Rhode Island; Bailey. 

Frond rather more than twice as long as broad ; segments inflated at base, sides entire, without 
lateral tubercles, and tapering into a long slender neck ; end lobe dilated, its notch linear. 
Empty frond minutely punctate ; f. v. segments with two inflations at the base ; f v. narrower, 
gradually tapering to the end, which is considerably dilated; projections rounded, with a 
sinus between ; tr. v, subquadrate, slightly concave at sides, with a rounded lobe at the 
centre of each end ; e. v. end lobe with a sinus at opposite external margins, angles thus 
protruded into four divergent rounded lobeluts. (A ) 

E. Rair!«ii, Rabenh. 

E. mediocre, leviter compressum, medio inflatum, diametro duplo circiter longius ; seniicellulis 
pyramidalibus, e basi ventricosa in lobum i)olarem rectum truncatnm siiiuato-atteiiuatis ; 
cytiodermate subtiliter punctato, punctis in liueas rectas ordinatis. (R.) 

Syn. — E. ansatiim, Eur. et auctores. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 1S4. 
E. Ralfsii, Rabenhorst, Flora Europ. Algarum, Sect. III. p. 184. 

Hab. — South Carolina ; Rhode Island ; Bailey. White Mountains, New Hampshire (F. W. 

Lewis). 

"E. ansatum, Ehrb. Frond aljout twice as long as broad; segments inflated at the base, taper- 
ing upwards without sinuations into a neck, end not dilated, rounded, its notch linear. Empty 



140 ERBSII-WATER AhGJE OP THE UNITED STATES. 

frond punctate; f. v. segments turgid on the surface, at the middle without circular inflations; 
tr. V. ellii)tic, witli a single largo inflation at each side ; c. v. end lobe entire at the margin, 
its divisions circular. (A.) 

Remarhs. — I have seen only a very few specimens in a gathering made in Saco 
I>akc, New Hampshire, by Dr. Lewis, which difter considerably from the typical 
form in the proportion of the breadth and length. There are also certainly four, 
if not more, umbonations on the face of each half-cell. These are nowhere dis- 
tinctly spoken of as existing, and Mr. Archer states there are none visible in the 
front view of E. ansatum. They are, however, represented in the side view of the 
original figure, and are said to be very noticeable by Mr. Archer himself, when 
the desmid is so looked at. In the Saco Lake specimens they are always seen in 
the front view with great difficulty, and in some cases I failed entirely to demon-' 
strate them, so that they do not aftbrd a good character for the indication of a new 
species. 

Fig. 1, pi. 13, represents a front view of a Saco specimen, magnified 450 dia- 
meters. 

G. Lobi polares non-evidenter discreti. 
C. End lobes not evidenthj distinct. 
E. ele^ans, (Breb.) Ktz. 

E. minus, oblonguni, dianietro dujtlo longins, utroque polo bifidum, segnientis introrsnm rotun- 
datis; scmicellulis sursum modice attenuatis, utroque margine laterali bi- vel tri- siuuatis, 
sinu superiori vel intermedio profundiori, sub polo utrinquo dente acute prominente ; eytio- 
dermate subtiliter punctato, punctis irregulariter sparsis ; zygosporis globosis aculeatis, 
aculeis elongato-sulmlatis. (11.) 

Long. 0.001 2"._0.002". Lat. max. circiter 0.001 1". (R.) 

Syn. — E. elegans, (Brebisson,) Ktjtzino. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 
185. 

Sab. — South Carolina; Georgia; Florida; Rhode Island ; Bailey. White Mountains, (F. W. 
Lewi.s). 

Frond minute, scarcely twice as long as broad, oblong; segments with their basal portion emar- 
ginate at the sides, connected by a broad neck with the terminal portion ; ends protuberant, 
rounded, acutely emarginate at the centre, pouting; s. v. with an inflation at the base of the 
segments, sides concave, ends rounded. Sporangium orbicular, spinous. (A.) 

Remarks. — According to Prof Rabenhorst E. rostratum, Ralfs, whicli is noted 
as an American species by Bailey, is a variety of E. elerjans. Its peculiarities, ac- 
cording to Rabenhorst, are as follows : " Forma magis evoluta, profundior sinuata, 
segmentis polaribus latioribus, angulis acutis, dente paulo longiore." 

Fig. U, pi. 21, represents the outline of the frond as viewed laterally; fig. 2, 
pi. 13, a front view of the frond, magnified 750 diameters. 

E. biiiale, (Turpin) Ralfs. 

]•]. niiiiinunn, dianietro paulo vel suljduplo longius, in sect, transversa oblongo-cylindricnm, 
medio tuniidum, utroque polo roluudatum ; semicellulis indistincte trilobis, lobis basalibus 



PRESII-WATER AhQM OF THE UNITED STATES. Ul 

latis, rotundatis vel siuuato-bi- tricrenatis ; lobo polari abbreviato late truncate, leviter cinai-- 
ginato, augulis acutis lateraliter plus minus porrectis ; cytioderinate subtilissinie punctate). 

Sijn. — E. hinale, (Turpin) Ralfs, British Dcsmidca;, p. 90. 

Bab. — Florida; Bailey. Pvhode Island, (S. T. Olney,) Thwaitcs. Pennsylvania; Wood. 

Frond very minute, scarcely twice as long as broad, oblong ; segments with their basal ])ortion 
either entire or bicrcnate at the sides, slightly contracted beneath the ends ; ends dilated, ncit 
protuberant beyond the angles, its central notch acute, broad ; tr. v. with two lateral infla- 
tions, end.s truncate, angles rounded. (A.) 

Hemarh. — Fig. 3, pi. 13, represents the front view of a frond, ningnified 750 
diameters. 

Genus MICRASTERIAS, Ac. (1827). 

Cellulaj compressa3, profunde constrictoe, a frontc orbiculares vel late ellipticre, a vcrticc fusiformcs 
cum utroquo polo acuto, semicellulae tri- vel quinque-lobaB ; lobi basalcs aut integri aut pluriplicitcr 
inciso-lobulati ; lobus polaris aut integer aut sinuatus aut emarginatus, et interdum angulis prodiic- 
tus et bifidus. Cytioplasma chlorophyllacea in celluls lumen subsqualiter <]istriliu1a, granula 
amylacea sparsa iuvolveus. Cytioderma plerumque la;ve, uonauuquam punctatum, granulalum vel 
mucronatum. 

Zygosporoe globosas, setate provecta acukis simplicibus, apicc bi- multi- fidis, nonnunquam repetito- 
multiliidis arniataj. 

Cells compressed, profoundly constricted, viewed from the front orbicular or broadly elliptic, from 
the vertex fusiform with acute ends. Semicells 3- or 5-hjbed ; basal lobes cither entire or many 
times incisely-lobulate ; end lobe either entire or sinuate or eraarginato, and sometimes with its angles 
produced and bifid. Chlorophyllous cytioplasm distributed nearly uniforndy in the cavity of the 
cell, surrounding scattered starch granules. Cytio<lerui mostly smooth; sometimes punctate; 
granulate or mucronate. 

Zygospores globose, at maturity armed with simple spines, whose ends bifid or nmllilid, and some- 
times repeatedly multifid. 

A. Semicellulas (rilohae. Lobi bamles horizonlales ; lobus polaris valcle tlitalafus, dorxo plane 
convcxus, truncatus vel leoiter relusus, a lobis basalibus sinii amplissimo disc7-elus. 

A. Semicells trilobate. B(i!<(il lubes horizontal ; end lobe strou<jhj dilated, with lite back con- 
vex, truncate, or slightly retuse. 

M. arciiata, Bailey. 

M. mediocris, quadrangularis, paulo latior quaui longa, profundi; pinnatifida; lobis basalibus 
angustis elongatis, arcuatis, in apicem acutum attenuatis, divergentibus; lobis i>olaribus 
angustusimis, utrinque graciliter productis, in apieem acutum attenuatis, in medio dorso 
modice retusis. (R.) 

Sijn. 31. arcuata, Bailey, Microscopical Observations : Smithsonian Contributions, vol. ii. 

Hab. — In stagnis. Florida; Bailey. 

" Quadrangular, segments three-lobed, the basal lobes long and arcuafe, subtcndcil by the trans- 
verse projections from the ends of the slightly notched terminal lobes." (Bailey.) 

M. e\pansa, Bailey. 

M. mediocris, tarn longa quam lata, lobis stellatira e.xi)ansis; lobis basalibus angustis in apicem 

acutum attenuatis, divergentibus, rectis; lobis polaribus e basi angusta sensim dilatatis, in 

medio dorso late sinuatis, angulis acutis (sed muticis). (Pv..) 
Syn. — M. erpansa, Bailey, Microscopical Observations : Smithsonian Contributions, vol. ii. 
Hab. — In stagnis, Florida; Bailey. 



142 FRESH-WATER ALGJ5 OF THE UNITED STATES. 

Segments tliree-lolied, basal lobes long, subeonical, acute ; termina. lobes slcndor, forked at the 
end, with the divisions much shorter than the basal lubes. (Bailey.) 

jTI. qiiadrala, Bailey. 

M. areuatae siniilis, sed duplo major, -semieellularum lobi basales minus arcuati, basi inQati, 
apice bidcntati et cjtioderma irregulariter granulatum. (R.) 

Z»ia?n.— 0.0043"— 0.0049". 

Syn. — M. quadrala, Bailey, Microscopical Observations : Smithsonian Contributions, vol. ii. 
Large quadrangular, three-lobed, basal lubes elongated, slightly curved, bideutate ; terminal 
lobes with two slender transverse bidentate projections. Bailey. 

III. flispiitata, Wood. 

M. magna, fere tarn longaquam lata, subpinnatisecta, sinu acuto, lobisaeqnalibus ; scmicellulispro- 
funde trilobis, lobis basalibus in apieem acute bidentatum valde attenuatis; lobo pulari valde 
dilatato, dorso rotundato, angulis lateralibus acutissimis. 
Long. ^15/=. 005". Lat. 7|g^" = .004". 

Syn. — 3Iicrasterias iiicisa, Ktz. Bailey, Microscopical Observations: Smithsonian Contribu- 
tions, 1860. 
Haud llicrasteria iucisa, Kutzing, Spec. Algarum, p. 171. 
Tetrachastrum Amer-icaiium, Akcu.'E.b., Pritchard's Infusoria, 1800, p. 725. 
Hah. — South Carolina; Georgia; Florida; Rhode Island ; Bailey. Penn.sylvania ; Wood. ' 

M. large, about as long as broad, subpinnatisected ; sinuses acute; semicells profoundly trilo- 
bate ; basal lobes strongly attenuate into the acutely bidentate apex ; distal lobes strongly 
dilated, rounded, with their lateral angles bidentate ; end lobe broadly dilated, lateral angles 
very acute. 

Remarks. — This desmid was first figured by the late Prof. Baik^y in his Micro- 
scopical Observations (Smithsonian Contributions), as M. iucisa of Ktz., and Ra- 
benhorst, in his Flora Europaea Algarum, confirms this identification. He has 
probably, however, never seen the plant itself, but merely accepts the opinion of 
Professor Bailey. Mr. Archer (Pritchard's Infusoria), thinks the American plant 
is certainly distinct from the European, and this seems to me correct. The points 
of difference are — the American form is nearly twice the size of the European, the 
sinuses are much more widened outwardly, and the lobes are reduced rapidly in 
breadth to a mere point at the end, the dorsum of the distal lobes is also, I believe, 
more rounded. In his description of T. Americanum, as he calls it, Mr. Arclier 
states the end lobe has its angles bidentate. In the only specimen I have seen, 
the angles end in a very sharp, almost spine-like point. Dr. Leidy found the spe- 
cies abiuidantly at Newport, Rhode Island, and his figure agrees with mine in this 
respect. In regard to the name, as there is already an M. Americaniim, the specific 
name of Archer cannot be adopted, and for a similar reason it would not do to call 
it 31. BaiJeyi. I have then been forced to give it a new title. 

Fig. 4, pi. 13, was drawn by myself from the single specimen I have seen; fig. 
4 a was drawn by Dr. Leidy from a Newport specimen. 

M. oscitans, Ralfs. 

M. magna, poena tarn longa quara lata, subpinnatisecta, a vertice elliptico fusiformis, utroque 
polo bifida; lobis basalibus horizontalibus conico-productis, apice bilidis; labo polari a lobis 
basalibus sinu aniplo ac rotundato disercto, plus minus cnnvexo, haud raro truncato, rarius 
leviter retuso, utririque producto acuminato, plerumque bidentato. (R.) 



FRESH-WATER ALG^ OP THE UNITED STATES. 143 

Z)ta?n.— 0.0047". Long. 0.0039". (R.) 

Syn. — M. oscitans, Ralfs, British Desmidiese, p. 76. Rabenhorst, Flora Europ. Algarum, 
Sect. III. p. 119. 
M. pinnalifida Ktz. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 119. 

Eah. — Florida; Rhode Island; Bailey. 

Frond about as broad as long, pinnatifid; lateral lobes separated from the terminal by a rounded 
sinus, horizontal, conical, their extremities bideatate ; end lobe short, broad, its lateral pro- 
jections short, conical, usually bidentate, narrower and shorter than the lateral lobes ; ends 
convex at the centre; tr. v. fusiform, e. f. punctate. (A.) 

Remarhs. — According to Prof. Rabenhorst M. j){nnatifida, Ktz., is a variety of M. 
oscitans, different from the typical form only in being smaller, and in having the 
lobes narrower. 

B. Semicellulas 3-vel b-lohx, pleruvique radiatim inciso-lobulatse. Lobi basales assurgentes 
aut non aut minus a lobo polari remoli. 

B. Semicells 3, or b-lohate, mostly radiately incisely lobulate. Basal lobes assurgent, either 
close to, or but slightly remote from the end lobes. 

* Semicellulae trilobx. 

' * Semicells trilobate. 

HI. Americana, (Ehrb.) Ktz. 

M. magna, oblonga, subpinnatiseeta, lobis polaribus paulum remotis, paene duplo longior quam 
lata; eytiodermate spiuuloso unde laborum margiues dentato-serrati couspiciuiitur ; collula 
e latere conspecta oblonga, in medio leviter constricta. utroque polo bicoruuta; semicelluliB 
basi tumoreplus minus distincto instructae, fere quinquelobfe, lobis basales lati.ssimi ii.-^deiiique 
profunde bilobati, lobulis late e.xcisis, scgmentis dentato-serratis; lubis polaribus plus minus 
productis, in medio late cxcisis, segmentis profunde bifidis. (R.) 

Diam.—Q.WiV. Long, circa 0.0051". (R.) 

Sifn. — M. Americana, KiJTZi.VG. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 189. 

Hab. — In stagnis. South Carolina; Florida; Bailey. 

Frond angular elliptic, more or less punctate; segments o-lobed ; lateral lobes broad, cuneate, 
their margins concave, inciso-serrate ; and lobe broad, cuueate, end exserted, bipartite at the 
angles, the subdivisions narrow, and minutely dentate at the extremities ; end concave. (A.) 

RemarTc. — Fig. 17, pi. 12, represents a plate of this species. 

M. Baileyi, Ralfs. 

M. parva, oblonga, granulata ; semicellulis trilobis, lobis basalibus a lobo polari sinn amplo 
discretis, excisura acute triangular! ill duas lacinias partitis, laciniis e basi latiori in apicem 
truncatum bidentatura attenuatis; lobo polari e basi angusta longe porrecto, sursum valde 
dilatato, in vertice leviter et late sinuato, angulis truncate, bidentato. (R.) 

Syn. — 31. Baileyi, Ralfs, British Desraidieoe, p. 211. 

Hab. — New York; Rhode Island ; South Carolina; Florida; Bailey. 

Frond granulated ; segments three-lobed ; lobes bipartite, end one much exserted. (Ralfs.) 

M. ringens, Bailey. 

M. niediocris, oblonga, margine granulata; semicellulis trilobis; lobis lateralibus bipartitis, 
laciniis divaricatis, apjce obtusis, truncatis vel bidentatis; lobo polari e basi angusta sursum 
valde dilatato, exserto, in vertice leniter sinuato, angulis truncato. (R.) 



lU FRESH-WATER ALG^ OP TUE UNITED STATES. 

Syn.—3I. rhnjens, Bailey, Microscopical Observations, pi. 1, fig. U: Smithsoniaa Contri- 
butions, vol. ii. 

Hab Florida ; Bailey. 

Oblong, segments three-lobed, coarsely granulated near the edge ; basal lobes subdividwl by a 

deep notch into two rather broad and obtuse or slightly bidenlate projections ; terminal lobes 

exserted, emarginate ; extremities bidcntate or obtuse. 

* * Semicellulse quinque-lobatae. 

* * Semicelh b-lohed. 

W. truncatn, (Corda) Breb. 

M. magna, orbicularis, aut lisvis aut subtiliter punctata; scmicellulis quinqnelobis, lobis inter 
se sinu obtusangulo subangusto discretis, basalibus et intermediis inciso-lobulatis, segmentis 
acute bidentatis; lobo polari late cuneato, in dorso truucato, niodo leviter convexo, modo 
leviter retuso, angulis aut bidentatis aut integris. (R.) 

Dwm.— 0.003" Long. .003G". 

Sijn. 31. truncata, (Corda,) Brebisson. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 

191. 
Bab. — Georgia; Florida; Rhode Island; Bailey. Pennsylvania; Wood. Rhode Island 

(S. T. Olney); Thwaites. 

Frond orbicular, smooth ; segments 5-lobed ; basal and middle lobes obscurely bipartite, ex- 
tremities bidentate ; end lobe very broadly cuneate, bidentate at the angles, and with a. slightly 
central concavity. (A.) 

Itemarhs. — The dimensions given above yvexe taken from the largest specimens 
I have seen, hut do not at all equal those given by Prof. Rabenhorst, his breadth 
is .0011". According to the same authority, M. crenata, Breb., is merely a variety 
of this species. 

Fig. 15, pi. 21, represents the outline of a frond of this plant. 

M. fiit'catn, Aa. 

M. perraagna paulo longior quani lata, levis ; semicellulis qninqne lobis (poene 7-lobis) ; lobis 
omnibus rectis ; lobis basalibus angustioribus, bilobulatis, lobulis bifidis, sinu obtusangulo 
vel acutangulo, segmentis liuearibus bidentatis (denticulis sajpe inasquilongis) ; lobis inter- 
mediis duplo latioribus, inciso-bilobis, lobulis iisdeni ac loboruui basaliura ; lobo polar! non- 
nihil anguste cuneato, prominulo, in apice plus minus profuude sinuato-vel undulato iuciso, 
angulis bidentatis. 

Diam.—jl%^" = .008". 

Syn. — M. rolala, Ralfs, British Desmidieai, p. Tl. 

M. fui-cata, Agardii. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 191. 

Hab. — South Carolina; Georgia; Florida; Rhode Island ; Bailey. New Jersey; Wood. 

M. very large, a little longer than broad, smooth ; semicells 5-lobed (scarcely '7-lobed) ; lobes 
all straight ; basal lobe narrower than the intermediate, bilobulate, lobules bifid, their sinuses 
acute or obtuse, segments linear, bidentate ; teeth often long and unequal ; intermediate lobes 
twice as wide as the basal, bilobate, their lobules of the same form as the basal lobe ; end 
lobes narrowly cuneate, prominent, more or less profoundly sinuately or undulately cut at 
the apex, angles bidentate. 

Remarhs. — According to Rabenhorst and others, tliere is a European form of 
this species in which the marginal teeth are wanting. This may exist in this 



FRESH-WATER ALG^ OP THE UNITED STATES. 145 

country, but I have never met with it. All the specimens which have come under 
my notice were obtained in " Shepherd's Dam," near Greenwich, Cumberland 
County, New Jersey. None of them were as large as the maximum of the European 
measurements of which Rabcnhorst gives 0.0109" as the diameter. 

Fig. 5, pi. 13, represents a frond of this species, magnified 260 diameters. 

M. denticiilata, Breb. ? 

M. permagna, paulo longior quam lata, Ijevis; semicellulis quinquelobis (psene 9 lobis) ; lobis 
intermediis et basalibus simillimis, bilobatis, lobulis item in lobulis bifulis duobus divisis ; 
lobo polare angusto, cuneato, in apice plus minus iuciso ; margine minute deuticulato. 

Biam.— hat .0092". Long. .011." 

Syn. — 31. denticulata, Brebisson. Ralfs, British DesmidicEe, p. 70, et Archer, Pritchard's 
Infusoria. 
M. denticulata, Brebisson. ? Rabenhorst, Flora Europ. Algarum, Sect. III. p. 192. 

Hab. — Pennsylvania; Wood. Florida; Bailey. 

Very large, a little longer than broad, smooth; semicells with five lobes (scarcely 9); basal 
and intermediate lobes alike bilobate, lobules also divided into two bifid lobules; end lobe 
narrow, wedge-shaped, more or less incised at its apex ; margin minutely denticulate. 

Remarlis. — Prof. Rabenhorst gives M. denticulaia, Breb. as merely a variety of 
M. furcata, Ac, stating that it only differs from the latter in the marginal incisions 
and teeth. Not having access to the original description of Brebisson I cannot 
express an opinion as to whether Prof R. is correct or not, but the specimen from 
which the above description was drawn up (and which is figured on plate 13) cer- 
tainly differs from M. furcata very essentially in the arrangement of its lobes, and 
is, I feel confident, M. denticulata, Breb. of Ralfs and Archer. 

Fig. 6, pi. 13, is a drawing of this plant, as seen by myself, magnified 260 
diameters. 

I?I. radiosa, Aa. 

M. maxima, orbicularis, Ifevis, anteccdonti simillima, differt inprimis scgmentis ultimis tumidis 
in apicera bi- tri- fidura attenuatis, lobo polari vix prominulo, apice siuuato, ad utrumque 
angulum bi- tri- dentato. (R.) Species mihiignota. 

DiOOT.— 0.0016". (II.) 

Syn. — M. radiosa, Agardh. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 192. 

Sab. — Florida ; Bailey. 

Frond orbicular, smooth ; segments 5-lobed ; basal lobes twice, middle lubes generally thrice 
dichotomous, ultimate subdivisions inflated, attenuate towards the end, bideutate; end lobes 
emarginate, its angles dentate. (A.) 

m. fimbriata, Ralfs. 

M. magna, orbicularis, Isevis (nonnunquam superficie aculeis singulis sparsis) ; semicellulis 
quinquelobis, lobis omnibus confertis, basalibus angustioribus, repetito bilobulatis, lobis inter- 
mediis duplo latioribus, repetito-bilobnlatis, lacinulis extremis leviter emarginatis, in angulis 
spinis elongatis armatis; lobo polari prominulo, in apice obtuse siniiato- vel- undulato-emar- 
ginato, angulis lateralibus rotundatis, ad marginem superiorem spinis singulis vel gcminis 
obsito (rarius nudo). (R.) Species mihi ignota. 

19 August, 1872. 



146 FRESH-WATER ALG^ OF THE UNITED STATES. 

• Diam.— 0051"— .0018". (R.) 
Sjjn. — M. fimhriata, Ralfs, British Desmidiea;, p. 11, et Rabenhokst, Flora Europ. Algarum, 
Sect. III. p. 193. 

Uab. — South Carolina ; Florida ; Bailey, 

Frond orbicular, smooth; segments 5-lobed, basal lobes twice, middle lobes thrice dichotomous; 
ultimate subdivisions acutely bidentatc; end lube very slightly esserted, its angles very 
slightly produced, bidentate, ends eniarginate. In transverse view is seen an inflated pro- 
tuberance just over the central isthmus, which may possibly exist in other species of Micras- 
lerias. (A.) 

M. papillirera, Breb. 

M. orbicularis, sujjcrficie hcvis, marginc extremo dentato papillifera; semieellulis quinquelobis ; 
lobis basalibus et intermediis wquilati.s, bilobatis; lobulis bifidis, laciniis liuearibus bidentatis, 
dentibus papilliferis ; lobo polari vix promiuulo, in apice siuuato, angulis et margiue deutato- 
niucronatis. (R.) Upecies mihiignota. 

i?jam.— 0.0045". (R.) 

gyn. — M. papillifera, Brebisson. Ralfs, British Dcsmidica;, p. 12, et Pi4Bi;niiurst, Flora 
Europ. Algarum, Sect. III. p. 194. 

Hah. — Florida; Rhode Island ; Bailey. 

Frond orbicular, having the principal sinuses bordered by a row of minute granules, otherwise 
smooth ; segments 5-lobed ; basal and middle loljes twice dichotomous, their ultimate shal- 
low subdivisions terminated by two, sometimes three, gland-like teeth ; end lobe eniarginate, 
its angles dentate. Sporangium as in M. denticulata, but considerably smaller. (A.) 

M. ^rnniilafa, Wood (sp. nov.) 

M. magna, suborbicularis, arete granulata ; semieellulis quinqnelobis, lobis inter se sinu angnsto 
discretis, basalibus et intermediis jjlerunique integris, lobo polari supra valde dilatato, in 
dorso medio leviter retuso ; margiuibus valde crenatis. 

Diam.— hong, ^i/ = .0043". Lat. t^JVo" = -0030". 

Nab. — South Carolina, (Ravenel) 

Large, suborbicular, closely granulate; semicells 5-lobed, lobes separated by narrow sinuses; 
basal and intermediate lobes mostly entire ; end lobe distally broadly dilated, broadly and 
very shallowly emarginate ; margin of frond strongly crenate. 

Remarhs. — The only specimens of this species that I have seen were collected by 
Prof. Ilavenel in a shallow ditch near Aiken, South Carolina, where they formed a 
greenish, gelatinous mass, Avith numerons desmids and diatoms. It is most closely 
allied to M. (nincakt, from Avliich it is separated by its entire lateral lobes, by its 
granulated surface, and its crenated margins. It also does not apparently attain 
as largo a size as that species. The grannies are very small in the central portion 
of the frond, but become larger as they approach the margin. 

Fig. 16, pi. 21, represents an empty frond of this species, magnified 460 diam- 
eters. 

M. Jenneri, Ralfs. 

M. magna, oblonga, ]ilornniquc siibfilitcr granulnta ; semieellulis quinquelobis; lobis basalibus 
et intermediis cequilatis, confertis, cuneatis, bilobulatis ; lobo polari late truncato vel late 
rotundato, in medio intcrdum leviter et obtuse emarginato, interdum nonnihil profunde eraar- 
ginato. 

Diam.—Uii. 4SJ'— 1/506'''= OOG"— .0062". Long. ^fS/—- rsVu/ = .00G2"_.0081", 



FRESH-WATER A L G .E OF THE UNITED STATES. I47 

Si/n. — M. Jenneri, Ralfs, Biitish Desmidica;, p. 16. 

Uab. — Prope Philadelpliia ; Wood. South Carolina; (Ravenel) 

Large, oblong, for the most part finely granulate ; semicells 5-lobcd; lobes wedge-shaped ; basal 
and intermediate, about equally broad ; end lobe broadly truncate or broadly rounded, in the 
middle sometimes slightly and obtusely emarginate, sometimes rather deeply emarginate. 

Hemarks.—l have found this species near Philadelphia, and also received it from 
Prof. Ravenel, by whom it was collected in South Carolina. The American plant 
differs from the typical form in not having the ultimate lobules emarginate, they 
being merely a little hollowed out in tlie centre, and sometimes scarcely this. The 
angles in some specimens are also more acute. Mr. Archer, however, speaks of a 
variety occurring in England, in which these lobules are not emarginate, and I do 
not think characters can be found separating the American from the European 
forms. Tlie median suture is in all the specimens very narrov/ and deep, a mere 
line, as it were, "extending nearly to tlie centre. 

Eig. 7, pi. 13, represents a frond of this species. 

M. Torreyi, Bailey. *■ 

M. perniagna, oblongo-orbieularis, Isevis, profundissirae lobata; semicellnlis quinquelobis, lobis 
basalibus profunde bifidis, laciniis infcrioribus apice bidentatis, suporioribus iutegris, lobis in- 
termediis profunde trifidis, laciniis superioribus bidentatis, inferioribus integris, lac. omnibus 
lanceolatis aciiminatis, inferioribus paulnm iueurvis, superioribus recurvis ; lobo polari non 
prominente, e basi angusta seusim dilatato, iu vortice acute sinuato, augulis integris acumin- 
atis. (R.) Species mihi ignola. 

Sijn. — 31. Torreyi, Bailey. Ralfs, Brit. Desmidiea?, p. 210. 

Hah. — Prope Princetown, New Jersey; Bailey. 

Frond smooth ; segments 5-lobed ; basal lobes bifid, middle lobes trifid, the subdivisions nearest 
the opposite segments and those nearest the terminal lobe bidentate at the ape.x ; tlic inter- 
mediate three terminating in acute points; all somewhat inflated and tapering ; terminal 
lobe narrow, not exsertcd, spreading at the angles into divergent tapering points, ends 
slightly emarginate. (A.) 

ITI. folinrea, Bailey. 

M. parva, subquadrata, Isevis; semicellulis trilobis, lobis lateralibus profunde bifidis (unde rec- 
tior semicell. quinqueloba;), lobulis iiiiEqualiter inciso-dentatis, lobulis inferioribus rectis, 
superioribus recurvis; lobo polari plus minus pruuiinento, anguste cuneato, in vortice plus 
minusve emarginato, angulis aut acutis integris aut productis, bidentatis. R. S^^ecie.-i mihi 
ignota. 

Syn. — M. foliacea, Bailey. Ralfs, Britii^h Desmidica;, p. 210. 

Ilah. — " Worden's Pond, Rhode Island; Bailey."' 

Frond subquadrate, smooth ; segments 3-lobed ; lateral lobes deeitly bipartite, inciso-dentale, 
their margins concave, inciso-serrate ; end lobe broad, cuneate, and exserted, bi|)artite at the 
angles, the subdivisions narrow, and minutely dentate at the extremities ; end concave. (A.) 

Genus STAURASTRUM, Meten. 

Cellulae libera natantes, in medio pins minus profunde constrietas ; seraicclhilfe a vortice 3-G angn- 
lares vel radiatas. Cytioderma aut keve aut punctatum aut verrueosum aut aculeatum, nonnunquam 
ciliis vel pilis obsessum. 

Cells swimming free, more or less profoundly constricted in the middle; semicells when seen 
from the vertex 3 to fi angular or radiate. Cytioderm either smooth or punctate, or verrucose or 
aculeate, sometimes covered with hairs or cilia. 



148 FRESH-WATER A L G .E OF THE UNITED STATES. 

A. Cytioderma ljeve vel rarissime subtiliter punctatum. 

Cytioderm smooth oh very rarely very finely punctate. 

1. Semicellularum anguli rolundati. 

Angles of the semicells rounded. 

St. ■ntiticiiin, Breb. 

St. a fronte orbiculare, loeve, profunde constrictum, nudum, vel muco plus miuusve firmo invo- 
lutum ; semicellulis ellipticis, a vertice conspectis 3-4 augularibus (rarius quinquangularibus) 
angulis rotundatis, lateribus levitcr sinnato-retusis; zygosporis aculeatis, aculeis elongatis, 
subulatis, furcatim fissis. (R.) Species viihi ignota. 

Z)m»i.— 0.0013"— 00014:". (R.) 

Syn. — S. muticum, Brebisson. Rabenhorst, Flora Europ. Algar., Sect. III. p. 200. 

E^ab. — South Carolina ; Rhode Island ; Bailey. 

Segments in f. v. elliptic, smooth, without spines ; e. v. with three or four broadly rounded 
angles, sides concave. Sporangium beset with numerous elongate somewhat stout spines, 
forked at the apex. (A.) 

St. orbiculare, (Eiirb.) Ralfs. 

St. suborbiculare, Iseve, saepius muco matricali involutum ; semicellulis divcrgentibus, semi, 
orbicularibus, dorso nonnunquam elevatis, angulis plus minus late rotundatis, lateribus plus 
minus sinuato-retusis ; zygosporarum aculeis elongatis, subulatis, iutegris. (R.) 

Diam— .002". 

Syn. — St. orbiculare, (Eiirb.) Ralfs, British Desmidiese, p. 125. Rabenhorst, Flora Europ. 
Algarum, Sect. III. p. 200. 

Hab. — Rhode Island ; Bailey. Pennsylvania ; Wood. Rhode Island ; (S. T. Olney) Thwaites. 

Segments in f v. semiorbicular, smooth, without spines ; e. v. with three broadly rounded angles, 
sides slightly concave. (A.) 

BemarJcs. — Fig. 17, pi. 21, represents the outline of the end view of a frond of 
this species. Fig. 8, pi. 13, is a drawing of the front view of a living frond. 

2. Semicellularum anguli mucronali vel aridati. 

Angles of the semicells mucronate or bristly. 

St. loiigi^piniiiii, (Batley) Archer. 

St. magnum triangulare, Iseve, angulis in aculeos geminos validos subulatos longe productum, 
lateribus subplanum. (R.) Species viihiignota. 

Syn. — Didymocladon longisjnnum, Bailey, Microscopical Observation.?. 

Hab. — Florida; Bailey. 

"Large, smooth, triangular, with two long spines at each angle." Bailey. 

St. dejectiiin, Brebisson. 

St. lajve, parvura, sinu amplo, obtusangulo (ve! acutangulo) ; semicellulis ellipticis (vel subtri- 
angularibus), dorso nonnihil convexo, utroque fine in aculeum achroum rectum vel varie cur- 
viitis productis; a vertice triangularibus (vel quadrangularibus), angulis sape rotundatis 
aculeo iiiterdum obsoleto imposito. 

Diam.— Lat. .^1^"— tAitt" = 0008"— .001". Long, t-Vott"— t-Vs/ = .0008"— .0001". 

Syn. — Staurastrum dejectum, Brebisson. Rabenhorst, Flora p]urop. Algarum, Sect. IIL 
p. 203. 



FRESII-WATER ALG^ OF THE UNITED STATES. I49 

Hah. — South Carolina ; (Tlavenel) Wood. 

Smootb, small; sinus ample, obtuse auglcd (sometimes acute angled?); seniicclls elliptic (or 
subtriangular ?), with the dorsum slightly convex, at the angles with a straight or curved 
transparent spine ; from the vertex triangular (or quadrangular ?), angles often rounded, 
with a sometimes obsolete spine superimposed. 

RemarTcs. — This species was collected near Aiken, Sonth Carolina, by Prof. 
Ravenel, who found it forming with various diatoms and desmids a slimy mass in 
a feebly running ditch. It agrees very well with the European form, except that 
it is not so large (at least the largest I ever measured did not come up to the 
size of their transatlantic brethren), neither does it appear to vary quite so much. 
In the description, I have placed in brackets those characters in which the European 
form varies, and the specimens I have seen do not. 

Fig. 18, pi. 21, represents outline of end of a semicell, magnified 750 diameters. 
Fig. 9, pi. 13, a front view, and 9 a the end view, of the living frond, magnified 
diameters. 

St. ariistiieruni, Ralfs. 

St. Iseve, St. cuspidatum quodaramodo simile, et eadem magnitudine sed isthnio destitutura ; 
semieellulis tumidis, in media parte subi-otundatis, lateraliter in lobum, basi constrietum, 
apice aristatum productis, lobis divergentibus, a vertice tri-quadrilobo-radiatis, radiis strictis 
iEquidistantibus cruciatim dispositis, iuterstitiis profuude exeisis. (R.) Species mihi ignota. 

Diam.—lnc\. arist. 0.0014". (R ) 

Syn. — St.aristiferum, Ralfs, British Desmidieae, p. 123. Rabenhorst, Flora Europ. Algarum, 
Sect. III. p. 204. 

Hah. — Georgia ; Rhode Island ; Bailey. 

Segments smooth, in f v. prolonged at each lateral extremity into a mamillate projection, which 
is terminated by a subulate, acute straight awn, the awns divergent, e. v. with three or four 
angles ; angles inflated mamillate, terminated by an awn, sides deeply concave in the centre. 
(A.) 

St. liCwisii, Wood. 

St. iKve ; sinu amplissimo, spinulo parvo armato et cum angulo obtuso ; isthrao nullo ; semi- 
eellulis a fronte late triangularibus, a vertice triangularibus et cum angulis uonnihil tumidis, 
et rotundatis ; anguiis spino maximo, robusto, acuto armatis. 

Diam. — Long. cum. spin, -j^^" = .0025"; lat. cnm. spin. tuVjtV = .00225". Sine spin. : long, 
gij" = .001666"; lat. t^'oW .001660". Spin.: long. -J^/ = .000066" 

Syn. — St. Lewisii, Wood, Proc. Acad. N. S. 1870. 

ffab. — In lacu Saco; (Lewis) Wood. 

Smooth, with a very ample sinus, which is armed with a small spine and ha.s a very obtuse 
angle; isthmus absent; scmicells from the front broadly triangular, from the vertex trian- 
gular, with the angles somewhat tumid and rounded ; angles armed with a very large acute 
robust spine. 

Remarks. — This desmid is most closely allied to St. aristifenim, Ralfs, but differs 
from it in outline as seen from the front, there being no mamellation of the ends. 
The spines in the sinuses are always wanting in the European species. 

Fig. 19, pi. 21, represents the outline of the end of a semicell, magnified 750 
diameters. Fig. 11, pi. 13, represents the perfectly formed frond, magnified 750 
diameters. 



150 FRESU-WATER ALGJE OF THE UNITED STATES. 

B. Cytioderma granulatum vel verrucosum. 

Cytioderm granulate or warty. • 

1. Semicellulse a vertice 3-7 mujtilares ; ainjuU jdus minus radialim elongali. 

Semicells seen from the vertex 3-7 angled; angles more or less radiutely produced. 

St. iiiarsai'ifaceiiiii, Eurb. 

St. mediocre, granulatum ; semicellulis convergentibus, subfusiformibns, in medio turaidis, 
utrinque productis, truncatis, a vertice orbicularibus, 5-7 radiatis, radiis obtuse truacatis 
achrois, hyaliuis, granulato-margaritaceis. (R.) Sxjecies mihi ignota. 

Diam.— 0.00135"— 0.0017". (R.) 

Syn.—St. margaritaceum, (Ehrb.) Menegheni. Rabenhorst, Flora Europ. Algarum, Sect. 

III. p. 206. 
Eab. — South Carolina; Georgia; Florida; Rhode Island ; Bailey. 

Segments in f. v. gradually widening upward.s, rough with pearly granules, outer margin eon- 
vex, produced at each side into a colorless, more or less attenuate, short process, having the 
granules in transverse lines, blunt and entire at the apex, e. v. circular, bordered by from five 
to seven short, narrow, obtuse, colorless, granulate marginal rays. (Archer.) 

St. dilatatlliii, Ehrb. 

St. parvum, granulatum ; semicellulis rectis, cylindrico-fusiforraibus, non tumidis, utroque fine 
obtusis vel subtruncatis, a vertice 3— 1-5 radiatis, radiis latioribus, truncatis vel rotundatis, 
achrois, hyaliuis, granulato-margaritaceis. (R.) Species mihi ignota. 

Dwm.— 0.0008"— 0.0011". (R ) 

Var. alternans. 
Semicellulis ellipticis rectis, utroque fine rotundatis, a vertice triradiatis, radiis obtusis, alter- 
nantibus cum semicellulfe inferioris. (R.) 

Var. tricorne. 

Semicellulis fusiformibus, nnnnunquam in medio subtumidis, baud raro isthmo distincto con- 
junctis, a vertice 3-4 angularibus, angulis truncatis vel obtusis, plus minus radiatiui pro- 
ductis. (R.) 

Hah. — Georgia; Florida; Rhode Island; Bailey. 

Sijn. — S. aJternans, Brebisson. Var. allernans et tricorne. Rabenhorst, Flora Europ. 
Algarum, Sect. III. p. 207. 

Remarlis. — Prof. Rabenliovst considers St. altervan.'i and tricorne, as simple varie- 
ties of St. dilatatum, whilst both Archer and Ralfs describe them as distinct. I 
have not seen either of them, and am not therefore entitled to olter an opinion. 
Mr. Archer describes the two species as follows : — 

St. alternans, Breb. 

Segments in front view elliptic or oblong, two or three times as broad as long, separated by a 
wide sinus, twisted, unequal; rough with very minute pearly granules; e. v. with three 
obtuse and rounded angles, forming short, not colorless rays, alternating with those of the 
other segments, sides concave. L. Tj'a,". Br. jx'os"- 

St. tricorne, Breb. 

Segments in f. v. somewhat fusiform, often twisted, rough with minute puncta-like grannle.s 
tapering at each side into a short, u.sually colorless process, blunt or divided at the apex; 



FRESH-WATER A L G^ O F T H E U i\ 1 T E D S T A T E S. 151 

e. V. tri-or quadriradiate, processes short, usually colorless, sides somewhat concave. >Spo- 
rangium orbicular, beset with spines ultimately branched at the apex. L. i^j^" — gjj". 

Bi " 

2. Semicellulae triangulares; anguli non producti, obtusi vel rolundati. 
Semicells triangular ; the angles not produced, obtuse or rounded. 

St. piinctiilatuiu, Breb. 

St. parvum, punctulato-granulosum; scmrcellulis enormiter ellipticis, dorso lato rutuudatis, a 
vertice triangularibus ; angulis non productis, obtuse rotuudatis ; lateribus uiodice retusis. 

Diavi.—L&t. T5'^"=.0012". 

Syn. — S. punctulatum, Bkebisson. Ralfs, British Desmidiese. Rabenhorst, Flora Europ. 
Algarum, Sect. III. p. 208. 

Ilab. — Pennsylvania ; Wood. 

Small, punctulate-grannlate ; semicells irregularly elliptic, with the dorsum broadly rounded 
from the vertex triangular; angles not produced, obtusely rounded; sides somewhat retuse. 

Remarks. — This desmid is exceedingly common around Pliiladelphia, growing 
in the greatest abundance upon the face of wet dripping rocks. It is represented, 
% 10, pi. 13. 

St. crenatum, Bailey. 

St. duplo circiter longius quara latum, in medio utrinque esscctione profunda rotundata ; 
semicellulis e basi cuueata ilabelliformibus, margiue superiore crenatis, a vertice triangularibus, 
angulis rotundato-truncatis, crenatis, lateribus siiiuatis glabris. (B.) Species mihi ignota. 

Syn. — St. crenatum, Bailey. Ralfs, British Pesmidieaj, p. 214. Rabenhorst, Flora Europ. 
Algarum, Sect. III. p. 220. 

" Segments cuneate ; outer margins crenate ; end view with three truncate and crenate angles." 

3. Semicellulas vertice 3-7 radiatee ; radii in apice plerumque bi- tri- fidi vel bi- tri- spini. 
Semicells 3-7 radiate at the vertex ; radii bi- ortri-fid, or bi- or Iri-spinous at the aptex. 

St. polyiiiorphiini, Breb. 

St. semicellulis ellipticis, subtiliter grannlatis vel tenuissime spinulosis, in medio magis minusve 
inflatis, baud raro ventricosis, rectis, nonnunquam incurvis, utrinque proccssu plus minus 
elongato, lineari, in apice 3-4 fido vel spinulis 3-4 tcnuissimis instructis, a vertice 3-4—5-6-7 
radiatis, radiis achrois, aut trifidis aut rotundatis, trispinis. (R.) Species mihi ignota. 

Syn. — St. polymorphum, Brebisson. Ralfs, British Desmidieaj, p. 135. Rabenhorst, Flora 

Europ. Algarum, Sect. III. p. 209. 
X»m?7i.— Long. 0.001". Lat. 0.00087". (R.) 
Hab. — Florida; Bailey. 

Segments in f. v. broadly elliptic or almost circular, rough with minute granules (sometimes 
with a few minute scattered spines), processes short, stout, tipped by three or four divergent 
spines ; e. v. with three, four, five, or six angles each produced into a short, stout process. 
Sporangium orbicular, beset with elongate spines, forked or branched at the apex. Archer. 

Var. CTl'tocei'lllll. {St. cyrfocerum. Breb.) 
Majus, ad gV", longum, semicellulis introrsum ventricosis, dorso late rotundatis, utrinque pro- 
cessu elongato, plerumque incurvo apice bi- vel tri-cuspidato instructis, a vertice triradiatis, 
radiis rectis vel leuiter curvatis, in apice aut bi- aut tri-cuspidatis. (11.) 



152 FRESH-WATER ALGJ3 OF THE UNITED STATES. 

S>/n.— Vat: St. ci/docerum, Beebisson. Rabenhorst, Flora Europ. Algarum, Sect. HI. p. 210. 

2fa6.— Rhode Island ; (S. T. Olncy) Thwaites. 

Segments in f. v. subciineate, gradually widening upwards, truncate at the end margin, rough 
with minute granules, the lateral processes incurved, divided at the apex ; e. v. triradiate, 
processes short, curved, sides slightly coucave. L. ^Ju". B. jj-j". (Archer.) 

St. parodoxum, Meyen. 

St. seniicelluli.s inflatis, dorso rotundatis vel rcctilinearibus, angulis supcrioribus in radium 
elongatum achroum hispidum, apiee trifurcatim productis, sajpius radio aujuali interposito 
a yertice tri- vel quadriradiatis, radiis strictis, trif'urcatis, longitudine corporis diani. a^quau- 
tibus vel superantibus. (R.) 

