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A HISTORY

OP THE

BRITISH

FRESHWATER AL(LE,

INCLUDING DESCRIPTIONS OF

THE DESMIDEJ; AND DIATOMACEJ.

ILLUSTRATING THE VARIOUS SPECIES.
BY

ARTHUR HILL HASSALL, M,D, LOND,

AUTHOR OF

THE "MICROSCOPIC ANATOMY or THE HUMAN BODY;"

LICENTIATE OF THE ROYAL COLLEGE OF PHYSICIANS OF LONDON;

FELLOW OF THE LINKSAN SOCIETY ;

MEMBER OF THE ROYAL COLLEGE OF SURGEONS OF ENGLAND ;
ONE OF THE COUNCIL OF THE EPIDEMIOLOGICAL SOCIETY,

ALSO OF THE BOTANICAL SOCIETY OF LONDON ;

CORRESPONDING MEMBER OF THE DUBLIN NATURAL HISTORY SOCIETY J

PHYSICIAN TO THE UNITED KINGDOM LIFE ASSURANCE

COMPANY.

IN TWO VOLUMES.

VOL. I.

LONDON:
TAYLOR, WALTON, AND MABERLY,

UPPER GOWBR STREET ; AND IVY LANE, PATERNOSTER ROW.

1852.

jiefcicatfotu

TO

JAMES SCOTT BOWERBANK, F.B.8. F.L.S,

&c. &c. &c.

DEAR SIR,

IT has long been my intention to dedi-
cate to you this humble endeavour to elucidate a
difficult and slighted department of Botany, and the
time has at length arrived for the fulfilment of this
intention.

In dedicating to you this History of the British
Freshwater Algae, and which is, I believe, the second
work which has as yet appeared, which exclusively
treats of the Algae of our fresh waters, and the only
one devoted to the consideration of the British species^
I am actuated, not by private considerations of
friendship, but entirely by public motives.

The skill which you have displayed in the micro-
scopic investigation of minute tissues, the generous

A 2

IV DEDICATION.

devotion of your time and your money to the ad-
vancement of Natural Science, and the deep love
with which you are evidently inspired for the works
of Creation, have impressed me with a strong respect
for your character, and singled you out as the in-
dividual with whose name I should particularly de-
sire to associate this Work.

I would therefore beg of you to accept of its
dedication, and believe in

The high consideration and esteem of
Yours most sincerely,

THE AUTHOR

PREFACE.

WHILE the Preface forms the first part of every work, as
the name implies, and precedes always the descriptive matter,
it is as invariably the last which is written, and the last often
to be read.

Nevertheless there are few portions of a work the endit-
ing of which is undertaken with more alacrity than the
writing of this same preface — the author's mind being
cheered by the near prospect of the completion of his task —
it may be of a difficult and an arduous task — in which the
obstacles to its successful issue were many, and the result prob-
lematical, and the hope of a suitable reward in recompence
of his toil either in the form of approbation, if deserved, or
money, should the undertaking be of a sufficiently popular
character to lead to so substantial a termination.

There is also another reason which renders the writing of
the preface an agreeable occupation. It is the opportunity
which it affords to the writer to render to those who have
aided him in his enquiries the acknowledgments which their
liberality and their kindness so strongly claim.

To Sir "W. J. Hooker, Dr. Greville, Mr. Borrer, Mr.
Harvey, and the Rev. M. J. Berkeley, names prominently
inscribed in the records of the successful cultivators of natural
science, the pursuit of which is the most peaceful and the
most pleasant of all employments, I am deeply indebted.
The two former gentlemen liberally placed at my disposal
their valuable collections of freshwater Alga, and Mr. Harvey
and Mr. Berkeley communicated to me numerous unique
specimens accompanied by valuable remarks.

VI PREFACE.

To Mr. Jenner, one of the most untiring and successful
of Cryptogamic botanists, and whose excellent Flora of
Tunbridge Wells is I believe the only one which contains
any thing like a complete list of the freshwater Alga, I am
likewise greatly indebted for numberless recent specimens of
AlgcBy which otherwise I had never seen, as well as for many
original and accurate remarks.

To Dr. G. J. Allman, my highly valued friend, and the
talented Professor of Botany in the Dublin University ; to
Dr. Johnston, of whose valuable instructions in zoophy-
tology I entertain a grateful remembrance, and to be the
pupil of such a master any man might be proud ; to MM.
Montaigne, Areschoug, Decaisne, and Mr. Shuttleworth,
whose residence in foreign lands precluded unfortunately
frequent communication, and from whom therefore I regret
that I have not been able to obtain more of that information
of which they are so largely possessed ; to Mr. Thwaites,
of Bristol, Mr. Sidebotham, of Manchester, Dr. Dickie, of
Aberdeen, Mr. M'Colla, of Ireland, and Mr. Thompson, of
Belfast, my warmest thanks are due.

I must not forget also to acknowledge the literary assist-
ance which I have derived from Mr. Coppin, of Trinity
College, Cambridge, nor omit to mention the deep obliga-
tion I am under to a lady for the devotion of much time to
the shading of many of the plates.

To Mr. Ross, the eminent optician, with one of whose in-
struments most of the nicer observations were made, my
acknowledgments are likewise due.

To the Subscribers also to this work I feel much indebted ;
their generous patronage has relieved my mind of consider-
able anxiety, for it has removed all pecuniary risk to myself,
if it has not insured a reward of the same nature.

Norland Villa, Addison Road North, Notting Hill.
July, 1845.

LIST OF SUBSCRIBERS,

RadclifFe Library, Oxford. Through
Dr. Kidd, Reg. Prof. Med.

University, Edinburgh.

Royal Dublin Society.

Edinburgh Bot. Society.

University, St. Andrew's.

University, Aberdeen.

Wernerian Society.

Nat. Hist. Society, Dublin.

Belfast Library. Through W.
Thompson, Esq.

Microscopical Society, Dublin.

The Rev. M. J. Berkeley, F.L.S.
3 copies.

J. S. Bowerbank, Esq. F.R.S. 3 copies.

L. W. Dillwyn, Esq. F.R.S. 2 copies.

W. Borrer, Esq., F.R.S. 2 copies.

M. J. Decaisne. 2 copies.

Miss Currer. 2 copies.

G. W. Braikenridge, Esq. 2 copies.

R. J. Shuttleworth, Esq. 2 copies.

Sir John Phillipart. 2 copies.

Sir. W. J. Hooker, V.P.L.S.

Dr. Greville.

Dr. Johnston.

J. C. Durnford, Esq.

Major Martin.

Professor Henslow, F.L.S.

Professor Balfour, F.L.S.

Professor E. Forbes, F.L.S.

T. Bell, Esq. F.R.S. and L.S.

J. Milne, Esq., F.L.S.

Dr. Dickie.

R. Embleton, Esq.

Rev. N. B. Young, M.A.
Rev. T. Salway, M.A.

C. C. Babington, Esq., M.A.
Rev. J. Henderson, M.A.
J. Janson, Esq., F.L.S.
Dr. Drummond.

J. Coppin, Esq., B.A.
J. Brown, Esq., F.B.S.E.
J. Dickinson, Esq., M.D.
J. G. Children, F.R.S.
Rev. W. H. Coleman, M.A.
J. F. Young, Esq., M.D.
F. Whitla, Esq.
H. Collins, Esq.
H. Bull, Esq.

D. Turner, Esq., M.A, F.R.S.
W. A. Leighton, Esq.

W. Hanson, Esq.

— Sharpe, Esq.

H. W. Palmer, Esq.

W. O. Newnham, Esq.

R. Hudson, Esq.

H. B. Fielding, Esq. F.L.S.

R. Hassall, M.D.

Mrs. Griffiths.

Miss Cutler.

A. Ross, Esq. M.M.S.L.

Dr. Leeson.

Professor G. J. Allman, M.D.

Dr. J. F. Davis.

Capt. T. Jones, M.P. F.L.S.

J. Minto, Esq.

W. Gourlie, junior, Esq.

Hon. W.H. Dawney, M.P. F.L.S.

Vlll

LIST OF SUBSCRIBERS.

Dr. Sharpey.

Lady Agnew.

J. A. Hankey, Esq., F.L.S.

J. Woods, Esq., F.L.S.

W. H. Harvey, Esq.

Rev. W. S. Hore, M.A. F.L.S.

G. E. Dennes, Esq., F.L.S.

W. C. Trevelyan, Esq.

General Irvine.

G. H. K. Thwaites, Esq., M.E. B.S.

C. Richardson, Esq.

G. S. Gibson, Esq.

E. J. Quekett, Esq., F.L.S.
Mrs. Stewart.

Dr. Graham, Prof. Bot. Edin.

J. Reynolds, Esq. Bot. Soc. Lond.

R. Ball, Esq., M.R.I.A.

S. Wallis, Esq., M.B.S.L.

J. Straker, Esq.

J. Hogg, Esq., F.L.S.

W. B. Carpenter, M.D. F.R.S.

H. Deane, Esq.

R. Balloch, Esq.

T. J. Taylor, Esq.

Miss M. Ravenhill.

S. Simpson, Esq. F.B.S.E.

G. Booth, Esq.

J. Riley, Esq., M.B.S.L.

D. Stock, Esq., M.B.S.L.

Mr. E. Jenner, A.L.S.

F. G. P. Neison, Esq., F.L.S.
J. Pym, Esq.

J. T. Mackay, Esq., M.R.I.A.
Rev. L. Jenyns, F.L.S.

G. B. Knowles, Esq., F.L.S.
Dr. Percy.

R. D. Alexander, Esq., F.L.S.

W. Osborne, Esq., F.L.S.

R. Ranking, Esq., F.L.S.

W. Bean, Esq.

D. Moore, E&q., A.L.S.

Dr. Pollexfen.

F. Stokes, Esq., F.R.S. and L.S.

Rev. N. Rolfe, A.M.

G. J. Lyon, Esq.

W. J. Horry, Ph. D.

R. J. N. Streeten, Esq., M.D.

W. Andrews, Esq , Secretary Dublin

Nat. Hist. Soc.
T. F. Bergin, Esq.
W. H. Cullen, M.D.
Sir. O. Mosley, Bart. F.L S.
T. B. Hall, Esq., M.L.B.S.
Baron Delessert.
- Webb, Esq.
W. W. Reeves, Esq.
J. Dalrymple, Esq.
G. M. Hutton, Esq.
J. Just, Esq.
J. Sidebotham, Esq.
R. A. Tudor, Esq.
R. Bell, Esq.
G. Rogers, Esq.
J. Hardy, Esq.
— Bladon, Esq.
- G. Blyth, Esq.
Sir J. Murray.
J. Garle, Esq.

Thos. Edmonstone, jun., Esq.
J. B. Estlin, Esq., F.L.S.
Sir P. G. Egerton, Bart., F.L.S.
J. Scouler, Esq., M.D. F.L.S.
G. P. Wright, Esq.
J. Lister, Esq.
J. W. G. Gutch, Esq.

E. Forster, Esq., V.P.L.S.

R. Robinson, Esq., M.D. F.L.S.

F. Eagle, Esq., F.L.S.

W. K. Loftus, Esq., F.G.S.

F. Sopwith, Esq.

A. Henfrey, Esq., F.L.S.

Dr. Lindley, Ph. D. F.R.S. F.L.S.

Dr. Knapp.

lobert Wigham, Esq.
Robert Callwell, Esq.

INTRODUCTION.

AT the period when the researches hereafter to be detailed
were undertaken with a view to publication, viz., in the
spring of the year 1840, no department of Cryptogatnic
Botany was in so unsatisfactory and obscure a state as that
of the freshwater Algce ; the works and memoirs, compara-
tively few in number, which had then appeared, either in this
country or on the Continent, abounding with descriptions
incomplete, inaccurate, or repetitions of the same productions
and facts under different forms and appearances.

That such should have been the case is not so surprising,
when the minuteness of the objects composing the majority
of this fertile class of Nature's exhaustless works is considered
(the individual parts of many of them being more slender
than the human hair), and when, also, the imperfection of
the microscopic instruments until recently employed in their
investigation, and their changing and fragile character, are
taken into account, these circumstances rendering a patient
and long-continued study of them necessary. It nevertheless
must be regarded as somewhat remarkable, that a field so
rich in discovery and of such high interest, until very lately,
should have been so little explored ; and that such would
have been the case, was certainly not in accordance ivith the
expectations of Vaucher when he penned the following
remarks in the introduction to his eloquent and admirable

B

INTRODUCTION.

"Histoire cles Conferves d'Eau Douce," — admirable, when the
epocli at which it was undertaken, and the means at his disposal,
are considered. " I wish," he says, at p. 8., " that those who
love Botany may see what are our riches in this respect, and
what are the discoveries reserved to their perseverance :
now that the way is open, more persons should engage them-
selves in the study of these objects, and they should be more
rapidly studied. If this work excites the attention of the
public, there should appear on all sides observations on new
Conferva and there will be announced, perhaps, productions
more singular than those which I describe. This taste for
research will not be confined to this one genus, but it will
extend to other neighbouring genera, which equally require
to be studied ; and this beautiful part of Botany will be in-
sensibly drawn from the confusion in which it has for so long
a time been found."

An additional reason why the knowledge of the freshwater
Algce, and particularly the Confervoid division of that tribe,
should for so long a time have remained in such a confused
and imperfect state, consisted in the want of a due appreciation
of the value of the characters founded on their reproduction,
these being of more importance, in the establishment of the
different families, genera and species, than all the other signs
and characters derived from attention to other conditions and
appearances of these plants. To a right appreciation of the
importance of attention to the reproduction of the Conferva
it is that the superiority of Vaucher's " Histoire des Conferves
d'Eau Douce, " is mainly owing, over other works on the same
subject, that close and amiable observer having made — and he
was the first, and almost the only one to do so — a knowledge
of their reproduction his chief aim and study. Thus the
majority of the earlier observers, and some even of recent
date, have deemed it sufficient to describe any plant of this
class merely from the appearance which it presented on a
first examination, without any reference to the stage of de-
velopement or condition of that plant ; and have of course
expected that the productions thus imperfectly recorded
should have been recognized with facility by subsequent in-

INTRODUCTION. 3

vestigators, and handed down to posterity. Such expecta-
tions, however, it is impossible to realise; and I agree with
Vaucher in thinking, that the wisest course to adopt would be
(except in some few cases, where the productions can with cer-
tainty be determined by other characters,) to notice only those
species whose reproduction has been satisfactorily made out.

In the present work, the necessity for which is in a
measure indicated by the preceding remarks, the characters
developed in the state of reproduction are relied upon, in the
framing not merely of the families and genera, but also in the
definition of species, for which they are even more valuable.

In this Introduction it is not intended that a full descrip-
tion should be given of the different modes of reproduction
and of the structure of the freshwater Alga, the details of
these coming under consideration with more propriety when
the divisions into families, genera, and species are treated of.
The general particulars of each will, however, be now noticed.

Linnasus supposed that all vegetable productions owed
their perpetuity to sexes : he did not, however, assign in his
system any fructification to the Conferva. Had Linnaeus,
nevertheless, been aware of the highly curious and interesting
facts which more recent investigation has made known, viz.,
of the phenomenon of the union of two cells, either in dif-
ferent or in the same filaments, which so frequently occurs
amongst the Conferva (see Plates 30 — 50. and 33.), he would
doubtless have regarded this commingling as not merely
strengthening, but proving the correctness of his views of the
sexual character of all plants. But it is to be questioned
how far the fact just alluded to would bear any such inter-
pretation, its tendency in support of the opinions of the illus-
trious Swede being completely neutralised by our acquaintance
with other facts, and chiefly with this, viz., that in a consi-
derable proportion of freshwater species, and probably in the
entire of the marine Conferva, no such conjunction of filaments
or commingling of the contents of two cells occurs, all the re-
quisites for the continuance of these being indisputably con-
tained within each cell, no exterior organs of reproduction ever
having been discovered in the vast majority of these. The

B 2

4 INTRODUCTION.

exact similarity of the contents of the different cells, — no
difference being detected, even with the assistance of the most
powerful glasses, — and the principal mode of growth of the
Conferva, by the extension and repeated sub-division of the
primary cell, — would tend to lead likewise to a similar con-
clusion.