Diam.— Cum rad. .0015". 

Syn.—Sf. parodoxum, Meyen. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 210. 

Jlab. — In lacu Saco, New Hampshire ; (Lewis) Wood. 

Semicells inflated, dorsum rounded or rectilinear, with superior angles produced into elongate, 
transparent, hispid radii with trifurcate apices, often furnished also with intermediate equal 
radii ; from the vertex three or four radiate, radii straight, trifurcate, equalling or longer thau 
the diameter of the body. 

Remarks. — I am indebted to Dr. Lewis for specimens of this species, which he 
collected at Saco Lake. 

Fig. 20, pi. 21, represents the end view of an empty frond. 

St. arachne, Ralfs. 

St, parvum, graeile, granulato-asperum ; semicellulis introrsum vcntricoso-globosis, angulis 
supcrioribus in cornu graeile, ineurvum, apiee obtusura, elongatis, a vertice pentagouis, 
qui.nque-radiatis, radiis elongatis linearibus achrois, obtusis, rectis vel leniter curvatis asperis. 
(RO 

i)/am.— Sine rad. .0005", cum rad. .0016r'. 

Syn. — St. arachne, Ralfs, British Desmidica;, p. 13G. Rabenhorst, Flora Europ. Algarum, 
Sect. III. p. 210. 

Hah. — In lacu Saco, New Hampshire, (Lewis) Wood. 

Segments in f. v. suborbicular, rough with minute granules, lower margin turgid, outer convex, 
tapering at each side into an elongate, slender, incurved process having the granules thereon 
in transverse lines, entire at the apex; e. v. circular, bordered by five slender, linear, colorless 
marginal rays. 

Remarh. — Fig. 21, pi. 21, represents an outline of the end view of the semicell. 

St. graeile, Ralfs. 

St. mediocre, granulate asperum, granulis in series transversas ordinatis ; semicellulis ventre 
valde inflatis, dorso truncatis, angulis in cornu rectum achroum graeile apiee trifidum pro- 
ductis, a vertice triradiatis, lateribus sinuatis. (R.) Species mihi ignota. 

Biam.— 0.0022". (R.) 

Srjn. — St. graeile, Ralfs, British Desmidicoe, p. 13G. Rabenhorst, Flora Europ. Algarum, 
Sect. III. p. 2n. 

Zfrtft.— South Carolina; Florida; Georgia; Rhode Island; Bailey. Rhode Island; (Olney) 
Thwaites. 



FRESH-WATER ALG^ OF THE UNITED STATES. 153 

Segments in f. v. triangular, ends truucato, rough with minute granules, tapering at each side 
into elongate, straight, slender, horizontal processes, terminated by three or four minute 
spines; e. v. triradiate, processes straight, sides concave. (A.) 

C. Cytioderma pilosum, spinulosum vel aculeatum. 

CyTIODER.M pilose, SPINULOSE or THORNy. 

St. polyfcichiiin, Perty. 

St. mediocre, tarn longuni quani latum, profunde constrictura, sinu ncutangulo ampliato, siiprr- 
ficie undique setosum ; semieellulis ellipticis vel subellipticis, divergentibus, dorso snliplariis, 
ventre tumidis, margine setoso-ciliatis, a vertice triangularibus, angulis obtusis, lateribus 
subrectis. (R.) 

Z)iam.— 7125" = . 0017". 

Syn. — St. polytrichum, Perty. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 2l4. 

iZaft.— Prope Philadelphia ; Wood. 

Moderately large, about as long as broad, profoundly constricted, with the acute angled sinus 
widened, surface everywhere furnished with setse ; semicells elliptical or subelliptical, diver- 
gent, the dorsum nearly plane, their belly swollen, the margin setose-ciliate, from the vertex 
triangular, the angles obtuse. 

Remarks. — This dcsmid appear-s to be rare in this coTintry, as it probably is also 
in Europe. I have seen but a single specimen, which I found amongst other alga; 
near Clielten Hills, north of the city. It agreed in all respects with the descrip- 
tion of Rabenhorst, as given above. 

Fig. 12, pi. 13, is a drawing of this plant, also fig. 23, pi. 21. 

St. Bavenelii, Wood. (sp. nov.) 

St. mediocre, paulo longius quam latum ; semieellulis a fronte ellipticis, a vertice triangularilnis 
cum lateribus convexis vel leniter retusis et angulis rotundatis ; isthmo connexivo subuullo, 
lato ; sinu acutangulo ; cytiodermate spinis acutis, robustis numerosis armato. 

Z>mm.— Long. „Vou'' = 0.0014". Lat. ^Vir" = 0-001". 

Hah. — South Carolina ; (Ravenel) Wood. 

Mediocre, a little longer than broad ; semicells from the front elliptical, from the vertex trian- 
gular, with the sides convex or slightly retuse, and the angles rounded ; connecting isthmus 
obsolete, broad sinus acute-angled ; cytioderm armed with numerous acute robust spines. 

Remarh. — Fig. 22, pi. 21, represents the front view of an empty frond of this 
plant ; fig. 22 a, the side view, and fig. 22 h, the end, all magnified 750 diameters. 

St. hirsutiini, (Eurb.) Breb. 

St. magnum, tertiam partem circiter quam longius quam latum, plus minus dense spinulosum, 
sinu plus minus lineari, acutangulo; semieellulis late ellipticis vel subsemiorbicularibus, 
spinis tenuibus strietis hirsutis, a vertice triangularibus, angulis obtuse rotundatis, lateribus 
rectis vel leniter convexis. (R.) Species mihi ignota. 

Dia„!._Sine spinis 0.0015". Zygospor. 0.0022". (R.) 

Sijn. — St. hirsutum, (Ehrenberg^ Br£bisson. Rabenhorst, Flora Europ. Algarum, Sect. 

III. p. 211. 
finfc.—Florida; Rhode Island; Bailey. Rhode Island; (S. T. Olney) Thwaitcs. 

20 August, 1872. 



151 FllKSU-WATER A L G .E OF THE UNITED STATES. 

Segments in f. v. semiorbicular, separated by a linear constriction, covered with very minute, 
very miinerous close set hair-lilie spines ; e. v. witlj tliree broadly rounded angles, the spines 
evenlv and numerously scattered ; sides slightly convex. Sporangium orbicular, besel wiib 
short spines, branched at the apex. (A.) 

St. Hystrix, R.vlfs. 

St. parvum, tertiam partem longius quam latum, angulis aculeatum (cseterum L-eve), sinu aeu- 
tangulo ; seniicellulis subquadratis, angulis late rotuudatis, dorso planis, a vcrtice 3-4 angu- 
laribus, angulis late rotundatis, plus minus dense aculeatis. (R.) Species mihi ignola. 

Z)mw.— 0.001"— 00089". (R.) 

Si/7i. — St. Hystrix, Ralfs, British DesmidieiE, p. 128. Rabenhorst, Flora Europ. Algarum, 

Sect. HI. p. 213. 
//a6.— Rhode Island ; (S. T. Olney) Thwaites. 

Segments in f. v. subquadrato, e.xtremities somewhat rounded, end margin nearly straight, fur- 
nished with a few scattered, suliulate, acute spines, chiefly conlined to the lateral extremities; 
c. V. with three or four broadly rounded angles, the spines scattered, chiefly confined to the 
extremities, sides concave. L. tq\s" — toV^"- l*''- ttVs" — ?ri"' 

St. Cerberus, (B.\ilet) Archer. 

St. parvum, tam longum quam latum, sinu rotundato, superficie tevi ; semicellulis oblongis 
utroque fine sinuato-truncatis, angulis in aculeum cuspidatum productis, in medio sursum et 
deorsum prominentiis geminis in aculeum elongatis instructis, a vertice triangularibus, angulis 
in apice truncato-vel siuuato-bi-cuspidatis, sub apice aculeis geminis brevibus prteditis. (R.) 
Species mihi ignola. 

Diam.—Qnm aoul. 0.00114"— 0.0013". (R.) 

Sijn. — Didymocladon Cerberus, Bailey, Microscopical Observations. 

St. Cereberus, (Bailey) Archer. R.ibeniiurst, Flora Europ. Algar., Sect. III. p. 215. 
Ilab. — Florida ; Bailey. 

Small, deeply constricted, segments three-lobed, lobes with four teeth, two of which project 
upwards and two downwards at each truncated angle. (A.) 

D. CyTIODERMA PROCESSIBUS NUMEROSIS, apice PLERUMQUE TRUNCATIS et DENTATO-FISSIS 
MUNITUiM. 

CyTIODERM with numerous processes, whose APICES ARE MOSTLY TRU.NCATE AND DEN- 

tately torn. 
St. fiircii^eriiiii, Breb. 

St. validum, submagnum, circiter tam longum quam latum, IsBve ve! subtiliter grannlatura, 
plerumque profundissime constrictura, sinu angusto lineari ; semicellulis oblongo-elliptiei.s, 
plus minus tumidis, angulis in processus bifurcum aut rectum aut divergentera longe pro- 
ductis, dorso processibus similibus 2, 3, 4, instructis, omnibus processibus achrois granulato- 
dentatis, granulis in series tTansversas ordinatis, a vertice 3-, 4-, 6-, 7-, 8-, 9-angularibus vei 
radiatis, angulis plus minus tumidis, in processus crassum achroum asperum in apice fissum 
productis. (R.) Species milt i. ignota. 

. Long. Sine process, 0.001S"_0.0010" ; c. pr. 0.003"'— 0.0032". Lat. sine proe. 0.00185"; 
c. pr. 0.002Y". (R.) 

Syn —Slaurastrum furcigerum, Breiusson. Rabenhorst, Flora Europ. Algar., Sect. Ill 
p. 219. 

Didymocladon fur cigerus, Ralfs, British Dcsmidies. 

77a&.— South Carolina; Florida.; Rhode Island; Bailey. 

St. iniinitiiin, Wood. 

St submagnum, fere ^ plo longius quam .atum, medio leviter constrictum, seraicellnlis a fronte 



FRESH-WATER A L G .E OF THE UNITED STATES. 155 

enoriiiiter lipxagoiiis, angulis in pi'Dcessns rectos ct divcrgcntes productis, dorso proccssibus 
similibus 4-5 iu.stnicto ; seraicellulis a vertice poI\'gouis vel suljoi'bioularibus margine proces- 
sibus numerosis, pleruiiique 9 instructo ; dorso pfoce-ssibus 5-8 instnictis; proccssibus omni- 
bus similibus, granulato-deutatis, apioe acliroo siniplicibus, bifurcatis vol flssis. 

Diam. — A vertice cum processibus, rnVuV = •004'75". Sine process. xs'uVij" = -002". 

Syn. — St. munitum, Wood, Proceed. Ac. Nat, Sc, 1869. 

Bob. — In lacu Saco, Xew Hampshire; (Lewis) Wood. 

S. rather large, about one-half longer than broad, slightly constricted in the middle ; semicells 
from the front irregularly hexagonal, the angles prolonged in straight divergent processes, 
and tlie surface furnished with four or five similar ones; semicells from tiic vertex polygonal 
or suljorljicular, tlie margin furnished with numerous |)rocesses, mostly about nine, and also 
with 5-S on the dorsum; jirocesses all similar, granulate-dentate, their transparent apices 
simple, bifurcate or torn. 

I^cmarks. — Tliis species is most closely allied to St. furcigerum, Bivb., from 
•which it is at once distinguished by the orbicular vertex. The constriction between 
the semicells is also very different. In St. muuUum it is a gradual, not very deep, 
hour-glass contraction ; in St. furcigrrum it is very narrow and linear. 

Fig. 13 «, pi. 13, is a front view of this plant magnified 260 diameters; fig. 13 i, 
the end view of the same. 

St. eiistephaniiin, (Euri:.) Ralfs. 

St. laterum integrornra angulis productis apice spinulosis, spinularum furc.atarum corona media 

dorsali. (R.) Species mihi ignota. 
Syn. — Deanddium eustei)hanuin. Eiirenberg, Terbreitung and Einfluss der !Mikro.sk. lA'ljens 
in Slid- und Nord-Amerika, t. 4, f. 23. 
Slaurastrum eustephanum, (Eiirb.) Ralfs, British Dcsmidica\ p. 215. 
Steplianoxanlhium eustephanum, KOtzi.n'g. Rabenhorst, Flora Europ. Algarum, Sect. 

III. p. 221. 
Staurastrum eustephanum, R.\lfs. R.\be.\'iiorst (Joe. cit.) 
Hah. — West Point, New York ; Bailey. 

End view triangular with six cmarginate spines on the upper surface; each angle terminated 
by a short ray tipped with spines. (Ralfs) 

St. senariiiin, (Ehrb ) Ralfs. 

Anteeedenti simile sed laterum parietibus spinulis furcatis binis (sex), corona dorsali senaria. 
(R.) Species milii ignota. 

Syn. — Desmidium senarium, Eiirenberg, Terbreitung. T. IV. 

Steplianoxanlhium senarium, KiJTZiNU. Rabenhorst, Flora Europ. Algarum, Sect. III. 

p. 220. 
Staurasinim senarium, (Eiirb.) Rai.fs, British Desmidicffi. Rabenhorst, (loc. ci/.) 

Segments smooth in end view with three angles, each terminating in a short process tipped by 
minute spines, without lateral processes, but with six others confluent at their bases ou the 
upper surface, divergent and forked. (Archer.) 

Genus XANTIIIDIUM, Ehrb. 

Cellulse singulfB vel gemina? concatenate, infiato-rotundatw, profunde constrictae ; semicelluliE 
compressas, oblongas, hcmisphsericae vel subquadrangulares, centre in tubcrculum rotundatum vel 
truncatum et deuticulatum protuberantes, ex transverse oblongo-rotundata;. Cytiodornia firinum 
setis, aculeis vel spinis simplicibus aut bi- tri-furcato-divisis armatum. Massa chlorophyllacea 
radiatim expansa, Zygospora^ arniade. (11.) 



156 FIIESH-WATER ALGJE OF THE UNITED STATES. 

Cells single or geminately concatenate, inflated, profoundly constricted ; semicells compressed, 
oblong, hemispherical or subquadrangular, protruding in the centre as a rounded truncate or den- 
ticulate tubercle Cytioderni firm, armed with sets, or simple, or bi- tri-furcately divided spines. 
C'hlorophyl radiately expanded. Zygospores armed. 

Eenuxrlc. — It has so happened that I have identified but a single species of this 
genus. 

3l. aciileatiim, Eiirb. 

X. parvum, singulum, sparsum, diaraetro ipse subnequale, ex obliquo ellipsoideum, diametro 
duplo longius, coustrictione obtusa lineari, semicellulis oblongis subreniformibus, basi sub- 
plauis, dorso late rotundatis, tuberculo centrali minus elevato, truncate, niargine autem crenato- 
dentato ; cytiodermate undique aculeis subulatis obsito. (R.) Species mihi ignota. 

Dmm.— (Sine aculeis) 0.0025"— 0.0029". (R.) 

Syn. — Xanthidiuvi aculeatum, Ehrenberg. Rabenhorst, Flora Europ. Algarum, Sect. III. 
p. 222. 

Sab. — Prope Savannah, Georgia ; Railey. 

Frond inf. v. broader than long; constriction deep, linear; segments somewhat reniform; 
spines subulate, short, scattered, chiefly marginal ; central protuberance cylindrical, truncate, 
border minutely dentate. (A.) 

X. Arctiscon, Eiirb. 

X. semicellulis globosis, binis, aculeatis, aculeis numerosis undique sparsis crassis asperis apice 
trilobis. (R.) Sj^ccies mihi ignota. 

Syn. — X Arctiscon, Ehrenbero. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 224. 

Hab. — America borealis ; Ehrenberg. 

Frond in f. v. about as long as broad ; constriction forming a wide notch ; segments narrowed 
at the base, with broadly rounded ends; spines numerous, restricted to the outer margin, 
scattered, elongate, stout, terminated by three or four diverging points. (Archer.) 

X. arniatiim, (Breb.) Ralfs. 

X. maximum, validum, solitarium vel binatim conjunctura, diametro plerumque duplo longius; 
semicellulis subcordatis vel angulari-rotundatis tuberculo centrali subelevato, truucato, mar- 
gine granulato-dentato prasditis ; cytiodermate verruculoso et processibus stepius geminatis 
truncatis apice inciso-furcatis instructo. (R.) 

Syn. — Xanthidium armalum, (Brebisson) Ralfs, British Desmidieaj et Rabenhorst, Flora 
Europ. Algarum, Sect. III. p. 222. 

Sa6.— South Carolina ; Florida ; Bailey. Saco Lake ; (Lewis) Wood. 

Frond large, in f. v. twice as long as broad ; constriction deep, linear ; segments broadest at 
the base; ends rounded or somewhat truncate; spines in pairs, principally marginal, short, 
stout, terminated by three or four divergent points ; central projections cylindrical trnncate, 
the border dentate ; e. f. punctate. Sporangium large, orbicular, with depressed tubercles, 
perhaps immature. L. jIj;". B. jf^". (A.) 

Remar7c.—¥ig. 17, pi. 13, is a front view of a frond, magnified 260 diameters. 

X. bii^enai'iuin, Ehrb. 

X. semicellulis globosis subangulosis, binis, aculeatis ; aculeis fasciculatis, fasciculis in quovis 
globulo senis. Species mihi ignota. 

Syn.—X. hisetmrium, Ehrenberg. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 224. 
X. Bribissonii, Ralfs. Archer, Pritohard's Infusoria, p. T3G. 



FRESH -WATER A L G .E OP THE UNITED STATES. I57 

Ilab. — America ; Ehrcubcrg. 

Frond in front view broader than long; constriction deep, acute not linear; segments subcllii)- 
tic, sometimes irregular spines subulate, geminate, marginal, central protuberance cylindrical, 
truncate border minutely dentate. L. (not including spines) 5^5^". B. 5J5" to ^^j". 

X. criiiitatuni, Breb. 

X. parFum, la;ve ; semicellulis subhaemispherico-reniformibus, utroque polo aculeo uuico in- 
curvo, ambitu aculeis octo geminatis, a dorso ovato-ellipticis, utroque polo aculeis teriiis, in 
medio plerumque aculeo abbreviato. (R.) Species mihi ignola. 

X»«am.— 0.00196". R. 

Syn. — X criaiatum, Brebisson. Ralfs, British Dcsmidiete, et Rabeniiorst, Flora Europ. 
Algarum, Sect. III. p. 224. 

ITah. — South Carolina ; Georgia ; Florida ; Bailey. 

Frond rather longer than broad; constriction deep, linear ; segments subreniforra or truncate 
at ends ; spines straight or curved, subulate, marginal, one at each side, at the base of the 
segment, solitary, the others geminate, in four pairs ; central protuberance short, conical. (A.) 

X. coronatiiui, Ehrb. 

X. semicellulis subglobosis binis, aculeatis, ubique asperis, aculeis crassis apiee truncatis triden- 
tato-coronatis quatuor utrinquc dorsalibus, uno utrinquc latere medio. (R.) Species mihi 
ignota. 

Syn. — X. coronaium, Ehrenbero, Yerbreitung, p. 138, et Rabenhorst, Flora Europ. Alga- 
rum, Sect. III. p. 224. 
Asteroxanthium coronatum, KIjtzing. Rabenhorst, {loc. cit.) 

Hab. — America ; Ehrenbcrg. 

Rcmarh. — Mr. Archer appears to think that this species is simply a form of 
Staurastrum furcigerum. (Breb.); see Pritcliard's Infusoria, p. 743. 

X. fasciciiIntiiiH, Eurb. 

X. parvum, singulum, constrietionc profundo linear! ; cytioderraate Isevi vel subla;vi ; semicel- 
lulis oblongo-reniformibus vol hcxagonis, diametro duplo longioribus, ambitu aculeis gracilil)us 
geminatis 4-6, a dorso ellipticis, utroque polo aculeis quatuor instructis. (R.) Sp>ecies mihi 
ignota. 

Z)iani.—0.0022S"— 0.00256". (R.) 

Syn. — X /ascicuZo/um, EHRENBERa. Rabeniiorst, Flora Europ. Algarum, Sect. III. p. 223. 

Sab. — South Carolina ; Georgia; Florida; Rhode Island ; Bailey. 

Frond about as long as broad; constriction deep, linear; segments somewhat reniform or sub- 
hexagonal, twice as broad as long, spines slender, subulate geminate, marginal, in four or six 
pairs ; central protuberance short, conical, somewhat truncate. (A.) 

Genus ARTHRODESMUS, Ehrb. 

Celluhe profunde constricts ; semicellukc compressa; aut oblong.x, utroque polo aculeo subulate 
firmo instructiB, aut quadraugulares, angulis in aculeum rectum vel curvum productis, a dorso vel 
ellipticae vel fusiformes. Massa chloropbyllacea in fascias quatuor radiantes disposita. (R.) 

Cells profoundly constricted ; semicells compressed or oblong, furnished at each end with a subu- 
late spine, or else quadrangular with the angles produced into straight or curved spines, the dorsal 
aspect, elliptic or fusiform. Chlorophyl masses disposed in four radiating fascia. 



158 F RES II -WATER A L G .E OF THE UNITED STATES. 

licmarj.-s.—l have found only a single iindesrrilxHl species of tliis genus, Lut the 
following Euroi)eaii forms have been detected in this country by Prof. Bailey. The 
genus appears to be, as Prof. Ilabcnhorst says, scarcely distinguishable from Xan- 
thidium or Slaarastrum. 

A. octocorniM, EaiiB. 

A. parvus, lasvis, constrictionc lata cxcavata; semicellulis trapezoideis, inciso-qnadriradiatis, 
radiis in aculeura acutissimum strictura porrectis, a latere elongato-ellipticis, diametro fere 
triple longiorilius, utroquo polo aculeum singulum gerentibus. (R.) 

j;/a,n.— O.OOOnu". (R.) 

<iyn. XanthiJiuiii ocfucoriie, Ralfs. Bailey, Microscopical Observations, p. 29. 

Arlhrode^inus octocornis, Ehrenberg. Rabenhorst, Flora Europ. Algarum, Sect. III. 
p. 223. 

ITab. — Florida ; Rhode Island ; Bailey. 

Frond smooth, iiiimito, about as long as broad; constriction a wide notch; segments much 
compressed, trapezoid, each angle terminated by one or two straight, subulate, acute spines, 
the intervals between the angles concave. (A.) 

a. Spine solitary at each angle. L. tj^t"- B. tsVs"- (■'^■) 

h. Larger spines geminate at each angle. L. toVij"- !>• sW- ('^) 

A. quadridens, Wood. 

A. late ovalis, vel suborbicularis, paulum longior quara latus, cum raargine crenato-nndulato; 
se.raicellulis nonnibil reniformibus, utroque fine aeuleo subulato, modice robusto, acuto, re- 
curve, armatis; cytiodermate cum verruculis paucibus modice minutis in seriebus paucibus 
dispositis instructo; semicellulis a vcrtice acute ellipticis, ct cum margine crcnato ct super- 
ficie sparse vcrruculosa. 

l>iam.—Uit. jij^uij" = .00075" ; long, j/^/ = .00125". 

Sijn. — A. quadridens, Wood, Proc. A. N. S. 18C9. 

Hab. — lu laeu Saco, (Lewis) Wood. 

Broadly oval or suborbicular, a little longer than broad, with the margin crenately undulate; 
semicells somewhat reniforra, at each end armed with a subulate, moderately robust, acute, 
recurved large spine ; cytiodcrm with a few smallish tubercles arranged in three or four rows ; 
semicells from the vertex acutely elliptical, with the margin creuate and the surface sparsely 
warty. 

Remarks. — This species approximates .1. dlccrgcns, from which it differs in tlie 
arrangement of its granules, its attaining not one-half the size, and, I believe, iu 
the larger and more robust spines. 

Fig. 2, pi. 20, represents an empty frond of this species. 

A.Incu§, (Breb.) Hassal. 

A. parvus tarn longus quam latus, constrictionc lineari obtusa vel late excisa; semicellulis 
oblongo-quadrangularibus, angulis externis aculeatis, interuis rotundatis iucrmibus, aculeis 
longis singulis divergentibus. (R.) 

Dmw.— Max. 0.00098". Long. 0.00091". Spor. (sine acul.) 0.00085". 

Si/n.—A. Incus, (Brebisson) IIassal, Fresh-Water Algii;, p. 357, ct Rabenhorst, Flora 

Europ. Algarum, Sect. III. p. 22G. 
7/a6.— Georgia; Florida; South Carolina ; Rhode Island ; Bailey. 

Frond minute, smooth, as long, or longer than broad, constrictions a deep notch or sinus; seg- 
ments with inner margin turgid, outer truncate ; spines subulate, acute ; sporangium orbii-uhir, 
spinous; sjiincs subulate. (Archer) 



niESn-WATER ALGJi OF Til JO UNITED STATES. 159 

A. coiiversrens^ Ehrb. 

A. liuvis mediocris, profuiide ct angusto coiistrictus, aouk'is coiivergeiitibus arniatus; Kciiii(_-cl- 
lulis ellipticis vel ovato-oblougis, iioiinuiiquaiu rciiifunuibus, uti'oque liuu aculfo luiigo liriiio 
incurvo iustructis. (R.) 

Z>mm.— 0.00185"— 0.0016". (11.) 

Syn. — A. convergens, Eurenbero. Habenhorst, Flora Europ., Algarum, Sect. III. p. 22T. 

Hob. — South Carolina ; Georgia; Florida; Rhode Island ; Railey. 

Frond smooth, broader than long ; constriction deep, acute ; segments elliptic, each having its 
lateral spines curved towards those of the other; ends convex. L. u'^j" — sJg" R- ts't?" — 
ok"- (Archer) 

Family ZYGXEMACE^. 

CellulfB cylindricce, ffiquipolares, similes, in familias filamcntosas arete conjunctiE, et cytioblasto 
central! plasmate plerumque radiante involute, et plasmate chlorophylloso aut ell'uso, aut efligurato, 
aut (plerumque) in fascius spirales ordinato, et granulis amylaceis instructae. Filum simplex. Pro- 
pogatio fit zygosporis conjugatione cellularum biuarum ortis. Conjugatio triplici modo, aut lateralis 
aut scalariformis vel genuflexa. Yegetatio fit divisione transversali repetita. 

Cells cylindrical, the same at both ends, closely conjoined into filamentous families, furnished with 
a central cytioblast wrapped up iu generally radiating protoplasm, and with chlorophyllous proto- 
plasm effused in shapeless masses or arranged in sfjiral filaments, and also v\'ith scattered starch- 
granules. Filament simple. Propagation takes place by means of zygospores, arising from the 
conjugation of two cells. Conjugation occurring in three way-s, lateral, scalariform, and genuflexuous. 
Growth taking place by means of transverse division of the cells. 

Bcmarhs. — Tlie family under consideration is among the commonest and most 
widely diffused of all the fresh-water alga?. In almost every ditch or spring, or 
dripping moss-covered rock representatives of it are to be found, so tliat wherever 
quiet water is they may be confidently looked for. The single filaments are so minute 
that frequently the unaided eye cannot distinguish them, but multiplication with 
them is such a rapid process, that wherever found they are in great masses. Tliese 
masses, when growth is acti\e, are of a beautiful intense green, glistening and 
shining with the gelatinous matter which coats the threads and makes the mass so 
slippery. They may be found in greater or less abundance at all seasons, but as 
tlip specific characters are largely of sexual origin, non-conjugating specimens are 
of little value. For this reason, Zygnemas are only Avorth gathering when in fruit. 
The spores appear to be formed only in the spring and early summer, at least these 
are the only times in which I have found fertile filaments. In this ncigliborhood 
I have collected them in excellent condition as early as the beginning of April and 
as late as the latter part of June. Further south, conjugation of course commences 
earlier, and fine fruiting specimens received by myself from Mr. Canby were col- 
lected in Florida by him in February. 

AVhen conjugating freely tlie mass of Zijgncma or Sinrogijra loses its beautiful 
bright green color and become dingy and even brownish, often very dirty looking. 
The collector soon learns to pass by the beautiful vivid mass, as comparatively 
worthless, and fasten upon the pale, wan, sickly, apparently dying specimens as 
prizes worthy of a place in his cabinet. 

In the Zggnemaceai the individual plant, as ordinarily considered, is a filament 



160 niKSlI-WATER ALG.E OF THE UNITED STATES. 

roniposrd of a varying number of cells placed, end to end, all alike, and each of 
tliem apparently independent of its associates. Each cell in one sense is, therefore, 
a perfect, complete individual, capable of living dissociated from its companions. 
How far the life of one of these cells is influenced by that of its neighbors is un- 
certain, probably to a slight extent, possibly not at all. At any rate, they are so 
far independent that the filament is rather a composite body than a unit of life. 
These cells are cylindrical, witli the ordinary cellulose wall, which can commonly 
be stained blue by iodine and sulphuric acid, and is often distinctly composed of 
layers, but never has any " secondary markings," each layer being precisely hke 
that superimposed upon it. Outside of the wall is a jelly-like sheath, which is 
mostly not discernible from its thinness and transparency, although it no doubt 
exists, as is proven by the slipperiness of the general mass. The primordial utricle 
is always present. The chlorophyl is variously arranged, most generally in bands, 
eitlier straight or spiral, sometimes in definite irregular masses, sometimes diffused 
through the cell. Imbedded in it are, at certain seasons, numerous minute, gene- 
rally shining, granules, which are either minute specks of starch, or little drops of 
oil. Besides these there are contained in it, especially in the bands of chlorophyl, 
more or less numerous comparatively large, oval or roundish bodies, with a distinct 
outline and a deeper color than the surrounding portions. These masses are pro- 
toplasm, dyed with chlorophyl-green, and are believed to be especially active in 
the formation of starch. At times, iodine turns them simply brown ; at others it 
colors their inner portions blue and their outer brown, showing them to contain 
starcli. The general cavity of the cell is occupied by fluid, in which is placed the 
nucleus. This is mostly single, but rarely, according to Njegeli and other authori- 
ties, double, and Ue Bary states that he has seen three nuclei in a single cell. I 
have never seen more than one, and think that even this is not rarely absent, having 
certainly repeatedly failed to demonstrate its presence. It is colorless, often with 
a nucleolus, transparently bright, irregular in form, placed in the centre of the cell 
with numerous arms radiating out from it, some of them ending within the cell, 
others connecting it with the primordial utricle. De Bary states that this nucleus 
occasionally is tinged green with chlorophyl, I do not remember ever to have seen 
it so. 

I have not infrequently seen numerous minute dark granules, similar to those 
seen in Closierium, scattered through the inside of the cell, in active motion. Some- 
times they are to be found collected in vast numbers near the ends of the cells, 
dancing and swarming about one another, and passing off in small streams from 
one end to the other, coasting along close to the primordial utricle, in a word, ex- 
hibiting precisely the same motions as are so common among the desmids. 

The Zygnema filament grows in length by a process of cell multiplication by 
division of the simplest kind. It seems to be somewhat uncertain whether the 
nucleus always divides into two as a part of the process or not. These plants 
multiply both by the separation of cells and their subsequent growth, and, by 
means of resting spores, the so-called Zyfjospores. 

The first appearance of separation of the cells is an evident disposition to tlie 
rounding off of the ends of the cells. The corners are first rounded and separated 



FRESII-WATEK ALU.E OF TUE U i\ 1 T E D STATES. 161 

and tliis continues until only the centres of the ends are in appof-ition, and in a 
little while even these separate. This certainly, at least, is tlie process in certain 
species ; but I have thought, that in other cases cells were separated by a simple 
splitting of the end wall, each cell retaining its half of the partition. 

The zygospores are produced by a process of union of two cells, to which the 
name of coiijugatio7i has been given. Very rarely, if ever, is there any difference 
between the cells before conjugation, and it has not existed in any species which has 
come under my notice; but, after conjugation, the receiving cell is frequently 
enlarged, the other remaining cylindrical. De Bary, however, states that he has 
found a small but constant difference between the fertile and sterile cells of 
Spirogjjra Heeriana. 

The first perceptible change in a cell about to produce a resting spore, appears 
to be a loosening of the primordial utricle from the outer wall, and a contraction 
of it upon the cell contents, which thus are crowded together and more or less 
deformed. Simultaneously with tliis, or a little after or before it, the side waU of 
the cell is ruptured and a little pullulation or process is pushed out, which directly 
coats itself with cellulose and rapidly enlarges to a considerable diameter, at the 
same time growing in lengtli until it meets a similar process pushing out from an 
opposing cell, or has attained as great a length as its laws of development will 
allow. "When two processes meet they become fused together, the end walls are 
ruptured, and the contents of one cell passing over are received within those of the 
other, or else the contents of both cells meet within the connecting tube and there 
fuse together. This is the more common mode of conjugation, in which two cells 
of distinct filaments become joined together by a connecting tube. It is evident, 
that, if the filaments are fertile to their fullest extent, there will be as many of these 
connecting tubes as there are pairs of cells in the filaments, and a ladder-like body 
will be formed, the original filaments corresponding to the side pieces, the connect- 
ing tubes to the rounds. Hence this method of conjugation has received the name 
of scalariform. 

In the so-called ^'■lateral conjugation" instead of cells of different filaments join- 
ing, adjacent cells of one filament unite togetlier to complete tlie process. The 
union of the two cells appears to take place in several ways. In accordance with 
one plan (fig. 1 o, pi. 14), connecting tubes, puslied out from near the ends of 
the cells, grow for a short distance nearly at right angles to the long axis of the 
filaments, and then bend at a right angle to themselves so as to run parallel to 
the filament-cells. The ends of these processes are, of course, opposed to one 
another, and coming in contact fuse together so as to form a continuous tube for 
the passage of the endochrome. Another method by which neighboring cells are 
sometimes connected is by the formation of coadjacent pouch-like enlargements of 
the opposing ends, and a subsequent fusion of these newly formed enlargements 
by the absorption of the end wall between them. (See fig. 2, pi. 14.) 

Sometimes I think the union of two neighboring cells is facilitated by a curved 
neck forming to one or both of them, so that they are bent at an angle to one 
another, and can readily be united by means of a straight tube. 

There is still another method of conjugation, the so-called genvjlexuous, in wliicli, 

21 August, 1872. 



1G2 FUESU-WATKU A L G .E O K THE UNITED STATES. 

instead of a connecting tnbc being formed as the medium of union, two cells of 
opposing lilanients become sharply bent backwards, so that their central portions 
arc strongly thrust forward as obtuse points, which, coming in contact, adhere and 
allow of a passage-way between the cells being made by the absorption of their 
cohering walls. 

A curious modification of, or departure from, the ordinary method of conjugation 
is sometimes seen, in the union of three instead of two cells. This is, I think, 
very rare, but has been seen by Meyen in the genus Zijynema, as well as by 
Schleiden and Ue Bary in Sj^nrogyra. I myself have observed it once or twice iu 
the latter genus. One of the cells plays the part of the female, receiving the con- 
tents of the other two, so that in it the primordial utricles of the three, with their 
contracted protoplasm, arc fused into a zygospore. 

The zygospore, however formed, varies in shape, but is mostly oval or globular, 
sometimes cylindrical, and when ripe is in most if not all species of a dark brown- 
ish color. It is described both by Pringsheim and De Bary as having three coats, 
but I luu e frcfpiently found it impossible to demonstrate the presence of all of 
these, and I believe that not rarely one of them is absent. The outer coat is 
developed first and is the thickest and firmest. Occasionally it is double, i. e. 
composed of two distinct layers or parts, as in /S/>. 2^^ot€''fa, iu which species the 
outer of these layers is the thickest, firmest, and most evident, whilst the imier 
layer is translucent and much less apparent. The second coat contains the 
coloring matter, which is sometimes brown, sometimes decidedly yellowish. The 
inner coat is not readily seen. It is elastic, thin, and is the last of the three to be 
formed. 

The princii)al contents of the ripe spore are protein compounds (protoplasm), 
oil-drops, starch granules, and pigment. The oil is generally much more abun- 
dant than the starch, and not rarely the minute, bright drops entirely replace 
the little granules. According to Prof. De Bary, the pigment frequently, but not 
always, reacts Avith sulphuric acid, as does that of the fungal family, Urcdinece, 
striking with it a deep blue. 

The germination of the spore, both in the genus Spirorjyra and Zijfjnema, is 
very simple. The first step is an elongation and growth of the protoplasmic 
central mass, together with the inner transparent cellulose coat, and a consequent 
rupturing of the outer two coats, through which the newly forming plant protrudes 
and finally escapes. In this way in the genus Splrofjijra an elongated club-shaped 
cell arises, one end of which is much larger than the other and contains all the 
chlorophyl. Sometimes a nucleus is perceptible in this cell, sometimes it is not. 
The larger end now becomes cut oft' by a partition Avail from the smaller; if no 
nucleus has been previously apparent it noAv becomes so, and the first stage of 
development is completed. Tlie filament after this grows by a simple repetition 
of the process of division in th(> larger end and the cells formed out of" it. The 
smaller end undergoes little or no change. In the genus Z[i<jnema, the cell that 
first emerges from the germinating spore is a perfect one, similar in all respects to 
those seen in tln^ fully formed filament, which is developed out of it, by a simple 
process of cell division. 



FRESH -WATER A L U J2 OF TUE UNITED STATES. 103 

• 
I Besides the true Zngoftpnres, Hassall many years since described bodies (Fresli- 
water Alga?, vol. i. pp. 132, 156, 170), wliic;h he found in filaments of this family, 
I and which resemble in all respects ordinary Zt/ijospores, but are produced each 
in a single cell without any .aid from a second cell. He affirmed that he had 
observed this phenomenon especially in two species, Spirogyra mirahiiis and 
; Zijgnema notah'dls. These observations were doubted by some, whilst others, as 
; Alexander Braim, supposed that there was a division of the cell protoplasm into 
I two distinct portions, and then a conjugation of these within the original cell, and 
that Mr. Hassall had overlooked these changes. Prof. De Bary, however, states 
that he has seen a great many instances of this production of spores without conju- 
gation (all in one species), and that there can be no doubt that llassall's obser- 
vations are substantially correct, and that no division of the primordial utricle such 
1 as was imagined by Prof. Braun takes place. Spores formed in this manner, as 
: yet have not been seen to develop. There is, therefore, no certainty that they are 
j capable of doing so. It is possible that they are merely the results of abortive 
j attempts at reproduction, Avanting the power of development because not fertilized. 
j Pringsheim and others have drawn from these bodies strong argument against 

the idea, that conjugation is to be looked upon at all as a sexual process. 
■ The arguments both for and against regarding conjugation as the simplest ex- 
i pression of sexual life are ably elaborated by De Bary, Untersucliungen iiler die 
\ FamU'ie dcr Conjugate m, p. 57, to which I must refer those desirous of following 
the subject further, contenting myself with expressing an agreement with the con- 
clusions there arrived at, namely, that in conjugation the first dawnings of sexuality 
are to be found. Looking at it in this light Prof. De Bary states his conviction 
I tliat the spores formed in the manner last described, bear the same relation to the 
j true Zygospore that the bud of a Phanerogam does to its seed, or the Zoospore of 
an CEdogoninm does to its resting spore. 

Quite a number of bodies have been described by the older authorities as being 

found within the cells of plants of this family, which more recent observers have 

I proven to be parasitic. Such are the " Spermatic spheres," transparent spheres 

motile by virtue of vibratile cilia, various monads, &c. «S:c., bodies for which it has 

j been claimed, from time to time, that they were sexual elements, spermatozoids. 

Genus SPIROGYRA, Link. 

CelluliB TegotativoB cylindrica;, ftisciis cliloropliyllosis si)ii-alil)us instructie. Conjugatio aut lafci'. 
alis aut scalarilbrmis aut et lateralis et scalarifonnis. 

Syn. — Spirogyra et Bhynclionema, KiJTZiNa, Rabenhorst, et auctores. 
Salmacis, Boet. 
Zygnema (pavtini'), Hassall. 

Ycn;etative cells cyliiulrical, furnished with .spiral ohlorophyl bands. Conjugation cither lateral 
or scalariforni or both lateral and scalariform. 

Bemarl-s. — The genus Spirogyra, as defined above, has been divided by Kiitzing, 

\ Rabenhorst, and others into two genera, the chai'iicters being drawn from the 

method of union of the conjugating cells; in the one case the neighboring cells of 

a single filament [lihytichoncma), in the other cells of distinct filaments {S^drogyra)^ 



104 FRESH-WATER ALG.E OF THE UNITED STATES. 

uniting to form the spore. This at first sii^lit appears to be a good ground for sepa- 
ration, but there arc certain species in wliich, undoubtedly, both the former und 
the hitter method of conjugation take place indifferently. Such species make a 
third "Toup so precisely between the two others as, to my mind, to fuse them toge- 
ther and necessitate either the acknowledgment of three genera or the denial of 
more tlian one. The latter seems to me the more philosophical course, 

A. CONJUGATIO LATERALIS (RhYNCHONEMA). 

A. Conjugation lateral. 

Sp. elonj^atn, Wood. 

Sp. articulis vegetativis diametro 1-20 plo longioribus; articulis sporiferis multo brevioribus, 
valde tuiuidis ; cytioderraate utroque fine protenso et replicate ; fascia unica, laxissime spiral!; 
anfractibus plerumque 7 ; sporis ellipticis, diametro 1-2^ plo longioribus. 

Biam.SpoT. 7/^/ = -OOIOG". Artie. Tegetat. 7/5^" =.0005". 

l^yn. — Jlhynchonemaelongatum^ooD, Prodromus, Proc. Amer. Philos. Soc. 1809, p. 137. 

Hab. — In aquis limpidis, propo Philadelphia. 

Sterile joints 7-20 times longer than broad; fertile joints much shorter, greatly swollen; cell 
wall at each end produced or folded in; chlorophyl filament 1, spiral lax; turns mostly 7 ; 
spores elliptical, 2-2^ times longer than broad. 

Remarks. — I found tliis species about the middle of March, fruiting in a little 
pool near Chelten Hills, six or eight miles north of this city. It did not form a 
distinct stratum by itself, but was floating, intermingled with great numbers of 
other filamentous algte, such as fragillarice, ziicinemce. Sec. It seems to be most 
closely allied to the European R. mlnimuvi ; it however not only attains a some- 
what larger size but also differs from that plant in the proportionate length of the 
sterile cells, in the number of the turns of the chlorophyl spiral in the cell, and in 
the proportionate length and breadth of the spore. 

Fig. 1, pi. 14, represents portions of sterile filaments magnified 450 diameters; 
1 a, a part of a fertile filament, magnified 450 diameters. 

Sp. piilchella, Wood. 

Sp. articulis sterilibus diametro 2-3 plo longioribus; sporiferis nonnihil tuniidis; fascia unica, 

anfractibus 3-4 ; sporis ellipticis, diametro fere duplo longioribus ; cytiodermate utroque fiin' 

protenso et replicato. 
Diam.—Aviw. Steril.75V'_7|^"=. 00033"— .0013". Spor. ^-^^^'•—^\%^"=.(iQ\r—MUr. I 
Syn.—Bh.ynconem.apulchellum,Woo^,'Pvodvom\ifi, Proc. Amer. Philos. Soc. 18G9, p. 138. 
Hah. — In stagnis, prope Philadelphia. 
Sterile joints 2-3 times longer than broad ; fertile joints somewhat swollen ; chlorophyl band 

one ; turns of spiral 3-4; spores elliptical, almost twice as long as broad; cell wall at each 

end produced or folded in. 

Remarks.— T\vi% species was found by myself fruiting in April, 1869, in stagnant 
ditches below the city, and in similar localities near Camden, New Jersey. It did 
not occur in masses but singly, intermixed with great numbers of other fruiting 
spirogyras. Most of the filaments seen were about .0010" in diameter; in but a 
single instance did they come much short of this. This species diff'ers from R 
clongatum, among other points, in the shortness of the tubes connecting the fertile 



FRESH-WATER ALG^ OF THE UNITED STATES. 1G5 

cells. I have never been able to identify an entirely sterile filament of this species; 
the measurements and description of the sterile cells were taken from infertile cells 
in filaments, which in other places had produced spores. 

Fig. 2, pi. 14, represents a fertile filament, magnified "iCiO diameters. 

B. CONJUQATIO SCALARIPOEMIS (SpIROGYBA VERA). 

a. Cij/iodermale lUroqiie Jine prolensum et rcplicatum. 
a. Gytiodcrm folded in at the ends. 

* Fascia spiralis iinica. 

* Spiral filament single. 

Sp. Weberi, Ktz. ? 

Sp. saturate viridis, lubrica ; articulis vcgetativis diamotro 3-20 plo longioribus; fructiferis 
nonnihil iuflatis; fascia dentata, ploniiiKiue uiiica sed lasciis diialtus in quavis cillula; s])ira! 
aufractibus 3-8; cytiodermate plerumque uti'oquo fiiiu prutcuso et replicato ; zygosporis cllip- 
ticis. 

I>iam.—Aviic. stcril. j-f-g-^"—j^%^" = .0()0S"—.0QV2". 

Syn. — S. Weberi, Kutzino. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 233. 

Eab. — In stagnis, prope Philadelphia. 

Deep green, slippery; sterile joints 3-20 times longer than broad; fertile joints not swollen ; 
ehlorophyl filaments mostly single, but sometimes two in certain cells, dentate ; turns of the 
spiral 3-8 ; eytioderm protruded or infolded at the oud.s ; zygospores elliptical. 

Remarhs. — This species, which is abundant around Philadelphia in stagnant 
ditches, I have found fruiting in the month of April. The number of spirals fre- 
quently varies even in the same filament. The infolding of the walls at the end 
of the cells is very often wanting in the fertile cells and occasionally is absent from 
one end of an ordinary vegetative cell. The American form agrees pretty well 
with the European, but is, however, larger, and also attains in its cells a greater 
proportionate length and has more turns of its ehlorophyl spirals. The lower 
limits of the American form are, however, so overlapped l)y the upper limits of the 
European, that it seems to me they must be considered identical. 

Fig. 19, pi. 12, represents a pair of fertile filaments of this species, magnified 
260 diameters; 19 «, part of a sterile filament, magnified '2G0 diameters; 19 A, out- 
line of a couple of fertile cells, magnified 260 diameters. 

Sp. protecln, Wood. 

Sp. saturate viridis, lubrica; articulis sterilibus diametro 6 plo longioribus; s])oriferisvi.\ tuniidis; 

cytiodermate utroque fine protenso et replicato ; fascia unica; aufractibus G; sporis oblongis 

vel ellipticis : meuibrano crassissimo. 
Diam.—Ari. steril. ^ij/ = .00146" ; spor. lat. T-igg"_7i-?/ = .00133"— .OOIG" long. ^^^" 

= .0033". 
Syn. — Sp. proleeta, Wood, Prodromus, Proc. Am. Philos. Soc. 1869, p. 131. 
Sp. deep green, slippery ; sterile joints 6 times longer than broad ; fertile cells scarcely swollen ; 

cell wall folded in at the ends; ehlorophyl band single ; turns 6 ; spores oblong er e!lii)tical, 

spore wall very thick. 

JRcmarl-f:. — I found this species in the latter part of April fruiting in a ditch 
in a meadow a little south of the mouth of Wissahicon Creek, near this city, 
and as late as the 25th of May in the "neck" below the city. It is remarkable 



166 FllESII-WATKU ALGAi OF THE UNITED STATES. 

for the very great thickness of the walls of the spore. There are two very appa- 
rent coats separated by a thin not very evident one. The outer is the thickest; 
it is verv thick, firm, and nearly colorless. Tiie inner coat is of a decided orange- 
brown. The parent-cells which give origin to these spores are slightly enlarged 
in diameter. Sometimes the spores, instead of being elliptical, are irregular in 
shape. 

Fi"-. 3 a, pi. 14, represents a sterile filament, magnified 250 diameters; fig. 3, a 
mature spore, magnified 4:50 diameters. 

Sp. iusignis, (IIassali.) Ktz. 

Sp. articulis sterilibus diametro 5-14 plo longioribus ; fasciis 2 (rarius 1-3), laxe spiralibus, 
aiif^ustis, ci-euatis; articulis fructiferis nonniiiii tuniidis ; cytiodeniiate utroque fiue rcplicatu 
vt'l pi-otuiiso ; zygosporis rubido-bruuueis, ovato-ellipticis. 

Diam.—O.OOli)". 

Syn. — Zyrjnema insigne, Hassall, Fresh-Water Algfe, p. 440. 

Sjiirogtjra iiisitjiiis, (Hassall) Kuxzinu. ItABEXHORST, Flora Europ. Algarum, Sect. 
III. p. 235. 
Sab. — In stagui.s, in'ope Pliiladfliiliia. 

Sterile joints 5-14 times longer than broad ; ehlorophyl filaments mostly 2 (rarely 1-3), la.xly 
spiral, narrow, crcnate ; fertile joints somewhat enlarged; cytiodcrin at each end folded iu 
or produced ; zygospores reddish-brown, ovate elliptical. 

Eemark. — Fig. G, pi. 16, represents this species. 

b. Cytioderma celhdae fine nee pi'olensum nee repllcalam. 

Cytioderm not infolded in the end of the cell. 
* Fasciss spirali unicse {raro duse). 
ChloropJiyl band single {rarely two). 
Sp. longata, (Yaucii.) Ktz. 

Sp. dense c;espitosa, late luteolo-viridis, valde lubrica; articulis sterilibus diametro 2-U plo 
longioribus, fertilibus sajpe tumidis abbreviatis ; fascia spirali lata, dentata ; anfractibus sub- 
laxis 2-5 ; zygosporis ellipticis. 

Diam.— 0.001". 

Syn. — GonjiKjala lungata, Vaucher, Ilistoire dcs Conferves d'Eau douce, p. 71- 

Sp. longata, (Yauch.) KiJTziNO. Kabenhoust, Flora Europ. Algarum, Sect. III. p. 23S. 

Hab. — In stagnis, prope Philadelphia; Wood. Khode Island; (S. T. Olney) Thwaites. 

Densely CiBspitose, bright yellowish-green, very slippery ; sterile joints 2-6 times longer than 
broad; fertile articles swollen, often abbreviate; ehlorophyl filaments broad, dentate; turns 
of the spiral somewhat loose, 2-5 ; zygospores elliptical. 

Remarlcs. — According to Prof Ilabenhorst, this species attains in Europe a 
diameter of .0011" and the cells a length of 8 times their breadth. The same 
authority also describes the fertile cell as being either not swollen, or moderately 
so (" ant non ant modice tumidis"). In all the specimens of our American forms 
which I have seen, the sporangial cells are very decidedly swollen. 

I'ig- 4, pi. 14, represents portions of sterile filaments, magnified 250 diameters, 
and fig. 4 a, a part of a fertile pair of filaments containing immature spores enlarged 
260 diameters. 



FRESII-WATEU ALG^ OF THE UNITED STATES. 107 

Sp. qiiinina, (Ag.) Kxjtz. 

Sp. saturate viridis, valde lubricata; articiilis stcrilibus diamctro 1-0 jilo longiinilius ; articuliri 

fertilibus vel baud tumidis vel nonnihil tumidis ; fascia uuica ; spine aufractibus modo dfii- 

' sioribus, modo laxioribus, nonnunquara laxissimis, pleruiuque 3, intcrdum l^-i ; cytiod(!riiial(; 

cellute utroque fine nee protenso ncc replicato ; zygosporis aut globosis aut ovalibus aut 

cylindricis. 

Dtam.— Artie, steril. 7J3j"_7l3/' = .0013"— .0017" ; sporis ^|^5" = .0014". 

Si/n. — Sp. quijiina, (Agardh)K1;tzing. Ivabenuorst, Flora Eump. Alg-ariim, Sect. III. p. 

240. 
JTab. — la stagnis, prope Philadelphia. 

Deep green, very slippery, sterile articles l-fi times longer than broad ; fertile joints scarcely 
or not at all tumid ; cidorophyl filament single; turns of the spiral sometimes denser, some- 
times laxor, sometimes very lax, mostly 3 in number, sometimes 1^-4 ; cytioderm neither 
infolded nor protruded at the end ; zygospores polymorphous, globose, elliptical or cylindrical. 

Remarks. — This species is very abundant in tlie ditches aronnd Pluladclpliia, 
especially in the " neck" below the city. I have found it fruiting profusely in the 
mouth of April. The spores vary very much in form, some of them being globose, 
others elliptic, and still others cylindrical, with obtusely rounded ends. All these 
forms may occur in a single filament. The spore cell also varies in the amount of 
its enlargement. In many cases it preserves its cylindrical shape completely ; in 
»ther instances it is markedly swollen. 

Figs. 4 e, 4 c, pi. 19, represent portions of sterile filaments of this species; figs. 
t a, 4 b, and 4 d, portions of fertile filaments. 

f f Fasciee spirala; diae i-rl pltn-es. 
ff Chlorophyl filaments tivo or many. 

"^p. decimina, (Muller) Ktz. 

Sp. sordidu viridis, lubrica; articulis sterilibus diamctro (O.OOl.TJ" — 0.001.59") plerumque 
duplo-, quadruplo fere longioribus, nonnunquam subieqiialibus, fertilibus aut non aut nioiliee 
tumidis; fasciis spiralibus plerumque 2, latis, decussatis, rarius 1 vel 3, anfractibus laxis 
1-H; zygosporis aut ovalibus aut late ellipticis vel subglobosis. (R.) 

iiijn. — ,S'/). decimina, (Muller) Kuizino. Eabenuorst, Flora Europ. Algarum, Sect. III. p. 
242. 

Hub. — Prope Philadelphia. 

Dirty green, slippery; sterile joints mostly from 2-4 times as long as broad (0.0013.5" 

0.00159"), sometimes about as long as broad ; fertile joints either moderately or not a( all 
swollen; spiral filaments mostly 2, broad, decussating, rarely 1-3, turns loose l-H; zygo- 
spores either oval, broadly elliptic, or subglobose. 



RemarJcs. — I find this species marked in one of my note-books as having been 
found by myself near this city. I have no distinct recollection of seeing it, and, 
having preserved neither figure, specimen, nor description, am forced to content 
myself with copying the description of Prof llabenhorst. 

Sp. dubia, Ktz. 

Sp. viridis in fructe dilute viridis; articulis sterilibus cylindricis diametro 1|^-2J plo longioribus ; 
fasciis spiralibus 2-3, angustissiinis, nodosis, anfractibus laxis 1-2 (=3-0); cytioderniate 
utroque fine nee protenso nee replicato, nonnihil crasso ; zygosporis polymorphis, aut sub- 



168 F RE S II- W ATE 11 ALG^ OP TUE UNITED STATES. 

clobosis aut ovalibns, ant subcylindncis, dianietro fequalibus aut | plo longioriljus ; artictilis 

fcrtilibns cylimlricis, hand tumidis. 

Diam.— Art steril. ^lU' = -00-2 ; spor ^l'/ — .002". 

Sy„. Sp. duhia, KuTziNG. Rabenhorst, Flora Eiirop. Algarum, Sect. III. p. 243. 

//„/,. — lu stag-nis, propc Philadelphia. 

Green, in fruit light green; sterile joints cylindrical, l|-2l times longer than broad; spiral 
filaments 2-3, very narrow, nodose, la.x, turns 1-2 ; cytiodcrm neither infolded nor protruded 
at the end, rather thick ; zygospores polymorphous, either subglobose, oval, or subcylindrical, 
as broad as long to J times longer; fertile articles cylindrical, not enlarged. 

Remarks. — I have fotmd this species growing in the ditches below the city, fruit- 
ing iibundantly in INIay. When in tliis condition it forms masses of a dirty, hghtish, 
yellowish-grccn. Tlic spores mostly fill pretty well the fertile cells. My specimens 
do not agree completely with the descriptions given of the European. The two 
forms, however, completely overlap one another, except in one character, namely, 
the shape of the sporangial cell. I liave never seen it swollen or at all tumid in 
American specimens, whilst in the European it is said to be " modice tumidis." 
This difference alone does not, however, seem to me sufficient to characterize a 
new species. I have seen specimens of this plant collected by Dr. Lewis at Cobble 
Mountain. They agree well with the Philadelphia specimens, except in attaining 
a little larger size, .0021", and in the sterile filaments having their walls very thick. 
The character of non-inflation of sporangial cells is perfectly preserved. 

Fig. 4, pi. 17, represents this species. 

Sp. rirularis, (Hass.\ll) Rabenk. {non Ktz.) 

Sp. saturate viridis, Inbrica; articulis sterilibiis diametro "I-ll plo longioribus; fertilibuscylin- 
dricis aut vix tumidis; cytiodermato tenuissimo, utroquc line nee protenso nee replicato, 
fasciis 4, lase spiralibus, modice angustis, nodulosis et seiTatis, aufractibus 2| ; zygosporis 
ellipticis, diametro 2-2^ longioribus. 

Diam.— Art ster. ^/^/-^IJ/ = .0012"— .OOUG" ; spor. ^ig^—^lg/. 

Syn. — Zygnema rivularis, IIassall, Fresh-Water Algte, vol. i. p. 144. 

Spirogyra rivularis, (Hassall) Qion KiJTZiNG) Rabenhorst, Flora Europ. Algarum, 
Sect. III. p. 243. 

Ilab. — In rivulis, Florida ; (Canby) Wood. 

Deep green, slippery ; sterile articles 7-11 times longer than broad, fertile cylindrical or slightly 
tumid ; cytioderm very thin, neither infolded nor protruded at the end ; chlorophyl filaments 
4, laxly spiral, moderately narrow, nodose and serrulate, turns 2^ ; zygospores elliptical, 
2-2^ times longer than broad. 

RemarJcs. — This species was collected by Mr. Wm. Canby in Pine Barren Run, 
near Hibernia, Florida. It is rather smaller than the European forms, but does 
not appear to be distinct from them. Rabenhorst, indeed, states that there are 
only two or three chlorophyl spiral bands in a cell, but Hassall in the description 
of the type states distinctly that in some instances there are four bands, and alsc 
figures the plant so. 

Fig. 5 a and h, pi. 17, represents sterile cells of this species, magnified 26C 



FRESH-WATER ALG^ OF THE UNITED STATES. 1G9 

diameters. Fig. 5 c is an outline of a pair of fertile cells enlarged to the same 
extent. 

Sp. parrispora, Wood. 

Sp. articnlis sterilibus diaractro 2-4 plo loDgioribus ; fructiferis liaud tumidis, diamctro l-2i i)lo 
lougioribus; fasciis spiralibus 4, angustis, nodosis, anlVactibus pluribus ; zygosporis parvis- 
simis, ellipticis, diamctro 1^-2 plo longioribus; cytiodurmate utroque fine nee protcnso uec 
re|ilicato. 

Diam.— Art steril 7|g5"=.003"; spor. diam. transv. yjg/— 7^3/= .002"— .0023",long. ^H^" 



30 " 



Syn. — S. parmspora, Wood, rrodromus, Proc. Am. Philos. Soe. 1SC9, p. 139. 

Ilab. — lu stagnis, Hibernia, Florida. (Wm. Canby ) 

Sterile joints 2-4 times longer than broad; fertile not tumid, 1-2^ times longer than liroad ; 
chlorophyl bands 4, narrow, nodose; turns many; zygospores very small, elliptieal, 1^-2 
times tonger than broad; cell wall not infolded at the end. 

Remarks. — I am indebted to Mr. Wm. Canby for specimens of this species, 
which he collected in a pond in the Fine Barrens near Hibernia, St. John's lliver, 
Florida. It is remarkable for the comparatively small size of the spores, which do 
not nearly fill the perfectly cylindrical mother-cells ; indeed they are only about as 
long as the latter are wide. This species closely resembles S. majiiscida, but is 
larger, does not, that I have ever seen, vary liive it in the number of spores, and is 
especially separated from it by the very small size of the latter. 

Fig. 7, pi. 15, represents a fertile pair of filaments of this species magnified 125 
diameters. 

8p. majuscula, Ktz. 

Sp. pallide et sordide viridis, fructus tempore fuscescens ; articulis sterilibus diametro (0.002'2" 
— 0.0025") 2^-4-10 plo longioribus; cytioderniate tcnui horaogcneo ; fasciis 3-4-5 (rarius 
T), modo subreetis longitudinalibus, modo lasissime spiralibus, nodosis; zygosporis globosis 
vel ovalibus. (R.) 

Syn. — S. majuscula, KiJTZiNO. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 244. 

Hab. — Prope Philadelphia. ? 

Pale and sordid green, fuscescent at the time of fruiting ; sterile joints 24-4-10 times longer 
than broad (.0022" — 0025") ; eytioderm thin, homogeneous ; spiral filaments 3-4-5 {^rarely 7) 
partly straigUtish and longitudinal, partly la.\ly spiral, nodose ; zygospores globose or oval. 

Remarlcs. — Shortly after I commenced to study the fresh-water alga?, I found 
below the city a fruiting Spirogijra, of which I preserved only a drawing, which I 
have since identified as apparently specifically one with the European S. majuscida, 
it differing only in not being quite so large; my measurement was ^-Jq^" = 0.002". 
Not having any specimens at hand, I have copied the description from the work of 
Prof. Rabenhorst. 

Fig. 1, pi. 15, was copied from the drawing alluded to. 

Sp. nitida, (Dn,Lw.) Link. 

Sp. coespitibus, lubrieis, saturate viridibns; articnlis sterilibus post divisioncni diametro snb- 
8equalibu.s, ante divisionem 2-3 plo longiorilms ; articulis fertilis aliis simillibus, baud tumidis ; 
fasciis spiralibus 4(3-4 R ), modice latis, anfractiljus 1-2; zygo.'^poris ellipticis. 
22 August, 1873. 



170 1' RES II -WATER ALG.E OF THE UNITED STATES. 

. Diam.— 0.0025". 

Si/n.—S. nilida, (Dillwyn) Link. Rabenuoust, Flora Europ. Algarum, Sect. III. p. 245. 

/7„6._Prope Philadeli>bia. 

Occum'ns?- in lubricous turfy masses, of a deep green color; sterile joints after division about 
a.s long as broad, before divisiou 2-3 times longer ; fertile joints similar to the others, nut 
tumid; spiral filaments 4, moderately broad, turns 1-2; zygospores elliptic. 

Remarl-s. — This species appears to be somewhat rare, at least I have found it 
but once, and tlicn only in small quantity. Rabenhorst states that there are occa- 
sionally only three spirals, and his maximum diameter is 0.0031"; he also speaks 
of the fertile johits as "vix tumidis." 

Sp. diliila, Wood. 

Sp. articulis sterilibus dianictro subaHpialibus ad duplo longioribus, frnctiferis baud tnmidis; 
fasciis spiralibus 5, angustissimis, laxis, valde nodosis ; anfractibus plerumque i, interduin 
1 ; zvgosporis sparsis, late ellipticis vol ovatis aut globosis; cytiodermate modice teuue, in 
utroque fine uec protcnso nee replicato. 

Biam.—Avtic. steril. j^^" = .003". 

Sijn.—S. diluta, Wood, Prodroraus, Proc. Am. Philos. Soc. 18G9, p. 139.] 

Edb. — In stagnis, prope Philadelphia. 

Sterile joints about as long as broad to twice longer, fertile cells not swollen ; chlorophyl kands 
5, exceedingly narrow, lax, strongly nodose ; turns mostly ^, sometimes 1 ; zygospores few, 
broadly cllijitical, ovate or globose ; cell wall moderately thin, not infolded at the cuds. 

BemarJcs. — I have found this species several successive seasons growing in the 
ditches in the Neck, below the city, especially in the neighborhood of the large 
stone barn, built by the great millionaire, and still known as " Girard's Barn." 
The spirals are very narrow and slender, and are moderately close to one another. 
They arc chiefly made up of a number of chlorophyl nodules, the connecting thread 
between which is often very faint. In all the fruiting specimens, as I have seen 
them, the spores have been very few in number, most of the ccUs of the fertile 
filaments appearing to have aborted, so that they are simply empty. In most cases 
only about every third or fourth cell contained a spore. 

Fig. 2, ul. 15, represents this species. 

Sp. setiforniis, (Roth) Ktz. 

Sp. saturate viridis, lubriea ; articulis sterilibus diametro paullum brevioribus ad 1^ plo lon- 
gioribus ; articulis fructiferis hand inflatis ; fasciis 3-8, latis, dentatis, interdum nonnihil 
remotis, sed soepe arete et dense conjunctis, nodosis ; zygosporis globosis vel late ovalibus. 

Diam. — .0035". 

Syn. — S. setiformis, (Roth) Kxttzino. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 246. 

Hah. — In stagnis, prope Philadelphia. 

Deep green, slippery ; sterile joints a little shorter to one and a-half times longer than broad; 
fertile joints not inflated ; spiral filaments 3-8, broad, dentate, sometimes somewhat remote, 
sometimes closely and densely conjoined, nodose ; zygospores globose or broadly oval. 

Rcmarhft.—^oriG of the descriptions which I have seen of this species state the 
number of the spiral filaments, but the other characters of the American form sc 
agree with those of the European plant that it is probable that this one does also, 
The jjlant is not uncommon in the Neck, fruiting in the spring. 



FRESU-WATEIl ALG.E OP THE UNITED STATES. m 

Fig. 3 a, pi. 15, represents part of a sterile filament of this species; 3 h, portion 
of a pair of fertile filaments, botli magnified 125 diameters. 

Sp. crai^sa, Ktz. 

Sp. Iffite viridis, denique sordide viridis ; articulis sterililjus dianietro sulinequalibns, poi5t divi- 
sionem interdum fere 5 [ilo broviori))us, autc divi.sionein Siepe fere 2 plo longioribus ; cytin- 
dermate tenui, bomogeneo, utroque fine nee protenso nee replieato ; fasciis spiralibus 4, 
deutatis vel tuberculatis, ssepe arctis, subtransversis, tenuibus ; anfractibus li-4 ; ccllulis 
fructiferis aliis simillimi.s, baud iuflatis ; zygosporis globosis vel cllipticis. 

Diam.—Max. .00G5." 

Syn. — Sp. crassa, Ktz. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 240. 

ffab In stagnis, prope Philadelphia. 

Bright green, but finally a dirty green ; sterile articles about a.s long as broad, sometimes after 
division only half as long, sometimes before division twice as long; cytioderni thin, homo- 
geneous, not infolded or produced at the ends ; spiral filaments 4, dentate or tuberculate, 
often close, subtransverse, thin; turns from 1| to 4 ; fertile cells very like the others, not 
inflated ; zygospores globose or elliptical. 

Remarks.- — This species is very common in the neighborhood of this city, occur- 
ring in springs, &c., but especially in the ditches in the Neck. It forms long, 
lubricous masses, of a bright green color, readily distinguishable by the size of the 
filaments, which are separated with ease by the unaided eye. I have gathered it 
repeatedly, in fruit, from the middle of April to the middle of June. In this state 
the mass has lost its bright green color, and when the filaments are closely examined, 
even without a glass, minute dark points mark the positions of the spores. 

Fig. 4 «, pi. 15, represents part of a filament commencing reproduction ; 4 &, fila- 
ments which have matured the spores; 4 c, a pair of conjugating filaments. 

Genus ZYGNEMA. 

Celhilae vegetativte cylindricffi. Massa chloropliyllaeea initio efi"usa et subhomogenea, postea dis- 
tiuctc granulosa aut per celiuUe lumen distributa, granula amylacea duo ceutralia involvens, aut in 
eorporibus duobus (in quaque cellula) plus minusve distincte stellatini radiantibus juxta nucleum 
centralum grauum amylaceum unicum involventibus collocata. Conjugatio scalariformis vel late- 
ralis. 

Vegetative cells cylindrical. Chlorophyl masses in the beginning effused and subhomogeneons, 
afterwards distinctly granular, eitlier distributed throughout the cavity of the cell, involving two 
central starch granules, or gathered togetlier into two masses (in each cell), with more or less dis- 
tinctly stellate radii and a central starch granule placed near the nucleus, one on each side of it. 

Z. iniiiig^ne, (Hassall) Ktz. 

Z. caespitibns et plerumquo natantibus vel in aqua diffusis, saturate viridibus vel sa>pc sordide 
flavo-viridibus ; articulis sterilibus diametro circiter a^qnalibus vel duplo longioribus ; conju- 
gatione scalariforme (et sa;pe simul lateral!, R.); zygosporis globosis; sporodermate Icevi. 

Diani.— Cell „VW = -00126" ; spor. ^^^^%^"—^J-,%^" = 0.00093"— O.OOOIG". 
Syn. — Tyndaridea insignis, Hassall, Fresh-Water Algoe, vol. i. p. 1 03. 

Zygnema in.wjne, (Hassall) Kutzing. Rabe.niioest, Flora Europ. Algie, Sect. III. 
p. 249. 
IJab.— In stagnis, prope Philadelphia ; Wood. Rhode Island ; (S. T. OIney) Thwaites. 



172 FRESU-WATER ALG.^ OF THE UNITED STATES. 

Csespitose and mostly floating or difTused in the water, deep green, or a dirty yellowish-green; 
sterile joints about as long as broad, or twice as long; conjugation scalariform (according 
to Rabenhorst somctiujes at tiie same time lateral) ; zygospores globose ; spore coat smootli. 

JRemarks. — This species is very common around Philadelphia, forming great 
masses in the ditches of the " Neck," growing in the semistagnant water along the 
railroads, and forming with other algse slimy coatings on the dripping rocks of the 
Wissahicon and various railroad cuttings. At certain times the cells are found 
crowded with endochrome, at other times they are almost empty. At certain 
seasons this plant multiplies with great rapidity after a somewhat peculiar fashion. 
Constrictions first appear in the filament at the junctions of the cells, which thus 
look as though their ends were rounding off. This goes on until the ends of the 
cells are greatly rounded, and are attached simply by their central parts, whicli 
soon separate. In this way I'fig. 8b, pi. xv.) the filament is resolved into its com- 
ponent cells, or more generally into as many pairs of cells as compose it, which 
when once set free in the water rapidly grow into filaments by tlie ordinary pro- 
cess of cell multiplication by division. In most cases the zygospores are placed 
in one of the parent-cells, but I have seen instances in which some of them wore 
formed in the connecting tubes. 

Fig. 8, pi. 15, represents this species. 

Z. ci'iiciatuiii,(VAucH.) Ag. 

Z. pallide viride, siccatnm fuscescens vel fusco-nigrescens ; articnlis sterilibua brevicylindricis 
diametro (0.0016" — 0.00195") fequalibus vel dimidio longioribus, rarius duplo longioribna, 
post divisionem factam haud raro dimidio brevioribus, fructiferis non tumidis; zygosporis 
plerumque globosis, maturis obscure fuscis, sporodermate subtiliter pungtatis. (R.) Species 
mihi ignola. 

Syn. — Zygnema cruciaium, (Yaucher) Agardh. Rabenhorst, Flora Europ. Algarum, Sect. 

III. p. 251. 
Tyndaridea cruciala, Hassall, Fresh-Water Algte, vol. i. p. ICO. — Uarvey. Bailes', 

Microscopical Observations, p. 21. 
Eab. — Northern States ; Virginia ; Florida ; Bailey. 

Pale green, when dried subfuscous or blackish fuscous. Sterile joints shortly cylindrical, equal or 
a little longer, or more rarely twice as long as broad (diani. O.OOIC" — 0.00195"), after division 
sometimes shorter than broad ; fruiting cells not tumid ; zygospores mostly globose ; wbeu 
mature, obscure fuscous, their coat minutely punctate. 

Genus SIROGONIUM, Ktz. 

" CelluloB vegetativae cylindricce, sporiferae subinflatse orculiformsB. Fasciae chlorophylloss loiigi- 
tudmales, parietales, leviter fle.xuosfe, nodosae (plerumque 2-3, rarius 4 in quaquo cellula), graiiula 
amylacoa 7-8 involutiB. Copulatio genuflexa, sine tubo conue.Yivo." R. In specie Americana 
fasciae chlorophyllosoe spirales et Spirogyraj illis similes. 

Tegetative cells cylindrical, spore bearing cells somewhat inflated, or orcnliform. Chlorophyl fila- 
ment longitudinal, parietal, somewhat flexuous, nodose (mostly 2-3 rarely 4 in each cell), coutaining 
7-8 starch granules; conjugation genuflexuous, without any connecting tubes. (Rabenhorst). In 
American species the chlorophyl filament spiral and like to that of Spirogyra. 

ItemarJ:«. —This genus Avas originally made by Kiitzing to contain a single 
species, wliich possesses the characters "iven in the diao-nosis of Prof Pvibcnhorst 



FRESH-WATER ALG^ OF THE UNITED STATES. I73 

I have met with an American plant, which has some of these characters, and at the 
same time others which have heen supposed to belong to the genus Spirofjyra. It 
unites the method of reproduction of Sirogouium and the arrangement of tlic 
chlorophyl band of Spirofjijra, standing as it were midway between them. It is 
not midway, however, but much nearer Sirogoidum, for the passage from a very 
loose spiral to a longitudinal flexuous filament is a brief one, and although in some 
cells of 5^. retroversum the spiral makes a number of turns ; in other long cells it 
scarcely gets around once, in other words the chlorophyl band is nearly straight. 
On the other hand, the reproduction is strictly that of S. sirictam, at least in 
all cases which have come untlcr my notice. There is, therefore, but one of two 
tilings to be done, either to miite Sirogonium with Sjnrogi/ra, or else to give up 
the arrangement of the chlorophyl as an essential character of the former genus. 
The great variance, in the latter respect, in our American species, greatly weakens 
the value of any such character, and I have, therefore, preferred tluj latter of the 
two courses. 

S. retroTersiiin, Wood. 

S. articulis sterilibus diametro T-15 plo loiigioribus ; fasciis spiralibus 1, rare 2, latis, granu- 
latis ; anfractibus 1-9 ; articulis fertilibus valde tumidis, retroversis ; conjugatione genufle.xa et 
sine tubo connexivo ; cytiodermate nonuibil crasso, utroque fine protenso vel replicato ; 
sporis ellipticis. 

Z>m77!.— Art. steril. 7IJ5" =.00146"; spor. lat. ^l^^"—jl"-^"=.00lS?j"—.00lG"; long, ^sj^" 
= 0033". 

Syn. — S. retroversum, Wood, Prodromus, Proc. Am. Pbil. Soc. 18G9, p. 139 

Sab. — In stagnis, prope Philadelphia. 

Sterile joints t-lS times longer than broad; chlorophyl band 1, rarely 2, broad, granulate; 
turns 1-9 ; fertile article very tumid, retroverted ; fertile cells scarcely swollen ; cell wall folded 
in at the ends; chlorophyl band single; turns G; spores oblong or elliptical, spore wall very 
thick. 

Bemarks. — I have found this species growing in stagnant ditches in the Neck 
below the city. In fruit the cells are almost always very markedly bent backwards, 
and have a broad pouch-like dilatation in front. Tlie spores are elliptical, and, as 
I have seen them, greenish and with a thin coat, but may not have been completely 
matured. 

Fig. 1, pi. IG, represents this species. 

Genus MESOCARPUS, Hassall. 

Cellulae massa chlorophyllosa initio diffusa, postea in fasciam longitudinalcm, hand raro fle.xnosam 
contracta; nucleuin centraleni et granum amylaceum unicum vel duo involvens. Zygospora globosa 
vel ovata, in tubo connexivo inter cellulas binas plus minus genuflexas formata. 

Chlorophyl mass in the beginning diffused in the cell, afterwards contracted into an often flexuous 
fa.-;eia, and involving a central nucleus and one or more starch granules. Zygospore globose or 
ovate, formed in the connecting tube between two more or less bent cells. 

M. iiicalaris, Hassall. 

M. eellulis sterilibus diametro 8-G plo longioribus, fertilibus valde curvatis ; zygosporis ovalibus. 
Diam.—Ma.x. 7IJ5 = .001 1". 



174 FRESTI-WATER A L G .E OF THE UNITED STATES. 

Syn.—M. scalaris, Hassall, Frcsli- Water AlgK, vol. i. p. lOG, et Rabenhorst, Flora Europ. 

Algarum, Sect. III. p. 257. 
Ilab.— In fossis, prope Philadelphia. 
Sterile cells 3-6 times longer than their diameter, fertile strongly curved ; zygospores oval. 

Remarks. — This species is abundant in the stagnant ditches near Camden. It 
ao-rees well with the descriptions of the European foriii. I have, however, never 
seen it in the state in which it has " fuscous spores." They have always been 
greenish, but very possibly were not fully matured. 

Fig. 5, pi. 15, represents a pair of cells of this species just commencing to con- 
jugate. 

M. parviiliis, Hassall. 

M. ccllulis diametro (0.00031" — 0.00041") 5-12 plo longioribus ; zygosporis globosia, plerumqiie 
0.00002" latis, sporodermate fusco Itevi. (R.) Species mihi ignola. 

Syn. — 31. parvulus, Hassal, Fresh-Water Algoe, vol. i. p. 1G9, et Rabenhorst, Flora Eunip, 
Algarum, Sect III. p. 257. 

Baft.— Rhode Island ; (S. T. Olney) Thwaites. 

Cells 5-12 times longer than their diameter (0.00031" — 0.00041") ; zygospores globose, mostly 
0.00062" broad, spore coat fuscous smooth. 

Genus PLEUROCARPUS, A. Braun (1855). 

Cellula3 eaedom quis in Mesocarpo ; copulatio lateralis et sporifera, nonnunquam gennflexa et 
plerumque sterilis. (R.) 

Cells like those in 3Iesocarpus ; conjugation lateral and sporiferous, somewhat genuflexuous and 
mostly sterile. 

P. inirabilis, Braun. 

P. cellulis diametro (0 0011" — 0.0013") 2-5 plo longioribus; zygosporis subglobosis, fusci-s, 
iKvibus. (R.) Species mihi irjnola. 

Syn. — llougeolia genuflexa, Agardh. Bailey, Silliman's Journal. New Series, vol. iii. 

Pleurocarpus mirahilis, A. Braun. Rabenhorst, I'lora Europ. Algarum, Sect. III. p. 
258. 

Hah. — West Point, New York; Providence, Rhode Island; Detroit, Michigan; Fort Winne- 
bago, Wisconsin ; Bailey. 

Cells 2-5 times longer than their diameter (0.0011" — 0.0013") ; zygospores subglobose, fnscoiis, 
smooth. 



Order Siphophycese. 

Alga unicellulares. Cellula utriculiformis, plerumque ramulosa ; ramuli vegetatione tcrminali 
prajditi, saepe demum septo discreti, et alteri in oosporangia, alteri in antheridia transuiutantiir. 
Cytioplasraa viridc, granulosum, mucilaginosum, vesiculis chlorophyllosis et granulis amylaceis 
replctum. Propogatio fit ant cytiogenesi libera, aut zoogonidiis ant oosporis. 

Unicellular algae. Cells utriculiform, mostly branched ; branches with a terminal vegetation, 
often finally cut off by a partition wall and transformed into antheridia or oosporangia. Cytioplasm 
green, granular, mucilaginous, filled with chlorophyl vesicles and starch granules. Propogation 
either by forming minute spores by free cell formation, or by zoospores, or by oospores. 



PRESH-WATEK ALGJ3 OP TKE UNITED STATES. 175 

3 

Family HYDROGASTRE^. 

Plantulas minimEe, terrestres, grcgariaj. Cellula initio globosa, postca clavato- vel pj-rifoi-nii- 
intumesceiis, basi attenuata elongata et in raniulos subtillissimos hyalinos partita. Cytioplasma 
iiuiciIagino.sum, tetate provecta gouidia divisiono simultanea trausformatuiu. Cytioderma lamellosum 
a3tate provecta dilabens et contabescens et gonidia liberans. 

Plants very small, terrestrial, gregarious. Cells in the beginning globose, afterwards clavate or 
pyriform, with an elongated, attenuated base, divided into very fine, hyaline branches. Cytioplasm 
mucilaginous, at maturity transformed by a simultaneous division into gonidia. Cytioderui lamel- 
late, at maturity wasting, withering away and setting free the gonidia. 

Remarks. — The Hydrogastrecu arc curious little unicellular plants, which grow 
upon wet earth. The matured frond is swollen up at one end to form a subglobular 
or pyriform head, whilst at the other end it is produced into a long, much-branched, 
very fine root-like portion -which enters the earth and maintains the little plant in 
its upright position. The green endochrome is contained almost entirely in the 
head, and forms generally a coat or layer in the outer portion of its cavity, the inner 
part of which appears to be occupied by a watery fluid. 

The only specimens which I have seen of this family were found growing in the 
mud left by the receding water of a recently drawn mill pond, by Dr. Billings, U. S. A. 
When I got them they were thoroughly dried up, and consequently no opportunity of 
studying their development was afforded. According to Iviitzing and Braun, the 
species is propagated ordinarily by the breaking up of the chlorophylous layer of pro- 
toplasm lining the wall of the cell into a larger number of very small globular spores. 
These, although not endued with the power of motion, seem from their method 
of formation and history to be homologous with zoospores. In most cases they 
are set free by the membrane of the parent-cell becoming gelatinously softened, 
swelling up, collapsing, and finally dissolving away. The little protococcoid cells 
then enlarging, develop at one end a hyaline prolongation Avhich penetrates into 
the ground. Growth and development continuing the upper end of the cell swells 
up into the ovate or globular head, whilst the lower becomes the hyaline, branch- 
ing, root-like portion of the new frond. No indication of this method of repro- 
duction was discoverable in the plants which Dr. Billings sent me. The evident 
affinities of the family with the Vauclwriacece render it exceedingly probable that 
there is in it some method of sexual reproduction, as yet undiscovered, allied to 
that which occurs in the latter. In some of tlie specimens sent me, there were 
wiiat appeared to be resting-spores (pi. XVI., fig. 2 «), occupying the whole of the 
cavity of the cell, from which they appeared to be finally discharged by a decay 
and rupture of the outer coat or wall. How these bodies were formed, and whether 
they really have power to reproduce the species I cannot tell. 

Genus HYDROGASTEUM, Desv. 

Character idem ac familioe. 
Characters that of the family. 

H. gr.inulatiim, (Linn.) Pesv. 

H. plerumqne gregarium, scepe aggregatum, baud raro confluens ; cellula e globoso-pyriformi, 
magnitudine serainis papaveris vel sinapios et ultra, prasino-viridi .superficie pulverulenta. (R.) 



176 FllESlI-WATER ALGJE OF TKE UKITED STATES. 

Syn.—Dotrydmm- arrjillaccum, Wallroth. Babenhorst, Flora Europ. Algarum, Sect. III. 
p. 205. 
Hydrogastrum granulatum, (Linn^us) Desv. Rabenhorst, loc. cit. 

Hah. Delaware ; (Dr. Billings) Wood ; West Point, New York ; Providence and Newport, 

Rhode Island ; Bailey. 

Mostly gregarious, often aggregate, not rarely confluent; cells pyriform, of the size of a poiipy 
or mustard seed and larger ; pea-green ; surface pulverulent. 

Hemarks.— The above description is taken from Rabenhorst's work, and applies 
to tlie specimens collected by Dr. Billings in the State of Delaware, excepting that 
I did not discover any of them to be confluent, nor was their surface distinctly 
pulverulent. Prof. Kiitzing gives as a comparative character between this and E. 
Wallroildi, the smaller size of the spores; but Prof. E.. says nothing about this. 
There were no spores in any of the American specimens, and I think it somewhat 
uncertain whether or not the plant is or is not either of the European species. It 
is very probable that it will be discovered that the only true specific characters are 
sexual, and consequently have not as yet been made out in any of the forms. 
Certainly the descriptions of the species as at present given seem to me not to 
contain any reliable characters. 

Fig. 2 a, pi. 16, represents a very young state of our American plant; fig. 2 is 
the perfected frond, both magnified ninety diameters ; fig. 2 a shows what is sup- 
posably a perfected resting spore magnified 160 diameters. 

Family VAUCHERIACE^. 

AlgfD monoicse, cocspitosa?, unicellularcs. Cellula vegetiva (tliallus) vegetatione terminal!, ntriculi 
formi-elongata et ampliata, promincntiis plus minus elongatis ramosa. 

Propagatio aut sexualis, fit oosporis ope spermatozoidiorum fecundatis, aut non sesualis zoogonidiis. 
Fructificatio triplex (melius organa fructificationis tria) : — 

1. Sporangium terminale, ex tlialli apice plerumque globoso-clavato-tumido formatura, septo dis- 
cretum, cytioplasmate obscure viridi, demum in zoogonidium (zoosporam, Thur.) unicum permag- 
num, ciliis vibratoriis dense obsitum abeunte farctum. 

2. Oogonium (oosporangium) laterale, sessile vel prominentia, plus minus elongata vel simplici 
vcl partita pedicellatum, cytioplasmate aetate provecta in oosporam singulam transmutato fetum. 

3. Antheridium laterale, sessile vel e ramuli lateralis parte suprema septo discreta formatum, in 
quo spermatozoidea (antherozoidea, Thur.) numeros issima nascuntur, denique erumpunt. Sperma- 
tozoidea oblonga, ciliis duobus inajquilongis, subpolo antico ortis instructa. (B.) 

Monajcious alga;, caspitoso, unicellular. Vegetative cells (thallus) growing'at the ends, elongate, 
utriculiform, and ampliate, more or less profusely branched. 

Propogation either sexual, with oospores which are fecundated by spermatozoids, or non-sexual, 
by means of zoospores. Organs of fructification of three kinds :— 

1. Sporangia, which are terminal and mostly formed from the separation of clavately swollen, 
globose apex of the thallus (often of a branch) by means of a partition ; in the sporangium arises 
a single, very large zoospore, which is densely clothed with cilia. 

2. Oogonia (oosporangia), lateral, sessile or pedicelate simple bodies, whose eytioplasm is finally 
converted into an oospore. 

3. Antheridium lateral, sessile, or formed out of the end of a branch ; the spermatozoids formed 
in them oblong, furnished with two unequal cilia, arising near the front end. 



FRESH-WATEll A L G Jii OF TUE UNITED STATES. 177 

Remarks. — The Vaucheriacea are araongst our most common fresh-water alira;. 
They occur generally in the form of vast numbers of individuals interwoven into 
broad mats, which have often both a felty look and feel. When growth is going 
on rapidly, these mats are of a beautiful vivid green ; but when the process of 
sexual reproduction has checked the life of the individual they become dingy and 
dirty looking. The thallus is composed of a single cell and is almost always 
branched. The branches never have, at least in any of our species, a definite 
arrangement, save only in that they always arise from the side and not from the 
point of the thallus. In the European species, V. tuberosa, however, the branches 
are said to arise both from the point and sides of the frond. 

The frond cell is generally nearly uniform in diameter and has a thick outer 
wall, which is composed of cellulose, as is proven by the action upon it of iodine 
and sulphuric acid and of the iodo-chloride of zinc solution. Within the cell are 
chlorophyllons protoplasm, starch granules, watery fluid, and a few scattered 
raphides or inorganic crystals. There is never any nucleus. The protoplasm is 
often very granular, and is mostly collected in a thick green layer upon the inner 
surface of the cell wall, leaving the centre of the cell free for the more watery 
contents. 

Growth, except in the very young fronds, consists exclusively in an increase in 
length, and takes place only at the ends of the thallus or in the portions near it. 
The branches are almost always simple, but are said in some species to give origin 
to secondary branchlets, and even, at times, to tertiary ones. They grow in the 
same manner as the main thallus, /. e. by additions to their ends. 

AVhen the thallus of a Vaucheria is ruptured by external injury, or, at times, 
when it is dying from some hidden cause, a number of bright green globes of 
various sizes are formed out of the endochrome. These appear to have the power 
of independent existence for some time, but whether or not they ever actually 
grow into new thalli I am unable to state. 

M. Walz asserts ,.th at he has observed in certain species the formation of a quiet 
spore without the intervention of sexual organs, and that the process is as follows. 
The end of a long or short twig swells up, and the chlorophyl and protoplasm from 
the neighboring parts accumulate in the enlarged portion. A partition wall then 
forms at the base of the latter, which is thus changed into a closed chamber, a 
sporangium. The- green contents then slowly gather themselves together into a 
denser and denser ball, becoming more and more separated, in so doing, from the 
wall of the sporangium, and finally secreting around themselves a distinct mem- 
brane. After the formation of a spore in this way, the sporangium opens at the 
apex and allows it to escape. The spore, after remaining quiet for some time in 
the water, at last germinates into a new frond, in a similar manner to an ordinary 
zoospore. In my earlier studies of fresh-water algoe, I noticed something very 
similar to this in one of our species, but convinced myself that the little body was 
nothing but a zoospore, whose normal development had been perverted by unto- 
ward influences, and therefore paid no more attention to the matter. It is proba- 
ble that the life-history of the bodies observed by M. Walz is capable of the same 
explanation. 

23 August, 1872 



178 FRESn-WATER ALG.-E OF TUE UKITED STATES. 

Althon"-h I have very frequently cultivated Vaucherias, I have never been so 
fortunate as to see them form their zoospores, nor indeed to see a zoospore in its 
motile state. The life-history of these bodies has, however, been fully and repeat- 
edly worked out by other observers. It is described by such as occurring in the 
following manner. One end of a branch first enlarges into a bulbous, often conical, 
point, into which the neighboring endochrome crowds itself. This point is next 
divided off by a partition wall from the remainder of the thallus and constitutes the 
zoosporang'mm, the contents of which rapidly condense into one or two masses, 
generally oval in shape, each of which eventually forms a zoospore. When the 
latter are matured, the apex of the zoosporanrjium opens, and the little bodies 
within slowly and gradually emerge, without any apparent cause for their motion. 
Sometimes, according to Cohn, instead of this steady outward passage, there are 
r('[)eated forward and backward movements of the zoospores within the case. The 
zoospore after its perfection is generally oval, and very large. Within it there are 
one or more vacuoles, and surrounding it is a layer of colorless protoplasm. It is 
remarkable for having its Avhole surface densely covered with short cilia. Its period 
of motile life appears to be very brief; according to Walz, that of the zoospore of 
Y. scricea, Lyngb., lasts only from one-half to one and a half minute, after which 
time the cilia are lost and a cellulose wall secreted around the mass. Germina- 
tion takes place by the growth of the cylindrical thread out from each end of the 
zoospore. 