Notwithstanding the difficulties which lie in the way of
regarding each cell of a Conferva as the representative of a
sex, the frequency with which the phenomenon of union of
the filaments, and commixture of the contents of two cells,
takes place, cannot be regarded otherwise than as most
curious, though the purpose to which it is subservient is so
obscure. It may be, that it merely serves to bring a number
of the reproductive granules into contact, and which, becoming
subsequently clothed with a membrane, are thus the better
preserved until the proper time for their germination arrives.

Another circumstance opposed to the sexual view as re-
gards distinct cells, is that, in those genera even in which
either the cells or their contents unite, exceptions occur in
which there is an absence of conjugation of the filaments,
and commingling of endochrome or vesicular contents of the
cells ; and in other cases there is conjugation, but no mixture
of the endochrome of the united cells.

Thus, so far as can be presumed, the information already
acquired would appear to be opposed to the belief in the
existence of sexes as applied to cells in the Conferva. A fer-
tilization of the sporules does doubtless occur ; and this I
believe to be effected through the agency of the following
structure, described, nearly as below, in the " Annals of Natural
History," vol. xii. p. 20. In this description it will be seen
that a double office has been attributed to it; I am now
induced to limit its use to the one, the important one, of
fertilization.

From the high developement of the cells of many Alga,
both marine and freshwater, as well as from their extreme
transparency, in many species, it might have been supposed
that the first discovery of those curious organs, termed cyto-
blasts, which exercise an influence so mysterious on the de-

INTRODUCTION. 5

velopement of cells, and whose presence in cellular*structure
is so constant as to lead to the suspicion that the association
of the two organisms is universal, would have been made in
this extensive tribe of Nature's wondrous works ; so far, how-
ever from this being the case, they have not as yet, so far
as I can learn, been noticed in any species of Alga; a
description of them, therefore, as they occur in two genera of
freshwater Conferva, Zygnema and Vesiculifera, cannot fail
to be of interest.

In the first of these genera, Zygnema, their structure is
exceedingly complicated.* Each cytoblast is solitary, and
usually occupies a central situation in each cell of a Zygnema.
It consists generally of two membranes, but sometimes
there are three ; the innermost of these being either circular
or elliptical, (the form varying with the species itself, as well
as its condition,) and presenting a nucleated appearance ; and
all are separated from each other by distinct intervals, which
are filled with fluid. The surface of the enclosed membrane
or membranes is smooth; while that of the external is ren-
dered irregular by the giving off of numerous tubular pro-
longations or radii, which terminate in the spiral threads
formed by mucus, endochrome, and large bright granules,
which I regard as the unfertilized zoospores.

Wishing to have a corroboration of my views respecting
the structure of the cytoblastic organ described above, and also
to learn as much respecting its anatomy as possible, I for-
warded a specimen of Zygnema nitidum to that able and most
obliging observer, J. S. Bowerbank, Esq., whose opinion of
its structure exactly coincides with my own, that gentleman
having in particular satisfied himself of the tubular nature of
the prolongations sent off by the external membrane, and of
their termination in the spiral threads.

The structure of this curious organ explains with apparent

satisfaction one of the offices which it is destined to discharge,

viz., that of a laboratory or stomach, in which the materials

necessary for the growth and vitality of the cell and its con.

tents are received and digested, and from which they are

* See Plate 17. Jig. 1, 2 3,

B 3

6 INTRODUCTION.

conveyed, by means of the tubular radii, to those organs by
which the materials are to be assimilated.

The cytoblast, therefore, is at first fixed in the centre of
the cell by the prolongations which proceed from it : but it
happens, that at a certain epoch these radii disappear, and
then the cytoblast floats freely within the cavity of the cell ;
the disappearance of the rays, the cessation of the growth of
the cells, and the assumption of the characters of reproduction
being almost contemporaneous, or, at any rate, events imme-
diately consecutive on each other, and the two latter being
readily accounted for by the disappearance of the radii.

The circumstance of the increased developement of the
cytoblastic body subsequent to the removal of the radii, gives
weight, to the opinion that this organ has yet another office
to perform, in addition to that of presiding over the growth
of the cells ; for were it not so, it might be expected that on
the disappearance of the rays it would shrivel up, and at
length become absorbed, as is the case with other organs,
their allotted duties having been performed : and the office
which I would attribute to, it, is one even of more importance
than that previously remarked upon, it being no other than
the fertilization of the brilliant granules entering into the
formation of the spiral threads, and which I regard, as before
noticed, as the unfertilized zoospores.

The adoption of the view which supposes the fertilization
of the reproductive bodies by means of the organ whose
complicated anatomy has been dwelt upon, would have the
effect of removing some grand difficulties in the way of the
complete understanding of these most interesting productions.
Thus, first, by furnishing a definite organ whereby fertiliza-
tion is occasioned, it removes the inability which has hitherto
been felt to explain in what way the intermingling of bodies,
in all respects so similar in organization and appearance as
the bright granules of the Conferva seem to be, can be re-
garded as giving origin to fertility : secondly, it does away
with the anomaly, which has always appeared to me so strange,
that a combination of the matter of two cells should invari-
ably take place in certain divisions of the Confervoid tribe of

INTRODUCTION. 7

productions ; while in other divisions of the same tribe, which
could not be supposed to differ fundamentally from the
former, no such phenomenon has hitherto been recognized ;
by shewing that this combination is not an essential to the
perpetuation of the species : and thirdly, it explains the per-
manence of species which have perished before union of the
endochrome and formation of spores have taken place.

I have detected cytoblasts in numerous Zygnemata, but
the best species in which to examine them are the larger
kinds, such as Zygnema maximum, Z. nitidum, and Z. belle.
Of the genus Vesiculifera, I have also found it in several
species : they cannot always be seen in these, owing to the
cells not being so transparent. I doubt not, however, but
that they are general in it, as well as other genera of Alga,
whether marine or freshwater. In this genus it is but a
simple vesicle ; at least, I have never observed it in any other
state. (See Plate 17. Jig. 6.)

The Rev. M. J. Berkeley has kindly favoured me with an
abstract of a paper by Hugo Mohl on the genus Anthoceros,,
published in 1839, and inserted in " Linna3a," vol. xiii. p. 273.,
in the cells of which an organ occurs bearing a considerable
external resemblance to the radiated structure met with in
the cells of Zygnema.

The following is a brief outline of the mode of formation
of this structure in the genus Anthoceros. When an imma-
ture cell of one of the species of this genus is examined, a
portion of its interior is seen to be occupied by a layer of
green granules, through which may be seen a cytoblast, the
other portion of the cell being colourless. Treated with
iodine, the layer formed by green granules, as also the colour-
less part of the cell, becomes yellow, showing that the whole
is really lined with a sort of quasi membrane. Gradually the
green layer becomes concentrated into two masses, which
commence to advance more and more towards the middle of
the cells, and the edges of these masses spreading in various
degrees over the inner wall of the cell, leave intervals of
various sizes, which give to them a cellular appearance.
" The nucleus, or cytoblast," Mohl observes, " has no part in

B 4

8 INTRODUCTION.

this formation. Frequently it is so concealed beneath the
green granular mass, that it cannot be seen without some
trouble : sometimes it lies near to or between both divisions
of the green mass, and then more easily comes into sight ; but
at the same time it is observable, that it remains unaltered,
and is foreign to the whole of the slimy structure described
above. The latter seems only so far to have a relation to it,
that its point of concentration is always at the place where
the nucleus lies, and indeed between it and the walls of the
mother cell."

Subsequently, the two masses become divided into four,
and the reticulated, appearance produced by the spreading of
the masses subsides into radii, which are similar in aspect to
those emanating from the cytoblast in the Zygnemata, each
arising separately from the masses, and terminating on the
inner surface of the cell. Finally, each radiated mass becomes
a perfect spore or cell, separated from each other by distinct
cellular walls, in which changes similar to those just described
take place for the production of other spores. The great
similarity in the structure of the incipient spores in the genus
Anthoceros with that of the radiated organs in Zygnema,
would lead to the supposition that they were identical in their
nature ; so far, however, from this being the case, I consider
that all analogy between them terminates with the outward
resemblance. The difficulties in the way of regarding the
structure in Zygnema as an incipient germ or spore, appear to
me to be insuperable ; for the question would immediately
arise, wherefore is it, that since the contents of two cells
generally go to form a single spore in the genus Zygnema,
and since this radiated organ is present in every cell, that the
one is suppressed, while the other is destined to give birth to
the future Zygnema ? Supposing, however, a satisfactory
solution of this difficulty to have been made, still another
arises. It is far from being an incontrovertibly established
fact, that the elliptical body formed in Zygnema by the con-
centration of the matter of two cells, and usually denominated
a spore, does really contain but a single germ. It is far
more consistent with known facts to suppose that they are

INTRODUCTION. 9

sporangia filled with fertilized sporules ; for this is .certain,
that numerous zoospores are formed within each cell, and
which may even be seen through the membrane of the spo-
rangia themselves by the aid of a good glass, these zoospores
being also identical with the brilliant granules of the Algce.

The highly interesting observations of Mohl on the genus
Anthoceros, the accuracy of which is in no respect questioned
by me, do not therefore occasion any modification of the
views expressed of the functions of the radiated organ in
Zygnema.

In October, 1843, I learned that Kutzing, in his " Phy-
cologia Generalis," published in August of the same year,
had noticed and figured the cytoblastic organ just described ;
and that Meyen had also previously observed it ; where,
however, this is recorded, I cannot ascertain. Kutzing thus
speaks of it : " Meyen has discovered in the Spirogyrce a
a peculiar central organ. In Sp. nitida it occurs in the middle
of each cell, but is here only to be easily seen in such cells as
are larger than ordinary ; and, from that cause, present more
lax spiral bands. By employing the tincture of iodine, one
observes these bodies more easily. Each organ becomes,
together with the delicate threads to which it is appended,
coloured brown by it. It consists of a (Schwal-gedriicken)
slightly compressed goniidium, through which may be seen a
peculiar nucleus in the midst, and a number of very fine
filaments, which extend from it, in a stellate manner, on all
sides, and are fastened internally to the spiral bands. At
the place where they are attached to these last, their points
become somewhat expanded. By means of these stellate
filaments the central body becomes suspended in the centre
of the cell. M. Schleiden calls these bodies cytoblasts, and
is of opinion that the so-called nucleus threads, to which they
are attached, are nothing else than very delicate streams of
sap, which proceed from the cytoblast, and return to it.
Without wishing to throw doubt upon this pretended flow
of sap, I must, nevertheless, own that I have not been able
to observe it with a microscope of Schiek's or Phoflschen's
manufacture ; but I have observed that the rays of Meyen's

10 INTRODUCTION.

central organ are really sometimes more than mere streams ;
at least, that they are mucous threads, since they become
tinged brown with the tincture of iodine, and do not in the
least alter either their form or position. Schleiden has also,
at the same time, observed reticulate, anastamosing little
streams upon the central wall of the cell, but especially at
the free ends where the green spiral bands cease, and the
cells consequently become lighter and more transparent.
This appearance, also, has not yet presented itself to me. J
have, however, more than ten years ago, seen in the Zygne-
mata, motions of very little granules, which resemble those
which I have already pointed out in Oedogonium vesicatum
and O. capillare. They extend sometimes throughout the
entire inner space of the cell, and are especially evident in
freshly broken-off terminal cells. That the cytoblast really
occasions this motion, I doubt, because it occurs in all
the other cells of the Alga which do not possess the central
organs."

Having thus described what I conceive to be the organ
whereby the reproductive germs are fertilized, we come now
to consider these bodies themselves, which, according to
some observers, are twofold — zoospores and spores. We shall
speak first of the former. When a portion of a Conferva,
for example a Vesiculifera, in an early condition of its growth
is placed beneath the microscope, in each cell are observed
numerous spherical granules, each having a dark central
nucleus, and the size and amount of these varying ex-
tremely ; and all being, at this period, connected with each
other by a tubular or vascular network.* As the species ap-
proaches to a state of maturity, these bodies will be seen to
have undergone a considerable increase of size and change of
form, they now being no longer spherical, but pyriform, the
inflated portions being filled with endochrome, in the midst of
which one or two incipient germs can, even at this early
period, be observed, and the apices, or, as they have been

* For an account of this, see paper by me in " Annuls and Magazine
of Natural History," vol. xii. p. 25.

INTRODUCTION. 1 1

termed, the rostra, being transparent; near which kalso is
sometimes observed a pinkish spot similar to that which is seen
in the infusory animalcules. The vascular network has now
disappeared, and the zoospores lie detached in the cell. At
length the granules become perfected, and they are now seen
moving restlessly about the interior of the cell, frequently
striking against its walls, as though anxious to escape from
the confinement of their narrow cell, and to rove about, inde-
pendent beings, through the waters, in search of an ap-
propriate abiding-place.. Having escaped from the cells,
which they are enabled to do, not as Agardh supposed, by
the multiplied knockings of their beaks against its sides,
whereby its fibres become displaced, but either by rupturing
its walls, through their increased developement, as in Lyny-
bya, &c., or by some special provision, as in Vesiculifera,
Zygnema, &c., they fall into the water, through which they
speedily begin to move hither and thither ; now progressing
in a straight line, with the rostra in advance ; now wheeling
round and pursuing a different course ; now letting their
rostra drop, and oscillating upon them, like (to compare
small things with great) balloons ere the strings are cut, or
like tops, the centripetal force being nearly expended ; now
altogether stopping, and anon resuming their curious and
eccentric motions. Truly wonderful is the velocity with
which these microscopic objects progress, their relative speed
far surpassing that of the fleetest race -horse. After a time,
however, which frequently extends to some two or three
hours, the motion becomes much retarded, and at length,
after faint struggles, entirely ceases, and the zoospores then
lie as though dead: not so, nevertheless ; they have merely lost
the power of locomotion; the vital principle is still active
within them, and they are seen to expand, to become par-
titioned, and, if the species be of an attached kind, each zo-
ospore will emit from its transparent extremity two or more
radicles, whereby it becomes finally and for ever fixed. Strange
transition, from the roving life of the animal to the fixed
existence of the plant ! In exact correspondence with this,
is what occurs with the Zoophytes.

12 INTRODUCTION.

So extraordinary were the statements from time to time
put forth relative to the spontaneous motion of the reproduc-
tive germs of many Alga — a class of productions always re-
garded as vegetable — considered to be, that many observers,
and some do even now, refuse to give their belief to their
accuracy. So numerous are the observers who have witnessed
the singular motions above recorded, that the facts announced
in reference to them must be regarded as amongst those
which ought to be generally received and adopted. For a
long time I myself doubted the reality of the existence of
zoospores ; I have now satisfied myself on this head, having
repeatedly witnessed their movements in very many Conferva,
but never as yet in any species belonging to the conjugative
tribe of Alga ; in which, however, Agardh declares himself
to have witnessed it. For extended observations on the
motion of the zoospores of the Alga, see, in " Annalcs des
Sciences Naturelles (Botanique), 1836," a memoir " Sur la
Propagation des Algues. Par J. G. Agardh. Extrait."

It is surprising that, out of the number of those
who now study the Alga, so few should have witnessed
the singular motion of the zoospores. The spring is the
best season for observing these bodies. If, at that time,
a number of Alga, collected indiscriminately from different
localities, are placed in a vessel of water over-night, and
allowed to remain undisturbed until the morning, usually
there will be noticed on the surface of the water a thin
green pellicle or scum: this, when examined, will be found
to consist of the zoospores of different species of Conferva,
in all possible stages of developement. Their motion is
most active early in the morning; and they would appear
to shun the light, as they are generally met with on the
side of the vessel farthest removed therefrom.

Next in interest to the discovery of the zoospores them-
selves, and for which science was mainly indebted to the
researches of J. G. Agardh, is that of the means by which
their motion is effected. J. G. Agardh declared that it
depended upon the movement of a prolongation or beak,
with which each zoospore was said to be furnished ; others

INTRODUCTION. 13

have endeavoured to account for it by reference to the
principle t)f endosmosis ; but neither of these explanations
can be deemed satisfactory ; the true cause of it depending,
according to the researches of M. linger*, and M. Gustave
Thuretf, upon the presence of cilia, similar to those of the
infusory animalcules. The following abstract of M. Thuret's
paper, on a subject of such high interest, cannot fail of
being acceptable.

The spontaneous movement of the spores of the Algaj
has been viewed by a great many observers. In certain
cases it is apparent to the unaided sight ; but until now, as
declares M. Dujardin, in his " Observateur, ou Microscope "
(Paris, 1843), they have not been able to discover by what
means the spores swim in the liquid. Nevertheless, the cilia,
or filiform tentacles, which serve them as locomotive organs,
do not appear to me more difficult to see. than the filaments
discovered by M. Dujardin in a great number of Infusoria ;
and if they have escaped an observer so practised, it is,
without doubt, because he has not continued his researches
with enough of perseverance, or else, that he has not made
them in all the conditions necessary for success.

In fine, the movement of the spores continues for some
hours, during which the locomotive organs are in incessant
agitation, and in consequence very difficult to distinguish.
The use of coloured infusions cannot but detect their exist-
ence. When the spore stops, the locomotive organs dis-
appear very quickly, without leaving any traces, and some
time after, the germination commences. It is necessary
then to seize the precise instant when the spores cease to
move; or, to make the chances of success greater, it is
necessary, when one finds those which move with vivacity,
to put them in contact with a reagent the action of which is
too feeble to alter their form, but enough to stop their
movements. Opium and iodine appear to me the agents
the most proper to obtain this result.

* Die Pflanze in Momente der Thierwerdung. Wien. 1843.
•f Researches sur les Organes Locomoteurs des Spores des Algues.
Par M. Gastave Thuret. Ann. des Sciences Nat., Mai et Juin, 1843.

14 INTRODUCTION.

The organization the most simple, is that which is found
in the Conferva; ; and I have reason to think that it repre-
sents a type general to the spores of the Alga. I have
studied it in the Conferva glomerata and C. rivularis ; the
spores are altogether alike in both species, and I have seen
in the one all that I have observed in the other. Their
form is turbinated; the thin extremity, deprived of endo-
chrome, to which the name of rostrum or beak has been
given, bears two cilia or filiform tentacles, the length of
which surpasses that of the spores ; they are the locomotive
organs. (See Plate I. Jig. 1, 2.) The spore moves ordinarily
with the beak in advance, and turns about in the water with
a movement of trepidation, which recalls to mind that which
I have observed in the animalcules of the anther of Chara :
this analogy applies itself more closely from the resemblance
of the organs of locomotion. From time to time the spore
suddenly stops ; and often, likewise, it twirls round upon its
great axis. The light exerts a marked influence upon the
direction of its march. A small quantity of the watery
extract of opium is sufficient to arrest their movements.
The tentacles are then easily distinguished by a linear power
of 240 times (la vue moyenne etant comptde a 25 centi-
metres). They are rendered still more visible by employing
the alcoholic tincture of iodine, more or less weak. If after-
wards the spores are left to dry between two plates of glass,
the tentacles will not be observed to be altered by the
drying, but they come in a manner more satisfactory and
positive upon the bottom of the microscope, because they
are placed in a medium less refracting. It is necessary to
remark, moreover, (and this observation applies to all spores
of the Alga which are prepared in this manner,) that, the
spore contracting itself by drying, the tentacles appear a
little longer.

It is in the morning more particularly that the greatest
number of spores of Conferva are found in action. Those
which one observes after mid-day are for the most part
stopped, or have already commenced to germinate. The mo-
tionless spores all present, towards the beak, a point coloured

INTRODUCTION. 15

»

red, which adds still further to their resemblance to certain
Infusoria, especially to some Thecamonadiens.

The Chcetophora elegans (var. pisiformis) presents to us
a more complicated organization. The beak bears four loco-
motive tentacles, instead of two. These spores are very small
also, and difficult to observe. (See Plate ~\..Jig. 10.)

In the Proliferce ( Conferva vesicata, tumidula, and alternata},
the organization is still more complicated ; and this difference
of the spores is an additional motive for separating these plants
from the real Conferva. Two species of this kind have served
me in my researches : the first seems to be referrible to Pro-
lifera rivularis of M. Leon Le Clerc* ; and the other, a great
deal smaller in all its parts, to Prolifera Candollii of the same
author. Both have the spores, the beak is rounded, and bears
a crown of filiform tentacles (see Plate \.fig. 13. 18.), which
opium or iodine renders motionless. Their movements are
very nearly the same as those of the spores of the Conferva,
but much more rapid, by reason of the greater powers of their
locomotive organs. When these spores are disposed to ger-
minate, they fix themselves by the beak to all tendrils which
float in the water, and throw out prolongations or root-like
clawa, which render them very adherent. The filaments of
Prolifera, or Conferva, are often rendered rough with this
kind of parasitic vegetation. This fact, ill understood, caused
the creation, by Vaucher, of the erroneous appellation of Pro-
lifera. If the plant is removed from the water at the
moment of the emission of the spores, they fix themselves
around the crystals produced by the evaporation of the liquid ;
and when the germination commences, one may see every
little crystal charged with a multitude of spores which
radiate in all directions.

The Vaucheria, estranged from the genera of which we
have been speaking, by its structure, and by the mode of the
formation of its spores, is distinguished equally by the dis-
position of its locomotive organs. The spore is an ovoid

* Sur la Fructification du Genre Proliferc. (Memoires du Museum,
torn. iii. p. 462. pi. 23.)

16 INTRODUCTION.

vesicle which attains the thirtieth of a millemetre in length.
It is entirely invested with cilia, rather short, the vibration
of which determines the advancing movement of the spore.
M. linger first pointed out these organs in a great and cu-
rious work recently published.* The interest of the subject,
and the facility of procuring each day fresh specimens, from
January until May, determined me to study that plant with
care. I proceed to give the result of my observations.

The tufts of the Vaucheria ( V. clavata) are formed of a
network of filaments, cylindrical, branched, continuous, which
enclose the green granules (endochrome) and colourless mu-
cilage. At the period of the formation of the spore, the
extremity of its filaments swell up in the form of a club, and
the green matter becomes there condensed, so as to assume a
blackish tint. (See Plate II. fig. 21, 22.) Near the base of
the enlargement the granules are seen separated the one from
the other, leaving an empty space as if the mucilage had
condensed itself in its turn, and driven the granules above
and below. This displacement continues until the endo-
chrome forms well-defined lines on each side. (See Plate II.
Jig. 23.) Then the great change takes place, which consists
in the operation which we are about to describe, viz. the
separation of the mother plant and of the reproductive body,
subsequently clothed with a membrane proper to itself
(epispore), possessing a distinct organization.

Although this phenomenon continues but for a few
minutes, it is easy to observe it, since the movement of the
granules is almost insensible. Moreover, the separation is
not discontinued after the first time. I have seen the
operation thrice repeated upon the same filament.

The spore then takes the form of fig. 24., that of an elon-
gated oval vesicle, whose two divisions are nearly black by
the condensation of the endochrome, the inferior division
containing much less endochrome. It is then that the crisis
approaches : the superior extremity suddenly becomes pro-
truded, the granular fluid empties itself into the protruded

* Die Pflanze in Moraente der Thierwerdung. Wien. 1843.

INTRODUCTION. 17

portion which quickly increases in volume, so that the opposite
extremity becomes separated from the filament. At the same
time the spore commences to turn on its great axis in such a
manner, as that all the granules which it contains are seen to
pass rapidly from right to left, and from left to right, as
though they moved in the interior of a transparent cylinder.
The operation by which the spore endeavours to escape
occasions a very marked contraction ; but in some few
instances it succeeds in disengaging itself, and springs with
rapidity into the surrounding liquid. The colourless part,
which corresponds to the beak, is always directed in advance.
The spore does not cease to turn upon itself, but its progress
is somewhat regular, quicker or slower in one direction or
another ; in general, it quickly reaches the edge of the glass as
though it tried to escape'; sometimes it stops ; then in an
instant afterwards it resumes its course. The epispore from
which the cilia proceed describes a large granular areola.
As to the cilia themselves, they are invisible by reason of the
rapidity of their movement ; but we may judge well of their
action by putting the spore in an infusion of carmine, indigo,
or gum water, &c. Nothing is more curious than to follow
its progress in a strong infusion of carmine for example.
The coloured granules through which the spore makes its way
are driven with force by the motion of the cilia; a rapid
current is established on each side of the spore, and a long
track is described after it. When it meets with an obstacle,
such as the filaments of Zygnema or Vaucheria, it becomes
deformed (or is put out of proportion) ; but the motion of the
cilia is not arrested. It is also the same when it is com-
pressed even to the extent of producing the extravasation of
the endochrome ; the vibration of the cilia continues in the
part not injured. I have observed many times the emission
of the spore in a coloured infusion, and then noticed that the
agitation of the granules by the motion of the cilia is not
felt until about a fourth part of the spore has been released.

It is necessary, in order the better to see the cilia, to
arrest them by means of some reagent, such as opium, iodine,
the proto-nitrate of mercury, &c. The effects of the watery

c

18 INTRODUCTION.

extract of opium are very remarkable : the motion is retarded
gradually, so that the play of these organs can be well dis-
tinguished. The iodine water, although it contains but an
extremely small quantity of iodine (73^), arrests suddenly
the cilia, which become plainly visible. The alcoholic
tincture of iodine may also be employed, but very weak. If
afterwards the spore is dried between two plates of glass, the
cilia will be sufficiently distinct to be seen by the simple
microscope.

M. linger has followed the movements of a liberated spore
in water during more than two hours. The greatest length
of time during which I have observed it with the microscope
has been nineteen minutes, and, in general, the motion con-
tinues but little more than half of this time : sometimes it ceases
almost immediately after the release. But it is necessary to
remark, that the spore, being placed upon the object glass,
was imprisoned between two plates of glass. The vibration
of the cilia continues sometimes after the spore is arrested ;
only it is not sufficiently strong to displace the corpuscle.
When at last they cease to move, the contour of the spore
undergoes during some instants a sensible alteration, which
announces, perhaps, the decomposition or the absorption of
the vibratile organs. The motionless spore delays not to
modify itself once again : it becomes spherical, the green
matter distributes itself equally, and the episporic membrane,
in part reabsorbed, at last escapes the sight ; very soon ger-
mination commences.

M. linger remarks that the escape of almost all the spores
takes place towards eight in the morning. Indeed, all the
work of the formation of the spore is carried on in the first
hours of the day. The tufts which I have gathered the day
before, and which presented no indication of the formation
being near at hand, were in general covered with spores
the next morning ; and after mid-day these were all gathered
on the surface of the water beginning to germinate.

It is easy to follow the progress of this germination under
the microscope : the elongation of the filaments progresses,
one might say, by eyesight ; for I have measured more than

INTRODUCTION. 19

once an increase of three-twentieths of a millemetre in an
hour. Moreover, the activity of this phenomenon, as of all
those which I shall hereafter describe, varies extremely,
according to the state of the tufts of Vaucheria which have
been gathered. It is the same with the diameter of the spores,
and the size of the filaments, &c., upon which one is not able to
give a certain determination. Therefore, in the figures which
I append to this note, all the modifications which the spores
of Vaucheria may present, either before or after their emis-
sion, ought not to be expected to be found; but I have
chosen in my drawings those which have appeared to me to
represent their most usual and characteristic state.

The power of germination is moreover carried in Vaucheria
to a point which appears to me to surpass all that is observed
in the vegetable kingdom. This plant, which consists, to
speak truly, but of a single cell, possesses in all its parts the
faculty of reproducing itself. The extremities of the fila-
ments kept for many weeks, evaporation being prevented,
continue to elongate until they have extended them-
selves beyond the plate of glass which serves to sustain
them. Again, when one of these filaments has undergone
lesions in many places, the green matter is seen to become
secreted gradually between one end of the injured places and
the filament, and to divide itself thus into many little
fragments, which form so many distinct individuals emitting
lateral prolongations, and not tarrying, without doubt, under
favourable circumstances, to reproduce a complete individual.

The phenomenon of the deliverance of the spore is not always
accomplished so regularly as I have described ; sometimes it
germinates without quitting the mother plant ; and from this
result the strange forms which I have represented in figures
35 and 36. Sometimes also the spore cuts itself into two
at the moment of its escape, and so gives birth to two spores,
smaller than the others, but capable of germination like
them, the one at the exterior, the other at the interior, of the
filament.

The transparent membrane which enclosed the spore, and
which became visible after its emission, is destroyed little

c 2

20 INTRODUCTION.

by little. It is perfectly homogeneous; it is but when
it commences to decompose that it takes on a granular ap-
pearance ; but it never presents those longitudinal striae which
I have remarked in that of Conferva and Zygnema.

I have not perceived any motion in the granules of the en-
dochrome, excepting in the case of the rupture of a filament.
The granules escape then in jerks ; they often collect them-
selves .into pellets, and sometimes the mucilage which ac-
companies them forms about them a species of membrane ;
but these masses of granules have never appeared to me
susceptible of organization into reproductive corpuscles ; in a
word, never have I seen them germinate.

The solubility of these granules in alcohol indicates their
resinous nature. Sulphuric acid diluted with water con-
tracts them into the centre of the filament to a faint ribbon
of a brownish green. When this reagent is employed of
greater strength, the granules resolve themselves into a
mass of a blackish green ; but the external membrane resists
the action of the acid. If recourse is had to ammonia, it
often happens that, by a phenomenon of endosmosis, the fila-
ments empty themselves entirely of their granules. This is
seen especially in the spores which have commenced to ger-
minate; the granules all issue by the extremity of the
filament in germination, and the external membrane, which
was not before visible but at the extremity of this filament,
remains entirely empty like to a glass ball. The ammonia
possesses also the singular property of imparting a light pink
coloration, or vinous red, to certain parts of Vaucheria, par-
ticularly to the superior extremity of the spore, when it is at
the instant of quitting the mother plant, and this part is
less furnished with endochrome than the rest.

If I have not indicated up to the present time to what
species of Vaucheria the observations which I have described
apply, it is because the species of this genus are esta-
blished upon bad characters. In truth, the organization of
the spore, such as I have described it, applies to Vaucheria
ovata D. C. = Vaucheria clavata D. C. et linger ; for I have
found once, upon the same filament, both this form
and that which has been named Vaucheria sessilis. A

INTRODUCTION. 21

little time afterwards, the same tufts again have given me
Vaucheria hamata, V. geminata, &c. The appendages
that Vaucher regarded as the corpuscles, and which served
him to establish his species, are very different from true
spores by the thickness of their envelope, and by the nature
of their contents. Crushed under the microscope, they
permit drops of a very refracting liquid to escape, which
alcohol dissolves not, but of which it renders the green
colour more brilliant. Sulphuric acid causes it to change to
a clear fawn, and iodine .to brown. It is true that these
appendages are formed, like the spores, by the condensation
of the green matter, and that they are separated from the
mother plant by a diaphragm ; but I have never found them
but upon filaments which have begun to disorganize them-
selves, and almost always they decompose with them. Now,
since I have constantly gathered in the same locality all the
individuals of Vaucheria which have served for my observ-
ations, and since I have seen them take successively all the
forms represented in the annexed plates, I believe that I
ought to unite Vaucheria ovata, clavata, sessilis, hamata,
terrestris, geminata., coespitosa, cruciata, into a single species,
which I propose to designate under the name of Vaucheria
Ungeri, in remembrance of the learned work of the German
author and his interesting discovery.