True sexual reproduction takes ])lace in this family by means of antlieridia and 
oogonia, male and female organs. All known species are mostly if not absolutely 
mona'cious, both organs being contained in the one individual and always placed 
in proximity. All of the species in which the development and structure of the 
sexual organs have been studied, agree in the essential points. 

The first appearance of the antherulium is as a little pouch projecting out from 
the side of the thallus. This increases in size and soon assumes the peculiar shape 
of the species. At the same time there is a diminution, according to M. AValz, of 
the chlorophyl in the antheridium, so that, when the partition wall forms and shuts 
off the cavity of the latter from that of the thallus, there are only a very few scat- 
tered green granules remaining. The antheridium at the time of separation con- 
tains, therefore, only transparent protoplasm, which soon becomes gramdar, and 
shortly afterwards exhibits the moving spermatozoids, which appear to be formed 
out of the thick layer of protoplasm that lines the inner surfiice of the cell wall. 
The point of the antheridium opens so soon as the spermatozoids are perfected, 
and allows them to escape. 

The formation of the oorjonla takes place very similarly to that of the antlieridia. 
There is the same little protrusion from the side of the thallus in the commence- 
ment of the process, the same after-growth aiid increase of this pouch, and the same 
formation of a separating wall between it and the main body of the frond. A very 
marked difference, however, is to be found in the contents of the two, the oogonium 
from the very commencement being crowded with chlorophyl and oil globules. 
When the oosporangium is completed, the end of it opens, and, at the same time, 
the contents gather themselves into a dense protoplasmic ball, which lies in the 



FRESn-WATER ALG^ OF THE UNITED STATES. 179 

centre. The spennatozoids, which are at this time aU'cady free in the water, arc very 
minute, longish, ellipsoidal or ovate masses, provided with two unequal cilia. These 
commonly both arise together from one end of the body, and are directed in oppo- 
site directions — one backwards, the other forwards. According to M. Walz, how- 
ever, in V. sericea the cilia arise from the opposite ends. According to De Bary, 
the spermatozoids of V. aversa, Hassall, contain reddish pigment-granules. M. 
Walz states that he has twice seen the process of impregnation in V. serk^xi, Lyngb., 
and describes it essentially as follows : After the bursting of the antheridium and 
the formation of the opening in the oogonium, the spermatozoid clustered around the 
little orifice in the latter, but were apparently debarred entrance by the presence of 
a glutinous jelly. After a time, however, one, and then another, forced a passage 
through this obstacle until finally a number gained access to the protoplasmic ball 
within. Over this they swarmed, pushing it and retiring and butting against it 
initil some of them actually forced their way into it and were absorbed by it. Im- 
pregnation being now completed, the oospore acquired a very sharp definite outline, 
and secreted in a very short time a membrane around itself. The changes which 
followed during its maturing consisted of the acquiring of a thick coat and the 
replacing of the chlorophyl within by a reddish-brown coloring matter. The ripened 
resting spore of almost all the Vancheria is provided with three coats, of which the 
middle is the thickest. The contents consist of protoplasm, reddish-brown pigment, 
and numerous oil globules. 

Genus VAUCHERIA. 

Genus nnicura, character idem ac familice. 

The only genus of the family, having the same characters. 

V. sessilis, (Vauch.) De Candolle. 

V. laxe intricata, pallide et subsordide viridis; thallo capillari, parce ranioso; oogoniis 2-3 
appro.ximatis, rarias singulis, ovatis vel ovali-oblongis, plus minusve obliquis, rostratis; anthc- 
ridio intermedio, raniuli modo brevi hamato, modo recto subulatu, subchnato, modo olongato 
et incurvato, hand raro circinato sustentato; oosporis maturis fusco-puuctatis, niembraua 
triplici iavolutis. (R.) 

Syn. — V. sessilis, (Yauch.) De Candolle. Rabenhorst, Flora Europ. Algar., Sect. III. p. 
267. 
V. caespitosa, (Yaucii.) Agardii. Rabenhorst, loc. cit. 

Hah. — Salem, North Carolina; Schweinitz. Common at West Point, New York; Waterville, 
Maine; Culpepper Co., Ya. ; Bailey. 

La.xly intricate, pale and subsordid green ; thallus capillary, sparsely branched ; oogonia 2-3, 
approximate, rarely single, ovate or oval-oblong, more or less oblique, rostrate; antheridia 
intermediate, sustained upon branches partly shortly hamate, partly straight suljulate, sub- 
clavate, partly elongate and incurved, and not rarely circinnate ; oo.spores at maturity, fus- 
cous-punctate, surrounded by a three-fold membrane. 

liemark. — I think I found this species near Philadelphia in my earliest re- 
eearches, but cannot speak certainly, having preserved neither notes nor specimens. 



180 FRESII-WATER ALGyE OF THE UNITED STATES. 

V. Tcliiliiia, Aa. 

\. tluillo ropeiito, ramulis erectis, uumerosis, fastigiatis, in csespitera velutinum laete viridem 
iiili-icatis ; oogoniis lateralibus singulis, globosis, sessilibus, antheridio paulo longiorc unico 
subulato leviter iucurvato consociatis (R.) Species mihiignota. 

Biam.—Oogoini 0.0023"— 0.0027". (R.) 

Syn.— V. velutina, Agardh. Rabenhoest, Flora Europ. Algarura, Sect. III. p. 214. 

Uab. — Salem, North Carolina; Schweinitz. Common at West Point, New York; Waterville, 
Maine; Culpepper Co., Va. ; Bailey. 

" Filaments exceedingly tough, interwoven into a dense, velvety, green stratum, pellucid below 
and creeping over the mud; branches near the extremity erect, fastigiate, and more or less 
crooked; vesicles solitary, globular, on short lateral peduncles." Carmichael. 

V. g^einiiiata, (Vaucii.) De Candolle. 

V. obscure vel sordide viridis, in csespites dense intricata; thallo capillari, tenaci, dichotomo; 
oogoniis duobus (rarius 1 vel 3),ovatis vel obovatis, oppositis, distincte pedunculatis, antheridio 
intermedio subulato, plus minus recurvo ; oosporis maturis fusco-niaculatis, sporodermate 
achroo e stratis tribus composito involutis ; sporangiis in eodem vel proprio thallo, cyathifonni- 
ampliatis truncatis et angulato-cornutis. (R.) 

Syn. — F. geminata, (Vauch.) De Candolle. Rabenhorst, Flora Europ. Algarum, Sect. III. 
p. 209. 

Ilab. — In stagnis, prope Philadelphia; Wood. 

Obscure or sordid green, densely interwoven into a turfy mass ; thallus capillary, tenacious, 
dichotomous ; oogonia two (rarely 1-3), ovate or obovate, opposite distinctly pediiaculatc, 
autheridia intermediate, subulate, more or less recurved ; oospores at maturity spotted with 
fuscous, their coat transparent and composed of three strata ; sporangia in the same or a sepa- 
rate thallus swollen cup-shaped, truncate and horned at the angles. 

Eemarks. — I have found this species in fruit but once, then it grew in a ditch 
below the city. Not having mounted any of it, nor having written a dcscriptiou 
of it at the time, I have been forced to simply copy that of Prof. Rabenhorst. 

V. polyniorpha. Wood. 

V. in c;uspitcs dense intricata ; thallo capillari, tenui ; antheridiis corniculatis ex ramuli lateralis 
apico formatis ; ramulis fertilibus interdum et oogoniis et antheridiis instruetis, interdura 
antheridiis solum ; oogoniis plerumque geminis, interdum singulis, globosis vel ovatisi soepc 
breve rostratis, plerumque distincte pedunculatis sed rarius sessilibus ; oosporis enormiter 
subglobosis vel ovatis ; sporodermate achroo, e stratis duobus composito. 

Syn. — V. pohjmorpha. Wood, Prodromus, Proceedings Amer. Philos. Society, I8C9, p. 140. 

Hah. — In aquis, prope "Buffalo Bayou," Texas; (Ravenel.) 

CiEspitose ; thallus hair-like, thin ; antheridia corniculate, formed of the apex of lateral branches; 
fertile branches sometimes furnished both with oogonia and antheridia, sometimes with 
antheridia alone ; oogonia sometimes single but mostly in pairs, occasionally shortly rostrate, 
generally distinctly pedunculate but sometimes sessile ; oospores irregularly subglobose or 
ovate, surrounded by a transparent double spore coat. 

Bemarks. — This species was collected by Prof Ravenel near the city of Houston, 
Texas. As T received the mass, it was labelled as being obtained from "a shallow 
slimy pool formed by drippings from the side of a ravine near Buffalo Bayou." 
The species probably grows in the water, evidently forming turfy mats. It is 



FRESH- WATER ALG^ OF THE UNITED STATES. 181 

remarkable from the fact that, whilst in many cases the little branches which pro- 
duce the antheridia give origin to the spores also, in others they do not ; so that 
there are numerous antlieridia, which are unconnected with any female organs. 
When a branch does produce both of the reproductive organs it usually forks into 
three short branchlets, thus giving origin to a pair of sporangia and a single curved, 
hooked antheridia. Sometimes, however, there is but a single female branchlet, 
and I have even seen a sporangium, immediately sessile upon a branch, which at 
its apex gave origin to a male organ. In the coat of the perfected spore, I have 
not been able to find more than two distinct strata. 

Figs. 3 and 3 a, pi. 20, represent sporangia and antheridia of this species ; 3 6, 
a simple, young and only partly formed antheridia, magnified IGO diameters; 3c, 
a perfected spore magnified 260 diameters. 

T. sericea, Lynobte. 

V. aquatica vel terrestris, csespitosa, vel sordide vel laete vel luteolo-viridis ; thallis tenuilius, 
dense intricatis, laxe et vage ramosis, ramisque saepe adscendentibus vel erectis ; oogoniis ses- 
silibus vol brevissime pedieellatis, 1-6 seriatis, unilatcralibus, oblique et enormiter ovalibus, 
ore lateral! producto rostellatis ; antheridiis in tliallo ipso juxta oogoniis sessilibus, cylin- 
draceo-subclavatis, deflexis ; spormatozoideis oblongis, puncto rubro notatis (teste de Bary), 
in utroque polo cilio uuico pra3ditis. 

Si/n. — V. aversa, Hassall, Fresh-Water Algae, p. 54. 

V. sericea, Lyngbye. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 271. 

Hab. — Prope Philadelphia ; Wood. 

Aquatic or terrestrial, occurring in turfy mats of a yellowish, dirty, or bright green color; fronds 
thin, densely intricate, laxly and vaguely branched, often together with the branches ascending 
or erect; oogonia sessile or very shortly pedicellate, 1-6 seriate, unilateral, obliquely irregu- 
larly oval, their lateral mouths produced into a rostelluni or beak ; antheridia sessile upon the 
thallus itself near the oogonium, somevphat cylindrical, subclavate, deflexed especially in age ; 
spermatozoids (according to De Bary) oblong, marked with a red point and furnished with a 
single cilia at each end. 

Remarks. — I can perceive no constant diff"erences between V. sericea, Lyng. and 
V. aversa, Hass. The extreme forms differ somewhat, but both are very common 
about Philadelphia, and everywhere grade into one another. Prof. Rabenhorst 
thinks that the two forms are scarcely distinct, and states that the most character- 
istic differences are, that in V. aversa, the thallus is much thicker, and the oogonia 
larger and more erect, whilst the oospores are smaller and consequently do not fill 
the cavity of their case. These differences are, except the last, simply differences 
in size, and seem to me to depend simply upon circumstances of growth. The rela- 
tively smaller size of the spore is a very frail hook indeed to hang a species upon. 

The plant grows in springs and actively running water abundantly in this neigh- 
borhood ; also on very wet ground, especially on that which is habitually overflowed, 
such as the face of dams, neighborhood of springs, &c. In the water, it is frequently 
on the ground, but also often clothes such objects as stones, largish sticks, &c. 

Order ]\eiiiatophyce£C. 

AlgiE multicelullares, chlorophyllosa^, niembranaccffi vel fdamentoss, raniificatione aut instructiU 
aut destitutfe. I'ropogatio Dt aut oosporis aut zoogonidiis, sed lunuiuam conjugationc. 



182 FRESII-WATER ALG^ OF THE UNITED STATES. 

Multicellular, cliloropliyllous alga;, membrauaceous or filamentous, furnished with or destitute of 
brauches. Propagated by oospores or zoospores, never by conjugation. 

Family ULVACE^. 

Thallus membranacens vel foliaceus, vel filiformis (Schizomeris?) rarius crustaceus, e cellularum 
strato unieo formatus, aut expansus aut tubuloso- vel vesiculoso-concrotus. 

I'ropogatio fit zoogonidiis, cytioplasmatis divisione repetita ortis. Zoogonidia oblonga, polo 
aiitico eiliis vel binis vel ternis vel quarternis iustructa. 

Thallus membranous or foliaceous, rarely crustaceous, composed of a single stratum of cells, either 
expanded or tubularly or vesicularly concreted. 

Propagation by means of zoogonidia, formed by the repeated division of the cytioplasra. Zoogoni- 
dia oblong, furnished with two, three, or four cilia at the anterior end. 

Genus PROTODERMA, Ktz. 

Thallus crustaceus, indeterminatus, substrate arete adherens, e cellulis anguloso-rotundatis, 
irregulariter ordinatis, arete conuexis compositus. 

Propagatio ignota. 

Thallus crustaceous, indeterminate, closely adherent to the substratum, composed of closely eon- 
joined irregularly arranged angularly rounded cells. 

Propagation unknown. 

P. viride, Ktz. 

P. viride, lubricum. 

Syn. — P. viride, Kutzing. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 307. 

Hab. — In aquario ; Wood. 

Green ; slippery. 

Remark. — I have seen a plant, which I take to be this species, growing on the 
glass and on pebbles in the aquarium of my friend, Dr. Fricke. 

Genus ULVA, Linn. 

Thallus nicmbranaceus, plane c.xpansus, angustus vel latus, nonnunquam latissimus, magis minusve 
undulato- crispatus, sa;pe laciniatus, baud raro perforatus, e cellularum strato uiiico formatus, callo 
disciformi parvo affixus, cetate provecta saepe libere natans. Cellulce anguloso-rotundatse, coeloplas 
matica;, parenchymatice conncxse. 

Vegetatio cellularum divisione in duas directiones repetitia. Propogatio fit zoogonidiis, in cel- 
lulis quibusdam cytioplasmatis divisione 4, 8-16 ortis, eiliis vibratoriis quaternis longitudine cor- 
poris longitudineni vix superantibus instructis. 

Thallus membranous, expanded, narrow or broad, sometimes very broad, more or less undulately 
curled or crisped, often laciniate, not rarely perforate, formed of a single stratum of cells, fastened 
by a small discoid thickened portion, in advanced age often swimming free. Cells angularly glo- 
bose, joined into a sort of parenchyma. 

Growth occurring by the repeated division of the cells in two directions. Propagation by 
zoospores, 4-8-1 fi of which are formed at once by a division of the endochrome of certain cells, 
and are furnished with four vibratile cilia scarcely longer than the body. 

tJ. merisiiiopedioides, Wood. 

U. ampla, mcmbranacea, late expansa, dilute viridis, tenuis, radiatim et enorniiter plicata, ambitu 
sajpe subrotundata; niargine undulato, interdum subcrcnato ; cellulis enormiter ovalibus vol 
angularibus, nnclco destitntis, quarternariis et in familias Merismopediarum modo obscure 
a.ssociatis. 

7)mm.— Cell. max. „i5iTTy" = .00041', plerumqno yjlno" — xugi^o" = .00016' - 00025. 



FRESII-WATER ALG^ OF TUE U J^ 1 T E L) STATES. 1S3 

Syn. — U. merismopedioides, 'Woop, Botanical Report of tLe United States Geological Ex- 
ploration of the Fortieth Parallel, p. 415. 

Hah. — In torrentibus, Diamond Range (alt. GUOO ft.), Rocky Mountains; (Sercno Watson) Wood. 

Thallus ample, broadly expanded, membranaceous, dilute green, thin, radiately and irreguhirly 
plicate with its outline often .somewhat rounded; its margin undulate or at times almost 
crenate; the cells irregularly oval or angular, destitute of nucleus, ciuarternary and obscurely 
arranged in families after the manner of a merismopedia. 

Remarlis. — Tlie largest fronds of this species that have come under my notice 
are about three inches long by two broad, thin, easily torn, and not all gelatinous. 
The portion by which they have been attaclied is very evident, near one of the 
margins, and from it broad undulations or folds radiate. Sometimes the frond is 
split up into palmate, lobe-like parts. 

) The cells are not closely approximate, but are placed in a homogeneous translucent 
membrane, in such a way as to remind one of a Merismopedia. 

I do not feel certain that this plant is distinct from U. orldculata of Rabenhorst, 
though for the present I have preferred so to consider it. His description is very 
brief and incomplete, as is also the original one of Thuret, which I have con- 
sulted. Prof. E,., however, gives U. latissima of authors as a synonym of U. or- 
hiculata, and certainly this plant is distinct from U. latissima, Harvey, of our 
'coast. Again it seems impossible that a plant growing near the summit of the 
llocky Mountains should be identical with one found on the coast of France. 
Prof Sereno Watson found this plant growing on rocks in a mountaiii stream of 
the Diamond Range, at an altitude of 6000 feet. 

i Genus ENTEROMORniA, Link. 

Thallus membranaceus, tubulosus vel utriculiformis, basj afBxus (saltem initio, postea sa;po libera 
natans), e cellularum strato unico compositus, saepe ramosus, baud raro ramosissimus. Fropogatio 
■ fit zoogonidiis. Jfoec zoogonidia proceantur in cellulis quibusdam 8-16 cytioplasmatis divisioue 
'repetita, in polo antico rostriformi ciliis duobus corpus duplo superantibus pra;dita. (R.) 

Thallus membranaceous, tubular or bladder-shaped, affi.^ed by the base (at least in the beginning, 
•often afterwards floating freely), comi)osed of a single stratum of cells, often branched, not rarely 
'very much branched. Propagation by means of zoospores, S-lfi of which are formed by the 
'repeated division of the protoplasm of a cell Their anterior beak-like portion provided with two 
cilia whose length is not less than twice that of the body. 

E. intfstin.ilis, (Linn.) Link. 

E. teres, forma et magnitudine admodum varia, saepe pedalis etiam supra, leptoderma, saturate 
vel pallide viridis, 6liformis vel intestiniformis, plana vel bullosa; cellulis 3-5-6 angularibus. 
i (R-) Species mihi ignota. 

" i)mm.— 0.00048" — 0.0008". (R.) 

Syn. — E.vitestinolis, (Linn.«us) Bailey, Silliman's Journal, N. S., Vol. III., et Rabenuorst, 
Flora Enrop. Algarum, Sect. III. p. 312. 

Hab — Hudson River, from Newburgh to New York City ; Narragansett Bay, Rhode 

Island ; Bailey. 
Terete, very various in size and shniie, often n foot or more in length, smooth, deep or ])ale 

green, filiform or intestiiiiform, plain oi' biillose ; cells 3-5-() angular; their diameter 0.00048' 

— 0.0008". 



im FllESn-WATEll ALGJi; OF TUE UNITED STATES. 

Genus SCHIZOMERIS, Ktz. ? 

Thallus filliformis, cylindneus, hie illic vaklo contractus, basi attcnuata aifisus. Vegetatio fit cel- 
lularuin divisione initio in duas postea in tres(?) dircctioneni. Propogatio iit zoogouidiis. Zoogo- 
nidia in thalli juvenis cellulis orta, ovata, polo antico ciliis tribus iustructa. 

Thallus filiform, cylindrical, hero or there strongly contracted, adnate by the strongly contracted 
base. Growth in the beginning by the division of the cells in two directions, afterwards in three 
directions. Zoogonidia formed in the cells of the young thallus, ovate, their anterior end furnished 
with three cilia. 

Remarhs. — The plant from which the above generic description has been drawii 
up grows abundantly in our ditches below the city. Whether it really belongs to 
the genus Scldzomeris or is the representative of a new group is somewhat uncer- 
tain. I have never seen the European plant, but, if I understand the descriptions 
of it, the cells in it are all arranged in a single plane. This certainly is not the 
case in the old plants of our North American form, for in them the cells are so 
placed as to make a thick opaque filament, the outside of which everywhere pre- 
sents the outer walls of cells. The life history of the European species has not 
been at all worked out, and I have refrained from actually indicating a new genus, 
in the absence of absolute knowledge upon the subject, because the specific cha- 
racters of the two plants are so much alike. 

I have had some opportunities for studying the life history of our American 
plant. The zoospore CFig. 1 c. pi. XVIT.) is of the ordinary conical or ovate form, 
with a very decided transparent anterior end, from which arise three cilia. As the 
number three is a rare one for cilia to exhibit, I have examined several zoospores 
with care, and am very certain that they had no more or less. It is, therefore, 
probable that the number is fixed for the species, although just possible that my 
finding several individuals in agreement was accidental. The zoospore after a 
period of free life, during wliich its motion is very active, becomes quiescent, and, 
its cilia withering away, attaches itself by its smaller end to some twig, stone, or 
other support. At the same time it appears to change its shape somewhat, grow- 
ing longer and narrower, and the smaller end spreading out to form a little foot. 
Simultaneously with these changes the young plant acquires a cellulose coat, and 
so becomes a perfect cell, in which I have never been able to detect any nucleus. 
After a while the cell thus formed divides transversely into two, which, of coinse, 
lay end to end. Each of these cells then grows until it attains a certain size, and 
then the transverse division is repeated. In this way the process goes on until 
finally a long filament is produced, which is composed of but a single series oi 
cells. These cells are much broader than long, and are placed end to end, so that 
the cylindrical frond is made up as it were of disks laid one upon the other. 
When the filament has in this way reached a certain stage of development, one ol 
two things occurs, cither the cells begin to divide at right angles to the plane ol 
their previous division, or else the production of zoospores takes place. In th( 
first instance each cell divides into two, four, or more cells. This division, I believe 
occurs in three if not all directions, so that each original cell is represented by i 
number of cells, and a sort of compound filament arises, out of which the maturec 



FRESH-WATER ALG^ OF THE UNITED STATES. 185 

large trichoma is formed by a continuation of growth, and, perhaps, by a repetition 
of the division. 1 have never been able to discover that any reproductive process 
whatever takes place in this compound filament, and am very confident it never 
produces zoospores. It is very possible, however, that it may in some way give 
origin to resting spores, although, as above stated, no indication of this has ever 
come under my notice. The zoospores are formed in the young fronds as follows : 
The endochrome in the cell concerned gradually separates in the ordinary manner 
into several distinct masses, which soon assume a more or less irregularly globular 
or pyriform shape. Whether the number of these masses is fixed for the single 
cell or not I am unable to state. These changes occur almost simultaneously in a 
number of consecutive cells, commencing with the most distal and rapidly spread- 
ing towards the base of the filament. When they are pretty well advanced, the 
walls of the cells undergo some alteration, probably a gummy degeneration, whereby 
they become soluble in the water. As the division of the endochrome occurs first 
in the most distal cells of the filament, so does also this change in the cellulose coat. 
When the endochrome masses are well shapen and distinct, they begin to exhibit 
motion, becoming uneasy, restless, changing their position, rolling on themselves, 
and pushilig against one another. At the same time solution of the cell walls com- 
mences, the partitions between the cells disappearing, and the outer walls spread- 
ing. These changes go rapidly forward, and in a little while the zoospores stream 
out from the fading end of the frond, jostling and crowding as though eager to 
enter upon their new life. 

Fig. 1 a, pi. 17, represents the basal portion of an old filament which has failed 
to form zoospores, magnified 125 diameters. Fig 1 b was drawn from a young 
filament during the process of forming zoospores ; owing to their rapid motion, the 
cilia of the latter could not be seen. This figure is enlarged 250 diameters. Fig. 
1 c represents a zoospore which has just become quiescent, and still retains its 
cilia, although they have lost their motile power. Fig. 1 d, c, c, represent the very 
young plant in different stages of growth. They are all magnified 450 diameters. 

S. Leibleinii, Ktz. ? 

S. la;te viridis vel saturate nigro-viridis. 

Dtam.— Max. ^^j". =.08''. 

Syn. — S. Leibleinii, Kutzino. Rabenhoest, Flora Europ. Algarum, Sect. III. p. 311. 

Hab. — In fossis, prope Philadelphia. 

Bright green to deep blackish-green; largest diameter of the frond 755". 

Remarks. — Owing to the profusion of zoospores produced by a single filament 
at one time, it is very usual to find large numbers of the younger plants attached 
so closely to some central body as to form dense masses of a beautiful green color. 
The support of these small masses is often entirely concealed, and I have frequently 
seen them moving freely about the jar, without any apparent cause, until the mystery 
was solved by finding that some unfortunate snail carried the forest on his back. 

The oldest filaments are perfectly opaque, showing, under the microscope, by 
transmitted light, no trace of their structure. 

24 Ausust, 1878. 



lyg FKESn-WATER ALG^ OF TUE UNITED STATES. 

The species is exceedingly common in the later summer and early fall months 
in the ditches and sluggish streams around the city, especially in the iN^eck. 

Family CONFERVACE^. 

Fila articulata aut simplicia aut ramosa, vegetatione terminali non limitata instructa. Articuli 
plcrumque plus minusve elongati, sod nonnunquam diametro breviores, cylindrici, raiius tumidi. 
Cytiodorma plerumque mauifesto lamellosum. Massa cliloropliyllosa granulata, vesiculas amjlaet'as 
involvens, parietalis vol in ietate provecta ssepe in celluloe centro contracta. 

Vegetatio 6t utviculi primordialis divisione semper in unam eandcmque (transversam) directionem 
repetitia. Propagatio fit zoogonidiis. 

Filaments articulate, simple or branched, growth terminal, unlimited. Joints mostly more or less 
elongated, but sometimes shorter than long, cylindrical rarely tumid. Cytioderm mostly plainly 
lamellate, chlorophyl masses granular, surrounding fine starch granules, parietal or often in the centre 
of the cell. 

Growth taking place by division of the primordial utricle always in one direction, namely trans- 
versely. Propagation by means of zoospores. 

Genus CONFERVA, (Linn.) Link. 

" Fila articulata simplicia. Articuli cylindrici. Massa chlorophyllosa homogcnca vel granu- 
lata, vesiculas amylaceas involvens. Propogatio ignota." (R.) ' 

Threads articulate simple. Articles cylindrical. Chlorophyl mass homogeneous or granulate, 
including amylaceous vesicles. 

Remarks. — A large number of forms of the genus Conferva have been described 
as distinct species by Kiitzing and other authors. The characters assigned to 
these species, however, do not seem to me in any way distinctive. I cannot believe 
it possible at present to recognize, define, and describe species in this genus, and 
believe that further studies must be made in their life-history, and other characters 
discovered before the different forms can be separated. Probably, as was the case 
with the CEdogoniacea?, when their sexual life is made out, in it will be found the 
vital differences. No doubt there are many species common to Europe and Ame- 
rica, but I have been entirely unable to determine them. Among the very earhest 
of my observations upon the fresh-water algae, before experience had taught how 
and what to observe, was one made upon what I suppose was a species of this 
genus. I have never met with the plant since, but as the observation has direct 
bearing upon the method of propagation, I mention it here, imperfect as it un- 
fortunately is. The plant was found growing on the mud along the Schuylkill 
River, near Gray's Ferry Bridge, below the city. The filaments were simple, of 
great length, and uniform in diameter; fig. 7 a, pi. 18, represents a portion of 
one magnified 500 diameters. The cells varied from about as long as broad to 
three times as long. The amount of endochrome in the cells also varied very much. 
In most of them, it was not nearly sufficient to fill the cavity, and was arranged as 
a central superficial band. Many of the cells were seen engaged in the production 
of zoospores. (Fig. 7 b, pi. 18.) Such were well filled with endochrome, which 
gradually condensed itself into a globular or pyriform mass in the centre of the 
cell. This, after a short time, began to exhibit activity, rolling upon itself and 
finally pushing about as much as its confined quarters would allow, until at last it 



FRESn-WATER ALG^ OF THE UXITED STATES. 187 

escaped into the water, through the cell wall. Each cell in this way gave origin 
to a single zoospore. The walls did not melt away in the water, and, as a nunihcr 
of consecutive cells underwent these changes at the same time, the filament or a 
portion of it was left as an empty shell. The zoospores were of the usual shape, 
with a bright anterior spot or beak. The number of cilia was not noted. After 
a time they settled down generally in clusters, attaching themselves to some fort-ign 
particle, dropping their cilia and acquiring a cellulose wall. (Fig. 7e, pi. 18.) They 
then elongated, underwent the ordinary cell division in a transverse direction, and, 
by the repetition of this, gradually grew into filaments similar to that from which 
they sprang. 

Fig. 7 (7, pi 18, represents a young filament just formed in this manner, magni- 
fied 500 diameters. 

Genus CLADOPHORA, Ktz. (1843.) 

Fila cc'Uularum scrie siinplici formata, varie ramosa. Rami filo central! similes. Cytioderma 
pioruinque crassum, laiuellosiini. Cytioplasma parietalc. 

Filaments composed of a simple series of cells and variously branched. Cytioderm mostly thick 
and lamellate. Cytioplasm parietal. 

Eemarhs. — The Cladophora are branched plants of rather rigid habits, which 
grow both in salt and fresh water. They are readily recognizable by their 
comparatively still appearance, the absence of gelatinous matter about them, and 
by the want of regularity in their branching. A large number of species have 
been described, most of which are marine. They are exceedingly difficult to define, 
and it is very possible that their hitherto undiscovered sexual reproduction maybe 
finally found to afford the only true characters. I have identified two European 
forms as growing near this city, and a third has been recognized by Prof. Harvey, 
as found in our northern States. 

I have never seen the production of zoospores in this family, but they are said 
to be formed by the simultaneous division of the layer of chlorophyllous proto- 
plasm, which fills the outer part of the cell cavity. They exhibit the power of 
very active motion even before their exit from the cell, which occurs through a 
papilloid orifice, mostly at the end of the cell, sometimes in its side. Their cilia 
are sometimes two, sometimes four in number, and their life-history appears to be 
precisely similar to that of other zoospores. 

CI. g^lonierata, (Linn.) 

Raniuli fili primarii in parte siiperiore atque ramorum ordinis secnndi et tertii plerumqne 
fasciculato- vel penicilliformi-aggregati. CelliiliB niaxima3 vegetse cytioplasmate cellularuni 
parieti retiformi- vel subspiraliter applicato. CeliuLe fructiferoe semper termiualcs, inforiores 
semper steriles videntur. (R.) 

Syn. — CI. glomcrata, (KtJTZiNG) Rabenhorst, Flora Europ. Algarum, Sect. III. p. 33T. 

Hah. — Lake Ontario; Pickering. Falhs of Niagara; Lakes Erie, Iluron, and Michigan; 
Fourth Lake, near Madison, Wisconsin ; Bailey. 

" Filaments tufted, bushy, somewhat rigid, much branched, bright grass-green ; branches 
crowded, irregular, erecto-patent, repeatedly divided ; ultimate ramuli sccund, subfasciculate ; 

articulations 4-S time.'; as long as broad." 



188 



FRESH-WATER ALG^ OF TUE UNITED STATES. 



RemarJcs.—Vvo(. Harvey says (Smithsonian Contributions): "I have received 
North American specimens from Milton, Saratoga County, N. Y., and from Lake 
Erie ; also from the Mexican Boundary Surveying Expedition." 

CI. fracia, Dillw. 

Clad, prima juventute affixa sed postea libere natans et ca;spites formans ; ramis ramnlisque 
sparsis, divaricatis, nonnunquaui refractis ; ramulorum eytioplasmate nou spiraliter ordinato; 
cytiodermate sajpe crassissimo ; cellulis fertilibus baud termiualibus, plerumque in ramulorum 
medio, aut eorura basi. 

Syn.— Cl. fracta, (Dillw.) Rabenhorst, Flora Europ. Algarum, Sect. III. p. 334. 

Jfab In flumine Schuylkill, prope Philadelphia; Wood. West Point, New York; Provi- 
dence, Rhode Island ; Bailey. 

In the young state fi.xed, but afterwards floating free and forming matted masses ; branches and 
branchlets scattered, divaricate, somewhat refracted ; cytioplasm of the branches not spirally 
arranged ; cytioderm often very thick ; fertile cells not terminal, mostly in the middle of the 
branches, sometimes in their base. 

CI. bracliysteleclia, Rabenhorst. 

C. per totam vitam innata, obscure viridis, sicca pallida, pygniaea, 2-4, rarlus Glinealonga, 
ramosissima, intricata, plerumque culmigena ; ramis priraariis ^V'" — jV " = 000295" — 0.0022" 
crassis, ramulis ultimis gV" — 70'" = 0.00141" — 0.00128" crassis ; articulis diametro 4-12 
plo longioribus ; cytiodermate subcrasso, hyalino, subtiliter plicato-striato ; eytioplasmate 
imprimis cellularum supcriarura laxe spiraliter ordinato. (R.) 

Syrt. — CI. hrachystelecha, Rabenhorst, Flora Europ. Algarum, Sect. III. p. 343. 

Hah. — Prope Philadelphia; Wood. 

Fi.xed through the whole life, obscure green, pale when dried, dwarfish, 2-4, rarely 6 lines long, 
very much branched, intricate, mostly attached to culms; primary branches 0.00295" — 
0.0022" thick, ultimate ramuli 0.00147" — 0.00128" thick ; articles 4-12 times longer than 
thick ; cytioderm thickish, hyaline, subtilely plicately striate ; cytioplasm, especially of the 
upper cells, laxly spirally arranged. 

Remarlcs. — I have notes of having identified this species at some time, but, 
having kept neither specimens nor detailed memoranda, have simply copied the 
description of Prof. Rabenhorst. 

FAfflLY OEDOGONIACE^. 

AlgSB monoicae vel dioicte. Fila articulata aut simplicia aut ramosa, cellula basali obovato-clavata, 
basi plerumque lobato-partitia vel scutata innata. Propagatio fit turn zoogonidiis turn oosporis 
fecundatione sexuali ortis. Zoogonidia formautur singula in quavis cellula, forma late ovali vel 
globosa, polo antico achroo corona ciliorum vibratoriorum prcedita. 

Oogonia singula vol plura (2-5) continua, plus minusve tumida, in quoque oospora singula, 
matura rubro- aut flavo-fusco-colorata, ante germinationem in zoosporas plerumque quatuor dilabens 
se format. 

Antheridia brevi-filiformia, 1-2-3-1 0-articulata, plerumque singula aut oogonio aut filo vegeto in- 
sidentia aut in individuis variis .sajpe cellula obovato-clavata subtentata. 

Monajcious or disecious algas. Filaments articulate, either simple or branched, fixed by the basal 
cell which is obovate-clavate, mostly with Its base lobately parted or shield shaped. 

Propagation sometimes by zoospores, sometimes by resting spores, the result of sexual impregna- 
tion. Zoospores formed simply in certain cells, broadly oval or globose, their anterior end trans- 
parent, and furnished with a crown of vihratile cilia. Resting spores single or in series of from 



FRESH-WATER ALG^ OF THE UNITED STATES. 189 

two to five, more or less tumid, single in each sporangium, at maturity reddish or yellowisli fuscou.?, 
before germination dividing themselves into (mostly four) zoospores. 

Antheridia shortly filiform, 1-2-3-10 articulate, mostly single, either upon the si)orangium or 
Tegctation cell. 

Remarhs. — The QiJdotjoniacrw have been by previous writers simply divided into 
two genera, (Edoijonium and Bulhochcvte. The plants represented by these two 
divisions have certainly many characters in common, as in the production of their 
zoospores and spermatozoids as well as in tlieir peculiar method of cell division. 
Yet they are so very diverse in some particulars in regard to the latter, as well as 
in their habit of growth and in the formation of their sporangia, that it has 
seemed to me that the diiferences between them were more tlian sufficient to clia- 
racterize merely genera, and that to each of these groups should be awarded the 
rank of a svib-family. 

Again, in the old genus of CEdogonhtm, we have very distinct groups, separated 
by differences in the most important of all the cliaractcristic portions of the plant — 
the sexual apparatus. These groups are the so-called Moncecious, Gynandrous, and 
Dicecious (Edogonia; the moncEcious division comprising those plants in which one 
individual gives origin both to the female and male germs; the gi/nandwus, those 
species in which the plant that produces the female germ gives origin also to a 
peculiar zoospore, the so-called androspore, which, after a period of motile life, 
settles down and develops a dwarf plant, the androecium, in which the sjici-mato- 
zolds are developed ; and the dicecious group containing species in which the male 
and female plants are distinct individuals. Dr. Pringsheim states (MorjJtoIogie der 
OEdofjon., p. 43) that these groups pass into one another, but in my opinion, by his 
own showing, they are sharply distinct. The nearest approach to such passage is 
between the first and second groups, and consists simply in the fact tliat in certain 
species the androspore when it settles down develops into a one-celled instead of a 
two or three-celled anthcridium. This to me does not seem to indicate a union of 
the groups, for the essential difference is not in the form or complexity of the an- 
thcridium, but in the circtnnstance that in the one case the female filament develops 
a spermatozoid capable of fertilizing the germ, whilst in the other it gives rise to 
a body which does not possess that power at all, but does have tlie capability of 
giving origin to a second plant, in which the spermatozoid is developed. The 
groups, therefore, appear to be sharply and distinctly definable. 

In the Bidhoclia'tiiC but a single genus has as yet been discovered, and this is 
distinctly gynandrous, but it seems probable that hereafter other plants of this 
subfamily will be found which are monaecious or disecious, so that we will have 
in the two subfamilies two parallel groups of genera. 

For the reasons above indicated I have ventured to divide the family into two 
subfamilies, the one comprising three, the other a single genus. The pcctdiarities 
of growth, production of zoospores, and sexual development will be found described 
under the particular subfamilies. 



190 FRESn-WATER ALG^ OF THE UNITED STATES. 

Subfamily CEDOGONIE^. 

Filamenta stricta, baud ramosa, sine setis veris, sed saepe apice sctiforma, elongata, hyalina. 

Filaments simple, not ramose, without true seta, but often with their apex seta-like, elongate, 
hyaline. 

Memarks. — The CEdogoniaceai are small filamentous plants, whose size is sufficient 
to render them visible to the unaided eye, and yet not sufficient to make each indi- 
vidual distinctly apparent. They grow mostly in quiet water, attached to almost 
any and every thing that can afford a foothold, fringing with apparent indifference 
stones, twigs, sticks, dead leaves, bits of glass, boards, etc. I have seen such 
masses of them crowding the whole surfixce of a j^hysa as to entirely conceal the 
animal and its shell, and present the curious spectacle of a perambulating, waving 
forest of bright green. The individual filament is composed of cylindrical cells, 
which are always Avithout a nucleus, and have their chlorophyl diffused instead of 
being collected into bands or stripes. The walls are mostly quite thick and 
marked near the distal end with circular striae, whose numbers bear relation to 
the edge of the cell, for these strife are the results of the peculiar method of cell 
multiplication by division, each one marking one such division. When an oedo- 
gonium cell has attained sufficient maturity and is about to divide, the first per- 
ceptible change is the appearance of a little circular line or streak near its distal 
end. About the same time and in the same place a fine partition is formed by an 
outgrowth from the primordial utricle, a probably double delicate wall of con- 
densed protoplasm separating the upper end of the parent cell from the lower or 
main portion. The upper end now begins to develop into a new cell. This de- 
velopment takes place by the formation of an entirely new layer of cellulose 
inside the little cell, i. e. between the new primordial utricle and the old cell wall, 
and afterwards by the lengthening of this layer by interstitial deposit in the usual 
way; the thick wall of the parent cell in no way directly participates in the 
growth (fig. 2 h, pi. 17). It is evident that as the new wall grows the old cell 
wall must be as it were raised up upon it, borne away as a little capping from the 
basal portion of the parent cell. Consequently when a young cell is watched 
during this process the little line-like incisure of the parent cell is seen to widen 
until it becomes an evident trench, and this trench grows wider and wider, until 
at last it is so broad as to be no longer a trench, and the little end of the parent 
cell simply caps its offspring. When the latter has fulfilled its allotted period oi 
growth, the process is repeated, the line of separation appearing this time just 
below the edge of the first cap. It is plain that the second new cell when formed 
must have a double cap crowning its extremity. At each repetition a new layer 
is added to the thickening cap, until at last it may be composed of six distinct 
layers, each projecting just beyond the next older one. Under the microscope the 
increased thickening of the distal end of a cell bearing such a crown-piece is not 
sufficiently evident to at first attract attention, whilst each edge of a layer appears 
as a stria. It is plain that the number of these stri« represents the number of 



FRESH-WATER ALG.E OF THE UNITED STATES. 191 

times division has occurred ; if there be four stria% four times ; six striae, six 
times, &c. 

Besides this method of development, in many species new cells are formed by a 
sort of puUulation, occuring in the end cell of the filament. The primordial 
utricle appears to rupture the wall of the distal extremity of the latter and grow 
out into a little pullulation, or teat, which very soon becomes separated from the 
parent cell, by the reformation, as it were, of the end wall of the latter. Tlie 
, new little cell thus formed coats itself with cellulose, and rapidly grows, especially 
in length, always, however, or "at least for a lengtli of time, remaining of a smaller 
diameter than the cell from which it sprang. By a repetition of this process a 
succession of cells is formed, each one of which, like the successive joints of the 
field telescope, is a little smaller than its proximal neighbor and contains less 
chlorophyl, until finally the cells are reduced to exceedingly fine, perfectly trans- 
, parent, colorless cylinders, which together form a seta or hair. 

J lleproduction takes place among the QLdo<jontaccce, both by means of zoospores 
1 and sexual organs. The former of these are quite peculiar, and, therefore, require 
j especial notice. 

I Only a single one is ever produced in a cell, and there is consequently no divi- 
! sion of the chlorophyllous protoplasm preceding their formation. The first change 
\ noticeable is a sort of confusion of the cell contents, the protoplasmic portion of 
which loosens itself, as it were, from the walls, and collects in a mass at the 
distal end of the cell. This mass after a short time assumes a more or less irregu- 
larly globose shape, and simultaneously the parent cell begins to separate from its 
I distal neighbor. This separation appears to take place commonly by a solution 
I of an exceedingly fine ring of the wall of the parent-cell, just at the origin of the 
transverse partition separating the two cells, and it is therefore brouglit about not 
by a splitting of the end partition wall, but by a circumcision of the side walls of 
the cell, and consequently the cavity of the latter is thrown open, tlie end wall 
1 remaining with and closing the distal cell, whose contents have not undergone 
f change. On the other liand, observation leads me to think that sometimes tlicre is 
i a splitting of the end wall. According to my observation, sometimes the filament 
is completely broken in two, but very commonly the two cells remain attached by one 
I corner, opening from one another as it were on a hinge-joint (fig. 2/, pi. 17). 

The gathering of the protoplasm, already spoken of, into a ball, is a slow process, 
I and the escape of this ball, through the opening formed in the manner described, 
takes place even more slowly. The motion is not at all perceptible, with a power 
j of a thousand or twelve hundred diameters. During the passage the ball becomes 
more or less twisted and deformed, but as it emerges the uncompressed portion 
sliortens and swells out, and when the mass of protoplasm is at last free in the 
water, it soon assumes a globular or regularly ovate shape. The mother-cell, thus 
bereft of its contents, is left dead and void. Tlic primordial utricle indeed still re- 
mains within, but it has lost all its wonderful powers, and is nothing but a shrunken, 
twisted, or folded dead membrane. What is the cause of tlie motion of the 
zoospore within the cell it is very difficult to determine. It certainly is not vibrating 
cilia. When the zoospore first escapes, it is, as already stated, an irregular lump 



li)2 FRESH-WATER ALG^ OF THE UNITED STATES. 

of strongly clilorophyllous protoplasm, homogeneous or with one or more roundish 
masses of darker green within it. As it assumes its shape, however, a very dis- 
tinct transparent spot appears at its smaller end. Whether this is an absolute 
vacuole or not, I have never been able to satisfy myself, but I am rather inclined 
to believe that it contains highly refractive transparent protoplasm. As this spot 
is perfected the cilia make their appearance. Whether they are actually first 
formed there, or whether, as is more probable, they are formed inside the cell, and 
are so folded against the general mass as to be invisible, I have never determined, i 
Dr. Pringsheim, however, figures them within the cell. I have seen them in i 
their early development long before motion commenced in them, but they were ., 
always perfectly formed as soon as apparent. They are present in great numbers, t 
making a crown or ring around the edge of the transparent beak-like end. "When '■ 
they commence to vibrate, their action is at first very slow, and the waves of 
motion run through them deliberately from one cilium to the other, but soon, > 
however, the motile impulses succeed one another more and more rapidly, until : 
the general mass of the zoospore begins to tremble, then to rock, and fiuaUy dart- ■' 
ing oif the little body hastens hither and thither through the water. The zoospore | 
of an (Edogonium is always readily distinguished from most other similar bodies by 
its large size and peculiar motion, which is a forward movement combined with a 
distinct rolling on its long axis. After a time the zoospore, coming in contact 
with some speck of matter to which it can attach itself, ceases its movements, 
the cilia rapidly wither away, and the end to which they have been attached 
swells out or elongates into a broad, or narrow, simple, bifid, or trifid process, 
placed at an angle to the main axis of the cell, bo as to form the so-called foot, the 
holdfast that anchors and fixes the new plant. Whilst this is taking place, the 
general form of the zoospore alters into that of a cylinder, a cellulose wall is 
secreted all about it, and the first cell of the new plant is complete. As soon as 
this cell is sufficiently matured, it begins to undergo division in the manner already i 
described, and to develop into the new filament. 