We have examined four different types of locomotive
organs in the spores of the Alga : analogous organs are to
be found, without doubt, in a host of plants of this class ; and
it is allowable for us to suppose that the different groups
present different forms. I should have been able myself to
add yet many genera to those which I have mentioned, but
I believe that it would be sufficient in this first work to in-
dicate the principal types which observation has, up to the
present time, made me acquainted with, and to cite for each
of them a genus in which this type is found. I would add
in conclusion, in order to give more authority to my asser-
tions, that M. Decaisne has verified the most part of my
results ; and that I owe him even certain of the figures which
accompany this note. (Ann. des Sciences Nat. 1843.)

c 3

22 INTRODUCTION.

That M. G. Thuret is in error in uniting all the species of
Vaucheria into one, will, by a reference to the descriptions
and figures of the genus Vaucheria, which accompany this
work, be at once perceived.

The animalcules contained in the cells of the filaments,
which occupy the interior of the globule of Chara, bear
considerable resemblance to the zoospores of the Algce ;
like them, owing their power of locomotion to the presence
of cilia, the anterior extremity of each being furnished with
two long lashes or cilia (see plate 62., fig. 5, 6.). If the
views of physiologists, however, respecting them be cor-
rect, an essential and functional distinction exists between
them ; the one being the sporules themselves, and the other
the organism, or instruments, whereby those sporules are
fertilized.

While the term zoospore has been applied to the moving
sporules of the Algce, the appellation of spore has been con-
ferred by some writers upon the large and usually elliptical
body formed in the different species of the genera Zygnema *,
Tyndaridea, Staurocarpus, Mesocarpus, Mougeotia, Vesi-
culifera, and perhaps Bulbochate, by the union and con-
solidation of the contents of two cells either in the same or
different filaments. Concerning the nature of this body,
considerable difference of opinion has prevailed and still
obtains. Vaucher, who has so accurately described nu-
merous species of Conjugates, thus speaks of it: — "At last,
on the 25th Messidor, an IX, in examining the remains of
the Conferva jugalis Muller, which I had followed since
the commencement of spring, I arrived fully and without
any doubt at this truth so desired, and which I had made
so long and so fruitlessly the object of my researches.
Almost at the same instant, and in the same day, or at least
in the same week, all the grains of the Conferva jugalis, of
which I had many thousands, opened themselves by one of
their extremities, in the same manner as the two cotyledons
of a seed whose embryo has become developed ; and from the

* See the figures of those genera.

INTRODUCTION. 23

base of the aperture there issued a green sac, at first very
small, but which soon extended itself in such a manner that it
surpassed many times the length of the globule. In the
interior of this sac appear soon the spires, they being ac-
companied by their brilliant points, as in a Conjugata entirely
developed. The tube itself exhibits divisions, at first one,
afterwards two, then a great number ; at last the Conjugata
detaches itself from its grain, and floats alone in the liquid,
and then nearly in size, and with two extremities, which are
still pointed, it resembles perfectly the plant which gave it
birth." In this description Vaucher is doubtless altogether
in error ; and it is difficult to conceive in what way he could
have been so imposed upon, a careful microscopic examination
of the " spore " alone being quite sufficient to convince the
observer that no such dehiscence as that represented by
Vaucher could take place. M. Decaisne * regards these
bodies as the true and only germs of the Conjugates or
Sunspores, as he has denominated them in removing them
from Agardh's extensive class of Zoospores. Mr. Jenner, an
indefatigable and excellent observer, writes me word that he
has witnessed the growth of these " spores," " which is, by a
general extension of the whole investing membrane or
membranes, which subsequently divides and subdivides into
other cells ; " and Kiitzing also, if I mistake not, states that
he has been a witness of their developement in Zygnema and
Vesiculifera, or CEdogonium. Agardh thus writes in the
memoir before alluded to concerning them in the Conjugata,
he not being acquainted with the fact of their formation in
the true Conferva: — "During the conjunction of a Conjugata,
one of the filaments is always giving, the other always re-
ceiving ; the spires of the giving filament first become
confused; and it is not until after the entrance of the matter
of that filament that they become irregular in the other, and
then the two masses become confounded together, to form
the elliptical or spheroidal bodies. The globules of which
the spires are composed do not clear themselves the one from

* Annales des Sciences Naturelles, Mai, 1842.
c 4

24 INTRODUCTION.

the other during the slow emanation of the matter from the
giving filament, and no trace of other motion is observed
amongst them. On the contrary, it is in the elliptical body,
constituted by the mingled contents of two joints, that I
believe to have recognized a phenomenon of locomotion
analogous to that described previously in reference to Con-
ferva area. After many fruitless researches, made for the
purpose of seeing the elliptical body develope itself into a
new filament, as Vaucher has described, I clearly saw them,
on the contrary, dissolve into numerous sporules, endowed
with a very rapid motion. Apart from the phenomenon of
union of the filaments, which distinguishes the Conjugates
from all other Alga, the only peculiarity in their propagation
is, that the elliptical bodies from which the sporules proceed
remain after many months without any change in them,
while they dissolve immediately in the true Conferva." My
own view of the nature of these elliptical bodies precisely
coincides with that of Agardh. They are to be considered, I
think, as so many sporangia stored with zoospores, which
they retain together and preserve from injury until the
period proper for their developement arrives. Each of them
is composed of at least two, and, according to Meyen, three
membranes, these being formed by the gradual inspissation
of the organic mucus enveloping the zoospores. At all
events, if they be not sporangia, and if they ever germinate,
as some suppose, but which I consider still to be very ques-
tionable, a second mode of reproduction, which some have
contended for, must be conceded to those plants possessing
them ; for it is very certain that the Vesiculifera, in the different
species of which are formed bodies in all respects analogous
to those of the Conjugate, are propagated principally, if not
exclusively, by zoospores. This is undeniable, and it is but
consistent with analogy to suppose, as Agardh has asserted,
that the Conjugates are perpetuated in the same manner.
The observation that they dissolve immediately in true Con-
ferva, does certainly not apply to the true oval or circular
organs formed in the true Conferva, with the existence of
which Agardh was not acquainted. These are, in all respects,

INTRODUCTION. 25

similar to those of the Conjugates, and are no less permanent
in their nature.

M. Decaisne combats the idea of the disintegration of the
spores of the Alga formed by the union of the endochrome
of two cells into zoospores. He states the fact, that the
contents of the spores are fluid. This argument is, however,
by no means conclusive ; the contents of the undoubted
zoosporous Alga are, also, for the most part, fluid; when,
however, the full developement has been attained, the fluid
disappears, and the cells are filled with zoospores. The same
may occur in the spores of the Zygnemata &c., as asserted to
be the case by Agardh.

M. Decaisne also, in his " Memoir on the Classification of
the Algce" strongly repudiates the idea of a double mode of
reproduction. The spores, M. Decaisne regards, as already
remarked, as the true and only reproductive bodies of those
Algce in which they occur, and asserts that in these Alga
zoospores are never formed. M. Decaisne thus clearly ex-
presses himself on this point : " Mais je crois pouvoir avancer
aujourd'hui que les zoosporees n'oftrent jamais de corps re-
producteurs resultant d'une concentration de la matiere verte
provenant de deux individus."

This generalization of M. Decaisne is surely untenable, for
it is perfectly certain that the usual and most frequent mode
of reproduction of the Vesiculiferce, in which spores alto-
gether analogous, as before stated, with those of the Conjugates
are formed, is by means of zoospores. The motion and de-
velopement of the zoospores of this genus of Algce I have re-
peatedly witnessed, in such a manner as to preclude all doubt
on the question. Now this fact in reference to the Vesiculiferce,
which may be relied on, leads to the adoption of one of the
following views, either that there is a double mode of repro-
duction in at least a certain number of those Algcs in which
true spores are formed, viz. by zoospores and spores, or else
that the oval bodies termed spores do become disintegrated,
in accordance with the statement of Agardh, into numerous
zoospores. On the " spores " themselves M. Decaisne has the
following remarks : " After the complete organization of the

26 INTRODUCTION.

reproductive body, the cells are absorbed, at least the spores
issue by a rounded aperture which they constantly present at
this period. These corpuscles have offered me in this case an
ovoid form, and I have seen them without exception issue
forth, presenting in advance their colourless extremity. "
Of the many hundreds of specimens of Conjugates which I
have examined, it has never occurred to me to observe the
slightest change in the primary form of the spores or spo-
rangia ; what they really are seems to me a point yet to be
determined, nor have I ever seen the colourless extremity
referred to.

The opinion of the production of the same species from two
organs so dissimilar in size and form as the zoospores and
spores are, is not so startling when the structure of these
is closely considered, as at first sight it might appear. The
zoospores being regarded as young cells of Conferva, con-
taining only one or two other incipient germs or zoospores,
and the spores as cells of larger growth, filled with
germs, or zoospores, which have arrived at or near their
maturity.

The organ contained within each capsule of the different
species of the genus Vaucheria, I regard likewise as a sporan-
gium filled with zoospores, the horns near it being identical
in function with the vesicle already described. The ciliated
ovum formed at the extremity of the filaments of Vaucheria
is of course different from the capsular bodies. Having thus
given a general outline of the more interesting and leading
facts connected with the reproduction of the freshwater Algce,
we shall next proceed to the consideration of their structure
and modes of growth.

The structure of the Conferva is exceedingly simple. An
outer membrane, transparent as water, invests a number of
cells, which exhibit under the microscope not unfrequently
a fibrous appearance. These cells do not communicate with
each other, although their truncate extremities are always in
apposition the one with the other. They contain a thick and
generally colourless fluid, in which are immersed, and some-
times scattered irregularly, as in the true Conferva, sometimes

INTRODUCTION. 27

disposed in starlike forms, and sometimes in spires, a number
of vesicular bodies, the immature zoospores, and in these it is
that the colouring matter of the plant chiefly resides. It is
from this viscid fluid, the quantity of which is so consider-
able, that the Conferva derives its nourishment and means of
increase, and not, at least so I consider, from the intercellular
substance of Mohl, to whose theory an objection occurs to my
mind, in the fact that it is not rational to suppose that the
nutritious fluid should be placed external to the cavities of
the cells, the contents of which it is destined to nourish.
Such is the view usually entertained, I believe, of the
general structure of the filamentous Algce. The opinion
at present held by Mr. Jenner as to their organization differs
considerably from that just stated, that gentleman declaring
that he has, in the Zygnemata, detected a third membrane of a
delicate and homogeneous appearance, and that it is by this that
the dissepiments are formed, and not by the second, which
terminates just at the situation of the joints, between which
it does not send down any partition walls. Thus the outer
membrane he describes as continuous, the second as a series
of short tubes, open at their extremities, placed end to end,
and the third as the true cells. Of the accuracy of this
ingenious view of the structure of the filaments of the
Zygnemata, Sec, I have not as yet been able to satisfy myself.
The investing membrane of the cells, one would suppose,
would be essential to the existence of a Conferva ; yet M.
Areschoug, in an excellent article on Hydrodictyon pentagonum,
states that that curious production does not possess it. In
the Ulvacece the cells are not usually placed in linear series,
but are scattered through a gelatinous substance, which is
usually furnished with an investing membrane.

As the different cells of a Conferva do not communicate
directly with each other, each cell may therefore be regarded
as possessing a separate and independent existence, inasmuch
as it contains all the parts requisite for the formation of an
entire Conferva. A Conferva then may be regarded, like the
associated Zoophyte, as a compound or aggregated being ; and
it is to this aggregation of similar parts that the Conferva owe

28 INTRODUCTION.

their very elegant and beautiful appearance under the micro-
scope. Much of the beauty of those most interesting of all
Nature's works, the Zoophytes, arises from the same cause.

Connecting the zoospores with each other, we find in most
of the Conferva a vascular structure. (See PI. 17.) In the
genera Vesiculifera, Zygnema, Microspora*, and doubtless
in many other Algae, the zoospores up to a certain period
of the developement are connected with each other, and
probably with the central cy toblast, by means of a tubular or
vascular network, in the angles formed by which the zoospores
are situated. This structure is most manifest in Conferva
crispata and its allies, and requires, in order that it may be
clearly seen, that the developement of the species should be
considerably advanced, and the zoospores somewhat scattered.
It may generally, however, be easily detected in the genera
Vesiculifera and Zygnema. In the latter the tubular formation
is not arranged in a reticulated manner, but occupies the
centre of each spiral thread. It is by the inosculation of the
tubular radii given off by the central cytoblast with this
vascular structure, that a direct communication is established
between that organ and the zoospores. f

In addition to the membranes above described, the zoospores,
with the vascular network, the sporangia, and the central cyto-
blast, two other organs have been noticed in the Conferva,
first by Mr. Bowerbank in a species of Zygnema, which I
transmitted to him, and subsequently by myself in a variety
of other species. The one is cruciform and adherent to the
interior wall of the cell. (See PI. 17. fig. 1, 2, 3.) It (Mr.
Bowerbank remarks) " is the vegetable structure which
secretes the ruphides." They are probably not definite organs,
but crystals. The other body is small, elongated, somewhat
curved, and attached to, or lying upon, the plant. (See PL 17.
fig. 1,2,3.) This (Mr. Bowerbank observes) is certainly " a
string of minute cytoblasts; and similar bodies, but more

* Cladophora Kiitzing.

f See " Annals and Magazine of Natural History," vol. xii. p. 20., for a
paper entitled, " Observations on some Points in the Anatomy and Phy-
siology of the Freshwater Confervae."

INTRODUCTION. 29

curved, are observed in the soft parts of the young lips of
shells, both marine and freshwater." Several of each of these
organs may be found in each cell.

All the separate and distinct structures and parts entering
into the formation of the Conferva have now been treated of:
certain peculiar adaptations and contrivances still remain to be
described, such as the inversion of the extremities of the cells
in many Zygnemata, the corrugated cells of the Vinculiferce,
the layer of fibres surrounding the main stems of some
Batrachosperms, the ciliary processes met with in the same
genus and others nearly allied, and the presence of silex in
some DiatomacecB. The further notice of these, however, will
be postponed until the individual genera come under con-
sideration.

The rapidity of the growth of Conferva, and indeed of all
the articulated Alga, has often been a subject of surprise to
many observers of Nature ; and to none more than myself has
it occasioned greater astonishment, until I became acquainted
with the reason of so surprising a developement of structure.
If the filaments of Zygnema nitidum be carefully examined
and contrasted together, it will be seen that in some the
length of the cells only just exceeds their diameter, and that
each cell usually contains four spiral coils, which together
perform from seven to eight turns in each, the coils almost
touching each other : that in other filaments the length of the
cells is more than three times the diameter, but that still each
cell contains only the same number of revolutions of the
spires, viz. seven or eight, which now, instead of being nearly
in opposition, are widely separated ; thus plainly proving the
elongated cells to be derived from the extension of the
shorter ones. And again it will be noticed in other filaments,
that the cells have returned to their original length, but that
each now contains only three or four spiral turns, thus
affording manifest proof of the division of the elongated
cells, and completing the chain of evidence which establishes
to demonstration the existence of the modes of growth to
which I have referred throughout all the cells in the species
of the genus Zygnema. The proofs now to be adduced, that

30 INTRODUCTION.

this mode of growth likewise takes place in all other Con-
ferva consisting of a single series of cells, are little less con-
clusive than those just enumerated. In most of the filaments
of these, the cells will be observed to be of various lengths,
some twice as long as others, and others again of every inter-
mediate length. Now, by means of this law of growth, the
variation in the length of the cells is at once and satisfactorily
accounted for, Avhich is not to be done in any other way.
But this is not all ; the progress of the formation of the
septa which divide the cells may be frequently traced,
a contraction of the cuticle and a division of the endochrome
gradually occurring, which is alone sufficient to establish the
reality of this law of increase or multiplication of cells in all
the true Conferva, and which may be stated to extend
likewise to all the other Alga — the Ulvacecc, Desmidea, and
DiatomaceoK. In those Desmidea however which are not
filamentous, but which are formed of two symmetrical cells,
the multiplication by growth is often very different. On the
separation of the cells from each other, each will throw out a
mass of viscid mucous matter, which will go on increasing
until it finally takes on all the characters of the primitive
cell. Now, particular stress should be laid on this law of
developement, since it is evidently very important, inasmuch
as it not merely so satisfactorily and so beautifully accounts
for the rapid growth of all articulated Alga — for it is simulta-
neously in operation in each of the many hundred cells of which
each filament is usually composed — but it teaches us like-
wise that much caution is requisite in employing the character
of the length of the cells for determining species, as it proves
that this character, which used formerly to be much relied
on for the purpose, is one subject to very great variation.
There is a limit, however, to this law of developement which
does not in the genus Zygnema allow of more than one or
two divisions of each cell, unless indeed the spiral tubes grow
likewise in an equal ratio, which may be the case, and then the
division of the cells may be frequently repeated. In those
Conferva which do not contain spiral tubes the multiplication
of the cells may go on to an almost endless extent.

INTRODUCTION. 31

Since the above observations were written*, my attention
has been directed by Mr. Francis to a lecture by M. Morren,
inserted in the " Bulletin de 1' Academic Royal des Sciences
de Bruxelles," for 1837, from the perusal of which it
appears that the growth of many Confervas, by the division of
the cells has been noticed by more than one observer. From
this lecture I make the following extracts : —

"In 1832, M. Dumortier published his memoir upon the
structure and developement of plants and vegetables, in which
he established with the greatest clearness the fact of the
increase of a number of cells by division. His researches
were carried on upon Conferva aurea, in which the terminal
cell elongates itself more than the others, in order to form in
its interior an intermediate production (partition), which
divides the cells into two parts, each becoming a new cell."
No one could be more explicit, observes M. Morren, who
goes on to say, "the division of cells by intermediate membranes
was examined likewise by M. Hugo Mohl in September
1835, upon Conferva glomerata, &c., a terminal cell of which
showed near its centre the commencement of a diaphragm
proceeding from the circumference towards the centre." This
is in all respects, M. Morren remarks in continuation, the
observation of M. Dumortier, but upon another species, and
it is all simply the fact previously noticed by myself upon
Cruciagenia, but transported from the Diatomacece to the
Conferva.

From this it appears that M. Morren would claim for
himself priority in the discovery of the increase of cells of
Conferva by division, but the single observation published
in August 1830, upon the genus Cruciagenia., an Alga
differing much in structure from true Confervoid productions,
would hardly suffice to establish for M. Morren this claim
any more than would the observation of Mirbel on the
division of the pollen cells give him a claim to the discovery

* The substance of the preceding remarks, on the growth of the Alga,
is extracted from a portion of an " Essay on the Confervas," read before
the Dublin Natural History Society and inserted in the " Annals and
Magazine of Natural History," vol. i. p. 431.

32 INTRODUCTION.

of the manner of the multiplication of the cells of Conferva.
Moreover, the investigations of MM. Dumortier and Hugo
Mohl do not go further than to prove, except perhaps the
remarks of the latter in reference to one species of the genus
Zygnema, that the terminal cell of each filament is successively
undergoing division, and not the far more important fact
upon which I have so particularly dwelt, that all the cells of
a Conferva or articulated Alga are constantly and almost
simultaneously undergoing a similar process of multiplication
by division.

M. Morren afterwards observes in his lecture : " In my
memoir on the Closteria, inserted in the " Annales des
Sciences Naturelles (partie Botanique), Mai, 1 836," I showed
that the colouring matter, the endochrome, in consequence of
polarization, divides itself in each cell into two opposite
masses, which become separated by the secretion of a trans-
parent liquid (a true intercellular substance, in which is
formed the double diaphragm, which by separating produces
slowly the dislocation of the two cones of the Closterium.

" I have since observed," continues M. Morren, " all the
particulars of this phenomenon of the formation of interme-
diate partitions in the Conferva, my observations having been
made on Conferva dissiliens. The articulations in this are
j very short, equalling their diameter or even less than this.
Now there is in these a green mass at first uniform, in which
appear peculiar globules, which become transparent vesicles,
more yellow than the rest of the colouring matter, presenting
finally spots more obscure, almost brown or red at the centre.
These bodies appear to me to be the male apparatus exer-
cising a true fecundation upon the rest of the endochrome.
But this mass, when the male cellules are developed, polarizes
and flows towards the two poles of the parent or general
cell. Then this cellule is seen to become elongated under
the dominion of this ebbing or polarization, and between
these two masses a transparent space is manifest. The com-
pressorium has proved to me that there is here a mucous
fluid or intercellular substance. Now upon the periphery of
this substance the condensation operates ; at first little by

INTRODUCTION. 33

little it proceeds towards the centre, and in place of a zone of
liquid substance there is a membrane duly organized and
fit to become divided into two membranes, each mass of
endochrome having its wall, or more correctly, its proper
membrane." In this account no mention is made as to
whether the cells, the division of which M. Morren witnessed,
were terminal or not.

My own views of the phenomenon of the division of the
cells of Conferva, and of the explanation to be offered of it,
differ considerably from those of M. Morren. All the cells
of a Conferva, until it has reached a state of maturity, are
continually increasing in length ; and it is only in certain cells
which have exceeded their standard length, that the gradual
separation of the endochrome into two masses is seen to
occur, and a transparent space to be left between them ; this
space is not, however, in my opinion, occupied by any form-
ative intercellular matter, such as that referred to by M.
Morren, who, in his explanation, asserts that the polarization
and separation of the endochrome first takes place, and that
afterwards the cells begin to grow. The first indication of
the formation of the partitions which are to divide the parent
cell into two, is not visible until after the separation of the
endochrome, and appears to consist in a solution of a portion
of the periphery of the centre of that cell, the divided edges
of the cell then becoming inverted separately, and growing
towards the centre, where they coalesce. Thus, according to
this view, the partitions of the cells are not, as M. Morren
would assert, new growths or formations, but merely an
extension of the separated margins of the parent cell.

A second mode of development *, of considerable import-
ance as regards the classification and description of the Alga,
still remains to be described. In many species of Conferva
more especially in the branched kinds, and in numerous other
Algce ; in the species of the genera Vesiculifera, Lyngbya,
Meloseira, Fragilaria, &c., there is not only a longitudinal de-
velopement of the cells, but there is likewise a lateral growth

* See Annals of Nat. Hist. vol. xi. p. 359.
D

34 INTRODUCTION.

of them ; so that if we examine any species in which this law
is known to exist, we shall observe, first, that the filaments
differ considerably in diameter in the same specimens ; se-
condly, if the species be a branched one, that the largest
filaments are near the centre of the specimen ; and, thirdly,
that the diameter of all the filaments, whether they be near
the centre or circumference, gradually decreases from base
to apex ; the observation of these three facts proving the
existence of the law of the lateral developement of cells,
and also showing it to be in the degree of their age. The
proportions of a specimen of a branched Conferva, therefore,
are in miniature those of a tree or shrub. This law has no
existence in the conjugating Conferva in the genera Bulbo-
chate and Desmidium, and in the majority of Oscillatoria. One
or two other observations still remain to be made in re-
ference to cells, to complete the interesting subject of the
developement of the Conferva. Prior to the discovery of the
multiplication of cells by division, the opinion was generally
entertained that each cell was at its commencement very
small, and that it increased little by little, until it attained
its perfect developement ; and this is the case with the cells
of parenchymatous tissue ; but in the examples where the
multiplication of cells takes place by division of those cells
which have already become great, nature takes a means for
the fulfilment of its end, altogether different, but not less
effectual.

It has already been mentioned that the different series of
cells of which the Conferva are composed, are all enveloped
in a continuous membrane, which serves to bind them to-
gether; there would appear, however, according to the re-
searches of Agardh and Hugo Mohl, to be another and direct
bond of union between the cells, not merely of the Algae,
but of all other plants, this consisting in an adhesive sub-
stance which Mohl has denominated " intercellular," by which
they are firmly united to each other. The same substance is
found coating the surfaces of the pollen granules, binding
them into masses.

Having thus traced the developement of the Conferva from

INTRODUCTION. 35

their earliest period, viz. from the condition of zoospores, and
having examined their structure and modes of growth, we
shall next proceed to make a few remarks upon their dis-
tribution and vitality.*

Not amongst the least beautiful of the many minute or-
ganizations, whose intimate structure the microscope, which
has so wonderfully extended of late our knowledge of the
natural world, has revealed to us, are the freshwater Alga,
and yet the majority of these constitute the rejected and
despised, by all but the true naturalist, scum and slime of our
still and soft waters ; but although many freshwater Algce
are, for an obvious and benevolent purpose, hereafter to be
mentioned, ordained by their Great Designer to be the tenants
of our impure and stagnant waters, there are other species
which are met with only in fresh and running streams, ad-
hering by one extremity to some object of attachment, the
other floating freely in the surrounding fluid medium in the
course of the stream, whose impetuosity and strength these
frail productions seem at first sight but ill able to withstand.
They find their protection, however, not less in the flexibility
than in the tenacity of their structure. This is the case
with the Lemanice, Lyngbya crispa, and with the beautiful
Conferva glomerata, which delight in the purest and most rapid
streams. The Ectosperma clavata of Vaucher, known by its
globular form and dark green shining appearance, is met
with only in the course of the waterfall or cataract, sus-
taining unharmed the whole force and weight of the foaming
waters which pour over it. The Batrachosperms, the most
elegant of all our freshwater Conferva, also usually dwell
in pure water, but are obliged, for the most part, from the
delicacy of their conformation, to confine themselves to such
streams and rivulets as are slow, and possess but little
strength ; while some Conferva, as many species of Zyg-
nemata, Tyndaridea and Mougeotia, are almost exclusively
confined to marshes, ditches, or shallow and extended pools,

* For a highly interesting memoir upon the connection of the cells of
plants, by Hugo Mohl, see Annales des Sciences Naturelles, second series,
torn. viii. (Botanique).

D 2

36 INTRODUCTION.

which dry up and disappear at the approach of summer, the
species inhabiting them having performed their allotted office
in the economy of nature, disappearing likewise, their lives
terminating with the exigency which called them into ex-
istence ; others are usually met with in the perennial waters
of our deep and clear lakes and ponds, and, though not them-
selves perennial, yet have probably a life of somewhat
longer duration extended to them ; as, for example, some of
the larger Zygnemata, certain species of Draparnaldia
and Lyngbya and Conf. crispata. I am inclined to think,
however, that the lives of but few species of freshwater
Algce extend beyond the period of a year, while it is very
certain that very many perish in a few months, or even
weeks, from the time of birth, in which case I can assert
from observation, that the species perishing thus early are
frequently reproduced in the course of the summer, when
the circumstances are favourable, some two or three times.
Very many Conferva die in the spring from the drying up
of the waters in which they dwell, at which season it is
wisely ordained that such species should mature their seeds ;
amongst these may be mentioned many species of the genera
Zygnema, Tyndaridea and Vaucheria ; others die at the ap-
proach of winter, but not all; a few linger through the
greater part of this season so unfavourable to the exercise of
the vital functions of plants. There are other species, again,
which do not require to be constantly immersed in water,
but are found upon those soils and in situations which retain
moisture for some time, as upon shaded and clayey pathways,
at the roots of trees, on banks, thatch, and at the bottom of
palings, the drippings from which they receive. In such lo-
calities, Conf. ericetorum, some Lyngbyece, Scytonemea, many
OscillatoricB and Nostochinece are met with. In these plants,
the strength of the vital principle must be very great, for
their filaments may be dried up for a considerable time ; but
on the application of moisture, they soon recover their
healthy appearance.

So abundant are the productions under our consideration,
that there is not a ditch or pool of any extent or standing

INTRODUCTION. 37

but furnishes one or more species, and even our mineral
springs are not entirely free from, them. From the uniform
nature of the element which the majority of the freshwater
Alga inhabit, it may be confidently anticipated that very
many of the species described in this work will, when the
Alga come to be studied with that diligence and care which
they so well merit, be found in most of the continental
countries. Of the species described by Vaucher, a consider-
able proportion are likewise indigenous to Great Britain.

Most of the freshwater Conferva, when in a healthy state,
are of a green colour, the shade being often extremely rich
and beautiful, but varying with the condition of the species,
and with the species themselves. The occurrence of this
colour is comparatively rare amongst the marine Alga, in
which it is usually more or less red or brown, the colouring
matter being operated upon probably by free acids in the salt
water.

Sometimes the Confervas are diffused through the waters
of a pond or lake, imparting to it a bright green colour, and
causing it to resemble so much of the purer element — the
sea. At others, the filaments of a number of different species
will become entangled, and float together upon the surface of
the water, wafted hither and thither by the wind, like a
beautiful cloud, the softness and richness of the tints of which
a painter would be immortalized could he imitate. It is only
during the early spring months, however, that the Conferva
retain this depth and beauty of colouring; for under the
influence of the rays of the summer sun, they very soon fade
and bleach, becoming ultimately, when the water in which
they dwell has evaporated, converted into the paper-like
substance which has recently attracted so much attention on
the Continent; indeed, so like to artificial paper is this
natural formation, that I feel assured an useful paper might,
by an artificial process, be made during the summer months
out of many abundant species of Conferva.

The Conferva, like most other productions, whether animal
or vegetable, whose organization is feeble, cling tenaciously
to life ; thus, they may be torn and cut up into a thousand

D 3

38 INTRODUCTION.

pieces, and yet each separated portion will retain its vitality
unimpaired, and go on increasing as before; but this is
owing, in a measure, also to the fact of each cell in the
series enjoying an independent vitality. They also sustain,
unharmed, considerable vicissitudes of weather, notwithstand-
ing which they are, however, regular barometers, rising and
sinking in the fluid medium which surrounds them alter-
nately, either as the sun shines, and warmth is diffused, or as
clouds and rain obscure the sky, and cold prevails. In this
way, too, they protect themselves in a great measure from
the alternations of weather, the water being much warmer
beneath the surface than on it. This power which the
Conferva possess of rising and sinking in water, in cor-
respondence with atmospheric changes, is to be explained by
reference to their specific gravity, which is in proportion to
the activity with which the function of respiration is carried
on. During the autumnal and early spring months, the
Conferva remain almost entirely at the bottom of the water,
except when tempted by a few sunny days to rise to the
surface, and expose themselves to the contact of the air, so
that the naturalist engaged in the investigation of these
productions is often surprised on visiting ponds in which he
beheld the day previously Conferva floating on the surface
in considerable quantity, to find that on his next visit they
have all vanished. The Conferva are also amongst the first,
if not the very first, subjects of creation to feel the approach
of more genial weather, beginning to vegetate sometimes so
early as the months of January or February.