In regard to the time when these zoospores are given off most abundantly, and 
the circumstances that influence the process, I can only state that it occurs when 
there is least tendency to the production of resting spores, probably in youngish 
plants, and I have thought was favored by a full supply of light, with a moderate 
temperature. 

Sexual reproduction occurs among the CEdotjouiaccce in accordance with three 
distinct types, to which the name of monceciotis, dicccious, and gynandrous has 
been severally applied. The characteristic differences are to be looked for in tlie 
production of the antheridife or male plant, the female germ being always pre- 
pared in essentially the same way. In most instances two cells are requisite for 
the production of the latter. At first there is nothing by which cells set apart for 
the formation of the female germ can be distinguished from ordinary cells. The 
proximal one of the pair finally, however, undergoes changes similar to those 
seen when a zoospore is to be formed, namely, a sort of confusion of the endo- 
chromc, and finally a gathering of it into a mass at the distal end of the cell. In- 
stead of there being a solution of the side wall of the cell, however, the end wall 



FRESH-WATER ALG^ P T H E UNI TE D S T A T E S. 193 

undergoes absorption, so that the cavities of the two cells are more or less com- 
pletely thrown into one. All or nearly all of the contents of the proximal cell 
now slowly pass into the distal one, which thus becomes crowded with chloro- 
phyllous protoplasm. At or before this period, the distal receiving cell undergoes 
a change in form, widening out greatly, and sometimes appearing actually to 
shorten, so that it is in most instances resolved into a more or less re<rular <rlobose 
or oval cell. As the sporangium or spore-case thus formed perfects itself tlie cndo- 
chromes of the two cells become completely fused into one mass, which gradually 
condenses and assumes a regular shape, until, in the form of the perfected female 
or receptive germ, it is a dark, opaque ball more or less completely filling the spo- 
rangial cell. At the same time, in order to aftbrd passage for the male germ, an 
opening is formed through the walls of the sporangium. This happens in two ways. 
The simplest of these is by the formation of one or more circular openings or 
pores in the wall. This pore is sometimes below, sometimes above the equatorial line. 
Its position, numbers, and form afford good specific characters. The second method 
is by the development of a little trap-door entrance at the distal end of the spore- 
case. This method is unknown in our American flora, and, never having seen it, 
I must refer to the papers of Pringsheim for details. 

The above-described mode of origin of the sporangium is the common one. In 
0. mirahile, AA^OOD, however, but one cell is concerned. This cell grows to an 
enormous size, far beyond that of its fellows, and its endochrome collects into the 
upper half of it, to be at last sliut off from the lower half of the cell by the forma- 
tion of a new cellulose partition or end wall ; or, in other words, the parent cell 
divides by a modified process of cell division, different from that common in the 
family. The distal daugliter-ccll contains all the endochrome. After the changes 
are completed, the appearance is the same as ordinarily presented, namely, an empty 
cell surmounted by the sporangium. Sometimes, even in plants in which the ordi- 
nary process occurs elsewhere, a single cell appears at times to have sufficient 
vitality to develop into a sporangium without aid from its neighbor, so that the 
latter will preserve its integrity, and the resting spore finally lie in proximity to a 
cell full of endochrome. 

In the moniccions CEdogoniacece, a single filament produces both the male and 
female germs. Certain cells appear to be set apart to develop into sporangia, whilst 
others give origin to the spermatozoids. No such plants have as yet been detected 
in North America, and I, therefore, pass on without speaking more in detail. 

The second mctliod in whicli the spermatozoids are produced is the most com- 
mon in our flora ; it is the so-called gynandrous plan. In this the single filament 
produces the female germs directly and tlie male germs indirectly. The former 
arise in the way previously described, whilst the latter are the resultant of a 
complex scries of life actions, as follows : One of the main cells of the originating 
filament, differing in no perceptible way from its fellows, instead of like them 
developing new cells, divides up by a simple process of cell division into two or 
more cells, each one of which contains very largely of chloropliyllous protoplasm. The 
protoplasm within each of these secondary or dauglitcr-cells soon condenses into an 
irregularly ovate or conical mass, which often, even within the cell, may be seen to 

25 September, 1S72. 



194 FRESH-WATER ALG^ OF THE UNITED STATES. 

have the transparent beak of the zoospore (pi. 18, fig. 2d). Inside of the cell 
the androqiorc, as it is called, shows no cilia, but when it is set free by a more or 
less complete solution of the cell wall, it assumes the form of the ordinary (Edoyo- 
nium zoospore, with a crown of cilia, whose vibrations soon cause it to dart through 
the water. These androspores are of course much smaller than an ordinary 
zoospore, and after a period of active motion, they attach themselves to the parent 
filament, generally either on or near the sporangial cell. Their first life-actions, 
after settling, are precisely like those of the zoospore, namely, dropping of the 
cilia, enlargement of the smaller end into the so-called " foot," an elongation of 
the general mass, and the secretion of an outer coating of cellulose. In this way 
a peculiar-shaped, somewhat ovate cell is formed, which contains a great quantity 
of rich protoplasm with mostly a small amount of chlorophyl. From such cells are 
developed the mostly two- or three-celled, perfect antheridia, which in gtjnandrom 
(Edogonia are generally to be seen, during the period of fructification, in numbers 
attached to the filament, mostly in the neighborhood of the sporangium. Their pro- 
toplasmic contents are remarkable for the activity of their movements, and I have 
seldom seen more beautiful and rapid cyclosis than they display — currents setting in 
all directions — particles actually brushing against one another (pi. 17, fig. 2/t). 
The spermatozoids are formed in the distal cell, sometimes one, sometimes more. 
In the species 0. mirahile. Wood, (pi. 18, fig. 2 g, 2 b) in which I have most 
carefully studied their origin, two are produced in the single cell. This cell is in 
the commencement of the process, although comparatively poor in chlorophyl, 
crowded with a rich solid protoplasm, which divides into two distinct masses, some- 
what in the manner seen in the commencement of ordinary cell division. As 
there is no distinct nucleus, of course there are no precedent nuclear changes. 
The masses thus formed gradually assume a more or less perfectly globular shape 
inside the cell, although I have never been able to see that they there develop cilia, 
and finally are set free by the lifting up of the end of the mother-cell, like a little 
trap-door. Their mode of escape through the exit thus off"ered is similar to that 
of the ordinary zoospore, which they resemble, except that they are much smallt-r, 
are much less rich in chlorophyl, and have the anterior clear space less defined. 
They are said to be furnished with a crown of cilia similar to that of the zoospore. 
I myself have never seen these, but do not doubt their existence. 

In the dlcvdom Q^dogonia there are distinct filaments, male and female, one of 
which produces the oosporangium with its contained germ, whilst the other gives 
rise directly to the spermatozoids. 

The resting spore which develops after impregnation is variously shaped, but in 
most instances is round or oval. It is often, if not always, furnished with two coats, 
the outer of which is tliick, firm, and frequently provided with surface appendages, 
such as tubercles, ridges, spines, etc. Besides these there is also, probably, a very 
delicate inner coat. The spore appears to be set free from its case by the decay of the 
latter, there being never, at least tliat I have seen, any regular dehiscence. Although 
I have made several attempts, it has never been my good fortune to observe anything 
'ike germination of these resting spores. Prof. Chr. Vaupell, however, has published 
an account of the manner as observed by himself. Some water containing fruitful 



FRESII-WATER ALG^ OF THE UNITED STATES. 195 

CEdogonia was allowed to dry in a glass, towards tlic close of September, and the 
greenish residue was placed in water in the following January. By March the 
resting spores were everywhere in active germination. The first change was a 
rupture of the two outer coats and the escape, through the slit, of the contents, 
still surrounded by a very delicate hyaline membrane. By this time the proto- 
plasm had divided into usually four (sometimes only two or three) greenish masses, 
each of which was oval in shape and had its own extremely thin, hyaline coat, 
and was therefore a perfect cell. The old outer shell of the spore laid discarded 
in the water and soon decayed, and in a little while the hyaline sac surrounding 
the four daughter-cells itself disappeared, leaving them exposed and naked. After 
awhile each of these cells opened at one end by means of an annular si)lit, cutting 
off the apex of the wall and allowing it to lift off like a little lid. Through the 
circular opening thus made, the contents now emerged. The point of the inner 
mass was colorless and directed towards the orifice, and the whole moved vigorously 
backwards and forwards until it finally escaped, as a perfected zoospore. This 
little bofly simulated very closely the ordinary zoospore, both in appearance and 
life-history, growing, after a brief period of activity, into an ordinary filament, m 
precisely the same manner as the zoospores. 

Genus CEDOGONIUM. 

Antheridia et oogonidia in individuo unico. 
Antheridia and oogonidia in the same individual. 

Remark. — No species of the genus QjJdogonium, as here defined, has as yet 
been discovered in this country. 

Genus miNGSHEIlMIA. 

Dioica. Antheridia et oogonidia in individuis distinctis orta. 
Dioecious Antheridia and oogonidia arising in distinct individuals. 

P. ineqiialis, Wood. 

P dioica; cellula basali biloba ; plantis femineis quam plantis masculis perniulto majoribus; 
oogoniis enormiter globosis vel subovoideis, poro laterale supra medium posito instructis; 
oosporis forma eadem, sed pauIo minoribus. 

Sijn. — (Edogomum inequale, Wood, Proc. Amer. Philos. Soc, 18G9, p. 141 

Hab. — In stagnis, prope Philadelphia. 

0. dioecious, basal cell bilobate ; female plant very mneh larger than the male plant ; oospo- 
rangium irregular!}^ globose or subovoidal, opening by a lateral pore above the middle ; 
resting spores of the same form as the sporangium, but a little smaller. 

Remarks. — This plant seems to be more closely allied to 0. gcmelUparum, 
Pringsheim, than to any other species. It agrees with it in the inequality of the 
male and female plants, in the shape of the sporangium, and the position of tlie 
lateral pore. The diameter of the female plant is often nearly four times that of 
the male, and the difference in length is much more apparent. The mother-plant is 
composed of from 3-6 cells in the most distal of which the spermatozoids are formed. 
I am not able to state how many of these bodies are formed in a single cell, having 



1<)G FRESH -WATER A L G .E OF THE UNITED STATES. 

only seen tlio latter wlifu iiioro or loss conipktely emptied, but, judging from the 
relative sizes, tliere must be several. In a eell containing a single spermatozoid, that 
body moved about freely, and at last escaped, apparently tlirough an orifice in the 
end wall of the cell. It made two attempts before getting out, and during its 
passage was distinctly constricted in the middle. It resembled in appearance an 
ordinary zoospore, but Avas of course much smaller, and was nearly devoid of color, 
having but a slight greenish tint. I found this species growing abundantly in the 
stagnant ditches of the Neck, below the city. 

Fig. 1 «, pi. 18, represents a young female plant; 1 h, a fertile plant with imma- 
ture spores. I c was taken from the supposed male plant alluded to in the text. 
The latter figure is magnified 450 diameters, the others 250. 

Genus ANDROGYNIA. 

Gynandra. Androsporic in plantis fcmincis ortaj ; postea Lane afE.xa! et in antheridiis se formant. 

Gynandrous. Androsporcs arising in the female plant ; after affixing themselves to this and 
developing into aiithcridia. 

A. llliilti>i|)ora, Wood. 

A. oogoniis singulis, vel binis vel ternis eontinuis, globosis instructa ; poro laterals distale; 
oosporis globosis, oogonii lumen replentibiis ; antheridiis plerumque pluribas, plauta femiuca 
insidentibus, cellula inferiore multo majoribus. 

Syn. — Oedogonium muUispora, Wood, Proc. Anier. Philos. Soc., 1809, p. 141. 

Hab. — In stagnis, prope Philadelphia. 

Oosporangia single or bi- or triseriate, globose with a distal lateral pore ; oospore globose, 
about the same size as the sporangial cavity; antheridia bi- or tricellular, curved, with the 
lower cell much the largest, generally adhering in considerable numbers to all parts of the 
female plant. 

Remarks. — This species differs from its nearest European congeners, CEdagon. 
Bothii iind CE. de^jrcssum, very markedly in the bicellular antheridia. I have never 
seen the spermatozoids actually emerging from their mother-cell, but have seen in 
the terminal antheridial cell a pair of oval bodies, which I took to be those bodies. 
Fig. 3, pi. 17, was taken from a filament of this species magnified 500 diameters. 
It shows spores in different stages of maturity, Avith an empty basal cell in cue 
case, and in the others without. Also male plants, one of tliem containing partially 
formed spermatozoids. The small arrows indicate the direction of cyclotic 
currents. 

A. iiiii'aliili!«, Wood. 

A. rare setigera ; articulis diamotro 2-8 plo longioribus ; oogoniis plerumque singulis, rnrc 
geminis, nonnihil ovatis, infra latis sed supra contractis ct medio tumidis ; pons lateralUms 
duobus supra medium positis ; oosporis aut late ovalibus aut subglobosis ; sporodermate baud 
signato ; antheridiis plerumque bicellularibus, interdum tricellularibus, plerumque in filo 
vegetativo infra oogonium aut in oogonio insidentibus ; spermatozoidois singulis et geminis. 

Diam.—Artic. veget t-.V— THtj"=-0004"— 0017". Spor. t>§j"_7|»/. 0024"— 0027". 
Syn.—CEdvgonium mirabile, Wood, Proc. Amer. Philos. Soc, 18G9, p. 142. 
Hah. — In rivulis quictis, prope Philadelphia. 



FRESn-WATER ALG^ OF THE UNITED STATES. 1<)7 

A. rarely sctigcrous ; articles 2-8 times longer tliaa broad ; oosporangia mostly single, rarely 
geminate, subovatc, in the lower portion broad, in the middle swollen, in the uiipcr part con- 
tracted ; the 2 lateral pores situated above the middle ; oospore subglobose or broadly 
ovate, its coats without markings; antheridia generally biccllular, sometimes tricellular, 
numerous, placed generally upun the female filament cither upon or below the oosporangia. 

Remarks. — This species wiis found growing in a ratlicr stagnant brook in the 
meadow by "Kobinson's Knoll," at the junction of the Schuylkill River and ^^■issa- 
hickon Creek, near rhiladeli)hia. The filaments, which vary very greatly in size, 
arc in their early history attached to dead leaves and sticks, but finally, I think, 
float free in the water. The larger, fruit-bearing filaments arc remarkable for their 
crookedness. None of the threads that I have seen ended in a seta-like portion. 

The fruit is produced in abtmdance, but very rarely is there more than a single 
spore in any one place. The method of the formation of the sporangia dift'ers from 
that of all the other CEdo<joiua which have come under my notice. Instead of 
two cells being concerned but one cell is employed. The cell (fig. 2 a, pi. 1<S) that 
is to be used for such a purpose grows much beyond the ordinary size, until it is 
nearly or cpiite twice as large as its neighbors. All tlie time it is well filled with 
chlorophyllous protoplasm. This now contracts and finally is all packed into the 
upper half of the cell. At or even before this time the lateral openings become appa- 
rent. There are two of them, situated just in the angle where the cell at its upper 
end commences to contract to the size of its fellow. At this tim(> T think fertiliza- 
tion takes place, although I have never actually seen the spermatozoids enter the 
orifices. The cell (fig. 2h, pi. 17) now divides into two by forming a wall separa- 
ting the lower empty half from the upper full one, which is to be the sporangium. 
The contents of the latter now condense into a ball, and it itself becomes more tumid 
in the middle. Finally a reddish-brown broadly globular spore (fig. 2 c, pi. 18) 
is formed. I have not been able to make out more than one distinct thick coat. 
The surface of the spore is smooth. The androsporcs are formed in a cell (fig. 
2 (7, pi. 18) which has grown beyond the normal size and then divided into four 
or five short cells, each of which gives origin, I believe, to a single androspore 
in its interior. The antlieridia are numerous, from 2 to G being commonly attached 
to the lower portion of the sporangium, or to the cells just beneath it. They 
(fig. 2 (', pi. 18) have a rather large foot, and are generally curved at the base. The 
distal of the two cells composing them is crowned with a little cap, and produces 
(me or sometimes two spermatozoids. These (figs. 2 h and 2 (j, pi. 18) during their 
escape arc always very much squeezed out of shape, but when free become globular 
or slightly pear-shaped. They are highly transparent and contain a few green 
granules. Their motion is at first slow, but soon becomes very active. The mode 
of egress from the cell is obtained by the cutting off of the upper end of it, the 
little cap opening like a trap-door. After this cell has been emptied, sometimes a 
second similar one is foruKMl, wliich bears it aloft. 1 have never seen spermato- 
zoids produced by this second cell. 

A. niintii, Wool). 

Filnm.T, plcrunupic in setam longam, terniinalem coloris e.tportam productum ; oogoniis pler- 
iinKpie singulis, globosis, interdum nonnihil hexagoniis, medio nunnihil tiimidis, poro laterale 



198 FRESn-WATER ALG^ OF THE UNITED STATES. 

infra medium posito ; oosporis globosis, oogonii lunion liaiul rcplentihus, superficie lineis 
elcvatis spiralibus quatuor iastructa; autheridiis bicellularibus (iiiturdum tricellularibus ?). 

Diam.—Si^oi: j!/=.002". 

Si/n. (Edogonium Hunlii, Wood, American Naturalist, 1868. 

Ilab. — In aquario meo. 

Filaments mostly produced into a long apical seta ; oogonia mostly single, globose, sometimes 
somewhat hexagonal, somewhat tumid in the middle, the lateral pore placed below the 
middle ; oospore globose, not filling the cavity of the spore case, its surface with four spiral 
elevated lines or ridges ; autheridia bieellular (sometimes trieellular '!). 



Remarks. — This little plant appeared in my aquarium some years since, forming 
a delicate fringe upon the various aquatic plants growing therein. Its color is a 
bright yellowish green, deepening to a very dark green in cells which arc crowded 
with granular protoplasm. The filaments vary very greatly in size, the largest I 
have seen were g^^ of an inch in diameter. They are provided with long, termi- 
nal seta, which are much more universally present than in any of the other species 
I have met with. The first step in the formation of a spore is the emptying of a 
cell into its distal neighbor, so that each spore case is placed at the end of an empty 
cell. These sporangia may bo single or they may be in series of two or more, 
separated only from one another by the eruptive cells just spoken of. The color 
of the mature spore is a very dark reddish-brown. The antheridia is bieellular, 
slightly curved, somewhat stipate, with a distinct foot. Its most common position 
is on the vacated cell just below the spore case. The zoospores, as I have seen 
them, are always globose. 

I have named this species after my friend. Dr. J. Gibbons Hunt, a well-known 
microscopist of this city, to whom I am greatly indebted for aid in my earlier 
microscopic studies. 

Fig. 2, pi. 17, represents different forms and parts of this plant. 2 a shows 
the end of a filament and the long seta-like lip. 2 h was taken from two' cells, ^ 
one of which had just undergone division, and shows very plainly the method of 
procedure ; lying as it were between the cells, and bearing the end of the lower 
one upon it, is the new little cell. Fig. 2 c represents a fertile filament with two 
mature spores and one not fully grown. Fig. 2 d was drawn from a filament just 
forming a spore, and shows the male plant i7i situ. Fig. 2 e represents a male 
plant (magnified some 1300 diameters) with the outer terminal cell scarcely more 
than a primordial utricle. The contents of the lower cell Avere in a state of in- 
tense motion; and the arrows are meant to indicate the directions of the currents. 
Fig. 2/ represents a portion of a filament with a zoospore just escaped and still 
quiescent. 

A. ecliinnfa, Wood (sp. nov.) 

A. valde elongata ; articulis diametro 6-14 plo longioribus; oogoniis globosis, plcriimnnc do 
pressis, ad .0014" crassis; oosporis oogonii forma et ejus lumen replentibus, valde aculualis 
poro laterale supra medium posito ; autheridiis bicellularibus ? 
Z>iam.— Spor. ^^Y^^"= .001". Cell. ^^V'—juJij" = -00033" — .0005". 
Hab. — In stagnis, Alleghany Mountains. 



FRESH-WATER ALG^ OP THE UNITED STATES. 199 

O. gynandrous, very elongate ; joints C-14 times longer than broad ; sporangia globose, mostly 
depressed, about .0014" in diameter; oospores of the same form as sporangia, whose cavity 
they almost fill; covered with sharp spines; the lateral pore placed above the middle; au- 
theridia bicellular ? 

Remarks. — I found this distinct species in a little stagnant pool in the 
wilderness, known as Bear Meadows, in Centre County, of this State. The fila- 
ments are very long, and were matted together into a sort of fibrous mass. The 
male plants were few in number, and were attached to the female plant in the 
neighborhood of the sporangia. I have not seen any composed of more than two 
cells. They are furnished with a well-marked foot, above which there is a short 
neck. As I have seen them they are nearly straight. 

I have not been able to make out more than one coat to the spores. This coat 
is very thick, and is furnished with numerous thorn-like spines. These are very 
sharp at the points, but at their bases are mostly very robust. 

Fig. 3, pi. 18, represents a spore of this plant magnified 750 diameters. 

Subfamily BULBOCH^TE^. 

Filuma ramosnm, .setis strictis hyaliiiis adirois e basi bulbosa et plus minns elongatis instruetum. 
Filaments branching, furnished with straight, hyaline, more or less elongated seta, arising from a 
bulbous base. 

Remarhs. — The Bulhoclicetece are at once separated from their allies the CEdogo- 
niea by their bushy, branched habit of growth. The shape of the individual 
cell is also entirely different, for instead of being regularly cylindrical they are 
almost always markedly dilated at their distal end, so as to be somewhat clavate, 
nor is the filament or its branches ever ended by a long seta-like series of narrow 
colorless cells. Many or all of the cells are, however, furnished with a single 
very long unicellular unbranchcd hair. These hairs are colorless, hyaline, and 
provided with a markedly and abruptly bulbous base. The BidhocltaiecE grow in 
similar positions to their allies, but are not nearly so common, nor when present 
do they grow in such abundance, very rarely, if ever, forming the dense forest-like 
fringes or the matted masses that some species of the (Edoijonieie do. They are 
reproduced both by zoospores and resting spores. 

The manner of the development of and growth of the plant from the zoospore 
is very peculiar. I have never myself studied it, but Prof. Pringsheim gives the 
following account: When the zoospore first settles down it produces a cell closely 
resembling that of an CEdogonium. The first change which occurs in this cell is 
the formation of a small, conical, transparent, colorless space at the apex, which 
space in a little while becomes separated from the mother-cell by a distinct par- 
tition-wall, and at the same time the apex itself is ruptured, and the point of the 
little growing cone pushed througli the opening. This rupture does not take 
place irregularly, but by a sort of circumscribed dertiscence, similar to that of the 
CEdogonmm, the top of the mother-cell being lifted up like a little trap-door, and 
finally pushed aside as the new conical cell grows elongate and becomes converted 
into a hair. After the formation of this ;ipical hair, the mother-cell midergoes 
division in a manner similar to that of an CEdof/onium. Near its distal end a 



200 FRESII-WATEU ALGyE OF THE UNITED STATES. 

circular slit appears, and at the same time a partition forms, so that from the 
mother-c(;ll are developed a small apical and a large basal daughter-cell. Tlic his- 
tory of tlie former of these is simply one of growth as regards the main axis. It 
increases in size but does not give origin to new cells. All such cells are formed 
out of the basal daughter-cell, Avhich, as already described, divides into a new 
apical and basal cell— the apical only to grow in the main filament— the basal to 
divide anew. It is always the basal cell that undergoes division, throughout tlie 
whole life-history of the plant, one cell alone contributing to the growth of the 
main filament. The filament thus formed bears upon its distal end the hair wliirh 
grew upon the original spore-cell, and this hair is, save only the basal cell, the 
oldest part of the filament. The cell upon Avhich it rests is the next oldest, the 
next to it in position, the next in age, and so on (from older to younger) down to 
the basal cell, the oldest of all, lying next to the latest born. 

Although the cells of the main filaments do not contribute to its development, 
yet it is from them that the lateral branches are formed. The production of a 
branch begins by the appearance of a clear space near the apex of the cell, but this 
clear space is placed, not exactly at the apex, but a little to one side. It soon becomes 
distinctly conical, enlarges, bursts through the old cell-wall, is cut off by a cellulose 
partition from its parent, and develops into a hair similar to that first formed, but 
placed at an angle to the long axis. It is remarkable that the opening for the 
exit of the growing hair occurs, not by a circular transverse slit, but by a longi- 
tudinal one, the two halves of the old cell-walls separating as the little cone pushes 
its way between them and persisting as a sort of sheath to its base. When the 
hair is perfected the cell from which it grew undergoes division in the usual way, 
save only that the cutting off of the old wall is done obliquely instead of trans- 
versely, so that the partition is oblique instead of horizontal, and the new cell 
grows at an angle to the old, instead of in the line of its axis. The new cell, 
consequently, is the starting point to a branch at an angle to the main filament. 
This branch, like the main filament, grows only by the repeated divisions of its 
primal basal cell, and bears aloft its seta. Secondary branches may arise from it 
precisely in the way that it arose from the parent stem, and thus at last is formed 
the bushy plant of the BuIbocJicvtcce. 

The zoospores closely resemble those of the Q^dogouiecc, and are oval or glo- 
bose masses of chlorophyllous protoplasm, with a transparent space at the smaller 
end, surmounted by a crown of cilia. Their mode of formation and whole life- 
history are also similar to that of the CEdogoniecE zoospores, up to the time when 
in their germination they begin to produce new cells. 

Sexual reproduction amongst all the knoAvn BullocJuctece is similar in its general 
aspect to that seen among the gynandrous CEdogonietP, but difi"ers considerably in 
detail. The oogonia are mostly formed in lateral branches. Their position in these 
branches varies in the various species. 

Since any cell from the next to basal to the most distal of all crowned witli the 
terminal seta may be converted into a oogonium, according to Pringsheim, the 
cell which is to form the oogonium arises in the usual way, by the division of a 
cell into two daughter-cells. The new daughter-cell, which is to develop into the 



FRESH-WATER ALG.E OF THE UNITED STATES. 201 

sexual part, docs not, however, rupture the old wall of the mother-cell, but grows 
out beyond it, and there dilates. The new cell is tlierefore divisible into two parts, 

I a proximal cylindrical portion, contained within the walls of the mother-cell, and 
a distal more or less globular piece beyond the latter. The chlorophyllous proto- 

I plasm now collects in this dilated portion, leaving the basal cylindrical part bare and 

■ empty. The oogonium is not, however, formed directly from this upper portion 
(the primitive oogonium, as it may be called), but a new wall forms within the latter 
and then it undergoes division much as did the primary cell. In this way it is that 
the upper and lower portions of the old wall, i. e. that of tlie primitive oogonium, 
remain as a sort of basal sheath and cap to the fully-formed sporangium. The 
little hole by which the spermatozoids find entrance to the contents- of the oogo- 
nium is always formed in the upper half of the wall of the latter. 

As stated, all the species of Bulhochceicw as yet known are gynandrous. The 

' antheridia resemble those of similar QiJdogoniccc, and their life-history is very similar. 
The development of the resting spores is said to take place as follows : The first 

( change is iir the color of the spore, the bright red becoming green, especially near 

I the margins of the cavity. The outer wall is then ruptured and the spore grows 
into a long oval body, whose contents are chietly green with a sprinkling of the 
original red. The protoplasm of this oval body gradually divides into four masses, 
which become more and more distinct, until they are at last well formed zoospores, 

I similar to those produced in the more ordinary method, except, perhaps, that they 
are redder. They are finally set free in the water by a solution of the cell wall 

I surrounding them, and enter upon a brief free existence, to settle down after a 

I little and grow into a fully-formed plant. 

Genus BULBOCH.ETE. 

Andropporse in planta ferainea. ortce, postea banc afE.xa3 et in antheridiis se formantes. 
Androspore arising in tlic female plant, afterwards affixed to it and developing into the autlieridia. 

j B. ignota, Wood. 

B. sparse ramosa, elongata; articulis diametro max. (.pj^iV = .0007"") H-3 plo longioribus; 
oogoniis long. ^J-^" = .0025", lat. sJ^^" = .0018", interdum lateralibus et sessilibus, inter- 
dum inter ramulorum cellulas vegetativas positis, dissepimento nullo ; oosporis ovalibus, longi- 
tudinalitcr nouuibil oblique et distante eostatis, iu ajtate provecta aurantiaco-brunueis, sporo- 
dcrmate crasso ; antheridiis 3-4 cellularibus, stipitatis. 

Syn. — B. ignota, Wood, Pi-odromus, Proc. Amer. Pbilos. Soc, 1809. 

Bab. — In aquis quietis, prope Philadelphia. 

B. sparsely branched, elongate with the joints 1^3 times longer than broad daW' = -00077") ; 
oosporangia .0025" long by .0018" broad, sometimes lateral and sessile, sometimes placed 
upon the apex of a branch, sometimes situated in the length of the branches between their 
cells; the empty cell which supports the sporangium without dissepiment; oospores, oval, 
filling rather closely the cavity of the spore-case, longitudinally somewhat obliquely and dis- 
tantly costate, when mature orange brown; spore-coat rather thick; antheridia 3-4 celled, 
scarcely stipitate. 

Remarks.- When I described and figured this species I had never seen tlie 
mature fruit, but very recently Mr. Quimby has communicated specimens to me. 

26 September, 1872. 



202 FUESII-WATEll ALG.E OF THE UNITED STATES. 

The color of the spore is orange brown, antl the thick coat is slightly tinged witli 
ycllowisli. The mature oosporangium is somewhat flattened at the sides, not so 
elliptical as the young spore, wliich I have figured. 

Fi<^ 5 «, pi. 18, represents a fragment of a filament showing young sporangial 
cells magnified 260 diameters ; 5 h, represents a branch with a youngish spore in it, 
ma"-nified 160 diameters; fig. 5 c, was taken from a male plant. 



.B. diimo^i.i, Wood 

13. articulis diaiiu'tro H-2 plo longioribus; oogoniis plenimqne in ramorura brevissiraorum 
iipicibiis positis st'd iiitcrdiuu lateralibus, pleruniquc setaiu terminaleiii gereutibus; oosporis 
enormiter ovalibus aut ovatis, nounihil indistincte longitudinaliter oblique yibarcte- striatic ; 
aniheridiis bicellulanbus, stipite iustructis, cellula basale medio tumida, supra sajpe contracta. 

Sijn. B. dumosa, Wood, Prodromus, Proc. Amer. Pliilos. See, 18G9, p. 142. 

Nab. — lu aqiiario mco. 

Joints l|-2 times longer than broad; oosporangia generally placed upon the ends of sLort 
branches but sometimes lateral, mostly carrying a terminal seta; resting spores irregulaiiy 
oval or ovate, somewhat indistinctly obliquely longitudinally and rather closely striate; aii- 
thcridia biccllular, furnished with a little stipe, their basal cell tumid in the middle, frequeutly 
contracted above. 

Remaihs. — This species appeared spontaneously during the latter part of tlio 
winter upon some large fresh-water algic which I was cultivating. It brandies 
irregularly and sometimes somewhat profusely, so as to have quite a busliy liabit. 
The antheridia appear to produce a single spermatozoon in the terminal cell ; at 
least as far as my observation has gone this is true. I think I have always found 
the distal cells of fertile plants emptied of their contents, as though they had fur- 
nished the androspores which had grown into the antheridia. This species is 
closely allied to B. gracilis, of Pringsheim, from which it differs in the position of 
the oogonia, in the relative breadth and length of the cell, and the number of colls 
composing the antheridia. 

Fig. 6 a, pi. 18, represents a filament of this species magnified 260 diameters; 
6 h, a male plant magnified 750 diameters. 

B. Canbyii, Wood. 

B. permagna ad .0.35" longa, sparse ramosa; articulis sterilibus diametro 2-8 plo longioribus: 
oogoniis lateralibus vel in raniulorum apicem positis, transverse enormiter ovalibus; oosporis, 
transverse enormiter ovalibus, pleruraque nonnihil triangularibus, oogonii lumen rcplentibus; 
sporoderniate crasso, baud costato, enormiter punctato ; antheridiis bicellularibus. 

Dlam.—Cc]\. steril. ^/jy^"_^J^/ = 00066—001. Spor. transv. tU/ = -00226. 

S)jn.—n. Canbyii, Wood, Proc. Amer. Philos. Society, 1869, p. U2. 

Hab.—\\\ aquis quietis, prope Ilibernia, Florida; (William Canby). 

B. very large, attaining a length of more than one-third an inch, sparsely branched ; sterile 
joints 2 to 8 times longer than broad ; oosporangia lateral or placed upon the ends of brandies, 
irregularly transversely oval ; oospores of a similar shape, often a little triangular, filling tlie 
cavity of the sporangium; spore coat thick, not costate but irregularly punctate. 

Eemarks. — It affords me great pleasure to dedicate this very handsome species 
to Mr. William Canby, by wliom it was collected in Florida, as an acknowledg- 
ment of favors received, and as a testimony of respect and high regard for him 



FRESH-WATER A L G uE OF THE UNITED STATES. 203 

personiiUy, and as bfing among the foremost students of American phanerogamic 
■botany. 

This species is more nearly allied to S. minor than to any other of the European 
I forms, but differs from it very essentially in size and habit. It is always, as I have 
'seen it, except in very young plants, sparsely and mostly dichotomously branched, 
and attains a very great length, at times probably exceeding the third of an incli. 
The spore is mostly sessile upon the distal ends of the cells of the filament ; in all 
such cases I have noticed that the cell upon which it was borne was divided in its 
■ middle by a partition into two cells. Not unfrequently the spore is raised upon a 
short branch. The male plants are attached to the female filaments generally in 
the neighborhood of the sporangium, to which they sometimes fasten themselves 
immediately. They are shortly stipitate, and composed of two cells. The mature 
spore is transversely oval, now and then slightly triangular, and is nearly of the 
; color of burnt sienna. Its .coat is thick, often slightly yellowish, and has on its 
: outer surface irregular punctations, looking like corrosions. These are not detach- 
able, except when the ruptured spore is more or less completely emptied of its 
contents. The sporangium closely invests the spore, and when the latter is matured 
undergoes a circular division, so that the top falls ofi" and allows the spore to escape. 
Fig. 6 c, pi. 16, represents a portion of a filament, magnified 260 diameters, 
j with a young sporangium and young male plants attached ; 6 b, represents a very 
' young plant, magnified 260 diameters. Fig. 6 a, was taken from a mature plant, 
and shows the mature spore. Fig. 6 e, shows in outline a sporangium and male 
plants attached ; whilst 6 d, was drawn from a sporangium which had perfected 
its spore and undergone the natural dehiscence. 

Family CHEOOLEPIDE^. 

Algae aercce, aureo-, aurantiaco- vel rubro-fusco-colorata3, siccatas soepe cante. Fila Tarie raraosa, 

eytioderraato crasso vel subcrasso, firmo, subcartilagiiieo pi'«dita, in pulvinulos raiiiutos vel iu stra- 

: turn tenue aut incrassato-tomentosum densissime aggregata vel implieata. Cytioplasnia oleosum vel 

' granulusum, aut rubellum, aureum, aut flavo-fuscum, intei-dum viride tinctuui, post mortem plerum- 

que expallescens. Propagatio fit zoogouidiis. 

^Ei-ial algae. Golden orange, or reddish fuscous, often grayish when dried. Filaments variously 

branched, furnished with a tliiek, or thiekish, subcartilagiuous cytioderm, densely aggregated into 

minute cushions, or a thin or tomentosely thickened stratum. C'ytioplasm granular or containing 

: oily particles, reddish-golden, or yellowish-fuscous, sometimes tinged with green; after death often 

colorless or nearly so. Propagation by zoospores. 

Remarks. — The plants of this family are so diff"erent from the others of the 
order, that it is a matter of considerable doubt whether or not they should be 
classified with them. They rarely possess distinct, well-pronounced chlorophyl, 

; and form mats or strata of some shade of reddish, grayish, or brownish, so that 
tlicy are very different in appearance from the other Confei-vacece. 

! I do not think their position can be certainly fixed until tlieir life-history has 

; been more fully developed. In assigning them this place I have simply followed 

I Prof. Rabenhorst. 



204 FRESH-WATER ALG^ OP THE UNITED STATES. 

Tlie only speciiiieiis (li;it liavc come to my notice are in a dried condition, and 
conscMjuently no possible opportunity has been afforded of studying the manner of 
reproduction. No one has as yet, at least to my knowledge, discovered any sexual 
reproduction in the family, but the method in which the zoospores are produced 
has been carefully studied, especially by Drs. Caspary [Reyenshurg Flora, iNoS) 
and liildebrand [Botanlsche Zeitung). The little motile bodies are not produced 
in the cells indiscriminately, but in certain ones set apart for the purpose, to whicli 
the name of zoosporangia is very applicable. These are large, globular, thick walled 
cells, which are generally provided with a protuberance at the top and marked by 
transverse wrinkles. They are most frequently situated upon the end of the filament 
or one of its branches, but are rarely placed in the middle of the thread, and still 
"more rarely the cell next below the zoosporangium elongates itself sideways and up- 
wards into a thread, so that the reproductive cell is left as a lateral one-celled brancli 
or process. When the zoosporangium is sufficiently matured the endocbrome 
breaks up into a number of minute masses, the future zoospores. Finally the 
crowning papilla of the mother-cell ruptures and allows the contents to escape as 
a well-formed vesicle, containing the perfected zoospores. It is said, however, that 
sometimes the vesicle is wanting, and the zoospores are discharged into the water. 
In the ordinary course, after a little while the vesicle lying in the water bursts 
and sets its motile contents free. The zoospores themselves are very small, accord- 
ing to Hildebrand, -^^-g— ^^^mm. in length, by -g-i^— g-f -g^mm. in breadth. In accord- 
ance with the same authority they are, when first discharged, cylindrical, but in a 
little while become flattened, and shaped like a flaxseed. They are biciliate and 
contain a large number of small, orange-colored particles. From thirty-two to 
sixty-four of them are formed in one zoosporangium, and neither light nor time of 
day appear to have any influence upon their birth. Hildebrand states that tlicir 
motile life lasts from eighteen to thirty-six hours, but according to Caspary, after 
continuing in motion for about an hour, they grow sluggish, sink, become globular, 
then elongate themselves and shortly undergoing transverse division, actively com- 
mence to form the new filament. 

Genus CHROOLEPUS, Ac. 

Fila distincte articulata, iiitrieata, cnormitcr ramosa. 
Filaments distinctly articulate, intricate, irregularly branched. 

C. aiireiiiii, (Linne.) Ktz. 

C. fills raraossimis, in stratum aureo-brunneum, ad duas trcs lincas crassum, caespitosum ct mollc 

intricatis vul in csespitulos aggregatis ; articulis enormibus, diamctro sesqui-, duplo ti'iplovc 

loiigiorilnis. 
Diam. — Max = .001". 

Sijn.—G. aareiim, (Linne.) Kutzing. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 311. 
Z/a6.— Little Falls, New York ; Godwinsville, New Jersey ; (Austin). Te.xas ; (Ravenel). 
Filaments very much branched, interwoven to form a yellowish-brown softish mat, two or 

three lines in thickness ; joints irregular, l^-S times longer than broad. 

Remarks.— I am indebted to Mr. Austin for specimens which are labelled 
" Forms dense yellow-brown cushions on rocks, at Little Falls, New York and 



FRESH-WATER ALG^ OF THE UNITED STATES. 205 

iGodwinsville, New Jersey." As dried, the plant is in extended, gray, felt-like 
Imasses. The walls of the articles as seen with the microscope are thick and 
irregular, and the joints themselves are also very irregular, the end ones being often 
swollen and rounded so as to give the branches a sort of bulbous termination. 

Among the Algte collected in Texas by Prof. Ravcncl, is a dried specimen CXo. 
100), labelled "On Bark, Houston, Texas," which I cannot separate from this 
species. It occurs in small tufts, which, as dried, arc of a very decided orange, 
and, no doubt, were still brighter during life. The articles are not so irregular as 
in Mr. Austin's specimens, but excepting in this and color when dried they agree 
^very well. Besides these I have several specimens from the same source, which 
are in extended mats and agree in all respects with their northern brethren. 

Our American form appears to attain a greater diameter in its individual fila- 
■ ments than does the European variety, but I know of no other character separating 
: it from tlie latter ; and consequently must consider them identical. The measure- 
ment given is an extreme one, .009" being commonly the limit. 

! 

I Genus BULBOTRICHIA, Kutz. 

Fila iiulistiucto articulatiX, aclirua, firnia, I'aiiiosa ; vaini iu apice intumcsccntes, sporangia con- 
stituentcs. 

' Filaments indistinctly articulate, translucent, firm, branched; the ends of tlie branches swollen so 
as to form sporangia. 

B. albida, Wood (sp. nov.). 

B. strato albido, coriaceo vel crustaeeo ; fills arete intcrtextis, enorniiter ramossissimis, coloris 
e.xpertibus; sporaugiis viridibus. 

Hab. — In muscis, Northern New Jersey ; (Austin.) 

Forming a white leathery or crustaceous stratum ; thread closely interwoven, irregularly and 
plentifully branched, colorless ; sporangia greenish. 

Remarlcs. — This curious little plant, which was sent me by Prof Austin, occurs in 
minute white patches growing on mosses at the base of stumps in woods. Some- 
times these are encrusted abundantly with the carbonate of lime, when they are 
hard and crustaceous. The sporangia appear to vary greatly in size ; sometimes 
they resemble very closely a single spore (probably their commencing stage). The 
bases of the branches are rarely, if ever, furnislicd with the bulbous swelling, given 
by Rabenhorst as a generic distinction, but such enlargements do occasionally 
occur in the course of the filaments and branches. The filaments are composed 
of a scries of cells, wliich are in places long, and have their end walls thin and not 
readily seen. 

Fig. 5, pi. 16, represents a part of a plant magnified 460 diameters. 

! Family Cn.ETOPHORACE.E. 

Algre aquatics vel palustres, rarius terrestres, plcruniqne nionoieas vel dioicae. Fila varia, sa>po 

dichotoine ramosa, baud raro fasciculatim ramnlosa, plcrumque in coespites vel pulvinulos cuniuhita, 

, in muco gelatinoso sublicjuido vel firnio nidulantia. Propagatio fit tnni oos])oris, tuni zoogonidiis. 

I Zoogonidia oriuntur aut singula aut geminis aut cytioplasmatis divisione 8-lC in quoquc sporangio. 



206 FRESII-WATER ALG^ OF TUE UNITED STATES. 

Aquatic, paludal, or rarely terrestrial algte, mostly raonaeeious or diajcious. Filaments various 
often dichotomously, but not rarely fasciculately branched, mostly aggregated into turl'y masses or 
little cushions, and generally surrounded by a firm or subliquid gelatinous mucus. Propagation hoih 
by zoos|)ores and resting .spores. Zoospores arising either singly or by the division of the cytiopla^u 
into 8-16 in each sporangium. 

Genus STIGEOCLONIUM. 

Fila arliculata, siniplicifcr raniosa; rami ranniliquc sparsi, rarius faseiculatini approximati, in 
apiccni acutum, .siBiio piliferum achroum attcuuati et picruuique longe prutcusi, sspius ramollis 
brevibus subulatis instructi. (R.) 

Filaments articulate, simply branched ; branches and branchlets sparse, rarely fasciculately ap- 
proximated, with their ends acute and frequently prolonged into an attenuate transparent seta or 
hair, and very often furnished with short subulate branches. 

Eevmrl-s. — Plants which are certainly referable to this genus are abuiulant in 
every place in which I have ever looked for fresh-water algae. I confess, how- 
ever, that although very much time has been given to their study, I have not been 
able to make out any distinct specific characters, nor any identifications from tlie 
diagnoses of M. Rabenhorst. In a certain spring northeast of the city, there grows 
one of these forms, which I have closely watched for several seasons. In tlie 
earlier state it appears at times to possess the characters of a young Cliaiophora 
(pi. 19, fig. 1), forming a small gelatinous base out of which the threads soon 
escape as they lengthen. It constituted a sort of mucoid layer adhering to the 
boards lining the stones witli waving masses of projecting filaments six or even 
eight inches in length. The filaments were mostly about -^-^-^i^" in diameter and 
much interlaced. 

The cells varied greatly in length, some being scarcely as long as broad, whilst 
others were eight or ten times longer. The short cells were generally densely 
filled with endochrome, whilst the long ones were nearly empty. The branches 
often ended abruptly, but were more frequently tipped with a long seta-like 
point. The method of branching is as varied as can be imagined, as is shown 
by fig. 4, pi. 16, and fig. 1, pi. 20, all taken from diff'ercnt plants of this species. 
I have frequently seen the production of zoospores, but no other method of repro- 
duction. In all cases a single motile body (fig. 4, pi. 16) was formed in each 
cell. These minute bodies are globular or pyriform, and within the cell exhibit 
no motion whatever. Their escape takes place very slowly through a lateral slit 
in the wall. No cause of the motion is visible, and during the passage the 
zoospore is often very much squeezed out of shape. According to Braun (Vcr- 
jungung), these zoospores possess a red eye-spot. I had not read his description 
at the time my observations were made, but did not notice any. The zoospores 
germinated in the usual way, elongating and growing into a cell with a transparent 
seta-like end, and finally undergoing repeated divisions to form the plant. 

M. Braun states that he has observed another process, in which the contents of 
a single cell undergoes a perpendicular division, so as to form four small zoospores, 
wliich escape from the cell in the same way as the larger one, and fiu'tlier says 
that he has never known these microgonidia to germinate. 



rUESU-WATER ALGJi OF THE UJSIITED STATES. 207 

Genus DEAPARNALDIA, Ag. 

Fila articulata ramosa, e cullulis magnis, maxime liyalinis, fascia chlorophyllosa latiuscula oniatis 
'semper sterilil)us foruiata, fasciculis peuicillato-raimilosissiinis, e oillulis iiiiiioi-ibus foi'tililjus coin- 
positis, plus minus dense obsessa. Articuli termiuales omuiuiu ramulurum iuanes achroi steriles, iu 
pilum Lyalinum plus minus elougati. 

; Filaments articulated, branched, formed of large cells which are chiefly hyaline, but furnished with 
a transverse chlorophyllous fascia, more or less densely clothed with penicillately raniul<ise fasciculi, 
formed of smaller fertile cells. Terminal articles of all the joints empty, IruuBpurcut, sterile, and 
elongate, iu a more or less hyaline hair. 

D. ^lomerata, (Vauch.) Ao. 

D. filis ramisque primariis aclirois vel subachrois, ad 0.001 4'l" crassis, articulis inferioribus 
diamctro ajqualibus vel paulo brevioribus, geniculis manifesto eoustrictis, fasciis chloropiiyl- 
losis angustis dilute viridibus; ramis iirimariis subrectangulo-patentibus, s»pe oppositis ; 
ramulorum fasciculis confertis, patcntibus, alteruantibus vel oppositis, dense ranicllosis, sub- 
ovalibus, obtusis. (R.) 

Sijn. — D glomcrala, (Yaucuer) Agarpii. Rabenhorst, Flora Europ. Algarum, Sect. III. 
p. 38. 

//a6.— Rhode Island ; (S. T. OIney) Thwaites. 

Filament and primary branches colorless or subcolorless, and reaching 0.0014T" in diameter, 
lower articles about as long or a little shorter than broad, manifestly constricted at the 
joints, chlorophyl fascia narrow, light green ; primary branches subrectangnlarly patent, 
often opposite ; fasciculi of branches crowded, patent, alternating, or opposite, densely 
ramellose, suboval, obtuse. 

Hemarks. — According to M. Thwaites the true Dr. ghmerata grows in Rhode 
Island, as he so identified specimens sent to liim by Mr. Oluey. These specimens 
iwere, however, in all probability dried, and if this was so, I confess not to attach- 
ing much weight to the identification. The i)/a^>ar«oWm, common near Philadelphia, 
is at once so like and yet so different from the description of D. (jlomerata, that I 
fam unable to fully satisfy myself whether it be a variety of the European species 
[or distinct from it. It differs very greatly iu the thickness of the stem and pri- 
'mary branches. I have given above P>'of Rabcuhorst's description of the Euro- 
pean variety, and now append one of th "; plant growing in this neighborhood. 

Tar. maxima. 
Dr. fills achrois, ad 004" crassis, articulis plerumqne dianietro duplo longioribus, in medio 
saepe valde tumidis ; ramis primariis achrois vel subachrois, oppositis vel alteruantibus vel 
ternatis, elongatis, dense ramell(jsis, cum ramulis lanceolatis ; ramulorum extremorum 
fasciculis dense ramelosis, ovjitis vel late lanceolatis, plerumque confertis ; ramulorum 
articulis inferiorilius plerumque dianietro (ad tsVs") subaequalibus, articulis superioriljiis 
diametro duplo aut triplo longioribus, plerumque piliferia. 

Hah. — Prope Philadelphia ; Wood. 

Filament transparent, attaining a diameter of 0.004", its nrtieles mostly twice as Inns- as 
broad, strongly swollen in the middle ; ])riinary branches colorless or subcolorless, o|q>osite, 
alternate or ternate, elongate, densely ramellose with the rarauli lanceolate ; fasciculi of 
extreme branches densely ramellose, ovate, or broadly lanceolate, mostly crowded, inferior 
articles of the branches mostly about as long as broad (uVfi"); s°P<^'"'°'' 8''*'<-"les two to three 
times as long, mostly pilifcrous. 



208 FRESn-WATEll A L G .E OF TUE UNITED STATES. 

Eemarks. In this form there are almost always numerous little clusters of branch- 
lets, "■ro\vin<'- iuiniediately from the main stem or large branches; such clusters are 
more ri<nd, more open, more broadly ovate, and less markedly piliferous than tho 
others. 

D. pliiinosa, (Vaucher) Aqardh. 

D. filis raiuisque primariis byalinis, plcnimqne 5V'" = O-OOITO" crassis; articulis diamotro 
sequalibus vel dimidio brevioribus, rarius paulo lougioribus, geuiculis vix aut modice cun- 
strictis, fasciis chloropliyllosis aiigustis Isele viridibus ; articulis infcrioribus ramulorum dia- 
metro ( lis'" — 35s'") a^qualibus vol subduplo lougioribus, psene torulosis, superioribus cylin- 
dricis ad ttI^"' attenualis, diamctro duple triplo-quiutuplo lougioribus, plerumque nou pili- 
feris ; ramulorum fasciculis dense 7-amellosis, elongatis, acute lanceolatis, erecto-subap- 
pressi'.s. (H. ) 

Sijn. Dr. jjlumosa, (Vaucuer) Aoakdu. Rabenhorst, Flora Europ. Algarum, Sect. III. 

p. 382. 

JIab. — In rivulis et aquis quictia 

Filament and primary branches hyaline, mostly g^^j'" = 0.001Y9" in diameter; articles as long as 
broad or one-half shorter, rarely a little longer, scarcely or slightly constricted at the joiuts, 
chloropliyl fascia bright green, narrow ; lower articles of the branches about as long as 
broad (155"' — 553'") or nearly twice as long, somewhat torulose, the upper ones cylindrical, 
as small as 553'", two to five times longer than broad, mostly not piliferous ; fascicles of 
bi'anchcs denst'b/ branched, elongate, acutely lanceolate, actually subappressed. 

Remarks. — 1 have found a iJra^x/rwaZJta frequently, which I believe to represent 
the European D. plumosa. As I have preserved, however, no specimens or 
descriptions, I have simply copied the description of Prof. Rabenhorst. 

D. Billing;!!)!!, Wood. 

D. valde gelatinosa ; filis et ramis primariis aehrois ad ^%%ts" crassis, sparsissime ramosis, 
articulis diametro 2-6 plo lougioribus, srepe medio valde tumidis ; fasciis chlorophyllis dilute 
viridibus, siepe nullis aut subnullis ; ramulorum fasciculis distantibus, late ovalibus vel late 
triangularibus, alternantibus vel oppositis vel triplice verticellatis, sparse ramosis, patentissi- 
mis ; ramulis pilis longissimis robustis terminalibus instructis ; oosporis globosis, monilifurme 
conjuQctis ; sporodermate crasso. 

Sijn.—D. Billingsii, Wood, Proc. Am. Philos. Soc, 1869, p. 143. 

Hab. — In aquis quietis, prope Philadelphia. 

Frond very gelatinous, filament and primary branches attaining a diameter of ^J^", very 
sparsely branched, their articles 2-6 times longer than broad, often very much swollen in 
the middle ; chlorophyl band light green, frequently almost or entirely wanting ; fascicles 
of branches distant, broadly oval or triangular, alternate, opposite, or in whorls of three, 
very open; ultimate branehlets terminating in a long, robust, hyaline hair; resting spores 
globose, with thick walls, arranged in long moniliform sometimes branched filaments. 

Remarhs. — I found this plant about the middle of March, 1869, floating on the 
surface of a little pool in the woods near Chelten Hills, a few miles north of 
Philadelphia. To the naked eye it appears as a gelatinous mass, resembling a 
Tetrafipora, but when closely examined this translucent jelly is seen to be filled 
with rather distant greenish points, which are the little clusters of branches. The 
largest specimens I have seen had attained a length of nearly two inches. The 
filaments are very transparent and have the branches placed at long intervals. 



FRESH-WATEK A L G .E 1' THE U i\ 1 T E D STATES. 209 

The ultimate branch groups are ovate or oval, and are remarkable for their open- 
ness, the branchlets being few in number and widely separated. Most of the ulti- 
mate branchlets are prolonged into a remarkably strong long hair. 

The cells of the main filaments are beautifully transparent, and are sometimes 
cylindrical but more generally are barrel-shaped. Both secondary and primary 
branches are often arranged singly, sometimes in pairs, not unfrequently in threes. 
When placed between two plates of glass and examined closely by the unaided 
eye, this species is readily distinguishable from our other Draj)anialdia, by its fas- 
ciculi of branches being so widely separated as to be not at all confused Avith one 
another. 

I have a single specimen which I believe to be in fruit. The resting spores 
(fig. 6, pi. 14) are in long branched chains. They are more or less globose, with 
a very thick outer transparent wall, and an inner green endochrome, which very 
probably becomes brownish at maturity. Except when they are branched, these 
scries of spores remind one very strongly of the filaments of some nostocs. 

I dedicate this very beautiful species to Dr. J. S. Billings, U.S.A., to whom I 
am under the greatest obligations for aid in the prosecution of this research, and 
whom I have ever found to imite the greatest scientific liberality with a strong en- 
thusiasm for and able prosecution of the study of these lower vegetable forms. 

Since describing this species I have received the Microscopical Journal for 1869, 
containing Dr. Hicks's paper upon D. crudata. The original description in the 
Linupean Transactions had escaped my notice. D. cruciata and D. BilUngsil are 
exceedingly closely related, yet if Dr. Hicks's description and figures be accurate 
they are probably distinct. Thus in the last species the ramuli are not placed at 
right angles to the main filament, nor are they ever in fours, both of which are 
given as characters of D. cruciata. They are, on the contrary, in D. BiUinfjsil at 
various angles, and commonly arise singly, but not unfrequently in pairs, and very 
rarely in threes. It is worthy of remark, on the other hand, that the figures of 
Dr. H. do not entirely agree with his description, as in no case are there more than 
two and frequently but a single branch at one place. The cells of the main fila- 
ment are also more barrel-shaped in our species than one would infer to be the 
case with D. cruciata. 

After aU, however, I think it very possible that both forms belong to the one 
species. 

Fig. 6, pi. 14, represents a small portion of the frond with fertile branches mag- 
nified 460 diameters. 

Genus CH^TOPHORA, Schrank. 

Fila articulata ramique primarii radiatini dispositi, e cellulis vegetativis elongatis, fascia cliloro- 
phjilosa in morem Draparnaldite et Stigeoclonii oruatjs compositi, sursura in raniulos mmiero- 
sissimos, brevius articulates, articulis extremis attenuatis ssepe inanibus non aut vix piliferis iii- 
Btructos, fasciculatos plus minus dense congestos divisi, niassa gelatinosa firraa, coriacea vel dura 
involuti, thallum globosum vol subglobosum aut plane expansum varie lobatum et fissum cou- 
stituentes. (R.) 

Filaments articulated, with the primary branches radiately disposed, composed of elongated vege- 
tative cells, ornamented with a chloropliyllous fascia like a Draparnaldia or Stigeoclonium, distally 
27 September, 1872. 



210 FRESH-WATER ALG^E OF TUE UKITBD STATES. 

resolved into very uumeroas fasciculate, more or less densely congested branches, with shorter 
joints, their end joints alternate, ol'ten empty, eitlier not or scarcely piliferous; surrounded by a firm 
coriaceous or hard jelly, so as to form a globose, subglobose, or expanded thallus. 

Remarhs. — I have never seen the production of the zoospores in this genus, but 
they are said to arise one in a cell, and to escape by a sort of lateral splitting of 
the wall, 

C. elegant, (Ruth) Agardii. 

Ch. thallo globoso vel subgloboso, pisi vel ccrasi magnitudine, dilute vel saturate viridi, nitido, 
superficie hcvi vel quasi tubereulata, elastice niolli, nonnuncjuam indurato ; fasciculorum 
ranuilis laxis vel confertis, articulis extremis brcvi-cuspidatis, sajpe piliferis. 

Syn, — C. elecjana, (Rotu) Agardii. Rabenuorst, Flora Europ. Algarum, Sect. III. p. 384. 

Hah. — United States. 

Thallus globose or suljglobose, of the size of a pea or cherry, light green, with the surface 
smooth or quasituberculate, elastic but soft, sometimes indurated ; branches of the fasciculi 
la.x or crowded ; end articles shortly cuspidate, often piliferous. 

Remarks. — One of the commonest of our fresh-water algaj is a plant belonging 
to this genus, whicli I think is probably the C elegans of Roth. I am, how- 
ever, unable to discover any characters separating C. pisiformis, G . ehgans, and 
perhaps C. tuhcrcuJosa, and hardly know by which of the three names our Ameri- 
can form should be known. Our plant grows generally in shaded pools, springs, 
and ditches in great abundance, adhering as little translucent balls to grasses, 
leaves, twigs, or anything that may be in the water. The size of the frond varies 
from the young one, not so large as a pin's head, to the old matured one, which 
may be nearly an inch in diameter. The color also varies greatly. It is always 
some shade of a pure green. The surface is mostly smooth, but sometimes it is 
so puckered up as to be a mass of large flat tubercles. It is these forms that I 
suppose to represent C. tuberculosa. The thallus is generally elastic, but at the 
same time soft, so that although readily compressed and pushed out of shape, it is 
entirely mashed with some difficulty, especially as, owing to its slipperiucss, it 
constantly escapes from the grasp. 

In regard to the individual filaments, the method of their branching and the 
proportionate length and breadth of the cells vary very much in different in- 
dividuals and probably at different ages of the same individual. 

Fig. 5, pi. 6, represents rather indifferently weU a young individual of this 
species. 

C. endiTiaDFolia, (Roxn) Ag. 

Cli. thallo lineari, subplano, semipollicari vel pollicari, nonnunqnara valde clongato, la;te vel 
obscure viridi, dichotoroo-subreticujatum-laciaiato (nonnunquara habitu Biccise Jluitarttis) ; 
fills ramisque primariis plerumque achrois, passim viridi-zonatis, parallelis; ramulorura fasei- 
culis lateralibus, plus minus densis, divaricato-patentibus ; articulis plus minus tuniidis, 
diametro seqnalibus vel subaequalibus ; geniculis constrictis ; cytioplasmate granuloso 
effuso. (R.) Species mihi ignota. 

Srjn. — C. endivixfolia, (Roth) Agardii. Rabenhorst, Flora Europ. Algarum, Sect. III. 
p. 383. 



FRESU-WATER ALG^ OF THE UNITED STATES. 211 

Hah. — South Carolina; (Ravenel) Wood. Rhode Island; (S. T. Oluoy) Thwaites. 

Thallus linear, flattish, of half to a whole tlmmb's breadth, sometimes greatly elongate, bright 
or obscure green, dicliotoniously subreticulately laciniate (sometimes with the habit of 
Riccia Jluitans) ; filament and primary branches mostly colorless, sometimes zoned with green, 
parallel ; lateral fasciculi of branches more or less dense, divaricately patent ; joints more or 
less tumid, diameter equal or subequal ; joints constricted ; cytioplasm effused granulate. 

Remarls. — I have never seen a living or well-preserved specimen of this species, 
and have, therefore, here simply copied the description of Prof. Rabenhorst. Prof. 
Ilavenel has sent to me dried algce labelled, and I think correctly, as belonging to 
this species, bnt their condition did not allow any scientific study of them. 

Genus PILINIA, Ktz. 

Fila articulata, erecta, simplicia vel dichotome ramosa, basi aCB.xa, in stratum cnistaccum sub- 
spongiosum, fragile aggregata. Propagatio adhuc ignota. 

Filaments articulate, erect, dichotomously branched, C.xcd by the base, aggregated into a some- 
what spongy fragile crustaceous stratum. Method of propagation unknown. 

P. diltitn, Wood, (sp. nov.) 

P. rupicola, in strato cano-viridi disposita ; fills ramisque fasciculatis, apice obtusis ; articulis 
diametro 1^ plo-3j plo longioribus. 

Diam. — Max. 0.0004". 

Eab. — In fontibus maximis, prope Bellefonte, Centre County, Pennsylvania ; Wood. 

Growing on stones and rocks, forming a grayish-green stratum ; filaments and branches fasci- 
culate, with the apices obtuse ; joints l-j-3|- times longer than broad. 

Remarhs. — Near Bellefonte, Centre County, Pennsylvania, there issues from the 
lim(>stone rocks the largest spring I have ever seen, giving rise to a creek-like tor- 
rent, which supplies the city with water, and passes on scarcely diminished in 
Volume. In this spring grows the curious algce under consideration, forming a 
somewhat lubricous crustaceous and stony stratum on the stones and rocks in the 
basin. This stratum is of a grayish-green color, and is quite friable, breaking in 
the direction of the filaments with the greatest possible readiness. "When placed 
under the microscope it is seen to be composed of filaments whose course is a 
direct one from the under to the upper surface. They are apparently rigid, pre- 
serving their courses, and not being intermatted. They are composed of cylindri- 
-jal, confervoid cells, and are dichotomously branched, and yet wlien viewed as 
a whole the filament and its brandies form a sort of fasciculus. The basal cell 
or cells appear to be globular. When I collected this plant I was forced by cir- 
cumstances to put the specimens in carbolic-acid water for future study, and, 
therefore, I have had no opportunity of studying their method of reproduction. 
I am not altogether satisfied in referring this plant to the PlUnia, and yet all the 
most important of the characters given by Rabenhorst are preserved by it. It 
certainly, however, dificrs very greatly from P. rimosa, Ktz. 

Genus APHANOCH^TE, Braun. 
Fila distinete articulata, prostrata, repentia, interdum in stratum irrcgulare plus minusve concreta; 
ramulis repentibus vel adscendentibus ; cellulis chlorophyllaceis, apice vel dorso setigeris. Propa- 
gatio zoogonidiis. 



212 FRESH-WATER A L G .E OF THE UNITED STATES. 

Threads distinctly articulate, prostrate, creeping, sometimes more or less concreted into an irregular 
stratum ; branches creeping or ascending ; cblorophyllous cells with the dorsum or apex setigerous. 
Propagation by zoospores. 

Re^narJ^. —Ses.ual reproduction has not as yet been discovered in this genus. 
According to Dr. Braun (Veijiing., Transhxtion of the Ray Society, p. 184, &c.) 
two zoospores are generally formed in a cell by a division of its contents parallel 
to the septa, but occasionally this division not taking place, the cell contents are 
resolved into a single zoospore. The zoospores themselves are nearly globular, 
biciliate, and unprovided with any reddish eye-spot. 

A. repens, Braun. 

A. fills procumbentibus pleruraque siraplicibus ; articnlis eylindricis aut tumidis, diametro snb- 
sequalibus ad 1-2 plo longioribus ; setis e cellularum dorso egressis, plerumque singulis sed in- 
terdum geminis, intcrdum nullis. 

X>iam.— Artie, jscijij"— Tsuiis" = .00025— .0004". 

Syn. — A. repens, Braun. Rabenhorst, Flora. Europ Algarum, Sect. Ill p. 391. 

Eah. — In (Edogoniis, prope Philadelphia ; Wood. 

Filaments procumbent, mostly simple; articles cylindrical or tumid, from as long as broad to 
twice as long; seta arising from the back of the cells, generally single, sometimes geminate, 
sometimes wanting. 

Remarks. — The specimens from which the above description was drawn up, were 
found growing on the filaments of CEdogoniam mirahile. Wood. They were re- 
markable for the rarity with which they were branched, for in but two or three 
cases out of a great number, were any branches detected. The articles were fre- 
quently twice as long as broad. In both these particulars the plant diff'ers from 
the typical European A. repens, but the descriptions of that form are so short and 
imperfect that I have preferred retaining the name for the American plant. 

Fig. 5, pi. 14, represents an ordinarily formed specimen magnified 460 diameters.' 
It had been kept for some time in weak carbolic-acid solution, and although the 
green of the chlorophyll was perfectly preserved, the stumps only of the setae 
were visible. How long the perfect setse are I canncJt at present say, not having 
made any notes on the fresh specimens. 

Genus COLEOCH^TE, Breb. (1844). 

Fila articulata ramosa aut in pulvinulum conjuncta aut in thallum planum subdisciforraem 
parenchymaticum concreta; articuli oblongi, antice plus minus dilatati, angulo superiori vel dorso 
ssepe in setam basi vaginatam producti. Propagatio fit turn oosporis foecundatione sexuali ortis, 
turn zoogonidiis. Zoogonidia in quaque cellula fructifera unica, forma subglobosa vel late ovalia, 
polo antico ciliis vibratoriis binis instructa. (R.) 

Filaments articulated, branched, either conjoined into a little cumulated mass or parenchematously 
concreted into a plain subdisci&rm tJiallus ; articles oblong anteriorly, more or less dilated, often 
furnished with a long seta on their dorsum or superior angle. Propagation occurring by means of 
oospores, formed by sexual organs or by zoospores. Zoospores subglobost or broadly oval, formed 
singly in the fertile cell, furnished at their anterior pole with vibratile cilia. 

Remarks. — I have seen a large number of specimens of, as I believe, two distinct 
species of this genus, but never having found any fruiting fronds, have not been 



FRESH-WATER ALG.E OF THE UNITED STATES. 213 

able to identify them. One of tlie forms grows in this immediate locality, and is very 
probably C. sciitdfa, Brel). The other was collected in Northern Michigan. It is 
characterized by its frond never being disciform, although composed of a single 
plane of cells parenchematously united. 

Class RIIODOPHYCE^. 

AlgfB multicelliilares, vegetatione teruiinalis noii limitata pra3dita3 
plenimque trioica^. 

Tliallus e cellularum seriebus vel stratis singulis vel pluribus compo- 
situs, aut nudus aut e cellularum stiato corticatus, forma quam maxime 
varius; membranaceus (Porpliyridium), crustaceus (Ilildenbrandtia), 
filamentosus et verticillatim ramosus (Batrachospermum, Thorca), fascii- 
formis (Bangia), foliaceus, etc. 

Cytioplasma plerumque rhodophyllo (Cohn), rarius phycho-chromate 
coloratum, granula amyloidea vel amylacea et sa3pe guttulas oleosas 
includens. 

Propagationis organa triplicis indolis, saepissime in plantas distinctas 
disposita. 

1. Orr/ana onascvla vel anfJwri'da e fasciculis cellurarum plerumque mo- 
niliformibus ramosis, denique in spermatozoidea vel spermatia fcecun- 
dantia {Sporidia I. Ag.) oblonga vel ovalia, achrod, immobilia dissolutis 
formata. 

2. Organa fcminea vel cysfocarjna Ktz. e soris nonnunquam monilifor- 
mibus formata, qui e placenta saepissime corticali evolvuntur, nudi vel 
cuticula mucilaginosa vel involucro inclusi, denique sporas [polijsporas) 
numerosas immobiles mox germinantes emittunt. Foecundatur cysto- 
carpiinn statu primordial! ope organi piliformis [trlcliogijne Thuret et 
Bornet) quorum spermatia copulantur. 

3. Tctrasporangia e cellula corticali unica valde intumescente formata, 
divisione utriculi primordialis cruciata quadrilocularia; in quoque loculo 
{ceUulis secundariis, soroi'iis) spora unica {tctrasporxi) se format, quae sine 
foecundatione germinat. (R.) 

Multicellular alga% mostly tritecious, furnished with unlimited not ter- 
minal vegetation. 

Thallus composed of cells in rows or in a simple or multiple stratum, 
either bare or provided with cortical strata of cells, exceedingly various 
in form; membianaceous (Pophyridium), crustaceous (Hildenbrandtia), 
iilamentous and verticillately branched (Batrachospermum, Thorca), 
fasciate (Bangia), foliaceous, &c. 

Cytioplasm mostly rhodophyllous, rarely phycochromatously colored, 
including amyloid granules or starch and frecpiently oil drops. 

Propagation by means of three immotile organs, generally placed 
upon distinct plants. 

1. Antlieridia composed of mostly moniliformly branched fascicles of 



2U FRESH-WATER ALG^ OF THE UNITED STATES. 

cells, Avliieh dissolve into oblong, oval, transparent immotile spermato- 
zoids {Sporidia Ag.). 

2. Cystocmyia Ktz., or PistilUdia, formed of somewhat moniliform sori, 
which are evolved from a generally cortical placenta, and are naked or 
surrounded by a mucilaginous cuticle or involucre, and finally emit 
numerous immotile spores {polyspores) , which quickly germinate. The 
fecundation of the cystocarpia occurs in their primordial state by con- 
tact of the spermatia with a piliform organ known as tricJiogonia. 

3. Tetrasporangia formed of single, greatly swollen cortical cells, be- 
coming cruciately quadrilocular by division of the primordial utricle ; in 
each loculus {secundary or sister cells) a single spore [fetrasjwrc) forms, 
which germinates without fecundation. 

K^MiLY PORPHYRACE^. 

Thallus mucoso-merabranaceus, foliaceus vel fSlamcntosus, e cellularuni soriebus vel strato unico 
formatiis, ])lenimquc purpurasceus, valde lubriciis. 

Vegetatio fit cellularum divisione in duas vel omnes directiones repetita. 

Propagatio fit tetrasporis. Cystocarpia noudum observata. 

Tliallus mucous-membranous, foliaceous or filamentous, formed of cells in scries or in a single stra- 
tum, mostly purplish, very slippery. 

Growth taking place by repeated division of the cells in two or all directions. 

Propagation by means of tetraspores. Cystocarps not yet observed. 

Remarks. — The only species of this family as yet observed in North America 
can hardly be said to have a definite thallus. They are rather multitudes of cells 
lieaped together and closely attached to one another into a shapeless expanded 
mass. 

Genus PORPHRYDIUM, Naeg. a849). 

Thallus mucoso-merabranaceus, suberustaeeus, longo lateque expansus, e cellulis globosis vel 
polyedricis compositus. Propagatio adliuc ignota. 

Thallus mucous-membranous, subcrustaceous, long and widely expanded, composed of globose or 
polyhedral cells. Propagation unknown. 

P. criicBilnin, (Ag.) Naeq. 

P. thallo saturate purpuro-sanguineo, lubrico; celluli.s anguloso-rotundatis. (R.) 
Diaw.— 0.00027"— 0.00035". (R.) 
. Hah. — New York. 

Syn. — P. cruentum, (Agard.) Naegel. Rabenhorst, Flora Enrop. Algarum, Sect. III. 
p. 397. 

Thallus deep crimson purple, slippery ; cells angled and rounded. 

Remarls. — The only specimen I have seen of this species was a little spock, 
adherent to a bone picked up on Governor's Island, in New York Harbor. It is 
very probable that it was a recent arrival, brought over, perchance, by some emi- 
grant. For it I am indebted to Dr. Billings, U. S. A. The description and 



FRESH-WATER A L G .E OF THE UNITED STATES. 215 

measurements given above are copied from Prof. Rabeuhorst's work. My specimen 
agrees well with it. 

P. luaj^nijiciiiu, Wood. 

P. cellulis globosis vel subglobosis, sa3pe nonnihil polygonis ct in niassam indefinite cxpansara 

coiifluentibus ; cytioplasmate purpurco, granulato; cytiodermate crasso, Laud lamelloso. 
Z)iam.— Cell cum. tegum. 5,8^^—5,'/^^. Tegum. 3^1 ^^—^^J^^. 

Spi. — P. magnificum, Wood, Proc. Am. Pbilos. Soc, 1869, p. 144. 

Hah. — lu terra humida, Texas ; Prof. Ravenel. 

Cells globose or subglobose, often somewhat polygonal and conjoined into an indefinite mass ; 
eudochrome purple, granulate ; cell wall thick, not laminate. 

Remarhs. — This species, which was collected in Texas by Prof. Ravenel, growing, 
I believe, on wet sand, is very distinct from the European plant, differing essenti- 
ally in size and form. In some instances the cells have a greenish tint, but this is 
possibly owing to immaturity, as such cells seem smaller than others. The whole 
mass to the eye has a very rosy purple tint, and although under the microscope it 
appears much darker and more purple, yet it often retains some of the roseate hue. 
At the edges of the masses the dark-reddish color often gives way to a very decided 
greenish tint, presenting an appearance which is very well represented in the 
drawing of the preceding species, in M. Mengehini's Mono(jrapMa Nostocldnearum 
Italicarum, &c., Memoire della Reale Academia delle Sclenze di Torrino. The cells 
are often closely united by their thick coats into a very coherent mass. With the 
ordinary cells I have occasionally seen other larger ones, of an orange color, Avith 
very thick walls. Are these resting spores ? 

Fig. , pi. 19, represents single cells of this plant magnified 750 diameters. 

Family CHANTRANSIACE^. 

Thallus filamcntosns. Fila articulata, e cellularum serie nnica forraata, ramosa, stricta, nuda, 
raro passim corticata, rami superne fasciculatim ramellosi ; articuli cylindrici. Cytiodcrma, homo- 
geneum, maxime hyaliuum. Cytioplasma homogeneum, plerumque purpurascens. Propagatio fit 
polysporis immobilibus, ovalibus, in ramellorum apice vel lateraliter formatis, corymboso aggrcgati.s. 
Antheridia subglobosa, terminalia. Tetraspora raro observatce. 

Thallus filamentous. Threads articulate, formed of a single series of cells, branched, straight, 
bare, rarely here and there articulate ; branches above fasciculately branched ; joints cylindrical 
Cytioderm homogeneous, mostly hyaline, cytioplasm homogeneous, mostly ijurplisli. Propagation 
by immovable oval polyspores formed on the ends of the branches or laterally and corymbosely 
aggregate. Antheridia subglobose terminal. Tetraspores rarely observed. 

Genus CHANTRANSIA, Feies. 

Familiie genus unicum. 

The only genus of the family. 

C expansa, Wood, 

C. caespitosa, in lapide stratum saturate violaceo-pnrpureum lubricum, indefinite expansnm, 

formans ; fills purpureis, modice raiuosis, fere 2 lincas longis ct ramis iilerumciue striclis ct 
rectis, soepe elongatis; ramulis fertilibus brevibus, asccndentibus; articulis diametro 3-8 plo 



216 FRESII-WATER ALGJi OF THE UNITED STATES. 

longioribus, extremis obtusis ; polysporia in rauiellis lateralibus racemosim et eonfertiin 
cuiuulatis, ovalibus vel iioiiiiiliil obovatis. 

IHam.—Vil 5iV(j" = -0004". Spor. transv. ^^\^" = .00027 long. s^Vir = .0004". 

Syn. C. expansa, Wood, Prodomus, Proc. Amor. Philos. Soc, 18G9. 

Hal. — In rivulis, prope Philadelphia. 

CiEspitose, forming a dark purple, slippery, indefinite stratum on stones ; filaments purple, 
moderately branched, almost 2 lines long, together with the branches strict and straight, 
often elongate ; infertile branches sometimes very few, sometimes very numerous ; fertile 
branches short, ascending; joints 3-8 times as long as their diameter, the final 'articles ob- 
tusely rounded : polyspores racemose, crowded on the fertile branches, oval or somewhat 
ovate. 

Rimarlcs. —This species was found growing in a running stream, forming a felty 
slimy coating upon large stones, looking so much like a stratum of OsciUaioria, 
that when I gathered it I thought it probably was a representative of that genus. 
The stratum, however, when carefully examined, is seen to be made up of an in- 
definite number of minute, very closely approximate tufts. The color was a dark 
dull purple. The plant may possibly be the Chantransia violacea, of Kijtzing, 
which it resembles in many particulars, but it is nearly twice as long and the fila- 
ments are considerably thicker. Its habit of growth also seems to be essentially 
difi'erent from that of tlie European plant, so that I have finally decided to con- 
sider it a distinct species. The exact locality of its growth is in a thickly-shaded 
portion of the stream that runs along the North Pennsylvania Railroad, just this 
side of Chelten Hills. 

Fig. 2, pi. 19, represents a filament magnified 125 diameters; fig. 2 a, a part of 
a fertile branch magnified 460 diameters. 

C. luacrospora. Wood (sp. nov.). 

C. casspitosa, subpollicaris, olivaceo-grisea vel saturate violaceo-purpurea; fills ramosis et 
ramis plerumque strictis et rectis, et elongatis; articulis diametro 3-8 plo longioribus; ramu- 
lis fertilibus brevissimis ; polysporis singulis vol gemiuis, sparsis, sajpe distantibus, globosis, 
interdum nounihil ovalibus. 

Diam.—Fil plerumque .0008— max. .001. Polysp. .0009. 

Hab. — South Carolina ; (Ravenel). 

Csespitose, about an inch long, olive-gray to deep-violet purple ; filaments a good deal branched, 
with the branches mostly straight and elongated ; fertile branches very short ; articles 3-8 
times longer than broad ; spores single or geminate, few, often distant, globose, or sometimes 
slightly oval. 

Remarks. — I am indebted to Prof Ravenel for specimens of this species pre- 
served in carbolic-acid Avater. They are labelled, " Dull olive green, growing 
against wooden boards in spring, Nov. 5, 1869. Aiken, South Carolina." The 
most of the mass is of the color noted, or at least approaches it, but a portion is 
almost blackish purple. The species is a very distinct one, characterized by 
the larger diameter of its articles and spores, by the paucity and shape of the 
latter, as well as by its variance in coloration. In some old specimens the cell 
wall is distinctly lamellate. I have only seen fruit on the purple filaments. The 



FRESU WATER ALG^ OF THE UNITED STATES 217 

spores, apparently not mature, liave a greenish-brownish tint. I have also received 
from Prof. Ravenel dried algte, which, apparently, are the same species as those 
from which this description has been written, but which, not being in fruit, cannot 
be absolutely identified. They are, as dried, of a bright bluish-green, and attain 
the length of an inch and a half or more. 

Fig. 3, pi. 19, represents a part of a branch of this plant magnified 460 
diameters. 

Family BATRACHOSPERAIACE^. 

Algae dioics. • Thallus filamentosus, articulatus, ramosus, aut violaceus, violaceo-purpurcus 
vel caeruleo-viridis, muco uiatricali involutus ; fills primariis ramisque e cellularum serie unica 
central! primaria et seriebus numerosis secundariis parallelis contiuuis vel interruptis externis cora- 
positis, aut ramulorum fasciculis verticillatis globoso vel subgloboso dense conglobatis a;quali 
distantia obsitis, aut ramulis simplicibus vel dichotomis dense ubique vestitis. Vcgetatio 
tcrminalis. 

Disecious algte. Thallus filamentous, articulate, branched, violet or violet-purple or bluish-green, 
covered with mucons; primary filament and branches composed of a single central series of cells, 
and numerous external, parallel, continuous, or interrupted secondary series; either furnished with 
globosely or subglobosely densely conglobate, equally distant verticillate fasciculi of branches, or 
everywhere densely covered with simple or dichotomous branches. Vegetation terminal. 

Genus BATRACHOSPERMUM, Roth, 1800. 

Thallus filamentosus, moniliformis, e cellularum serie unica meduUari, accessoriis parallelis corti- 
cata conjposltis, ramulorum fasciculis subgloboso-conglobatis obsessns. 

Thallus moniliform, composed of a simple series of medullary cells and cortical accessory parallel 
series, clothed with subglobosely conglobate fasciculi of branches. 

Remarha. — The Batruclioapcryns are amongst the very largest of the fresh-water 
algae, forming gelatinous branched masses from a few inches to even more than a 
foot in length. The fronds are very freely and very irregularly branched, and are 
evidently composed throughout, i. e., both in regard to the main filaments and the 
branches, of two portions, a central axis and much more slender short transverse 
branchlets, which often end in a long hair, and are arranged more or less exclu- 
sively in groups, so as to form, to the naked eye, at regular intervals, little balls or 
knots, the whole plant thus presenting a sort of moniliform aspect. Sometimes, 
however, these glomeruli are placed so closely together, and grow so large that 
they become confluent, and the branch to which they are attached appears as a 
uniform thick and very gelatinous cylindrical cord. 

The axis both of the stem and the branches of a BatracTiosperm consist ori- 
ginally of but a single series of cells. The development of new cells takes place 
in two ways, the one of which results simply in an increase in the length of the 
axis, the other in the production of branches. The first of these is the ordinary 
process of cell multiplication by division, and occurs only in the end cells, so that 
no new cells are ever formed in the central portions of the axis, which increases 
in length solely by the addition of new cells at the end, and by longitudinal growth 
of the old ones. The first step towards the formation of a branch is the produc- 
tion of a little pouch-like protrusion near the upper end of a cell. This increases 

28 September, 1873. 



218 FRESH- WATER A L G .E OF THE U ^' I T E D STATES. 

in size and soon being cut off from the parent-cell by a partition, forms a complete 
cell, the starting point of a new branch. If this cell has been formed alone, with- 
out companions, it is the beginning of a main branch, and divides after a very brief 
period transversely, the new cell thus arising in a little while itself divides, and so 
tlic process goes on until the axis of a large branch, similar to the parent axis is 
developed, and which, like the parent axis, increases only by a division of the end 
cell and longitudinal growth of the central ones. 

When a glomerulus is to be formed instead of a single pouch, a number appear 
around the upper end of a cell, and become cut off as new cells. Each of these 
is the starting point of a new row of cells, which not only grows, at least up to 
a certain point, by the division of the end cells, but which also gives rise to a 
large number of branches in a way precisely similar to that in which it itself was 
developed, i. e., by the formation of little lateral protrusions, &c. These secondary 
branches have a life-history similar to that of the branch whose offspring they are. 
They continually give origin to new branchlets in the way just described, which 
branchlets themselves produce fresh offshoots, and so it goes on until at last the 
forest of branchlets making up the dense glomerulus is evolved. It has been 
just stated that the original axis of the main filament or any branch is composed 
of a single simple series of large cells ; when an old Batrachosjjerm is placed under 
the microscope, however, it is at once evident that the axis is in reality formed of 
such a series lying in the centre and covered over and often hidden by numerous 
longitudinal series of smaller cells. These latter do not belong to the original 
axis, but are secondary additions to it, and arise in this Avay. Whilst a glomerulus 
is being developed certain of the basal cells of its constituent branches give origin 
in the usual manner to branchlets, which, instead of growing outward to form a 
part of the glomerulus, grow upwards or downwards, closely hugging and finally 
enveloping the original axis, and at last forming a distinct cortical layer to it. 

Very frequently in well-advanced Batrachospenns there will be seen scattered 
among the glomerulus large, round, firm, dense balls composed of a great number of 
small closely-attached cells. These are the reproductive bodies. According to H. 
Graf zu Solms-Laubach {Botanische Zeltung, 1867, p. 161), they are the result of 
sexual reproduction, and are developed from aniheridia and trichogonia (female 
organs) in the following manner : — 

The antheridia are small roundish cells full of a colorless protoplasm, which is 
remarkable for the very numerous bright granules which it contains. They occur 
either scattered or in groups, and are placed upon the upper ends of peculiar ovate 
cells, also filled with a colorless protoplasm. Most frequently there is a single 
antheridium to the basal cell, sometimes two ; the latter number appears never to be 
exceeded. When matured, the antheridia open and allow their contents to escape 
in the form of roundish or flattened bodies, which never, as far as known, acquire 
cilia, and have, therefore, no power of spontaneous motion. These bodies, which 
are believed to be spermatozoids, are unprovided with anything like an external 
membrane, and are composed of protoplasm identical with that in the antheridium. 

Whilst these changes are occurring, certain cells in other localities are being trans- 
formed into female organs, to which our author applies the name of Tiicliogonia. 



FRESU-WATER A L G .E OF THE UNITED STATES. 219 

These are borne upon cells similar to those supporting the antheridia. At first 
they are not markedly different from the other cells, but soon undergo a very rapid 
growth. This is not, however, regular, and is not partaken of by a band of tissue 
about one-tliird way from the basal end, so that at last a long somewhat flask- 
shaped cell is produced, with a very marked contraction at the point indicated, 
separating it into two portions. The wall of this cell is thin but very distinct, and 
the cavity is filled with a homogeneous or very sparsely granular protoplasm, which 
is continuous through the narrow neck-like portion. After a time there appear 
one or more large irregular vacuoles, with actively moving corpuscles in them, and 
at the same time the neck appears to be stopped with a slimy substance. Careful 
examination with reagents shows that this is cellulose, and that it does not com- 
pletely block the passage-way through the isthmus. At this time there appear lying 
upon the free end of the trichogonia globular or flattened bodies, without external 
membrane, corresponding in all respects with those already described as being pi'o- 
duced in the antheridia. The end of the trichogonium generally enlarges at this 
period into a sort of roundish knob, and by and by the end wall between this and 
one of these globules becomes absorbed, so that there is a free communication 
between the two. "Whilst this is going on the globule acquires a thin, delicate 
coat, and there appears in it a vacuole similar to those preexisting in the tricho- 
gonium. 

The first result of this impregnation of the trichogonium is the deposit of new 
cellulose, and the complete blocking up of the passage-way through the isthmus 
or narrowed portion. Already before the fecundation, the upper cells of the 
branches supporting the trichogonia have produced numerous branchlets, which 
growing upwards more or less completely cover that organ. After impregnation 
the cells near to the trichogonium become much larger and broader, their vacuoles 
disappear, and are replaced by a dense granular dark greenish-brown protoplasm. 

These cells now show a great activity in the production of numerous branches 
in the usual way, but it is the upper two alone Avhich, with the tricliogonium that 
they support, are concerned in the formation of the fruit glomerulus. These put 
out all over their surface an immense number of protrusions, which soon in the 
ordinary way become the parents of as many twigs or branchlets, which growing 
and branching, precisely as do the vegetative branches, soon become excessively 
crowded. The base of the trichogonium participates also in this production of 
branches, and at last a dense ball is formed of pseudoparenchymatous tissue by 
the forced adhesion of the crowded twigs. The central cells of the glomerulus 
thus formed are very large and bladder-like. The outer part of the ball is com- 
posed of innumerable radiating rows of small cells, the end cell of each branch 
being roundish so as to present a convex external face. At maturity these 
cells open and allow their contents to escape as round masses, which appear to 
have no membrane, but begin at once to grow and secrete cellulose. Their after- 
history has not been made out with absolute certainty, but they are believed to 
directly develop the new plant. 



220 FRESn-WATEll A L G yE OF THE UNITED STATES. 

B. jnoniliforine, (Roth.) 

13. iiollicare, bi- tripollicarc, raro pedale, muco gclatinoso plus minus firmo involutum, viola- 
ceum, fuscum, rufo-brunueum, purpureum vel casruleo-viridiscens, vage ramossissimum ; ramu- 
lorum articulis omnibus conibrmibus, oblongo-subclavatis, extremis nonnuuquam setigeris; 
iuternodiis uudis vel ramulis accessoriis singulis sparsis instructis. 

Diam. — Tetrasp. globulus ^^Jj = .006. 

Syn. B. moniliforme, Koth. Rabenhoest, Flora Europ. Algarum, Sect. III. p. 405. 

Hab. In aquis puris, Michigan ; Gray. New York ; Bailey. Virginia; Jackson, Alabama ; 

Tuomey. South Carolina ; (Ravenel) Pennsylvania; New Jersey; Wood. 

One inch to a foot in length, clothed with a more or less firm gelatinous mucus, violet, fuscous, 
reddish-brown, purple, or bluish-green, vaguely and profusely branched; joints of the 
branches similar, oblong-subclavate, the outer ones sometimes setigerous; internodes naked 
or furnished with a few scattered accessory branchlets. 

Remarlis. — This species is very abundant in fresh, cool rivulets, in springs, in 
limestone waters, in pine-barren streams, and even occasionally in ditches, wherever 
I have botanized in Pennsylvania and New Jersey. It varies greatly in size, in 
color, and other partictilars. 

The branchlets, as I have observed them, are most generally not setigerous, but 
at times they are provided with seta of moderate length. 

I have found numerous fruiting fronds, but in none of them was the fruit in 
great abundance, not nearly so much so as in the Rocky Mountain species. 

B. Tagiiiu, (RoTii) Agaiidh. 

B. vage ramossissimum, uni- vel tripollicarc, fuscum vel aerugineum ; iuternodiis inferioribns 
ramellis numerosis obessis, superioribus nudis vel subnudis ; raniuloruni articulis extremis 
setis longissimis instructis. 

Diam. — Tetrasp. globulus 5|§y= .00333. 

Syn. — B. varjum, (RoTii) Agardh. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 406. 