In the preceding pages it has been assumed that the fresh-
water Alga are really what many observers have been
inclined to doubt, viz. vegetable productions or plants, they
being led so to do, first, from the curious and extraordinary
motions of the zoospores already described, and second, from
the peculiar and animal fo3tor which the different species
exhale during decomposition. Their true position in the
scale of organized beings has been, it seems to me, satis-
factorily determined, not merely by reference to certain re-
semblances which they bear to vegetables in appearance and

INTRODUCTION. 39

organization, but also and mainly by chemical analysis. In
the 14th volume of the second series of the " Annales des
Sciences Naturelles (Botanique, 1840)" is an elaborate and
highly interesting memoir by M. Peyen, on the chemical
composition of vegetable tissue. In this memoir, M. Peyeii
establishes a distinction between animals and vegetables
based upon the chemical difference which he has ascertained
to exist between the cellular membranes of the respective
divisions of the organic world. The vegetable tissue, M.
Peyen finds, to exhibit invariably a TERNARY composition,
that is, it is composed of three out of the four elementary
constituents of which all bodies are formed, viz. carbon,
hydrogen, and oxygen in nearly fixed proportions, as follows : —
carbon 44, hydrogen 6, oxygen 50. The composition of the
animal tissue or membrane, on the contrary, is as invariably
QUATERNARY, or formed of all the elementary constituents in
less fixed proportions. This generalization is arrived at by
an extensive and careful analysis, not only of animal sub-
stances, but also of examples of most of the families and
orders of Phanerogamic and Cryptogamic plants. Amongst
the freshwater Algce an analysis was made of Conf. rivularis,
Oscillatoria, and Chara, these all offering the same result as
the other analyses of vegetable tissue, and therefore being con-
clusive as to the vegetable character of the Confervoid division
of the Alg(B. It is to be regretted that an analysis was not
made of the DesmidecB and JDidtomea, with a view to de-
termine more certainly than has yet been done their position
in the scale of beings. That the Desmidece are really vege-
table productions, scarcely a doubt remains, iodine demon-
strating the presence of starch in abundance in the contents
of their cells.

•The following are the steps adopted by M. Peyen in order
to free the membrane of the Conferva rivularis and Oscillatoria
from all extraneous matter, and thus to prepare it for
analysis : —

" I tried next to test, with the same object in view, very
many Conferva. Soda, by dissolving with heat the investing
membrane of the filaments of Conferva rivularis, separated

D 4

40 INTRODUCTION.

from each other the long cells, which, applied end to end, and
more or less filled with green matter, occupy all its tubular
capacity."

" In order to remove entirely the green matter, it was
necessary to open the cells which retained or held it, by
means of dissolvents. I contrived to effect this by squeezing
slightly together moistened Conferva, drying the mass,
afterwards submitting it to the action of lime, then alcohol,
ammonia, solutions of soda and potass diluted, removed
the azotized substances and green matter in solution.
Chlorine effaced the last traces by eliminating also a
brown substance ; hydrochloric acid, water, ether, and
alcohol perfected the purification by removing carbonate of
lime and fatty substances. The purified membranes of
Conferva rivularis and Oscillatoria presented then the com-
position of the other vegetable tissues."

The nature of the contents of the cells of the Conferva
is, it would appear by the preceding remarks, more complicated
than one would be led to suppose from a consideration of
the structure of the cells themselves. Starch is found in
them in considerable quantity, azotized substances, a fatty
matter, a colouring substance, and an odoriferous principle,
as well as salts. The Chara, M. Peyen remarks, contains
granules of starch, green azotized bodies, soluble azotized
substances, a fatty matter, a colouring substance, an
odoriferous principle, recalling the marshy odour of many
Conferva, chloride of potassium, carbonate of lime adherent
to the exterior of the membrane, and silica.

Nitrogen, as is now well known, is the animalizing principle.
It is found, however, not as an organic constituent, but
merely as a product in small quantities throughout the
vegetable kingdom. It is especially noticed in the seeds of
the Graminece, in the Fungi, and in the delicate reproductive
organs, in the pollen, &c. As a rule it has been remarked
that its presence is constant in the young parts and organs
of plants in which there is always a high degree of vitality,
in the establishment and maintenance of which this substance
would appear to be an essential element. M. Peyen, in the

INTRODUCTION. 4 1

Memoir already referred to, lays down the following pro-
position with regard to nitrogen.

" In the two kingdoms, the bodies which admit azote to
the number of their principal constituents, are indispensable
to the accomplishment of the laws of life."

A distinction may be established between animals and
vegetables', moreover, by a consideration of the effects of
different reagents applied to their tissue. This distinction is,
however, less satisfactory than that derived from a knowledge
of their chemical composition. " Vegetable membranes,"
M. Peyen remarks, "which are well aggregated, are not
sensibly alterable in the presence of a host of reagents, such
as iodine, chlorine, the alkalies, and acids diluted, tannin,
many neutral salts, alcohol, and creosote, which colour,
attack, dissolve, or strongly contract the membranes of
animals, but the distinction which is founded upon their
elementary composition is still more certain."

The same agent, iodine, seems to detect the presence of the
product starch, and of the element azote, by imparting to
starch globules a blue tint, and to those substances contain-
ing azote a yellow coloration.

A few remarks upon the subject of circulation may here
be introduced. If we except the order Characea, to be
described in its proper place, but few traces of a circulation
in the freshwater Conferva exist. There is probably a
motion of fluid in the tubular structure which connects the
light green granules of the Alga, and in the rays which
proceed from the central organ in Zygnema ; there is also,
doubtless, an action of endosmosis and exosmosis carried on
between the different contents of the cells, and between these
and the water in which the Conferva dwell.

The uses of the freshwater Conferva may be regarded as
fourfold ; two of these uses pertain to the animal creation in
general, the other two to man in particular.

The first and most obvious use to notice is, the abundant
supply of delicate and nutritious food which they furnish to
myriads of the inhabitants of our fresh waters. It is scarcely

42 INTRODUCTION.

possible to place a fragment of any Conferva under the micro-
scope, without perceiving some of the numerous forms of life
which dwell amongst its filaments ; and the structure of many of
which is so beautifully adapted to the wants of the creatures,
and to the existence which they are destined to lead, as to
raise in the mind of the beholder the liveliest feelings of
admiration.

The second purpose to which the Conferva are sub-
servient is one of great importance, being the purification
of the fluid in which they dwell, laden, as it frequently is,
with various deleterious gases, arising from the death and
decomposition of various animal and vegetable substances;
thus deriving their own origin, for the most part, in the
midst of impurity, they are the agents employed in removing
this impurity, which salutary office they perform in the
following way. Amongst the most noxious of these gases to
animal life are carbonic acid and carburetted hydrogen ; now
carbon, the base of these, constitutes the pabulum, or food, of
plants. These two gases, then, the Conferva decompose,
retaining the carbon for their own support, and setting free
the oxygen and hydrogen ; thus not merely decomposing and
removing what is hurtful, but restoring to the water oxygen,
the essential to all animal life whether found in air or water.
Seeing, then, the important purpose which these apparently
frail and insignificant productions fulfil, who is there who
would venture to remove even this one small and remote link
from the chain of Nature's works, and would be answerable
for the consequences of its removal? Who can tell what
baneful influence might not arise, and spread disease and death
through whole districts? a calamity which, even as things
are now ordained, is occasionally permitted to overtake us.
Should any individual be sceptical as to the influence of
these productions, and whether a respiration of the kind I
have alluded to, and attended with the same results, really
occurs, let him put into a tumbler of water a little of the
first Conferva which he may meet with in his next ramble,
and, placing it in the rays of the sun, watch it for a short

INTRODUCTION. 43

time ; he will soon observe globules of a gas, at first small,
but soon becoming larger, to collect upon the surface of the
filaments, which, when they have attained a sufficient size,
will quit their attachment, rise to the surface of the water,
and at last lose themselves in the surrounding air. This
will, I think, satisfy him that a respiration of some kind is
carried on ; and should he wish to ascertain the nature of the
gas thus eliminated, whether it be really oxygen or not, this
may be done by procuring a considerable quantity of any
floating species of Conferva, and placing it in a trough of
water, over which should be put a glass jar also filled with
water, having an air-tight collar adapted to it, so disposed as
to catch the gaseous globules as they ascend. As soon as
the glass jar becomes filled with the gas, let the air-tight
collar be removed and a piece of ignited phosphorus be
quickly plunged into the interior of the jar, when the brilliant
and dazzling combustion which will instantaneously ensue
will afford a proof conclusive of the nature of the elimination.
The honour of this discovery, if it can be deemed one, for it
is but the extended application of the common principle of
the respiration of plants generally, is in this country attri-
buted to Priestley ; but so obvious is it that it scarcely re-
quired the penetration of a mind like his for its detection :
Yaucher alludes to it cursorily.

The third use of the Confervce is a moral one. Every
created thing, rightly viewed, is capable of imparting this
moral lesson, be it the kingly lion or the spurned reptile;
the beautiful and scented flower, or the more humble pro-
ductions which have been engaging our attention. There is
no imperfection acknowledged in nature, nor are there,
strictly, degrees of comparison; everything is superlative,
is best and perfect from the hands of God who made it, alike
unsurpassable and inimitable.

Then, lastly, there is the intellectual benefit derived by those
who study this or any branch of Nature's works. There are
those who regard the pursuits of natural history as trivial and
tending to no useful purpose ; but these are but superficial ob-

44 INTRODUCTION.

servers, with hearts and minds alike incapable of appreciating
the depths and hidden beauties of the study. I maintain, in
opposition to these, that there is room in the contemplation
of, and search after, the laws and phenomena of animal and
vegetable life and growth, for the exercise of an enlarged
and enlightened understanding.

HISTORY

BRITISH FRESHWATER ALGA

" H y a dans chaque plante bien examinee une preuve vivante de
1'existence du grand Etre que governe cet univers. Les divers arrange-
ments qui presentent les organes sont autant de petits problemes pro-
poses par la grande Intelligence a notre faible intelligence qui en derive.
•Tavoue, au moins pour moi-merae, queje n'examine pas une simple fleur
sans etre etonne de la sagesse qui en a dispose les diverses parties, et sans
apercevoir dans le detail, ou dans 1'ensemble, le texte de meditations
les plus profondes." — Voucher.

" Je crois que la principale utilite que Ton doit retirer de cette etude,
se trouve dans les gouts simples qu'elle inspire a ceux qui la cultivent.
Le jeune homme qui s'y applique avec ardeur, se derobe par son moyen
aux passions turbulentes du premier age, et fortiue sans cesse sa sante par
des exercises agreables." — Voucher.

47

ALG^E FILIFORMES.

FAMILY SIPHONED.

Characters. Algas composed of a continuous branched and
cylindrical cell. Reproductive organs external.

GENUS VAUCHEEIA D. C.

Char. Frond here and there occasionally inflated. Repro-
ductive organs of two kinds, consisting of capsules and
anthera or horns, lateral or terminal.

Vaucheria D. C. in Vaucli. Conf. ; Lyngb. 65. t. 19. 23. ;
E. B. 1766. 933.; Flor. Dan. t. 1724. 1727.; Grev.
Algae Brit. t. 1 9. Ectosperma Vauch. Conf. t. 2, 3. ;
Unger in N. A. N. C. xili. p. 789. 140. ; Conf. Sp.
Dillw, 1. 15, 16. 47. 74.

OF all the freshwater Alga none are more interesting or
more curious than those which we are about to describe. It
was from a knowledge of the reproduction of this genus, which
was first clearly made known by Vaucher, in his excellent
work on the Alga, the only monograph at the period in ex-
istence devoted exclusively to the consideration of the fresh-
water division of the tribe, that naturalists were led to entertain
the notion of sexes in this class of plants, a notion which
even now it is by no means easy in all cases to discard.

The Vaucheria are first described in this work, because
amongst the freshwater Alga they seem to stand alone, exhi-
biting no distinct relation to any other genus of that division
of the Alga, although to the genera Codium and Bryopsis,
amongst the marine species, they manifest a close affinity.

The organs of reproduction of the Vaucheria are of two
kinds, being composed of capsular bodies, and of filaments,

48 SIPHONED.

placed close to the capsules, which have been termed anther,
fiom the analogy which they present to the anthers of Pha-
nerogamic plants in situation, and, as some even consider, in
function.

The nature of the large oval or spherical bodies, one of
which is contained in each capsule invested with its proper
membrane or membranes, does not seem to be satisfactorily
determined. Vaucher states in his " Histoire," that he has
traced their growth and developement into perfect plants ; but
the observation does not appear to have been placed beyond
question by the additional testimony of other witnesses.

With respect to what Vaucher terms the horn, from its
curved appearance, although he would seem to have entertained
but little doubt that it really performed the office which he
assigned to it, viz., that of an anther, nevertheless, he was
unable to bring forward any direct proof that it did so ; and
this he appears himself to have acknowledged and regretted,
as will be seen from the following passage : — " Nevertheless,
I am not sufficiently certain of the functions to which the
horn which accompanies the seeds is applied. It is in truth
constantly placed in the neighbourhood of the grains, and it
is seen, especially in Vaucheria (Ectosperma Vauch.) ovoidea
to shed its powder ; that is incontestable ; still I have
always desired some direct evidence which should convince
me of the use of this horn."

That the horn has an office to fulfil in relation to the spores
or sporangia, none can doubt who consider its almost con-
stant presence, the situation which it occupies with reference
to them, the shedding of its granular contents, and the
subsequent changes which it undergoes indicative of its
having performed the duty allotted to it. What the exact
nature of this duty is, cannot as yet be determined, although
every additional observation which has been made tends to
strengthen and confirm the view of its function adopted by
Vaucher, viz. that it is the organ by which fertilization is
effected. The truth of this statement will be evident from
the following remarks : —

In page 17. of Vaucher's " Histoire des Conferves d'Eau

VAUCHERIA. 49

douce," the following observations occur. Alluding to the
horns, Vaucher observes — -- " At first they are straight and
opaque, and consequently contain the green fecundating
matter; gradually they incline towards the grain, and surround
it, so that they rest upon it to shed their powder. When
the seed is separated, they are empty, and assume a spiral
form ; and what confirms me still more in the opinion, that
the horns fulfil the functions of stamina is, that all the Ec-
tosperms which are provided with them have no other en-
largement, and that, on the contrary, those which have other
enlargements are altogether destitute of the horns."

If the horns approach the seeds in some cases, the con-
verse is true in others ; and the propriety of this will be
evident when we consider the position of the horns with
reference to the grains or 'germs in some species. In Vau-
cheria geminata, the germs which are furnished with pe-
duncles approach the horns, in contact with which they
remain for some hours, and then gradually they raise them-
selves from it, and the peduncles which support them curve
backwards away from the horns. This gradual approach of
the grains to the horns, and their subsequent retraction from
them, strengthen the conclusion that this organ is necessary
to the grains. For Voucher's assertion to be correct, that the
horns approach the grains in the case where there is but one
anther, situated midway between two spores, it would first
have to turn towards and reach the one spore, and then act
in like manner towards the other ; the improbability of which
is self-evident ; but, on the other hand, how simply are the
germs brought within the influence of the horn by their ap-
proach to it on each side.

The " other enlargements " in which the horns are absent,
referred to by Vaucher, I presume to be terminal enlarge-
ments of the threads, as in Vaucheria clavata, and which are
altogether of a different nature from the capsular bodies de-
scribed. Oval inflations of the filaments do also occur occa-
sionally : the presence of these, however, is by no means
constant, and they do not seem to be in any way connected
with reproduction.

50 SIPHONED.

Additional evidence in favour of the influence exerted by
the horns consists in the fact of the capsules or seed-vessels
being either perforated or prolonged into a short tube, just at
the place where it comes in contact with the horn. This aperture
may fairly be presumed to be intended to facilitate the admission
to the spores of the granular matter discharged by the horns.

Allusion has already been made in the Introduction to the
powers which many Conferva possess of resisting low degrees
of temperature. The spores of the different species of
VauchericB would appear to be endowed with this power to a
remarkable extent. " In spite of all my precautions, the
frost of winter reached the water of my vase, and my grains
became enveloped (engagees) in very thick ice. They remained
thus until the period of the thaw, that is to say, during
fifteen days, and when they reappeared, I believed them at
first to be too much injured to hope for any success ; but I
called to mind very opportunely the experiments of Spallan-
zani upon the different degrees of cold which seeds would
bear, without losing in consequence the faculty of germination ;
and well convinced that the Conferva exposed to the open
air had not been more fortunate than mine, I resolved not
to abandon my observations." The observations were con-
tinued ; and, as states the text, the grains germinated, to the
infinite delight of Vaucher.