Hah. — In aquis quietis, Uintah Mountains, Nevada ; (S. Watson). 

Vaguely branched, one to three inches long, brownish or aeruginous ; internodes — the inferior 
covered with a dense mass of branchlets — the superior naked, or nearly so; last articles oi 
the branchlets provided with an extremely long seta. 

Remarlcs. — I have received from Mr. Screno Watson some half a dozen dried 
algee, which I have referred to B. vagxtm, with some doubt. They are labelled as 
having gro-wn in shallow water, in a beaver pond, in Pack's Canon, Unitas, Uintah 
Mountains, Nevada, at an altitude of 7000 feet. All the descriptions of B. ragnm 
whicli I have seen are singularly imperfect; in none is it stated how large the spore 
masses grow, and how plentifully the branchlets are provided with seta. As fnr 
as the descriptions go, however, my specimens agree with them, and I have, there- 
fore, refrained from indicating a new species. The plants are remarkable for the 
profusion and extreme length of the seta, and for the quantity of fruit which 
they produce. The fruit masses are small but very compact, scarcely more than 
half the size of those of the preceding species. The verticles of branchlets are 
often completely joined, and as it were almost swallowed up by the mass of inter- 
vening scattered branchlets which arise directly from the main axis. In the distal 



FRESH-WATER ALG^ OF THE UNITED STATES. 221 

portions of the fronds, however, the glomeruli are more fasciculate and more 
distinct, for although sometimes so close as to be almost confluent at their spread- 
ing edges, at their bases they are distinct. This species very probably attains a 
much larger size than indicated by my specimens, and possibly varies as much in 
color as B. moniliforme. 

Genus TUOMEYA, Harvet. 

" Frond cartilaginous, continuous, solid, at first transversely banded, afterwards aunularly con- 
stricted ; composed of a longitudinal axis, and two strata of peripheric cells. Axis columnar, 
consisting of several longitudinal cohering filaments, beset with closely placed whorls of moniliform 
ramelli, whose branches anastomose horizontally and vertically into a cellular peripheric membrane, 
which is coated externally with moniliform filaments, gradually developed. Fructification probably 
in the superficial filaments. 

T. fliiTiatilis, Harvey. 

Hab. — On stones, in rivers and streams. River in Alabama; Prof. Tuomey. Near Fred- 
ericksburg, Virginia; Prof. Bailey. 

Fronds tufted, an inch or two in height, scarcely as thick as a hog's bristle, much and irregu- 
larly branched, bushy ; the branches alternate or secund, scattered or crowded, twice or 
thrice divided, and set with scattered patent ramuli which are slightly constricted at the in- 
terstices, and taper to an obtuse point. When young the branches and ramuli are perfectly 
cylindrical, and when examined under a low power of the microscope show a surface com- 
posed of minute, dotlike cells, placed close together, and marked at short intervals with dark- 
colored transverse bands. These bands disappear under a higher magnifying power. They 
are indications of the nodes of the axis of the frond seen through the peripheric stratum. 
In old, fully developed specimens the branches and ramuli are annularly constricted at short 
intervals, the nodes becoming swollen, whilst the internodes remain unchanged. When a 
young branch is bruised between two pieces of glass the axis may be readily extracted. It 
consists of several parallel longitudinal jointed threads combined together at closely-placed 
nodes, from which issue horizontal dichotoraous filaments, composed of roundish or angular 
cells. These excnrrcnt filaments spread both horizontally and vertically, and their branches 
anastomose into a cellular mass or fleshy membrane, which forms the inner peripheric stratum. 
In young plants a portion of the frond, between the axis and periphery, is hollow, but in 
older ones the cavity is quite filled up with cells. The external surface of the cellular peri- 
phery is clothed with a coat of moniliform filaments gradually developed, and forms what is 
above called the second peripheric stratum. These are found only in fully-grown specimens; 
they consist of much smaller cells than those of the inner stratum ; they are more strongly 
colored, and I consider them to be connected with fructification. The color is a dark olive. 
The substance is brittle, rigid when dry, and the plant scarcely adheres to the paper. The 
generic name is in memory of the late Prof. Tuomey, of Tuscaloosa." 

Remarhft. — I have no knowledge of this plant, and have simply copied the de- 
scription of Prof. Harvey; Smithsonian Contributions, 1846. 

Famly LEMANEACE^. 

Algae rivnlares vel fluviatiles. Thallus e proerabryone confervacea enascens, setaceus, snbsimplice 
vel fasciculatim ramosus, cavus, nodosus, e cellalarum stratis internis et corticatis formatus. Noduli 
plerumque papillarum corona instrncti. Polyspora; numerosie, in seriebus ramosis moniliformibus 
fasciculatim aggregataj, sine fecundatione germiuantes. 



222 FRESH-WATER ALQ^ OF THE UNITED STATES. 

Al"-fC growing in streams and rivers. Thallus developing from a confervoid prothalloid filament, 
setaceous, almost simple or fascieulately branched, hollow, nodose, composed of internal and corti- 
cal strata of cells. Nodules generally provided with a corona or papilla. Polyspores numerous, 
fascieulately aggregated iu branched moniliform scries, germinating without fecundation. 



Genus LEMANEA, Bory. 



Genus unicum. 
The only genus. 



Bemarlcs. — The plants belonging to the genus Lemanea are quite peculiar in 
aspect and habit. They grow exclusively in fresh water, especially frequenting 
streams whose current is rapid, and whose waters are chilled by the mountain air. 
Their frail, tubular, scarcely-branched fronds offer but little resistance to the 
water, whilst their lower end is swollen into a sort of discoid root, which adheres 
firmly to the stones. The frond is mostly blackish or brownish, and is formed of 
two distinct portions or layers, of which the outer or cortical is composed of small 
closely cohering, colored cells ; the inner of much larger cells, which have thick 
colorless walls, and are placed so as to leave more or less numerous interspaces. 
In the immature frond there is also a longitudinal central column, besides some 
slender many-jointed filaments, passing obliquely through the cavity, but as final 
development takes place these seem to disappear. The mature frond is alternately 
contracted and expanded throughout its length. In the narrow portions the inner 
tissue often blocks up the tube entirely, whilst the dilated parts are loosely filled 
with the spores, which are produced within the frond. The spores themselves are 
oval, thick ish-walled cells, whose endochrome changes from greenish to a very 
decided yellow during the process of maturing. They are joined together to form 
rows or series, which are not simple, but are very much branched, so that from a 
central basal roAV arises a complex bush-like mass (pi. 20, fig. 4). These spore- 
clusters are always distinct, a number of them existing in each sporangial node of 
the frond. 

Dr. B. Wartmann described, nearly twenty years ago, very fully tlie way in 
which the spores germinate and develop into the frond. The first step, according 
to this authority, consists in the elongation of the spore and the projection of one 
end, which is soon cut off by the formation of a transverse partition, and consti- 
tutes a new cell. This multiplying in no strikingly peculiar way soon develops 
into a branched confervoid filament. A large number of these filaments are gene- 
rally produced in one place at one time and form a very apparent greenish layer. 
Finally certain cells in branches of these filaments swell up and become very much 
broader than their fellows, undergoing, at the same time, division so rapidly that 
they become very short. By and by they divide also in the direction of their 
breadth, so that instead of a simple series of cells there arises a compound mass. 
This is the beginning of the new frond. At first it is dependent upon the parent 
filament, but soon acquires a root-like process at the base and develops rapidly 
into the complex cartilaginous plant. 



FRESH- WATER ALG.E OF THE UNITED STATES 223 

li. toiMilosa^ (KoTu) Ag. 

L. subsimplex, pleriimque arcuata, cartilaginea ct nonniliil rijrida, 1-2 polliccs loiisa; nodal is 
approximatis, papillis applauatis, pleruraque 4-6 enormiter verticellatis, vel nonuiliil sparsis, 
iuterdum nounihil coufluentibiis ; sporis ovalibus. 

Diam. — Sporis. transv. max. t^jits" — ts^tsis"- 

Syn. — L. torulosa (Roth) Ag. Rabenhorst, Flora: Europ. Algarura, Sect. III. p. 411. 

Eab. — 111 fluraine, Kentucky; (Short) Harvey. Pennsylvania; Virginia; New York; New 
Jersey ; Wood. 

Subsimple, mostly arcuate, cartilaginous and somewhat rigid, 1-2 inches long; nodules ap- 
proximate, with their papules applanatc, mostly 4-G, irregularly verticillate or somewhat 
scattered, sometimes sliglitly confluent; spores oval. 

Remarhs. — This plant attains a length of about two inches, and grows in masses 
attached to rocks, often forming a sort of turfy covering to them, in rapidly run- 
ning water. In mass it has a grayish or blackish appearance. The filament has 
a grayish groundwork, with a dark band at the position of the nodes, which are 
enlarged and inclose the spores. The transverse outline of the filament is a very 
irregular circle. I have found this species very abundant in the rapid water of the 
Schuylkill, just above Flat Rock Tunnel, on the Reading Railroad, eight or nine 
miles above Philadelphia. Prof. E. D. Cope has sent me specimens collected by 
himself in swift streams in Western Virginia, and Mr. Austin has obtained it in 
similar situations in Northern New Jersey, Mr. Austin has also sent me specimens 
collected in Canada West. 

Li. fliiviatilis, Aa. 

L. simplex vel parce ramosa, quatuor uncias longa (interdum spitbamea?), recta vel subrccta ; 
nodulis subremotis, papillis verticillatis niagnis obssesis; sporis globosis vel subellipticis. 

Z)mm.— Spor. tsoV— t^'oW- 

Syn. — L. fluviatilis, Agakdh. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 411. 

Eah. — In rivulis, Alabama ; T. M. Peters. 

Simple or sparsely branched, 4 inches long (sometimes growing of a span length ?), straight or 
nearly so ; nodules rather distant, papillte verticillate, large, prominent. 

Bemarlis. — The only specimens I have seen of this species were sent me by 
Prof. Ravenel. This plalit is larger and heavier than L. torulosa, from which it is 
also readily distinguislicd by its very large prominent papillae. These are in 
slightly irregular whorls of three or more. The spores vary in shape from that 
of a globe to that of a somewhat four-sided ellipse ; in the latter case being some- 
times nearly twice as long as broad. Prof Rabenhorst speaks of the plant attain- 
ing the length of a span. I have never seen it over four inches. 

L. catenata, Ktz. 

L. ad uncias 5 longa, regulariter constricta, simplex, compressa, arcnata, in massa obscure 
violacea; papillis nullis; sporis enormiter ovalibus vel subglobosis. 

Diam — Spor. transv. max t^'o'ow" = -001". 

Syn. — L. catenata, KUtzing. Rabenhorst, Flora Europ. Algarum, Sec. III. p. 412. 



22i FRESn -WATER ALG^ OF THE UNITED STATES. 

jjab. In rivulis frigidis montaiiis Diamond Range, Rocky Mountains ; (Sereno Watson). 

About 5 inches long, regularly constricted, simple, compressed, arcuate, iu mass obscure violet; 
papules wanting ; spores irregularly oval or subglobose. 

Remarks. — I have received specimens of the plant from which the above diag- 
nosis was drawn, from Mr. Sereno Watson, labelled " Mountain stream, Diamond 
llano'e, altitude 6500 feet." In the dried state they are closely interwoven into a 
dark purple, rigid thin mass. When soaked out they preserve the same color in 
mass, but each individual stem has a general light yellowish, neutral ground tint, 
with dark-purplish or greenish-black bands at regular intervals. At the position 
of these bands the filament is nearly round and contracted, whilst between them it 
is compressed and enlarged. The spores are placed, not at the swelling, but at 
the constrictions, corresponding to the dark rings in position. They are quite 
irregular in shape, and of a faint yellow tint. The filaments between the little 
knots of spores appear to be hollow. Their walls are everywhere very thin when 
compared with L. torulosa, hence they are more flaccid. The species agrees in 
every respect with Pi-of. Rabenhorst's diagnosis of L. catenata, Ktz., a native of 
cold mountain streams of Germany and Switzerland. I regret, however, very 
greatly that I have had no opportunity of comparison with European specimens, or 
a fuller description. 



SUPPLEMENT. 



The following species, of which the author has not seen specimens, Avcre inad- 
vertently omitted from their proper places in the monograph. They are all con- 
tained in the Nerei^ Boreali-Americana of Prof Harvey. The following descrip- 
tions and remarks are simply copied from the work mentioned. 

Tetraspora lacunosa, Chauv. 

Frond at first tubular, then flat, or irregularly lobed, menibranaceo-gelatinous, pale-green, erery- 
where pierced with roundish holes of various sizes. Chauv. Alg. Norm. Jireb. Alg. Fal. p. 
11, t. 1. KiUz. Sp. Alg. p. 22T. T. Godaji, Be Breb. KiUz. Tab. Phyc. t. 30, /. 3. T. 
perforata, Bailey, 31. S. 

Hab. — la fresh-water streams. Abundant near Westpoint, Prof Bailey ; Providence, Rhode 
Island, Mr. Olney. (v. s. in Herb. T.C.D.) 

Frond at first funnel-shaped, afterwards splitting open, and then flat, e.xpanding upwards and 
irregularly lobed, everywhere pierced with roundish holes of various sizes, large and small 
intermi.xed. These holes increase in size and numbers with age, and thus at last the frond 
becomes an open network. The substance is very gelatinous, but rather firmer than in some 
other species of the genus. The color is a pale green; and the hyaline gelatinous membrane 
is filled with roundish granules set in fours. 

Kiitzing's figure of T. Ooileyl answers well to our plant. I have not seen any 
authentic specimens of T. lacunosa, which is referred by Kiitzing to his T. luhrica, 
var. (3., but the description given of it applies to the American plant. When care- 
fully dried, it forms a very pretty object for the herbarium. (^Cldorospermecc, p. 
61.) {Harvey, p. 61.) 

l^ostoc (Horiuosiphon) arcticnm, Berk. 

Fronds foliaceous, variously plaited, green or brownish ; filaments at length (their gelatinous 
envelope being dissolved) free. Berk, in Proc. Lin. Soc. fide An. Nat. Hist. 2d Scr. vol. 
10, p. 302. 

Eab. — On the naked soil, in boggy ground. Assistance Bay, lat. 75° 40' N. Pr. Sutherland, (v.s.) 

"Fronds foliaceous, variously plicate, sometimes contracted into a little ball. Gelatinous 
envelope at length efl'used ; connecting cells at first solitary, then three together; threads, 
which arc nearly twice as thick as in N. commune, breaking up at the connecting cells, so as 
to form new threads, each terminated with a single large cell, the central cell becoming free." 
Berk. I. c. 

" It grows," says Dr. Sutherland, " upon the soft and almost boggy slopes around 
Assistance Bay; and when these slopes become frozen at the close of the season, 

29 Ootober, 1872. ( 225 ) 



226 SUPPLEMENT. 

the plant lying upon the surface in irregularly plicated masses becomes loosened, 
and if it is not at once covered with snow, which is not always the case, the wind 
carries it about in all directions. Sometimes it is blown out to sea, where one can 
pick it up on the surface of the ice, over a depth of probably one hundred fathoms. 
It has been found at a distance of two miles from the land, where the wind had 
carried it. At this distance from the land it \'i'as infested with Podurce, and ] 
accounted for this fact by presuming that the insects of the previous year had de- 
posited their ova in the plant upon the land, where also the same species could be 
seen in myriads upon the little purling rivulets, at the side of which the Nostoc 
was very abundant." At p. 205 of his Journal, Dr. Sutherland further mentions 
having tried it as an article of food, and found it preferable to the Tripe de Roche 
of the arctic hunters. Its nutritive qualities are probably equal to those of the 
jelly derived from other Algae. {ChlorospermecB., p. 113.) 

IVostoc flagellifbrnie, Berk, and Curt. 

Terrestrial ; frond cartilaginous, linear, very narrow, compressed and often channelled, raucb 
branched, irregularly dichotomous; branches solid, densely filled with moniliform curved 
threads. Berk, and Curt. No. 3809. 

Hah. — On naked aluminous soil, at San Pedro, Texas, Mr. Charles Wright, (v.s.) 

Fronds several inches in length, half a line in diameter, lying prostrate on the surface of the 
soil, much branched in an irregularly dichotomous manner; branches exactly linear, com- 
pressed, often channelled on one or both sides, thinned in the middle and incrassated to the 
edge. Substance firm and clastic, cartilaginous, solid, densely filled with moniliform, curved or 
curled, interlaced threads, which are set longitudinally in the frond, and lie nearly parallel to 
each other. Color dark olive. 

A very curious and most distinctly marked species, differing from others of this 
genus, much in the same manner that Clucto^^hora endiviccfoUa does from the ordi- 
nary globose forms of Ch(etophora. {Gldorosjiermeoi, p. 115.) 

IVostoc inicroscopiciini, Carm. 

Fronds densely aggregated, very minute, globose or oblong, immersed in a blackish crust; fila- 
ments few. Carm. in Hook. Brit. Fl. 2, p. 399. Harv. 3Ian. Ed. 1, p. 184. N. muscorum, 
Hass. Br. Fr. Wat. Alg. x>. 292, t. 1i,fuj. 4. 

Hah. — "Stones in a small stream, Baffin's Bay," Dr. Sutherland, ^tZe Prof. Dickie. 

I have not seen American specimens. In Britain this species grows among 
mosses on exposed calcareous rocks, but not in water. The above specific charac- 
ter is taken from the British plant. The fronds are rarely more than the tenth of 
an inch in diameter, and contain two or three beaded filaments lying in a copious 
transparent jelly. {Gldorospermece, p. 115.) 

Genus Htdrurus, Ag. 

Frond fixed at base, cylindrical or compressed, elongated, branched, gelatinous. Structure: 
seriated, but separate, cellules, filled with bright-green endochrome, inclosed in gelatinous parallel 
tubes, ranged longitudinally in the frond, and surrounded by a common gelatinous envelope. 



SUPTLEMENT. 227 

• 

Of this genus several species have been described by authors, all having a close 
resemblance to each other, and all very variable in ramification. Indeed it is 
almost impossible to fix characters by which they can be permanently kept apart ; 
and instead of adding another specific name to the already too numerous list, I 
prefer to consider the American specimens received as constituting a luxuriant 
variety of the best known of the established species. All previously recorded 
species or varieties of these plants are natives of rapid rivers and streams in 
various parts of Europe. {^GhlorosjjermecB, p. 118.) 

Hydriiriis penicillatus, var. occidentalitu, Harv. 

Frond very long (1-2 feet or more), much braiuhed; branches very irregular, scattered or 
crowded, wormlike, tapering to a fine point, nalied or clotlied with feathery villous ramuli ; 
cells ellipsoidal or pear-shaped, twice as long as their diameter. 

Hab. — On the rocky bottom of rivers and streams, in a strong current. Santa Fe, New Mexico, 
Mr. Fendler, February to April, ISiT. (v.s. in Herb. T.C.D.) 

Fronds attached at base, one or two feet long, from one to four lines in diameter, very much 
and irregularly branched ; branches scattered or crowded, simple or divided, a foot or more 
in length, attenuated to a fine point, sometimes smooth and naked, but generally densely 
clothed with slender, villous ramenta, spreading to all sides. The gelatinous tubes or .sheaths 
in which the cells are seriated are very obvious, and lie close together in longitudinal, paral- 
lel strata. The cells are of large size, bright-green color, and variable shape ; some are twice 
as long as others. 

This I had at first supposed to be a new species, but now regard it as a very 
gigantic state of H. penicillatus, Ag., which under various forms and of various 
sizes is common in alpine streams in Europe. I fear characters derived from the 
shape and size of the cellules are not more to be depended upon than are those 
taken from the ramification. (^ChlorospermecB, p. 118.) 

Draparnaldia oppof^ita, Ao. 

Frond vaguely much branched ; joints of the main filament as long as broad, or shorter ; pencils 
of ramuli mostly opposite, densely set, lanceolate-acuminate in outline, plumose, bi-tripinnate, 
the apices much attenuated. Ag. Syst. p. 59. Kittz. Sjy. Alg. 351. Lyngh. Hyd. Dan. tab. 
&b,fig. A. Batraehogpermuvi Americanum, Schweinitz. 

Hab.— In clear streams. New York, Professor Bailey. New Jersey, Mr. Jackson, (v.s.) 

Frond 2-3 inches long, gelatinous, capillary, irregularly much branched ; the branches patent, 
lateral, more or less divided, and set with lesser ramuli. Main filaments with short articula- 
tions, as long as their breadth, or shorter, transversely banded. At every two or three nodes 
and sometimes at every node a pair of opposite penicillato-multitid ramuli are thrown off. 
These are bright green, ovato-lanceolate in outline, much acuminated and twice or thrice pin- 
nate, their pinnules somewhat constricted at the nodes, and tapering at the apex into long, 
needle-like, hyaline points. Their cells are commonly nucleated and filled with endochrome. 

Whether tliis be permanently distinguishable from D. glomerata is doubtful. It 
has externally the aspect of that species, but its microscopic characters are nearer 
those of D. i>liunosa. 



GEOGRAnilCAL LIST OF SPECIES. 



Class PHYCOCHROMOPHYCEiE. 

Order CYSTIPnOR.E. 

Family CHROOCOCCACE^. 
Cbroococcus 

refractus, Woorl. Ilab. near Philadelphia, 

multicoloralus, Wooil Huh. near Philadelphia. 

thermopliiUis, Wood. Hub. Uenton Springs, Owen 

Co., California. 

Gloeocapsa 

sparsa, Wood. 



Caelospbserium 

dubium, Griin. 



Bah. near Philadelphia. 



Merismopedia 

nova, Wood. Huh. near Philadelphia, 

couvoluta, Breh. Hah. Spring Mills, Montgomery 

Co., Pa. 

Order NEMATOGENE.E. 

Family OSCILLARIACE.'E. 
Osclllarla 

chloriua, Klz. Hah. near Philadelphia, 

corium, Ag, Hah. New York, 

decorticans, Getier. Hah. Northern U. States. 

Frohlichii, Klz. Hah. Schuylkill River, near 

Philadelphia, 
imperator. Wood. Hab. near Philadelphia, 

limosa, Ag. Hab. near Camden, New Jersey. 

mnscorum, Ag. Hah. West Point, New York, 

neglecta, Wood. Hub. near Philadelphia, 

nigra. Vouch. Hab. New York ; Philadelphia, 

tenuis, Ag. Hab. Rhode Island ; New York ; 

Virginia, 
tenuissima, Ag. Hah. Warm Springs of Washita. 

Chthonoblastus 

repens, Ktz. Hah. New Y'ork ; Massachusetts ; 

Rhode Island. 



Lyngbya 

bicolor, Wood. 

muralis, Ag. 



Hab. Schuylkill River, near Phila- 
delphia. 
Hab. Whale Fish Islands, Davis 
Straits, British America. 



Family NOSTOCHACKiE. 

Sub-Family Nostoce.t;. 
NOBtOC 

Austiuii, Wood. Huh. New Jersey, 

alpiuum, A'(;. Hah. Alleghany Mountains ; Clover 
Mts., Nevada ; BafEu'.s Bay, British America, 
calcicola, Ag. Hah. Catoosa Springs, Georgia, 

calidarium. Wood. Hah. Beuton Ppiings, Owen 

Co., California, 
caeruleum, Lyn. ' Hub. New Jersey. 

Cesatii, Bah. Hub. Kansas, 

comminutum, Kt:. Hab. near Philadelphia, 

commune. Vouch, Hah. New Jersey ; Rio Bravo, 

depressum. Wood. Hab. New Jersey, 

punctatum. Wood. Hab. New Jersey, 

pruniforme, Agh. Hab. New Jersey, 

verrucosum, Vaiich. Hab. Maine, 

sphjeriuum. Vouch. Hah. Centre Co., Pennsylvania. 

Sub-Family Spekmosirex. 
Anabasna 

gelatinosa. Wood. Hah. near Philadelphia, 

gigantea, Wood. Hah. near Philadelphia, 

flos-aquae, Kt:. Hah. Round Pond, West Point, 

New York. 



Cyllndrospermuin 

comatuiu, Wood. 
flexuosum, Rob. 
macrospermum, Ktz. 
miuutum, Wood. 



Huh. Niagara, Canada. 

Htih. near Ihiladelpliia. 

Hah. South Carolina. 

Hah. near Philadelphia. 



Dolichospermum 

polyspermum, Klz. Hab. near Philadelphia, 

subrigidum, Wood. Hab. New Jersey. 

Family RIVULARIACEjE. 
Nostochopsis 

lobatus. Wood. Z/ul. Schuylkill River, near PhiKv 

delphia. 

Glolotrichla 

augulosa, liolh. Bob. Hudson River, near West 

Point. 



( 229 ) 



230 



GEOGRAPniCAL LIST OF SPECIES. 



Gloiotrichla 

incrustata, Wood' 

Rivularla 

cartilagiuea, WooJ. 

Zonotrlcbla 

miiiutula, Wood. 



Hab. Schuylkill River near 
Philadelphia. 

Hah. Northern Michigan. 



Ilab. Clear Pond, Adirondack 
Mountains. 

mollis, Wood. Hah. Cave of the Winds, Niagara. 

parcezonata. Wood. Hab. Cave of the Winds, 

Niagara. 

Dasyactls 

mollis, Wood. Hab. Cass River, Northern Michigan. 

Mastlgonema 

elongatum, Wood. Hab. Philadelphia, 

fertile. Wood. Hab. Alleghany Mountains, Centre 

Co., Pennsylvania, 
halos. Wood. Hab. Stonington, Connecticut, 

sejunctum. Wood. Hab. Cass River, Northern 

Michigan. 



Mastlgothrlx 

fibrosa. Wood. 



Hab. near Philadelphia. 

Family SCYTONEMACE.E. 
Scytonema 

Austinii, Wood. Hab. Little Falls, New Jersey, 

calotrichoides, Klz. Hab. South Carolina, 

cataracta. Wood. Hab. Niagara River, Niagara, 

cortex, Wood. Hab. South Carolina, 

dubium, Wood. Hab. Cumberland Co., New Jersey, 
immersum, Wood. Hab. Cumberland Co., New 

Jersey. 
Myochrous, Ay. Hab. West of Crow's Neck, West 

Point. 

Naegelii, Klz. Hab. near Bellefonte, Centre Co., 

Pennsylvania. 
Ravenellii, Wood. Hab. South Carolina, 

simplioe. Wood. Hab. Aiken, South Carolina. 

Ihermale. Hab. South Carolina. 



Tolypothrlx 

distorta, Mul. 



Hab. near Philadelphia ; West 
Point, N. Y.; Rhode Island ; 
Madison, Wisconsin. 



Siroslpbon 

guttula. Wood. Hab. South Carolina, 

lignicola. Wood, Hab. South Carolina, 

neglectus, Wood. Hab. New Jersey, 
pellucidulus. Wood. Hab. near Hiberuia, Florida, 

pulvinatus. Hab. Northern Now .Jersey, 

scytenematoides, Wood. Hab. South Carolina. 

Stlgonema 

Ravenellii, Berkeley. Hab. Lookout Mountains, 

Georgia. 



Class CHLOROPHYLLACEiE. 
Order COCCOPHYCE^ 
Family PALMELLACEiE. 
Pleurococcus 



pulvereus. Wood. 

seriatus, Wood. 

Falmella 

dura, Wood. 
hyalina, Lyn. 

Jesenii, Wood. 

Pagerogalla 

stellio. Wood. 



Hab. Boiling Springs, near Belle- 
fonte, Centre Co., Pennsylvania. 
Hab. New Jersey. 

Hab. near Philadelphia. 

Hab. From Rhode Island to 
Wisconsin. 

Hah. near Philadelphia. 



Hab. Bear Meadows, Alleghany 
Mountains, Centre Co., Penn- 
sylvania. 



Tetraspora 

bullosa. Roth. 
gelatinosa, Roth. 

lubrica. Roth. 

Dlctyosphaerium 

pulchellum, Il'oorf. 

Rhaphidium 

falcatum. 
polymorphum. Ft. 



Hab. Salem, North Carolina. 

Hab. Salem, North Carolina; 

Newburgh, New York. 

Hab. Northern Atlantic States. 



Hab. near Philadelphia. 

Bab. near Philadelphia. 
Hab. near Philadelphia. 



Family SIROSIPHONACE.S:. 
Siroslpbon 

acervatus. Wood. Hab. South Carolina, 

argillaceus, Wood. Hah. South Carolina, 

compactus, .ly. /7a6. Salem, Massachusetts ; New 

Jersey. 
Crameri, Br. Hab. Mount Tahawus, Adirondack 

Mountains, 



Family PROTOCOCCACEiE. 

Polyedrium 

enorme, Ral/s. 



Hah. Florida. 



Sceaedesmus 

aculus, Meyen. Hab. Rhode Island ; near Phila- 

delphia. 

obtusus, Meyen. Hab. Georgia ; Rhode Island. 

polymorphus, Wood. Hab. near Philadelphia- 

quadricauda, Turp. Hab. Rhode Island ; Penn- 

sylvania. 

rotundatus. Wood. Hab. near Thiladelphia. 



GEOGRAPHICAL LIST OF SPECIES. 



231 



Hydrodictyon 

ntriculatum, Roth. 



Fediastrnm 

Boryanum, Tut. 



Hab. West Point and Wee- 
hawken.New York; Mexi- 
can Boundary ; Pennsyl- 
vania ; New Jersey. 



constrictum, Hassall. 



Eab. Rhode Island ; Pennsyl- 
vania; Georgia; Florida. 
Hab. South Carolina; 
Georgia ; Rhode Island. 
duodenarius. Hab. South Carolina ; Rhode Island. 
Ehrenbergii, Corrfa. Ilab. Rhode Island; South 
Carolina ; Georgia ; Florida, 
pertusum, Ktz. Bab. Rhode Island. 

Selenaea, Ktz. Hab. Rhode Island. 

Family VOLVOCINE^. 
Chlamydococcus 

nivalis. Hab. Greenland ; Rocky Mountains. 



Volvox 

clobator, Linn, 



Bab. United States. 



Order ZYGOPHYCE^. 

Family DESMIDIACE.S!. 
Palmogloea 

clepsydra, Wood. Ilab. near Philadelphia. 

Penium 

Bieliissonii, Men. Ilab. South Carolina, 

closterioides, Ralfs. Ilab. South Carolina. 

Digitus, £*r6. //u6. Pennsylvania; New York; 

Georgia, 
interrnptum, Brfb. iTat. near Grahamsville, South 

Carolina. 
Jenneri, Ralfs. Hab. Florida, 

lauiellosum, Br^b. Hab. Rhode Island, 

uiargaritaceum, Ehrb. Hab. Rhode Island, 

miuutum, Cleve. Hab. Rhode Island; South Caro- 
lina; Georgia. 



Closterlum 

acerosum, Schr. 

Amblyonema, Ehrb. 

angustatum, Ktz. 

areolatum, Wood. 

Cucumis, Ehrb. 
Dianse, Ehrb. 

Ehreiiliergii, Mi?n. 
Jenucrii, Ralfs. 
juncidum, Ralfs. 



Hab. South Carolina ; Georgia ; 
Florida. 
Hab. West Point, New Y'ork; 
Providence, Rhode Island. 
Hab. Rhode Island ; New Hamp- 
shire; Pennsylvania. 
Hab. Northumberland Co., 
Pennsylvania. 
Hab. New York. 
Hab. Georgia; Florida; Pennsyl- 
vania; Rhode Island. 
Hab. Philadelphia. 
Hab. Rhode Island. 
Hab. Saco Lake, New Hampshire ; 
South Carolina. 



Closterlum 

Leibleinii, Ktz. 

lineatum, Ehrb. 
Lunula, Mailer. 

maximum, tar. 
moniliferum, Bory, 
parvulum. Nag. 
rostratum, Ehrb. 
setaceum, Ehrb. 



striolatum, Ehrb. 
Venus, Ktz. 

Tetmemorns 

Brebissonii, Men. 
giganteus, Wood. 
granulatus, Breb. 

levis, Ktz. 

Pleurotaenium 
Baculum, Br^b. 
breve. Wood. 
clavatum, Ktz. 
constrictum, Bailey. 
crennlatum, Ehrb. 



gracile, Rab. 
hirsutum, Bailey. 
nodosum, Bailey. 

Trabecula, Ehrb. 



undulatum, Bailey. 
verrucosum, Bailey. 

Triploceras 

gracile, Bailey. 



Hab. Georgia ; South Carolina ; 

Penusylvania. 

Hab. Pennsylvania. 

Hab, South Carolina ; Florida ; 

Georgia ; Pennsylvania. 

Ilab. Pennsylvania. 

Hab. Georgia ; Rhode Island. 

Hab. near Philadelphia. 

Hab. near Philadelphia. 

Hab. Stonington, Connecticut ; 

Providence, Rhode Island ; 

Pennsylvania ; Georgia ; 

Florida. 

Hab. Centre Co., Pennsylvania. 

Hab. South Carolina. 



Hab. Atlantic States. 
Hab. Centre Co., Pennsylvania. 
Hab. Rhode Island ; Pennsyl- 
vania ; South Carolina. 
Hab. near Philadelphia. 

Hab. Georgia. 
Hab. District of Columbia. 
Hab. South Carolina ; Georgia. 
Ilab. Rhode Island. 
Hab. Rhode Island ; New Jer- 
sey ; Pennsylvania ; South 
Carolina ; Georgia ; Florida. 
Hab, Florida. 
Hab. United States. 
Hab. South Carolina ; Georgia ; 
Florida; Pennsylvania. 
Hab. Pennsylvania ; New Jer- 
sey ; South Carolina; 
Georgia ; Florida. 

Hab. Florida. 
Hub. Rhode Island. 



Hab. Rhode Island; New Jersey; 
New Hampshire ; Florida; Georgia, 
verticillatum, Bailey. Hab. with the last. 



Spirotaenla 

bryophila, Bre'b. 
condensata, Br^b, 



Hab. near Philadelphia. 

Hab. Pennsylvania ; Rhode 

Island; Florida. 



Bairbuslna 

• Brebissonii, Ktz. Hab. Florida : Georgia ; South 

Carolina; Rhode Island. 
Dldymopriam 

Grevillii, Ktz. Ilab. Pennsylvania; South Caro- 

lina ; Georgia. 



232 

Spbaerozosma 

excavatum, Unlfs. 

pulchrcm, Buileij. 
serratum, BaiUij. 

Hyalotheoa 

disilliens, Smith. 

mucosa, Merl, 



GEOGRAPHICAL LIST OF SPECIE S. 



Ilah. Rboile Island ; South 

Carolina ; Georgia ;, Florida. 

llah. New York ; New Jersey. 

Huh. South Carolina ; Georgia ; 

Florida. 



Hub. Rhode Island; Pennsyl- 
vania ; South Carolina ; Florida. 
Hah. Rhode Island. 



Desmidinm 

aptogoniiuii,' Viieh. Ilab. South Carolina ; Georgia, 
quadrangulatum, Ktz. JM'. South Carolina. 

Swartzii, Ag. Ilah. Atlantic States. 



Aptogonium 

Baileyi, Ralfs. 

Cosmarium 

amoenum, Bri'b. 
bioculatum, Dr^b, 
Botrytis, Bnry. 
Brebissonii, Men. 

Broomei, Tliw. 
caelatnin, Ralfs. 

commissurale, Bri'b. 

connatum, Brib. 
creuatum, Ralfs. 
cucuniis, Corda. 



Euastmm. 

binale, Tiirp. 

circulare, Hassal. 
crassum, Brib, 
Didelta, Turp. 



depressum, Raileij. 
margaritiferum, Turp 

Menegbenii, Bri'b. 
ornatum, Ralfs. 
ovale, Ralfs. 
pyramidatum, Brt'b 

Quimbyii, ^yoo(l. 
snblobatum, Brib, 

suborbiculare, H'rwr/. 

ti'tropthalmum, Klz. 
Tbwatesii, Ralfs. 
uudulatum, Corda. 

EnastTnin 

affine, Ralfs. 
ampuUaceum, Ralfs. 



Ilah. Rhode Island ; New Jersey. 



Ilab. Florida ; Rhode Island 
Hab. Rhode Island. 
Ilab, Pennsylvania. 

Hub. White Mountains, New 

Hampshire. 
Ilab. Pennsylvania ; Georgia. 
Ilab. near Albany, New York ; 
South Carolina. 
Ilah. White Mountains, New 
Hampshire. 
Ilab. Florida. 
Ilab. Rhode Island. 
Ilab. New Hampshire ; Pennsyl- 
vania ; South Carolina ; 
Georgia; Florida. 

Hab. Florida. 
Hab. Pennsylvania ; South 
Carolina; Florida; Mexico. 
Hah. Pennsylvania. 
Hab. Rhode Island. 
Hah. Pennsylvania. 
Hah. Pennsylvania ; Georgia ; 
Florida. 
Ilab. near Philadelphia. 
Hah. Rhode Island ; Georgia ; 
Florida. 
Hah. Lake Saco, New Hamp- 
shire. 
Hab. New Jersey. 
Hah. Florida. 
Hab. Rhode Island ; South 
Carolina? 

Hab. South Carolina : Georgia. 
Hab. South Carolina ; Florida. 



elegans, Brih. 
gemmatum, Brib. 
insigne, Ralfs. 
multilobatum, Wood, 

ohiongum, GreviHe. 
ornatum, TI ood. 
Ralfsii, Jiabeiih. 

verrncosum, Ehr. 



Ilah. Florida ; Pennsylvania; Rhode 
Island. 
Hab. Rhode Island. 
Hah. United States. 
Hah. South Carolina ; Georgia ; 
Pennsylvania ; Rhode Island. 
Hab, United States. 
Hah, Rhode Island. 
Hab. Florida ; Rhode Island. 
Hab. Saco Lake, New Hamp- 
shire. 
Hab. Rhode Island. 
Hab. Saco Lake, New Hampshire. 
Hab. South Carolina ; New Hamp- 
shire ; Rhode Island. 
Hah. Rhode Island ; South 
Carolina ; Georgia; Florida. 



Micrasterlas 

Americana, Ehrb. 

arcuata, Bailey. 
Baileyi, Ralfs, 

denticulata, Breb. 
disputata. Wood, 
expansa, Bailey. 
fimbriata, Ralfs. 
foliacea, Bailey. 
furcata, Ag. 
granulata, Wood, 
Jenneri, Ralfs, 
oscitans, Ralfs. 
papillifera, Breb, 
pinnatiflda, Kiz. 
quadrata, Bailey. 
radiosa, Ag. 
ringens, Bailey, 
Torreyi, Bailey, 
truncata, Corda, 



Hab. Florida; South Carolina. 

Hab. Florida. 

Hab. New York ; Rhode Island ; 

South Carolina ; Florida. 

Hab, Pennsylvania; Florida. 

Hab. Atlantic States. 

Hah. Florida. 

Hab. South Carolina ; f lorida. 

J3a(i. Worden's Pond, Rhode Island. 

Hab. Atlantic States. 

Hab. South Carolina. 

Hah. near Philadelphia. 

Hab. Florida ; Rhode Island. 

Hab. Florida ; Rhode Island, 

Hah, 

Hah. Florida. 

Eab. Florida. 

Hah. Florida. 

Hab. near Princeton, New Jersey. 

Hab. Atlantic States. 



Staurastrum 

alternans, Brib 



arachne, Ralfs. 
aristiferuQi, Ralfs. 
Cerberus, Bailey, 
crenatum, Bailey, 



Hab. Georgia ; Florida ; Rhode 
Island. 

Hab. Saco Lake, New Hampshire. 

Hah. Georgia ; Rhode Island. 

Hah. Florida. 

Hab. Rhode Island. 

cyrtocerum, rar., Brib. Hab. Florida. 

dejectum, Brib. Hab. New York ; South Caro- 

lina. 

dilatatum, Ehh. Ilab. Southern Atlantic States. 
eustephanum, Ralfs. Hab. West Point, New York, 
furcigerum, Brib, Hah. South Carolina; Florda; 

Rhode Island. 



G E O G R A P U 1 C A L 



Staurastrum 

gracile, Bul/s. 

liirsutum, Ehrb. 
Hystrix, Ralfs. 
Lewisii, Wood. 
longispinum, Arch. 
niargaritaceuui, Ehrb. 

muuitum, Wood. 

muticura, Dr(b. 

orliiciilare, Ehrb. 

paratloxum, ilry. 

polymorphiim. 
polytrichum, Per. 
piinctulatuui, Drtb. 
Kavenellii, Wood. 
senarium, Ekrh. 
tiiuonie. Men. 



JJab. South Carolina; Georgia; 

Florida ; New York ; Rhode 

Islaud. 

Ilub. Florida; Rhode Island. 

Hub. Rhode Islaud. 

Ilab. Saco Lake, New Hampshire. 

JTab. Florida. 

Uab. Saco Lake, New 

Hampshire. 

Hab. Saco Lake, New 

Hampshire. 

llab. South Caroliua ; Rhode 

Island. 

I/nb. Rhode Island ; 
Pennsylvania. 

Uab. Saco Lakej New 

Hampshire. 

Hub. Florida. 

Uab. near Philadelphia. 

//./6. Pennsylvania. 

Uab. South Carolina. 

Uab. America. 

U b. Georgia; Florida; Rhode 

Island. 



LIST OF SPECIE 

Spirogyra 

majuscula, Klz. 
uitida, Dill. 
protecta. Wood. 
parvispora, Wood. 
pulchella. Wood. 
quinina, Ag. 
rivularis, Uasaull. 
setiformis, Roth. 
Weheri, Kiz. 



Xanthidium 

aculeatum, Ehrb. 
.•\rctiscon, Ehrb. 
armatum, Br(b. 

hisenarium, Ehrb. 
cristatura, Br(b. 
corouatum, Ehrb. 
fasciculatum, Ehrb. 

Arthrodesmus 

couvergeiis, Ehrb. 

Incus, Brib. 

octocornis, Ehrb. 
quadridens, Wood. 



Uab. near Savannaii, Georgia. 

Iliib. North America. 

Uab. South Carolina; Florida: 

New Hampshire. 

Uab. America. 

Uab. Southern Atlantic States. 

Uab. Amai'ica. 

Etdi. South Carolina; 

Georgia; Florida; Rhode Islaud. 

Uab. .Soulh Caroliua ; Georgia; 

F'lorida; Rhode Islaud. 

Uidi. Georgia; Florida; South 

Carolina; Rhode Island. 

Uab. Florid.-i ; Rhode Island. 

Uah. Lake Saco, New 

Hampshire. 



Family ZYGNEMACE/E. 
Spirogyra 

crassa, Kiz. 
decimiua, MiiK 



diluta, Wood. 
duhia, Ktz. 
elongata, Berk. 
insignis, Uns. 
longata, Vanch. 



Uab. near Philadelphia. 
Uab. near Pliiladeljihia. 
Uah. near Philadelphia. 
Uab. near Philadelphia. 
Uab. near Philadelphia. 
Uab. near Philadelphia. 
Uab. Rhode Island ; rear Phila- 
delphia. 



S. 233 



Uab. near Philadelphia. 
Uab. near Philadelphia. 
Uab. near Philadelphia. 
Uab. Hihernia, Florida. 
Uab. near Philadelphia. 
Uab. near Philadelphia. 
Hah. Florida. 
Uab. near Philadelphia. 
Uab. near Philadelphia. 



Zygnema 

insigue, Uassal. 

cruciatiuu, T'u«c/i. 

Sirogonium 

retioversura, Wood. 

MesocarpuB 

scalaris, Uassall. 
parvulus, Uassatt, 

Pleurocarpus 

niirabilis, Braun. 



Uab. Rhode Island ; near Phila- 
delphia. 
Uab. Virginia; Florida; 
Northern States. 



Uah. near Philadelphia. 



Uah. near Philadidphi.a. 
Uah. Rhode Island. 



Uab. New York ; Rhode Island ; 
MichiMn; Wisconsin. 



Order SIPHOPHYCEyE. 

Family IIYDROGASTREiE. 



Hydrogastrum 

grauulatum, Linn. 



Uab. Delaware. 



Family VAUCUERIACE/E. 
Vaucherla 

aversa, Uassall, 
geminata, Vatich. 
polymorpha, Wood. 
sessilis, Vatieh. 



Uah. near Philadelphia. 

Uab. near Philadelphia. 

Uab. Texas. 



Uab. New York; Maine; Vir- 
ginia; North Carolina. 
veUUina, Ag. Uab. New York; Maine; Virginia; 

North Caroliua. 



Order NEMATOPnY('E..E. 

Family ULVACEiE. ' 



Protoderma 
viride, Ktz. 



Uab. Philadelphia. 



triva 

merismopedioides, Wood. Ud>. Diamond 

Range, Rocky Mountains. 
Enter omorpha 

inte.stiualis, Linn. Uab. Hudson River; Narra- 

gansett Bay. 

Schizomeris 

Leibleinii, Klz. Uab. near Philadelphia. 



30 October, 1872. 



2U 



Conferva. 



GEOGRAPUICAL LIST OF SPECIES. 

Family CONFERVACE.a:. 



Ilab. Uuitfd States. 



Cladophora 

bracliystelecba, Rab. Ilab. near Philadelphia. 

fracta, Dill. Ihib. I'ennsylvauia; New York ; 

Rhode Islaud. 