This faculty of resisting cold is bestowed upon the Vau-
cherice and many Conferva, and especially upon their seeds,
with the evident design of guarding against the extinction of
the species, which would be almost certain to occur upon the
freezing up of the waters of the ditches in which they are
usually found. The power also which these plants, and es-
pecially their seeds, retain of sustaining high degrees of tem-
perature, is scarcely less remarkable, and is doubtless im-
parted to them with a similar provident intention. This
power in the case of the spores is to be explained by reference
to the compact capsule which surrounds them, and which
prevents the evaporation of the interior moisture. Another
precaution adopted by nature to guard still further against
the risk of the extermination of any species, is the fact
that very many Conferva (the Vaucheria included), and

VAUCHERIA. 51

especially such species as inhabit shallow and extended waters,
mature and shed their seeds prior to their drying up, and that
the special period of their doing this varies in a measure with
that of the exhaustion of the water.

Further research will doubtless disclose many other species
in addition to those described to be inhabitants of the
fresh waters of Great Britain. Few species of the genus
Vaucheria dwell in the sea. They bear, however, a close
analogy to the marine genera Bryopsis, Codium, and especially
Ectocarpus. M. Decaisne places the Vaucheria in his class
Aplosporece, a class in which the Batrachospermecz find a place.
They are much more nearly related to his Sunspores, than
to the family of Batrachosperms.

a. Vesicles lateral, solitary.
1. VAUCHERIA DICHOTOMA Ag.*
Plate IV. Fig. 1.

Char. "Frond setaceous, dichotomous, fastigiate. Vesicles
solitary, globose, sessile" — Grev.

Hooker's Brit. Flor. vol. ii. p. 319. ; Conf. dichotoma, Eng-
lish Botany, t. 932. ; Harvey's Manual of British Algae,
p. 147. ; Berkeley's Gleanings; Dillwyn's British Con-
fervae, t. 65.

Hob. " In ponds and ditches ; frequent ; annual ; spring
and summer."

"Fronds setaceous, a foot or more in length, dichoto-
mously branched, forming wide strata at the bottom of pools,
and frequently filling them ; colour, a pale yellowish green,
and occasionally dark." — Harv. I much doubt whether this
is anything more than a condition of Vaucheria sessilis, the
capsule being of precisely the same form as in that species, and
upon undoubted specimens of which it is by no means uncom-
mon to find solitary capsules. A yellowish or olive green is the
colour of all the species of the genus when aged and in seed.

* The abbreviation of the name of the individual affixed to the specific
denomination of any production does not necessarily imply more than the
fact, that the person thus alluded to was the first to place that production
in the genus with which it is in this work described.

E 2

52 SIPHONED.

2. VAUCHERIA DILLWYNII Ag.

Plate IV. Fig. 3.
Char. Frond flexuous, terrestrial. Vesicles sessile, globose.

Grev. Alg. Brit. p. 191. t. 19.; Hooker, Brit. Flor. p. 320. ;
Conf. frigida, Dillwyn's British Conferva}, t. 10. ; Conf,
frigida Roth, Cat. Bot. 1. p. 166.; Harvey's Manual, p.
147.; Fl. Germ. 111. p. 491. Conf. amphibia fibrillosa et
spongiosa, C. terrestris exilis fibrillosa, Ray's Synopsis, p.
59. n. 7.

Hab. Cheshunt : A. H. H. Sussex : Mr. Jenner.

This species is by no means uncommon, forming patches
of a bright green colour, on moist and clayey ground. This
Conferva, Mr. Dillwyn observes, is not unfrequently found
in turnip fields during the winter and early months of spring,
particularly in a northern exposure, and on a cold soil. The
patches vary in size, but are usually two or three inches in
extent, adhering but slightly to the soil, and consisting of
loose, unconnected filaments. The form of the capsules,
which are rarely pedunculated, will at once distinguish this
from all other species which have hitherto been described.

3. VAUCHERIA REPENS Hass.
Plate VI. Fig. 7.

Char. Frond terrestrial. Capsules avicular, or in the form of

a bird's head.

Hassall, in Annals of Natural History, vol. xi. p. 430.
Hab. Growing on a footpath near Royston, Essex, Feb.
21st, 1843.

This forms patches upon the moist earth, like the preceding,
from which it is not to be distinguished without the aid of a
lens. The form of the capsules, as seen in the figures, is very
different from that of Vauclieria Dillwynii, and by it the
species may at once be known. I have only once met
with it.

VAUCHERIA. 53

4. VAUCHERIA HAMATA Vauch.
Plate V. Fig. 1.

Char. Capsules ovate, pedunculate, overhanging the in-
curved anther.

Ectosperma hamata Vauch. Hist, des Conf. d'Eau douce, p.
26. pi. ii. fig. 2. ; Hassall, in Annals of Nat. Hist. vol. xi.
p. 439.

Hob. Vicinity of Cheshunt ; not uncommon.

This species is very distinct, and first occurred to me at
Cheshunt, in a ditch half filled with water, in company with
Vaucheria geminata. " It differs from all the others by the
manner in which it carries its grains. The peduncles which
sustain them are much elongated, and they bear at their ex-
tremity two little threads: the one is recurved and receives
the anther, the other is shorter and straighter, and carries the
grain." — Vaucher.

5. VAUCHERIA TERRESTRIS Vauch.
Plate V. Fig. 2. ^ '

Char. Frond irregular, terrestrial. Capsules pedunculated,
resting almost directly on the recurved anther.

Ectosperma terrestris Vaucher, Hist, des Conf. p. 27. pi. ii. ;
Grev. Alg. Brit. p. 191. ; Hook. Br. Fl. p. 320. ; Berk.
Glean. Alg. t. 9.

Hob. Cheshunt : A. H. H. Shady places, frequent,
Sussex : Mr. Jenner.

This Vaucheria, like V. Dillwynii and V. repens, is also
terrestrial, and like them also forms patches on damp and
clayey soil, which frequently present a bristled appearance,
occasioned by a number of short and vertical branches, which
arise from the horizontal creeping fibres.

The species bears some resemblance to the preceding ; the
peduncle is larger, coarser, and not so forked as in it, and the

E 3

64 SlPHONEvE.

seed-vessel, which is of smaller size, rests almost immediately
on the incurved anther.

Found in fructification, according to Vaucher, in the
autumn ; my specimens were obtained in a hedge at
Cheshunt in March, and were also in fructification.

b. Vesicles lateral, sessile, geminate.

6. VAUCHEKIA AVERSA Hass.
Plate VI. Fig. 5.

Char. Capsules usually in pairs, and in the form of a
bird's head, with the beaks averted from each other. Spo-
rangia circular, not entirely filling the cavity of the capsule.

1 la—all, in Annals of Nat. Hist. vol. xi. p. 429.
Hob. Vicinity of Cheshunt.

I have now met with this species repeatedly ; it is one of
the best marked and most peculiar of the genus, the
beaks of the capsules being turned in opposite directions at
once, distinguish it from all other known species, in which,
when the vesicles are in pairs, they are directed towards
each other. This averted position of the capsules renders
the existence of a distinct horn or anther essential for each.
In the form of the seed-vessels, and in the circumstance of the
sporangia not filling the entire cavity, the species resembles
Vaucheria ornithocephala.

7. VAUCHERIA ORNITHOCEPHALA Ag.
Plate VI. Fig. 4.

Char. " Vesicles binate or quaternate, with a short beak, and
pellucid border, upon short, straight peduncles" — Harv.

Grev. Alg. Brit. p. 193. ; Hooker, BritFlor. p. 320. ; Conf.
vesicata Dillw. Brit. Conf. t. 74. ; Harv. Manual Brit.
Algae, p. 148.

VAUCHERIA. 55

Hab. Near Bristol : W. W. Young. About Edinburgh : Dr.
GreviUe.

This species would appear to be one of the rarest of the
genus. I have myself never encountered it.

8. VAUCHEKIA SESSILIS Vauch.

Plate IV. Fig. 2.

Char. Capsules pyriform, large, sessile.
Ectosperma sessilis Vauch. Hist, des Conf. d'Eau douce,
Grev. Alg» Brit. p. 192. ; Hook. Br. Fl. p. 320. ; Eng.
Bot. t. 1765. ; Harv. Manual, p. 148.

This is one of the most abundant species of the genus.
The vesicles are almost as often solitary as in pairs ; and in
this state I apprehend it constitutes the Vaucheria dichotoma
of writers. The spores are frequently noticed to be of a
reddish colour. This appearance is common to all the species
of the genus, and is probably the result of age, and also an
indication of the presence of azote.

c. Vesicles pedunculate, in pairs, lateral.
9. VAUCHEEIA GEMINATA Vauch.
Plate III. Fig. 1.

Char. Capsules situated on a divided peduncle, common to

both. Anther intermediate.

Ectosperma geminata Vauch. Hist, des Conf. p. 29. pi. ii»
fig. 5. ; Grev. AlgjeBrit, p. 193. t. 19 . ; Hook. Br. Fl.
p. 320. ; Eng. Bot. t. 1766. ; Harv. Manual, p. 148.

The filaments of this species are much finer than those of
any of the preceding ; the seed-vessels, too, are smaller, and
represent a sphere hollowed out on the inner side, or towards
the anther. The peduncle is common to both seed-vessels :
after ascending for some distance from the filament from
which it rises, it sends off laterally two branches, on each of

E 4

56 SIPHONED.

which a capsule rests, the continuation of the peduncle forming
the anther.

Occasionally it happens that the capsules are sessile, and
the plant bears some resemblance to Vaucheria sessilis ; it
differs, however, in being altogether much smaller, and in the
form of the capsules.

It was first discovered in England by W. Borrer, Esq., as
far back as 1807. It is by no means uncommon throughout
England.

d. Capsules in clusters, lateral, pedunculate.

10. VAUCHERIA RACEMOSA Vauch.

Plate III. Fig. 2.

Char. Capsules usually four in number, placed upon a pe-
duncle common to all, which terminates in a single anther.

Ectosperma racemosa Vauch. Hist, des Conf. d'Eau douce,
p. 32. pi. ii. fig. 8. ; Grev. Alg. Brit. p. 195. ; Harv. in
loc. cit. p. 149.

Hob. About Edinburgh : Dr. Greville. Vicinity of Ches-
hunt, not uncommon.

" This species is one of the most common, and is found in
nearly all ditches, principally in the spring. It is loaded
with little bouquets manifest to the unassisted sight, and
which with the microscope seem to be formed of a common
peduncle, subdivided into pedicels, each of which carries on its
summit a spherical body, in every way resembling the grains
of other ectosperms, but nearly half as small again. In the
middle of this bouquet is the horn, which, without doubt,
performs the function of a male flower, and which is here
but a prolongation of the peduncle. The number of grains
varies from five to seven, but commonly four are met with."
— Voucher.

It is this species which is most frequently infested with
the curious parasite, Cyclops lupula of Mtiller, which occasions
the growth on the filaments of such extraordinary-looking
appendages, in the midst of which the parasite resides.

VAUCHERIA. 57

A second racemose species is described by Vaucher, but
this has not as yet been found in England ; it differs in several
essential respects from Vaucheria racemosa. The grains, like
those of V. racemosa, are all supported on a common peduncle
furnished with pedicels ; but they are much larger and of a
different form, and each, moreover, is supplied with a distinct
anther.

e. Capsules in pairs, terminal.

11. VAUCHERIA OVOIDEA Vauch.
Pkte V. Fig. 3.

Char. Capsules in terminal pairs, a recurved anther being
placed between each pair.

Ectosperma ovoidea Vauch. Hist. p. 30. ; Spec. Plant,
p. 1634. ; Flor. Ang. p. 954. ; Flor. Scot. p. 979. ;
Withering, iv. p. 129. ; Roth. Flor. Germ. p. 1. No. 7. ;
Cat. Bot. i. p. 16., ii. p. 192.; Conf. amphibia fibrillosa
et spongiosa Dill. Hist. Muse. p. 22. t. 4. fig. 17. B.
and C. B. ramis elongatis ; Grev. Alg. Brit. p. 1 94. ;
Harv. in Hook. Br. Flor. p. 320.; Conf. amphibia
Dillw. t. 41.; Conf. furcata B. Fl. Ang. p. 592.;
Withering, iv. p. 128.; Ceramium ccespitosum Roth.
Flor. Germ. iii. pp. 1. 175.; Cat. Bot. i. p. 154. ii.
p. 186.; Conf. palustris filamentis brevioribus et crassior-
ibus Ray, Syn. p. 447.

" Amongst flowering plants we find several instances of
striking varieties produced by the more or less watery
situation in which individuals chance to grow ; and perhaps
no botanist would acknowledge the two most opposite
varieties of Myosotis scorpioides, or Lotus corniculatus, to
be the same species, without an opportunity of tracing them
through their several gradations. The same may be said of
the present plant, which has hitherto formed two species, and
it is only after a careful examination that I have united
them as one."

58 SIPHONEJE.

" On the edges of ditches, and in similar situations, it
frequently occurs in masses so densely matted, as to hold
water like a sponge, with its surface beset by erect branches,
which give it a very bristly appearance. In this state it is
well known to botanists as the C. amphibia of all modern
authors. Its hue is a bright green, becoming ash-coloured
with age. The root I have not been able to discover, and
the entangled mode of its growth renders it impossible to
ascertain the length of the filaments. These are repeatedly
divided with distinct patent branches, which, as before
mentioned, when the plant grows in shallow water, so that
some of them are exposed to the air, send out patent ramuli
of a stunted growth, from being out 'of their proper element,
which by their erectness give the plant its bristly appearance;
yet, at the same time, if whilst in this state the waters rise
so as to overflow the plant, their length is gradually increased,
and losing their erect position, they yield to the current,
and become the Ceramium c&spitosum of Roth ; and after
having thus changed, if by the subsidence of the waters the
surface is again exposed to the air, the filaments, of course
disposed horizontally, give the plant a bristly appearance by
again throwing out erect patent ramuli." — Dittw.

The above description of Mr. Dillwyn, is applicable, I
suspect, not merely to Vaucheria ovoidea, but to, perhaps,
nearly all the Vaucherice which dwell in shallow water. F.
ovoidea delights, according to Vaucher, in the purest water,
that of fountains for example ; and it is certainly not so
common as might be supposed to be, if it were the only
species of the genus which assumed a csespitose character ;
for out of the many hundred examples which I have examined,
I have never yet been so fortunate as to procure the plant in
seed. On the young, dense, and spongy tufts it is rare to
find capsules of any kind.

M. Decaisne describes movements of the capsular body of
this species altogether analogous to those of V. clavata, detailed
in the Introduction.

VAUCHERIA. 59

f. Capsules numerous, lateral, on separate peduncles.

12. VAUCHEEIA POLYSPEKMA Hass.
Plate VI. Fig. 6.

Char. Frond minute. Capsules separate, in the form of
a bird's head, pedunculated, varying in number from
three to Jive, but usually there are but three sporangia,
not entirely filling the cavity of the seed-vessels or cap-
sules.

Hassall, in Annals of Nat. Hist. vol. xi. p. 429.
Hob. Vicinity of Cheshunt.

This species, which is by no means uncommon, may be dis-
tinguished from all others known to me by the fineness of
its filaments, which are not half so large as those of our other
British species, no less than by the form and arrangement of
the seed vessels. These are slightly pedunculate, varying in
number from three to five, but usually there are but three,
the apices or beaks of which are neither turned towards or
averted from each other, but are all directed one way. The
resemblance which the capsules bear to a bird's head when
viewed sideways is very remarkable, and this resemblance is
rendered still more striking by the fact of the circular sporan-
gium occupying only the central portion of each, and which
therefore represents the eye of the bird.

It is remarkable to observe that in this Vaucheria there
are no distinct horns or antheras, the base of each vesicle
before its complete formation appearing to represent the
anther.

g. Proper Capsules none, Antherce none.

13. VAUCHERIA CLAVATA Vauch.
Plate II.

Char. Frond ccespitose, the extremities of the branches
clavate.