Ilab. Lakes Ontario, Erie, 
Huron, and Michigan. 



glomerata, Linn. 

Family (EDOGONIACEiE. 



Androgynia 

echiuata, Wood. 
Huntii, Wood. 
mirabilis, Wood. 
multispora, TTow^. 

Pringsheimia 

inrequalis, Wood. 

Bulboch^te 

Cauhjii, Wood. 
dumosa, Wood. 
ignota, Wood. 



Hub. Florida. 
Ilab. near Philadelphia. 
Hub. near Philadelphia. 
Ilab. near Philadelphia. 

Hub. near Philadelphia. 

TTuh. Ilibernia, Florida. 
Ilab. near Philadelphia. 
Ilab. near Philadelphia. 



Family CIlROOLEPIDEiE, 
Chroolepus 

aureum, Klz. 



II((b. New York ; New .Jersey ; 
Texas. 



Bulbotrichia 

alljida, Woml. 



Ilab. Northern New Jersey. 



Family CHiETOFHORACE^. 
Stigeoclonium. 

Eab. Eastern United States. 



Draparnaldla 

Billingsii, Wood. 
glomerata, Vauch. 
masima, nir., Wood. 



Ilab. near Philadelphia. 

Ilab. Rhode Island. 

Ilab. near Philadelphia. 



Drapernaldia 

plumosa. Vauch. 

Cbaetophora 

elegaus. Roth. 
eudiviaefolia, Roth, 



nab. near Philadelphia. 

Hub. Eastern United States. 

Uab. Rhode Islaud ; South 

Carolina. 



Pilinia 

diUita, Wood. Hob. Centre County, Pennsylvania. 

Coleochaete. 

Hab. Eastern United Slates. 



Aphanochaete 

repens, Braun. 



Uab. near Philadelphia. 



Class RHODOPHYCEiE. 

Family PORPHYRACE.ffl. 
Porphrydium 

cruentum, Ag. Ilab. New York, 

magnificum. Wood. Hub. Texas. 

Family CHANTRANSIACEiE. 
Chantransia 

expansa, ir«oi/. Ilab. near Philadelphia, 

macrospora, TTood. Hab. South Carohna. 

Family BATRACHOSPERMACEiE. 
Batrachospermum 

monililorme, Roth. Ilab. Eastern United States. 

Tagum, Roth. Uab. Uintah Mountains, Nevada. 



Ilab. Alabama : Virginia. 



Tuomeya 

fluviatilis, ITari'. 

t 

Family LEMANEaCE^. 

Lemanea 

catenata, Ktz. Hab. Diamond Range, Rocky 

Mountains, 
fluviatilis, Ag. Eab. Alabama, 

torulosa. Roth. Uab. Virginia ; Kentucky ; Penn- 
sylvania ; New Jersey. 



BIBLIOGRAPHY. 



Agardh (Karl Adolf). 

Dispositio Algarum yueciae. Luudae, 1810-12. 
ADmarkuiugar om sliigtet Lemauia, samt beskrifning 

om tvenue nya arter deraf. Kongl. Sveiiska Ve- 

tenskaps Akademiens Handliugar, xxxv., 1814, p. 33. 
Beskrifning af eu ny art Conferva. Ibid., 1814, pp. 

195-200. 
Synopsis Algarum Scandinavia, adjecta dispositions 

universali Algarum. Luudse, 1S17. 
De metamorphosi Algarum. Isis vou Oken., 1820. 

Regensburg Flora, vi., 1823. 
Species Algarum rite cognitiB cum synonymis, differ- 

entiis Ppecificis et descriptiouibus succindis. Gri- 

phiae, 1823-28. 
Systema Algarum. Lundse, 1824. 
Aufziihlung einiger in den Ostreichischen Lamlern 

gefundenen neuen Ciattungen und Arten von Algen, 

nebst ihrer Diagnostik und beigefiigteu Bemerkungeu. 

Regensburg Klora, x., 1827. 

Einige Bemerkungeu iiber Urn. Dr. Meyen's kritisclie 
Beitrage zum .Studium der Siisswasser Algeu. 
Regensburg Flora, 1S29. 

Icones Algarum Europsarum. Leipzig, 1828-35. 

Agardh (Jakob Georg). 

Observationer pa Sporidiernes rorelse lies de grona 
Algerne. Stockh. Acad. Handl., 1836. 

Beobachtungen iiber die Bewegung der Sporidien in 
den griinen Algen. (Translation.) Regensburg 

Flora, 1S40. 

Bidrag till en noggrannare kannedom af propagations — • 
organerne hos Algerne. Stockh. Acad. Handl., ISSO. 

Observations sur la propagation des Algues. (Trans- 
lation.) Aunal. de Scien. Natur., vol. vi., 1836. 

Auadema, ett nytt slilgte bland Algerne (Anadema, 
genus novum confervearum familias). Stoikli. 
Acad. Handl., 1846. 

Algologiska Bidrag. Ofversigt af Konigl. Vetenskaps 
Akademiens FOrhandliugar, .Sjefte Argaugen, 1^49. 

Nya Algformer. Ibid., Arg. xi., 1854. 

Species, genera etordines Algarum. Lundae, 1848-G3. 

AUman (George James). 

On a new Genus of Algse belonging to the family Nos- 

tochinefe. Annals and Magazine of Nat. HLstory, 

1843, vol. xi. p. 161. 
On an undescribed Alga aUied to Coleocliffite scutata. 

British Association Report, 1847. 
On an apparently undescribed genus of Fresh-Water 

Alg:e. Ibid., 1847. 
On two undescribed Algae. Proceedings Royal Irish 

Acad., 1847. 
On microscopic Algae as a cause of the phenomenon of 

the coloration of large masses of water. I'hytolo- 

gist, vol iv., 1852. 



Alqnen (P. d')- 

Notes on the Structure of OscillatorijB, with a descrip- 
tion of a new species, possessing a most remarkable 
locomotive power not Cilia. Journal Microscopical 
Soc, iv., 1856. 
Amici (Giovanni Battista). 

Descrizioue di un' Oscillaria. Firenze, 1833. 

Andrejewsky (Erastea). 

Ueber die Vegetation in den Biidern von Abano. 
Graefe und Walther's Journal fiir Chirurgie und 
Augen Kraukheiten, 1831. Annalen der Chemie 
und Pharmacie, 1832. 

Note sur les vegetaux qui croissent autour et dans les 
eaux thermales d'Abauo. Annals Scien. Nat., 

Bot.) 1835. (Translatiou.) Edinburgh New I'hilos. 
Journal, six., 1835. 

Archer CWilliam). 

Description of two new species of Staurastrum. Dub- 
lin Nat. History Soc. I'rocredings, 1856-9. Kat. 

History Review (Dublin), vi., 185U. Journ. Micros. 

Society, 1860. 
Notice on some cases of abnormal growth in the Des- 

ruidiaceae. Ibid., 1-56-9. Ibid., Ib59. Ibid., 

1860. 
Observations on the genera Cylindrocystis, Mesotaenia, 

and SpirotKuia. Microscop. Journal, N. S., vol. viii. 
On the conjugation of Spirotjeuia condensata. Ibid., 

N. S., vol. viii. 
Catalogue of Desniidiaceae (Dublin) Nat. Hist. Rev., 

vol. iv. Microscopical Journal, vol. vi. 

Supplementary Catalogue of Desmidiaceae (Dublin), 

with descriptions and figures of a new genus and 

four new species. Natural Uistor. Rev., vol. v., 

1858. 
Notice of the occurrence near Dublin of a Unicellular 

Alga, believed to be allied to that alluded to by 

Hofnjeister (Aun. Nat. Hist. 3ser. vol. i., Jan. 1858). 

Nat. History Review, v., 1858. Dublin Zool. Bot. 

Assoc. Proceedings, i., Ib59. 
On a new species and genus of the Desmidiaceae, with 

some remarks on the genera Micrasterias and Euas- 

trum. Nat. Hist. Rev., vol. vi. 
On the occurrence of Zoospores in tlie family Desmidi- 

acea?. Dub. Nat. Hist. Soc. Proc. iii. Journ. 

Micros. Society, I860. Nat. Hist. Review, vol. vii. 

On Asteridium occurring in Peniuin dig! lata. Micro- 
scopical Journ., vol. vii. 
Record of the occurrence new to Ireland, with a note of 

a peculiar condition of the Volvocinaceous .Alg,T9 

Stephanospliaera pluvialis, &c. Ibid., vol. vi. 

On two new species of Saprolegnieae. Ibid., vol. vii. 
Description of a new species of Cosmarium and of a 

new species of Xantbidium. Dubl. Nat. Hist. 

Soc. Proc. iii., lb59-62. Nat. Hist. Revieyr, vol. 

vii., 1860. 



( 235 ) 



2;36 



B 1 K L I G U A P II Y 



Archer (William). — Continued. 

Description of a new species of Miciasterias, witli re- 
marks ou the distinction between M. rotata (Halts) 
anfl M. deiiticulata (lireb.). Dublin Nat. Ilisl. 
Soc. Proc, vol. iii. Micros. Soc. Journ. ii., 18()2. 

Description of a new species of Cosiuarium (rorila),of 
^taurastrum (Meyen) ; of two new species of Closte- 
riuni (Nitzsch), ami of Spirotienia (Breb.) Dub- 
lin Nat. Hist. 8oc. Proc. iii. Miuroscop. Soc. Journ., 
vol. ii., lyiJ2. 

Ou a new species of Ankistrorlesmus (Corda), with re- 
marks as regards Closterium Griffitbii (Berk), and 
C. subtile (Breb.). 

OiiClosterinraaciculare(West). Microscopical Soc. 

Journal, ii., 1^^02. 

An endeavor to identify Palmogloea raacrococca (Ktz.), 
with description of the plant believed to be meant 
and of a new species, both referrible to the genns 
Arthrodesniu3 (Ehrb.). Dubl. Nat. History Soc. 

Proc. 17., 18U2. Hedwigia, lSb'4. 

Desciiption of a new species of Cosmariuni (Corda), 
and of Arthrodesmus (Ehrb.). Dub. Nat. Hist. 
Soc. Proc, iv., 18U2-3. 

Observation on Wicrasterias Mahabule^hwarensis (Ilob- 
son), and on Dooidiuin pristidse (llobson). Dubl. 
Nat. Hist. Soc. Proc, iv., 1SG2-Ii3. Microscopical 
Journ., N. S., vol. vi. 

Description of a new species of Docidiura from Hong 
Kong. Dubl. Nat. Hist. Soc. Proc, iv. Micro- 
scop. Jouru., N. S., vol. vi. 

Description of two new species of Cosmarium, of Pe- 
nium, and of Artlirodesmus. Microscop. Journ. 

N. S., vol. iv., Hedwigia, 1864. 

Description of two new species of Staurastrum. Mi- 
croscopic Journ., N. S., vol. vi., 1839. 

On a new genus and species of Desmidiaceae. Ibid., 
N. S., vol. vi. 

On some cases of abnormal growth iu Desmidiacese. 
Ibid.,N. S., vol. vi. 

Ardissone (Francesco). 

Enumerazione delle Alglie della maroa di Ancona. 
Fano, 186t). 

Areschoug (Johann Erhart). 

De Hydrodictyo utriculato. Lunds, 1S39. 
Ueber die Vermehrungsart dis Wassernelzes (Hjdro- 
dictyon utriculatuiu Ruth). Liuii;ea, vol. xvi., 

1842. 

Om Aclilya prolifera, viisauda pa lefvande fisk. Stock- 
holm, Ofversigt Kou.Vetensk. Akad. Fiirhand. 1844. 

Algarum minus rite cognitarum pugillus primus, tab. 
12. Linnjea, 1842. 

Die Arten der Gattung Ulva. Nova Acta R. Soc. 

Scient. Upsal. Ser. IU., vol. i. 

Copulationem hos Zygnemacea). Stockholm, (Ofver- 
sigt K. Veutensk. Akad. Forhaud. 1853. Regens- 
burg Flora, 1855. 

Arrondeau (Theodore). 

Essai sur les Conferves des Environs de Toulouse. 

Act. Soc. Linnaea de Boideaux, 3 Series, torn. iv. 
Observations sur I'Drganization du Zygnema orbiculare, 

Hassal. Sessions des Congr^s Scientifique de 

France, xix., 1852. 

Bailey (John 'Whitman). 

A sketch of the Infusoria of the family Baccilaria, with 
some account of the most interesting species which 
have been found in a recent tour in the U. States. 
American Journal of Sciences, First Series, vol. xli. 
i). 184. Vol. xlii.p. 88. Vol. xliii. p. 321. 



Eailey (John Whitman). — Cnntinned. 

tin some new species of American Desmidiaceic from 
the Caiskill Mountains. American (-ieolot;i.st aud 
Nat. A.-iSoc. Reports, 1843. Amer. Jourm N S 
vol. i., 1846. ■ ■' 

Notes on the Algae of the United States. Ibid. 

New Sfries, vol. iii. pp. 80, p. 329 Vo.. vi. p. 37. 

Microscopical Observations made in South Carolina 
Georgia, and Florida. Suiitlisouian Contributious 
vol. ii. 

Notes on new species and localities of Microscopical 
Organisms. Ibid., 1853. 



Balfour (John Hutton). 

Observations on the Sjmres of Cryptogams, and on the 
reproductive processes in some Algae ami Fungi. 
Proceedings of the Royal Society of Ediul)urgh, Ses- 
sion of 1807-8. 

Bary (Heiarioh Anton de). 

Bericht iiber die Fortschritte der Algeukunde in den 
Jahreu 55, 56, 57. Bolanishe Zeitung, 1858. 

Sur la generation sexuelle des Alj,ues. Anual. Scieu. 
Natur. (3ot.), tome v., 1856. 

Beitrag zur Kenntniss der Aci.lya prolifera. Bota- 

nisclie Zeitung, 1852. 

Uber die Copulation der Desmidiacien. Berlin, Bo- 
tanische Zeitung, 1857. Regeiisb. Flora, 1S57, p. 
693. 

Ueber das vortweltliche kleinste Siisswasser Leben in 
jEgypten. Monatsbericht.der Kon. Akad., 1S53. 

Beitrag zur Kenntniss der uiedersten Algeiiformen ncb.st 
Veisucheii ihre Entstehung betrelfend. Sitzungs- 
bericht d k. Akad. zn Wieu, Bd. xi., 1853. 

Beitrag zur Naturgescliichte der Schwilrrasporen. Ver- 

handluiigen des naturhist. Vereins der preus- 

sisch. Rheinlande und Westphalens. Bonn, 1855. 
Untersuchuugen iibcr die Familie der Conjiigateu. 

Leipzig, 1858. 
Uber die Algengattnngen CEdogonium und Bnlbochsele. 

Verhandlnngen der Senckenberg naturwissen. Ges- 

selscbaft zu Frankfurt. 1854. 
Beitrag zur Kenntniss der Nostocaceen, insbesondere 

der Rivularieeii. Regeusburg Flora, 1863. 
Einige neue Saprolegnieen. Pringsheim's JalirbucU 

fiir wissens. 13otanik, bd. 2, 1860, p. 169. 

Bary (Heinrich Anton de) el M. Woronin. 

Beitrag zur Kenntniss der Chytridieen. Freilmrs;, 
1863, also Berichte der naturforsclieuden Gesell- 
schaft iu Freiburg, Band, iii., Heft. ii. 

Bauer (Francis). 

Microscopical Observations on Red Snow. The .lour- 
nal of Science and Arts (Royal Inst. Gr. Br.), vol. 
vii., 1819. 

Some experiments on the Fungi which constitute the 
coloring matter of the Red Snow discovered in liaf- 
fin's Bay. Philosophical Transactions, London, 

1820. 

Microscopical Observations on the Suspension of Mns- 
cular Movements in Vibrio tritica. Philosophical 
Transactions, 1823. Ann. Sci., vol. ii., 1824. 

Begglato (Francesco Secondo). 

Delle teriue Euganee memoria. Padova, 1835. 

Berkeley (Miles Joseph). 

Gleanings of the British Ales, being an Appendix to 
the Supplement to English Botany. London, 1833. 



B I B L I U L; R A P II Y 



231 



Berkeley (Miles Joseph). — Continxied. 

Desciiiitiuii of Closterium Griffithii, n. sp. Auuals 

aud Jlagaziiie of Natural History, 1S54. 
Ona new vegetable Parasite on flsUes. Gardener's Cliro- 

nicle, lb(j4. Aniialde Scieu. Natur.,vol. ii., v. Ser. 
Note on tlie recent discoveries in relation to the Miuro- 

gonidia of Fresh-water Algx. Journal of Liuneau 

Society 1., 1857. 

Biasoletto (Bartolommeo). 

Dialcune Algbe microscopiclie Soggio. Trieste, 1S32. 
UeberdieMetamorplrose der Algeu. Regeusburg Flora, 

1838. 
Ueber microscopische in cliemiscben Solutionen eutste- 

lieude Algen. Isis vou Okeu, 1833. 

Bory de St. Vincent (Jean Baptiste M. A G.). 
Memoire sur les genres Conferva et Byssus. Bordeaux, 

1797. 
Essai mouographie sur les Oscillaries. Paris, 1827. 

Braun (Alexander). 

Ueber das Wassernetz, Hydrodicfyon utriculatura, Rotli. 

Verliandluugen der Seliweizerisclien Gesellsuhaft fur 

die gesammte NaturwissenscUaft, 1847. 
Ueber das Vorkommen beweglicher Samen bei den 

Algen. Ibid., 1847. 
Betraclitungen iiber dieErscheinung der Verjiingung in 

der Xatur, inbesondere in der Lebens und Bildungs- 

geschiclite der Pllanze, Leipsig, 18fil. Translated 

and republished by the Ray Society, London. 
Ueber Spirulina Jeuneri. Botanische Zeitung, 1852. 
Chlamydococcus pluvialis bei Berlin. Ibid. 
Algarum unicellularum Genera nova et minus cognita, 

prsemissis observationibus de Algis uuicellularibus 

in Genere. Leipzig, 1855. 
Ueber Chytridium, eine Gattung einzelliger Sclunarot- 

zergewiichse auf Algen uml Infusorieu. Abliand- 

lungeu der K. Akademie der Wissenscliaft zu Berlin, 

1855. 
Ueber neue Arten der Gattung Chytridium und iiber 

die damit verwandte (rattung Rhizidium 

Monatsbericht. 1S5G, p. 587. 
Ueber einige mikroskopischen Algen. Botanische 

Zeitung, 1856. 
Ueber Protoccus pluvialis. Botanische Zeitung, 185(j. 

Brebisson (L. Alphonse de). 

Description de deux nouveaus genres d'Algues fluvia- 

tiles. Annales des Sciences Naturelles, 1844, vol. i. 
Liste des Desmidiees observees en Basse-Normandie. 

Paris, 185(1, avec 2 planch.; also Mem. Soc. Scienc. 

Nat. de Cherbourg, 1854. 

Brebisson (Ii. Alphonse de) et Godey. 

Igues des Environs de Falaise. Memoires de la So- 
ciete Academiiiue de Falaise, (Bot.) 1835. 

Brongniart (Adolphe Theodore) at Bory de St. 
Vincent. 

Botanique du voyage antour du monde sur la Coquille. 
Cryptogaraes, vol. ii. de texte, avec atlas gr. in folio, 
de lUO planches color, et uoir. Paris, 1829. 

Brdgger-(Chr. G.). 

Erster Bericht iiber das kleinsle Leben der rhilti^chen 
Algen. Jahresberiebt viii. der naturforschenden 

Gesellschaft Graubiindens. Churwalden, 1863. 

Bnsk (George). 

On the structure of Volvox globator. Microscopical 

Transactions, vol. i. 
On the occurrence of Sarcina ventriculi in the human 

stoniacli. Microscopi- Jourii., vol. i., 1842. 



CandoUe, Pee De CandoUe. 

Carradori (Gioracchino). 

Delia traostcprmazioue del Nostoc in Tremella verrucosa. 
Prato, 1797. 

Carter (H. J.). 

Note on a species of Nostoc from Bind. .Tnurn. of tliB 

Bombay Branch of the Royal Asiatic Society, v., 1855. 

On Fecundation in the two Volvoces and their specific 
diifereuces ; on Eudorina, Spongilla, Astasia, Euglena, 
and Cryptoglena. Annals auil Mag. Nat. llist., 
1859, p. 1. 

On Fertilization in Eudorina elegans and Cryptoglena. 
Ibid., 1858, p. 237. 

On specific character. Fecundation, and abnoi-mal de- 
velopment in Gildogouium. Ibid., 1857, p. 21). 

Cams (Carl Gustav). 

Beitrag zur Geschiehte der untir '\Vasser an verscliie- 
deneu Thierkiirperu sich erzeugendeu ScUinuiiel- 
oder Algengattuug. Nova Acta Acad. Goes. Leopold. - 
Car. Natur'Cur. Bd. xi., Bonn, 1823. 

Caspary (Robert). 

Vermehruugsweise von Pediastrum elliptit-um. 

Botanishe Zeitung, viii., 1850. 
Description of a new British Alga belonging to the 

genus Schizosiphon. 

Annals of Natural History, vi., 1850. 
Ueber die Zoosporen der Gattung Chroolepus. Regens- 

burg Flora, 1857. Berlin Botanische Zeitung, 1857. 
Till. Zoospores of Chroolepus. Quarterly .Journal of 

Microscopical Science, July, 1859. Annal. Seieu. 

Natur. (Bot.), vol. is., 1858. (Translated from Re- 

gensburg Flora). 

Cesati (Vincenzo barone). 

Ueber die Vermehrung von Hydrodictyon utriciilatuiu 
Roth. Hedwigia, 1852. 

Chauvin (Frangois Joseph). 

Observations raicroseopi<|ne sur la Conferva zonata. 
Memoires Societe Linneenne de Normandie, 1826-7. 

Observations niicroscopique sur la mole de reproduc- 
tion de la Conferva rivularis. Sessions des Cou- 
gres scientifi»|ne de France, 1833. 

Esamen comparatif des Hydrophytes non articulees do 
la France et de I'Angleterre. Ibid., 183. 

Recherches sur I'organisation, la fructifiiuation et la 
classification de'plusieurs genres d'algues, avec la 
descriptiou de quelque especes iuedites. Caen, lf.42, 

Cienkowskl (L.). 

Algologishe Studien. Botanische Zeitung, 18EG. 

Ueber einige chloropliyllhaltige Gloeocapsen. Bota- 

nische Zeitung, 1865, p. 21. 

Die Pseudoeonidien. Pringsheim's Jalirbuch, Bil. i., 
1858, p. 370. 

Rhizidium Confervae glomerate. Botanische Zeitung, 
1857. 

Clave (P. T.). 

Bidrag till kiinnodomen cm Sverige.s siitvaltensalger 

af familjen Desniidiese. cifvers af k. Vet. Akad. 

Forhandl. Arg. 20, iS. 10. Hedwigia, 1864. 
Oin de Svenskaar'erna af Sliigtet Vancheria, DeCand. 

Stockholm, 1863. Hedwigia, 1864. 
Fiirsok till en monografi ofver di Svenska arterna af 

alsrenfamilien zygneniacete. Nova acta Reg. Socie- 

tatis Scientarum Upsaliensis, 1868. 
laktt.agelser ofver den hvilande ffidogonium ((Edogo- 

dinm Sporens). Ofvers af k. Vetenskap-Akad., p. 247, 

1864. Translated in Microscopic Journal. 



238 



B IIH.IOGU AT 11 Y. 



Cohn (Ferdinand Julius). 

Zur Ia-1i]« voui Waolistljum iler Pllaiizenzelle. Aeatl. 

Caes. Leopold. Nova Acta, xsii., 1847. 
NachtraLje zur Naturgeschiuhte des Protococcus uivalid 

Ktz. Ibid., xxii., 1847. 
Uiiber die Entwickeluugsgeschiclite der Pflanzeiizelle. 

Uebersicht der Sclilesiscbeu Gesellsuhaft fiir viiter- 

laudiscliB Cultur, 1849. 
Uel)er blaUilailiche Fiirbuiigcn dureli inikroskopisclie 

Organismeu. Ibid., 1800. 
On a new genus of the family Volvocinere. Annals 

and Mag. Nat. Hi.st., 1852, translated from Siebold 

and KoUiker's Zi-itschritt fur wissenschiiftliclie 

Zoologie, vol. iii., 1S.')2. 
Ueber Keiniung der Z.vgnem.'en. Uebersiclit der 

Schles. Gesell. fiir vaterl. Cultur, 1S52. 
Ueber Protococcns crust.nceus Ktz. Hedwigia,1851. 
Untersuchungen iiber die Entwickelungsgesfhichte der 

raikro-skopisclien Algen und Pilze. Nova Acta 

Akad. Cass. Leopold., xxiv., 1854. Micros. Soc. 

Journ., iii., 185.5. 
Ueber die Fortplianznng von Spliaeroplea annulinn. 

Monatsbericht der k. Preus. Akad. VVissensch. zn 

Berlin, 1855. Ann. and Mag. Nat. Hist., 185(j. 

Ann. Sci., Natur. (Bot.), v., 1S56. 
Ueber das Gesclileclit der Algen. Uebersiclit der 

Schles. Gesell. vaterl. Cultur., 1855. Report of 

the British Association for tlie Advancement of 

Science, 1855. 
Beobacbtungen iiber deu Bau und die Fortpflauzuug 

von Volvos globator. Uebers. ScUl. Gesell. vilterl. 

Cultur., lS5li. Annals and Magaz. N»t. Hist., 1S57. 

Ann. Bci. Natur. (Bot.), 1856. Comptes Rendus, 

xliii. Micros. Soc. Journ., 1857. 
Ueber einige neue Algen Schlesiens. .Tahresbericht 

des naturwissen. Vereins zu Breslau, 1857. 
Ueber lebendige Organismeu in Triukwasser. Ibid., 

1853. 
Ueber contractile und irritable Gewebe der Pllanzen. 

Ibid., ISlJO. 
Contractile Gewebe im Ptianzenreiche. Ibid., ISGl. 

(Translated) Annals and Mag. Nat. Hist., xi., 1863. 
Ueber das Verhiiltniss der Zellen in den niederen 

Pllanzen und Tliieren. Ibid., 1861. 

Ueber rothen Schnee. Ibid., 1861. 
Ueber die Algen des Cailsbader Sprudels und deren 

Antheil an der Bildung des Sprudelsinters. Ibid., 

1862. 

Ueber die Verbn-itung der .Algen, insbesondere in 

den Meerens Europa's. Ibid., 1862. 
Verhalten der griinen mikroskopiscbeu Pllanzen und 

Thiere zum Licbte. Ibid., 1863. Microscop. 

Journ., N. S., vol. vii. 

Beitrage zur Physiologie der Phycnchromaceen und 
Florideen. Schultzes Archive fiir Mikrosc. Ana- 
tomie, 1867. 

Ueber Chlaraydomonas marina, Cidm. lledwigia, 1865. 

Comelli (Francesco). 

Intoriiuo alle alghe microseopiche del Dr. B. Biasoletto 
Relazione. Udine, 1833. 

Corda (August Karl Joseph). 

Obsi'rvations microscopiqncs sur les Animnlcnles des 
eanx therniales de Carlsbad. Almanach de 

Carlsbad, IPe annee, 1840. 

Die Algen. Sturm's Deutschland Flora, 2e Abtliei- 
lung 1829-32. 



Corti (Bonaventura). 

Osservazioni niicroscnpiselie sulla Treniella 
1774. 



Luc 



Crouan (P. L., and H. M., brothers). 

Observations microscopiiiues sur le genre Mesogloia 

Aganlh. Auual. Scien. Natur. (Bot.), vol. iii 

1835. 
Observations microscopiques sur la dissemination et 

la germination des Kciocarpes et sur le^ Conferva 

scutulata. Ibid. vol. Xii. 

Note sur le genre Spirulina. Memoires de la SocietO 
Imper. des Scien. Nat. de Cherbourg, ii., 1854. 

Currey (Frederick). 

On gtephanosphaera pluvialis. Microscopic Journ., 
vol. vi , 1858, p. 131. 

On some British Fresh-Water Alga;. Ibid., p. 207. 

Bareste (Camille). 

Memoire sur la Coloration de la mer de Chine. 

Annal. Scien. Natur., vol. i., 1854. 
Meinoire sur les Animalcules et autres corps organises 

qui dnnnent a la mer une couleur rouge. Annal, 

bcienc. Nat. (Zool.), 180.5. 

Davaine (C). 

Conierve parasite sur le Cyprinus Carpio. Memoires 

de la Soc. de Biologie, 1851. 
Retdierches physiologiques et pathologiques snr les 

Bacteries. Comptes Rendus, Paris, 1868, tome Ixvi. 
Recherches snr les infusoires du sang dans la maladie 

eonnue sous le nora de sang de rate. Ibid., Ivii., 

1863. Journ. de Pharmacie, xliv., 1863. 

De Candolle (Augustin Pyramus P.). 
Flore Franijaise. Tom. vi. 
Rapport sur les Conferves. Journal de Physique, de 

Chiuiie et de I'Histoire Naturelle, liv., 1802. 
Notice sur la Matiere qui a colore le lac de Morat en 

Rouge an Printeuips de 1825. Memoires de la 

Societe Nat. de Gencive, tome iii., 1826. Edinburgh 

Jouiu. Scien., 1827. 



et 



Antoine Joseph Jean 

Ann.al. 



Derbes (Alphonse) 
Solier. 

Sur les organs reproducteurs des Algues 

Scien. Natur. (Bot.), xiv., 1850-1851. 
Memoire sur quelques points de la physiologie des 

algues. Paris, 1856. 

Dillenius (John Jacob). 

Historia Muscorum. A General History of Water 
Mosses and Corals, containing all the known species, 
their names, places of growth, and seasons. 85 tab. 
London, 1763. 



Dillwyn (Le^vis Weston). 

Svnopsis of the British Confervs. 
"l810. 



Loudon, 180(1- 



Dippel (Leopold). 

Beitrilge zur Losung der Frage "Kommt der Zellmem- 
bran bios ein Waehsthnm von Aussen nach Innen zu, 
Oder besitzt dieselbe ziigleich ein solchea von Innen 
nach Ausen. Botanische Zeitung, ix., 1851. 

Zur Primordialschlauchfrage. Regensburg Flora, 

xxxix., 1856. 

Ueber die F<irtpflanzuug der Vaucheria sessilis. 
Regensb. Flora, xxxix., 1856. 

Zelltheilung derUlothrix zonata. Abbandlnngen der 
uaturforscbenden Gesellscbaft zu Ilalle, 1867, p. 43. 

Druce (T. C). 

On the rppmduetive processes in the Confervoide.ie. 
Micros. Journal, 1860, p. 71. 



B 1 B L 1 O G K A r U Y. 



239 



Duby (Jean Etienne). 

Botauicou Gallicum. Tome ii. Paris, 1828. 
Singiilier mode de multiplication du Pediastium ellip- 

ticum. Supplement a la Bibliotlieque Uuiverselle de 

Ueneve. ArcUives des Scieuc. Nat. et Pliys., tome 

xvii., 1851. 
Reproduction des Algues. Bibliotlieque Uuiverselle 

des Sciences. Ueueve, vi., IbliU. 

Dufour (Louis). 

Eleuco delle Alghe della Liguria. 

Duffin (A. B.). 

Some account of Protoplasm. 
1860, vol. iii., N. S., p. 1251. 



GenoTa, 1864. 



Microscop. Journal, 



Ducluzeau (J. A. P.). 

Essai sur I'histoire uaturelle des Confervas des Envi- 
rons de Montpellier. Moutpellier, 1SU5. 

Dujardin (Felix). 

Histoire Naturelle des Zoophytes, avec pi. 22. 

Paris, 1841. 
Sur quelques Vegetans inferieurs et partieulier, sur le 

Nostoo. Annales Franvaises et Etrangers d'Ana- 

tomie et de Physiologie (Laurent et Baziu). Paris, 

1839. 

Ehrenberg (Christian Gottfried). 

Die Infusionsthiercheu als vojkommene Organismen. 
Mit 64 Tafeln. Leipzig, 1838. 

Mikroskopiscbe Analyse des curlandischen Meteor- 
papiers von 1686 und Erliiuteruug desselben als ein 
Product jetzt lebeuder Conferveu und Infusorien. 
Mit 2 Tafeln. Berlin, 1839. 

Verbreituiig und Einfluss des mikroskopischen Lebens 
in Slid- und Nord-Amerika. Mit4 Tafeln. Berlin, 
1843. Mouatsbericht der k. Preus. Akad., 1841. 

Passat-Staub und Blut-Regen, ein grosses organisches 
unsiclitbares Wirken und Leben iu der Atmosphare. 
Mit 7 Tafeln. Berliu, 1849. 

Mikrogeologie. Das Erden und Felsen schaffende Wir- 
ken des unsichtbar kleinen selbsstiiudigen Lebeus 
auf der Erde. Leipzig, 1854. 

Nebst Fortsetzung (Bogen 1-22). Daselbst, 1S56, 

gr. fol. 88 Seiten, uur mit Umschagtitel niclit beendigt. 

Ueber die seit 27 Jahenr nocli wobl erhalteneu Orgaui- 
satious-Praparate des mikroskopiscbeu Lebens. Mit 
3 Tafeln. Berlin, 1862. 

Zur Mikrogeologie, von Christian Gottflled Ehrenberg. 
Seiner Majestiit Friedrich Willjelm IV., Kouig von 
Preussen zugeeiguet. Ein umi vierzig Tafelu mit uber 
viertausend grossentheils colorirten Figuren.gezeich- 
net vom Verfasser. Daselbst, 1854, gr. fol. 31 
Seiten mit 41 Tafelu und 49 Bliittern dazu gehuriger 
Erklarung. 

Mikroscopische Algen und Bryozoa als Begleiter der ira 
P'euerstein Fossilen Infusorien. Monatsberichte k. 
Preuss. Akad. Wissens. zu Berlin, 1836, p. 114. 

Uebersicht des Mikroscopischeu Lebens in CaKfornien. 
Ibid., 1852, p. 423. 

Beitrag zu Bestimmung des Stationiiren Mikros. Lebens 
iu bis 20,000 Fuss Alpenhiihe. Mouatsber. Akad. 

. Wissen. 1858, p. 426. 

[For a further list of microscopic papers by Ehrenberg, 
10 double columns, see Register fiir die Monatsbe- 
richte der Kouig. Akademie der Wissenschaften zu 
Berliu vom Jahre 1836 bis 1858. Berliu, I860.] 

Ettlngshausen (Eonstantin von). 

Die Proteaceeu der Vorwelt. Sitzungberichte der 
Mathemat. Naturwissen. Classe der Kaiser. Akad. 
der Wissenschaften. Wieu Bd. vii., 1851 und baud 
viii., 1852. 



Famintzln (A.) und J. Boranetzky. 

Zur Entwickelung.sgpschichte der Gonidien uiid Zoos- 
porcnbildiiug der Flechten. Meiuoires de l'Ai:aiIumie 
Imperiale des Sciences de St. Petersbourg, 1867. 

Die Wirkung des Lichtes auf Algen und einige andere 
ilinen nahe verwandte Organismen. Priugsheim's 
Jahrbuch fiir Wissens. Botan. Bd. vi. 

Influence de la lumiere artificielle sur le Spirogyra 
Orthospira. Annates des Sciences K.aturelle, vol. 

vii., 1867. 

Influence de la lumiere sur le movement des Chlamedo- 
mouas, OsciUatoria, &c. Ibid. 

Fischer (Leopold Helnrich). 

Beitriige zur Keuntniss der Kostochaceen. Berlin, 
1853. 

Der Nostochaceen. Botan. Zeituug, 1853. 

Fleischer (Johann Gottlieb). 

Ueber Protococcus rdseo-persicinus Kiitz. Wurtemb. 
Jahrb. xvii., p. 55. 

Flotow (Julius von). 

Chroolepis Korberi. Fw. Botauische Zeitung, viii., 
1850. 

Floto-w (Julius von) und Ferdinand Julius Cohn. 

Ueber llematoccocus (Protococcus) pluvialis. Nova 
Acta, Bonn, 1843-1850. 

Focke (Gustav Waldemar). 

Physiologischeu Studieu. Heft i., 1847. lleft ii., 

1854. Bremeu. 

Uber die Copulation der Bacillarien utuI Desmidiaceeu- 

Regensb. Flora et Berlin Botan. Zeit. 1857. 

Frauenfeld (George Iliiter von). 

Die Algen der dalmatischeu Kiiste. Wien, 1854. 

Fresenius (Johann Baptist Georg Wolfgang). 

Ueber Sphaeroplea auuliua. Botanische Zeitung, 1851. 

Ueber den Bau und das Leben der Oscillarien. Mu- 

seum Senckenb.. 3 baude. 

Ueber die Algengattungen Pandorina, Gonium, uml Ka- 
phidium. Abhaudluugen Senckenb. naturh. Ges- 
selsch., 1857. 

Fries (Ellas Magnus). 

Systema Orbis Vegetabilis. Pars 1., Plantae Homone- 

meaa. Lundse, 1825. 
Corpus Florarum provincialium Snecise. — I. Flora 

Scanica. Upsaliaj, 1835. 

Gaebel (E.). 

Beitrag zur Keuntniss der Spermatozoidien. 
Hedwigia, 1868. 

Gaillon (Benjamin). 

Essai sur les causes de la couleur verte des ventres. 

Rouen, 1831. 
Aper(;u d'histoire naturelle et observations sur les 

limites qui separent le regne vegetal du rdgne animal. 

Boulogne, 1838. 
Observations microscopiqnes et physiologiques snr 

I'UIva iutestinalis. Precis Analytique des Travaux 

de I'Academie de Rouen, 1821. 
Observ.ations microscopiques sur le Conferva comoides. 

DiUw. Am. Sci. Nat., 1824. 

GirodChantrans (Julius). 

Recherches chimiijues et microscopiqnes sur les Con- 
ferves, Bisses, Tremelles, etc. Paris, 1802. 



240 



Ij 1 B L I O G K A 1' U V 



Glurup. 

Sjit'Lies, genera et ordines Algarum. Botanische 

Zeitung, 1852, p. 701. 

Goethe (Johann Wolfgang von). 

JIittheiluiii,'eii aus der rHauzeuwelt. Nova Acta, 

Boim, Bii. XV., 1S31. 

Goppert (Heinrich Robert). 

Bemerkungen iiber das Voikouimen von Pflanzen in 
lieisseu Qu«llen und iu pewiUiuIiuh warmeii Boden. 
Wiegman's Archives, 1837. 

Goppert (Heinrich Robert) tuid Ferdinand Julius 
Cohn. 

Ueber die Algen Sclilesiena. Debersiclit der Arbeiteu 
und Verilnderungen der Sclilesisehen fiesellscbaft 
liir vilterlandische Cultur. Breslau, ISOO. 

Goodsir (John). 

On the Conferva which vegetates on the skin of the 
Goldfish. Annals and Mag. Nat. Hist., vol. ix., 
1842, p. 333. 

Gravenhorst (Johann Ludwig Christian). 

Einiges aus des lufu^^o^ieuwelt. Nova Acta, Bonn, 
bd. xvi., 1832, p. 841. 

» 

Gray (John Edward). 

On the arrangement of the Families and the Genera of 
Chlorospermous Algse. Annals and Mag. Nat. 

Uist., 1801, p. 404. 

Greville (Robert Kaye). 

Scottish Cryptogamic Flora. Edinburgh, 1823-29. 

Griffith (John 'William) aiul Arthur Henfrey. 

Micrographic Dictionary, Ed. 2. Loudon, ISGO. 

Gruno'w (A.). 

Specimen Florae Cryptogams Septeminsularem Algs. 
Abhandluugen des zoolog.-botanischeu Vereins, 18iJl. 

Die Desmidaceen und Pediastreen einiger Osterrei- 
chischen Moore, nehst einigen Bemerkungen uber 
heide Familien im AUgemeineu. Verhandlungen 

der k. k. zoolog.-botanischen Gesellschaft iu Wien, 
1858. 

Ueber neue oder ungenligeud gekannte Algen. Ibid., 
18G0-G1-U2. 

Ueber die in Rabenhorsts Pecaden ausgegebenden 
Siiswasser-Diatomaceen und Desuiidiaceen von der 
Insel Banka, &c. Kabenhorst's Beitriigen, Ueft ii., 
Leipzig, 18G5. 

Hannover (Adolph). 

Ueber eine contagiiise Coufervenbildung auf dem Was- 
sersalamauder. Archiv fiir Auatouiie, Physiologie, 
und wissensoh. Medeuiu. (J. Miiller), 1839. 

Femere Erliiuterung der coutagioseu Coufervenbildung 
auf Froscheuund Wassersalamauderu. Ibid., 1840. 

Hartig (Theodore). 

Ueber die Funktionen des Zellkcrns. Botanische 

Zeitung, xii., 1S54. 

Ueber das Veihalteu des Zellkerns bei der Zellen- 
theilung. Ibid., 1854. 

Beitrage zur Entwickelungsgescliichteder Pflanzenzelle. 
Botanische Zeitung, 1S55. 

Ueber die Conjugatiou der Spirogyrea. Regensburg, 
Flora. 



Harvey (William Henry). 

Mauuul of the British Alga. 



London, 1844. 



Harvey (William Henry). — Continued. 

Index Generuni'Algarum. A Systematic Catalogue of 
all the Genera, Marine and Fresh-water. London 
ISGO. 

Phycologica Britannica, or a History of the British Sea- 
weeds. London, 184G-1851. 

Nereis Borealis Americanse. Part III. Chlorosperiueae. 
Sujithsouiau Contributions. 



Hassal (Arthur Hill). 

Observations on the genera Zygnema, Tyndaridete, and 
Mougeotia, with descriptions of new species. 
Annals and Mag. Natnr. History, &c.., 1842. 

Observations on a new group (Vesiculasperniffi), genua 
(Vesiculifera), and subgenus (Vesieulifera "coiri- 
posita) of Fresh-water Conferva", with descriptioua 
of species mostly New. Ihid., 1842. 

Observations on the growth, reproduction, and species 
of the branched Fresh-water Confervse, mostly new, 
with observations on some of the genera. Ibid., 
1S43. 

Observations on some points in the anatomy and phy- 
siology of the Fresh-water Algse. Ibid., 184S. 

Observations on the genus Mougeotia, or two new genera 
of Fresh-water Algse, and on Tyndaridea, with de- 
scriptions of species. Ibid., 1843. 

Observations on the growth and reproduction of Eiitero- 
morpha intestiualis. Proceedings of the Linuffiau 
Society of London, 1849. 

Essay on the distribution, vitality, structure, modes of 
growth and reproduction, and uses of the Fresh- 
water Confervje. Ibid., 1849. 

A History of the British Fresh-water Alg». 2 vols., 
100 plates. Loudon, 1845. 

Hawlett (Frederick). 

On the structure and circulation of Nitella transluccns. 
Intellectual Observer, Louduu, 18GG. 

Hazslinkszky (Friedrich). 

Die Algen Flora Uugarns und seiner Bundesliinder. 
Mathematische Naturwisseu. Mitiheilungen. der 
Ungarisckeu Akademied. Wisseuchaften, Pest. bd. v. 
18G8. 

HedTwIg (Romanus Adolf). 

Tremella Nostoch. Commentatio. Lipsias, 1798. 

Archiv fiir die Botanik (Ua^mer), ii. (1799-1801). 

Bemerkungen iiber das Studium und die Untersuchnng 
der Wassergewiichse, nebst Beschreibung ziveier 
neuen Conferven (Conferva globulifera und C. fenes- 
tralis) und der Spongia Rothii. Ibid., iii., 1803-5. 

Hermann (Johann). 

Botrydium argillaceura Wallr., ob Alge oder Flechte. 
Regensburg Flora, 18GS, p. 129. 

Hicks (John Bruxton). 

On Fresh-Water Algae. Microscop. Jouru., N. S., vol. 

vii. 
On the Diamorphosis of Lyngbya, Schizogonium, and 

Prasiola. Ibid., N. S., vol. i. 
On the Motionless Species (Statospores) of Vol vox 

globator. Ibid., N. S., vol. i. 
Remarks on Mr. Archer's Paper on Algffi. Ibid., vol. 

iv. p. 253. 
On the Am;eboid Form of Volvox globator. Ibid., 

1860, p. 99. 
Observations on the Gonidia and confervoid fihmients 

of Mosses, and on the relation of their Gonidia to 

those of Lichens and of certain Freshwater AlgJE. 

Trans. Linuieau Soc, 18U2, p. 5G7. 



BIBLIOGK Al'U Y. 



241 



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Ueber ein Cliroolepus mit Zoosporeubildung. Sitz- 
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Beitrage znr Algen-und Dialomeen-Kunde Sclilesieus, 
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Hobson (J.). 

Notes ou Indian Desmidese. 
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Ueber die Entstebung nnd Metaraorphoseu derniederen 
vegetablischen Organismen. Kegeusb. Flora, xviii., 
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Husemann (Theodore). 

De Animalibus et Vegetalibus in Corpora Iluniano p*ra- 
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Zeitung, s., 1852. 
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