60 SIPHONED.

Ectosperma clavata Vauch. Hist, des Conf. d'Eau douce, p.
34. pi. iii. fig. 10. ; V. Ungeri, M. G. Thuret, in Annales
des Sciences Naturelles ; Berk. Glean. Alg. t. 10. ;
Harvey, in Manual, p. 149.

So far from agreeing with M. G. Thuret as to the pro-
priety of referring all other species of Vaucherics to this one,
and constituting a single species of the whole under the
name of Vaucheria Ungeri, I am of opinion that V. clavata
itself ought not to be regarded as a distinct species, but
merely as a condition of almost any one of the numerous well-
defined species which have been described. I am led to en-
tertain this opinion from having repeatedly observed that
the club-shaped extremities are present, terminating many
of the filaments of almost all the species which are now
recorded, and the distinctness of which cannot for a single
moment be doubted. True it is that very many specimens
covered with capsules do not present the club-form dilatations
of the filaments, and also that these latter are generally present
when the former are altogether wanting. But these facts
admit of a rational and interesting explanation, entirely con-
sistent with the view here expressed. The specimens of
Vaucheria furnished with capsules, and those having them
not, but possessing the claviform filaments, are usually met
with under very different circumstances, the one for the
most part in still water, and the other in flowing, such as
streams and cascades, that is, the one set of specimens are
found in circumstances favourable for the developement of
capsules and anthene, and for permitting the mutual in-
fluence, which these organs are supposed to exert on each
other, to take place ; and the other kind, or second set, are
encountered in localities most unfavourable for these purposes
and ends, and in which in many cases it would be impossible
for capsules to develope themselves, the filaments being con-
stantly washed and pressed upon by the force and weight of
the incumbent and flowing waters. This leads to a necessity
on the part of Nature, who is so fertile in resources in times
of difficulty and danger, to adopt some other mode of repro-

VAUCHERTA. 6 1

duction for plants so circumstanced, and thus effectually to
guard against the extinction of the species — her great care.
This she beautifully and securely effects by ordaining that
the reproductive bodies should appear at the extremity of the
filaments, that is, in a situation where they are least or but
little exposed to the impetuosity of the stream or cascade
which may roll over them.

Vaucher remarks of the species as follows : — " It is met
with in the pure and running waters of fountains and rivulets,
and it attaches itself to the wood and stones which there are
found, and upon which it forms tufts of a bright green. It
appears to be composed of tubes, which are more slender than
in the other species, and present likewise a more lustrous ap-
pearance ; it is soft and unctuous to the touch ; its extremities,
principally in winter, are for the most part terminated with
oval and not articulated masses, of which mention is made
above. Their powder expands itself easily, especially when
one irritates them with a needle ; I have vainly sought for
the grains of the plant ; I have never been able to see them,
although the species is very common, and I have sought for
them for two successive years."

So far back as 1826, some interesting remarks were made
on this plant, or state of one, by M. Frank linger, which
may not be deemed uninteresting. They are taken from
Charlesworth's " Magazine of Natural History."

*c I found," says M. Frank linger, " near Vienna in a
ditch containing some clear water, derived from the recent
melting of the snow, a Conferva, which, after cleansing from
the clay which surrounded it, I deposited in a wine-glass
and placed in a window, where I could observe without dis-
turbing it. This was on the 5th of March, 1826. Two days
afterwards I noticed the production of a crowd of new ramuli,
several lines in height, and rising from the general mass like
a fine green miniature sward. On the 9th, these filaments
produced fructification in the form of a darker green globule
at their summits, by which I knew my plant to be the
Conferva dilatata, Cat. Bot. Koth., or the Ectosperma clavata
of Vaucher.

62 SIPHONEJE.

" As I continued my observations, I happened to look at
the surface of the water, and was not a little astonished to
find it covered, especially towards the side of the vase, with
minute globules, unequal both in colour and size. Many of
them swam freely about here and there, moving at their
option in one way or another, retiring and approaching one
another, gliding round globules that were motionless, stopping,
and again setting themselves in motion exactly like animated
beings.

" Conjecturing the identity of the green globules that pos-
sessed motion with those that had none, I immediately began
to examine whence these infusory animalcula derived their
origin, and what relation they bore to the green globules
and the fructification of the Conferva.

" The next day I perceived a great number of the globules
aggregated around the bubbles of air, disengaged from the
Conferva and floating at the surface. Some of them were
of a dark-green colour, and either round or elongated ;
others more transparent, tumid, and with one or two appen-
dages diverging from or at right angles with each other ;
these were evidently plants in a state of germination ; other
globules again were oval, very dark at one extremity, and
almost transparent at the other ; these swam about freely.

" Within the space of an hour I succeeded in tracing not
only the diminution of vitality and death of the Infusoria,
but also the subsequent developement of the dead animals into
germinating plants, in such a manner as to establish the
truth of the fact. But on the 12th of March, I had the
pleasure of ascertaining distinctly the origin of these minute
bodies. I undertook to observe without interruption one of
the tubercles of fructification, which I have already mentioned
as terminating the filaments, in order to discover what became
of the green matter enclosed within it. I had observed it for
the space of half an hour when the following changes became
perceptible.

" The globule became gradually darker in its colour, and a
little transparent at its extremity: in the middle it was
evidently somewhat contracted, and had some ' traces of

VAUCHEKIA. 63

spontaneous motion. I could scarcely believe my eyes when
I perceived the contraction to become more decided, and a
cavity to be formed at the base. The contraction at length
divided the globule into two smaller globules, which moved
spontaneously towards the summit. As the developement
proceeded, the cavity and the uppermost globule became
enlarged, while the inferior globule became diminished : the
latter at length disappeared, and the remaining large globule
escaped by a terminal orifice, ascending till it reached the
surface of the water. The whole of this process occupied
about thirty seconds ; but from subsequent observations it
may be stated generally to take up one minute."

M. linger has, in his late work, verified the correctness of
the above observations in all essential particulars, and has
further proved that the motion of the spores is owing to
their surface being covered with vibratile ciliary organs, until
lately supposed to be eharacteristic of animal life. M. G.
Thuret has also more recently published an excellent memoir
on the formation and developement of the spores in Vaucheria
clavata. See Introduction.

" From the Constancy that is observed in the Number Figure Place
and Make of all the principal Parts ; and from the Variety in the less.
Man is always mending and altering his Works; but Nature observes
the same Tenor, because her Works are so perfect that there is no
place for Amendments ; nothing that can be reprehended. The most
sagacious Men in so many Ages have not been able to find any Flaw in
these Divinely contrived and formed Machines, no Slot or Error in this
great Volume of the World, as if anything had been an imperfect Essay
at the first (to use the Bishop of Chester's Words :) Nothing that can be
altered for the better ; nothing but if it were altered would be marred."
— Ray's Wisdom of God.

64 THOREjfl.

FAM. II. THORE^E.

Char. Main filaments solid, inarticulate, Jiliform, branched,
beset toith short byssoidal, simple, or sometimes ramose
and articulated Jibrillce. Reproduction, according to
Kutzing, capsular, and springing from the Jibrilla.

2. THOREA Bory.

Char. Same as those of the family.

Thorea Bory, in Annales du Museum, xii. 126. t. 18.
(excel, sp. fig. 34.) Hydroph. Voy. Dupern. t. 24. fig. 3.
Agardh species, ii. 123. Poly coma Palis, in Journ. Bot.
108. p. 123.

" The Thorece appear to be related to the Batrachosperms,
with which M. Decandolle has confounded the species dis-
covered by M. Thore. They ought to follow them in a
classification. Like them, they present filaments of two
kinds, and they are, for the most part, slippery under the
fingers when one touches them ; but the filiform filaments
with which the plant is clothed are neither fasciculated nor
verticillate. Whatever may be the fructification of the
ThoretB, it can never be disposed like that of the Batracho-
sperms, which consists of naked buds aggregated and placed
in the centre of the verticilli, or wholly formed by the
branches.

" With the exception of the last species, which is a parasite
of certain lichens, the Thorea are aquatic plants. They
dwell in the coldest fountains, have an aspect which is
peculiar, extreme flexibility, the property of uniting themselves
into mucous masses at the sources of waters, adhere strongly
to paper in drying, and take on the appearance of life when
they are replunged into the liquid in which they have grown."
—Bory de St. Vincent.

THOREA. 65

It might be supposed by some, from what has been said
in reference to the affinities of Thorea with the Batracho-
spermSf that it would naturally find a place amongst that
family, from which, however, it must be admitted, though
bearing certain resemblances to it, to be considerably es-
tranged by its solid and inarticulate filaments.

This genus was constituted by Bory, in honour of Dr. There,
" Naturaliste de Dax, auteur d'une Chloris du departement
des Landes," by whom one of the species of the genus was
discovered.

1. THOREA RAMOSISSIMA.
Plate XVI. Figs. 3, 4.

Char. Filaments very long and much branched. Colours,
when recent, blackish green, turning to violet in drying.

Bory, in Annales du Museum, vol. xii. page 128. pi. 18.
fig. 1. Conf. hispida ramis vagis flexuosis longissimis
obductis ramulis setaceis, Drap. ined. Conferva hispida
Thore, Mag. En eye. t. vi. p. 398. Conferva hispida
Thore, Chloris, 442. Conferva flexuosa jilamentis cylin-
draceis vittosis subgelatinosis ; ft. aqua angusta, filamentis
ramosis, violaceo subfuscis ; 7. pannensis. filamentis ramo-
sissimis, violaceo griseis, Bory, I.e. t. ii. p. 366. Batracho-
spermum hispidum Cand. Syn. 12. ; Flor. Franc, ii.

. p. 60. Th. Lehmanni Lyngb. t. 13.; Harvey in
Manual, page 120.

" The Thorea ramosissima grows in the Adour, where it
adheres to stones, to rocks, to branches, and to the stems of
trees which are found upon its margins. It is only to be
obtained there when the waters are low, in June and July.
It is again met with in the Seine, between Neuilly and Paris,
attached to different bodies, and particularly to the bottom of
boats.

" From a little disc fixed upon the inundated bodies, proceed
certain filaments of the size of an ordinary thread, which
from their origin are ramified. The branches are always

F

66 THORKfi.

shorter than the filaments which give origin to them. The
first are always simple, the latter are covered with new
shoots, still shorter, up to near the extremities, these are
usually simple, so that the last branches are constantly
naked.

" The whole plant is covered with a fine and mucous down,
about half a line long or more. This down gives to the
branches the appearance of little cylindrical stalks of the
size of a crow-quill. It is composed of simple " (rarely
branched) " threads in the form of cilia, in which the joints
are not apparent with a simple magnifying glass, but in
which they are distinguished when they are submitted to
a very strong lens.

" The branches of Thorea ramosissima are often many feet
in length, and float gently in the water, whose course they
follow. Their colour is an obscure and deep green. They
assume very frequently on paper a very elegant scarlet tint.
When they arc macerated in pure water, they soon acquire
the same tint, and they communicate it to every thing which
surrounds them. Pieces of flax, cotton, and silk contained
in the same vessels become dyed in a manner often very
intense. This circumstance has made me presume that some
use in the arts might be made for the fecula of Thorea ra-
mosissima"

After detailing numerous chemical experiments, M. Bory
de St. Vincent concludes his description of the species with
the following remarks : — "As to the use which might be
made of the fecula, that is easy ; painters have found its tint
more soft and more brilliant than that of violets obtained by
other processes; but I doubt whether this beautiful colour
would be very durable, by reason of the action which oxygen
necessarily exercises upon it, as one of the experiments we
have related shows."

The capsules, as seen in fig. 4. of plate xvi., which figure
is taken from Kiitzing's " Phycologia Generalis," would ap-
pear to bear a close resemblance to those of Trentepohlia
pulchella, being, as in that species, small, pyriform, corymbose,
and subinvolucrate ; the secondary branches are occasionally,

THOREA. 67

though rarely, again branched : this is also seen in Kiitzing's
figure.

Mr. Harvey, in his " Manual," writes, " Of this beautiful
plant, I have seen no British specimens. I introduce it on
the authority of a note in the late Mr. Templeton's MS.,
whose well-known accuracy leaves no room to doubt his
correctness in this instance, though he has not preserved a
specimen in his * Herbarium.' "

" It may be (for ought I know, and as some Divines have thought) part
of our Business and Employment in Eternity, to contemplate the Works
of God, and give him the Glory of his Wisdom, Power and Goodness,
manifested in the Creation of them. I am sure it is part of the Business
of a Sabbath day, and the Sabbath is a Type of that Eternal Rest ; for
the Sabbath seems to have been first instituted for a Commemoration of
the Works of the Creation from which God is said to have rested upon
the Seventh Day. It is not likely that Eternal life shall be a torpid and
unactive State, or that it shall consist only in an uninterrupted and endless
Act of Love ; the other Faculties shall be employed as well as the Will
in Actions suitable to, and perfective of their Nature ; especially the
Understanding, the Supreme Faculty of the Soul, which chiefly differ-
enceth us from brute Beasts, and makes us capable of Virtue and Vice
of Rewards and Punishments, shall be busied and employed in contem-
plating the Works of God and observing the Divine Art and Wisdom
manifested in the Structure and Composition of them, and reflecting
upon their Great Architect the Praise and Glory due to Him, then shall
we clearly see to our great Satisfaction and Admiration the Ends and
Uses of these Things which here are either too subtle for us to penetrate
and discover, or remote and too inaccessible for us to come to a distinct
View of." — Ray.

f 2

68

FAM. III. LEMANE^E.

3. LEMANIA Bory.

Char. Frond attached, coriaceous, ramose, and cellular. Outer
cells small, polygonal, and firmly adherent; interior
larger, more lax, sphcerical, and empty. Sporules mo-
niliform, fasciculate, naked, arising from the inner vesicles,
and occupying the interior of the frond.

Lemania Bory, in Annales du Museum, vol. xii., also in
Diet, class, ix. 274. ; Agardh, in Act. Holm., 1814, t. 1.
species 1, 2. Nodularia Link, in Schrad. Jour., 1809,
p. 9. ; Lyngb. t. 29. Gongycladon Link, in Hort.
Physic. 6. Trichogonus Palis, in Jour. Bot., 1808,
p. 123. (excel, sp.) Vertebraria Rouss, in Desv. Jour.
Bot. i. 143. Apona Adans. 13. Polysperma sp. Vauch.
t. 1. f. 3., 1. 10. f. 1, 2. Conf. sp. Dillw. t. 29. ; E. B.
1763.

The genus Lemania, like some other genera of freshwater
Alga, would appear to stand .almost alone, exhibiting no
very exact relation with any other division of this tribe, and
the only plant to which it bears any definite resemblance
appears to be the Enteromorpha intestinalis, and this only in
its ramose habit, and in the cellular structure of the frond,
the reproduction in Lemania, though simple, being wholly
different from that of Enteromorpha.

Vaucher, in his description of his genus, Polysperma} of
which Conf.fiumatilis formed the type, has not erred far from
the truth, and his generic name might, with propriety,
have been retained ; the chief mistake which he committed,
was in associating with Conf. fiuviatilis the Conferva glo-
merata, a plant in every way dissimilar to the former.

The branches of the fronds of the Lemanice, in their young
state, are cylindrical; soon, however, they are seen to be-
come dilated at regular intervals. If one of these dilatations

LEMANIA. 69

be pressed between the fingers, their contents Nwill be forced
out : on examining which, with the microscope, the observer
will be astonished to perceive that it is made up of a number
of beaded and plant-like bodies, which the inquirer would be
inclined, at first sight, to regard as the species in its young
state : this opinion, on further investigation, would be found
to be erroneous ; for if these tufted bodies be watched, and
kept in water for some time, the beads of the filaments will
soon be perceived to separate from each other, and each ul-
timately to become developed into a young plant resembling
that from which the seed was derived. The separation of
the sporules which compose the beaded threads likewise takes
place naturally within the frond, and it is by their develope-
ment that the dilatations of the stems, already referred to,
are produced, and by which an apparent resemblance to the
Batrachosperms is imparted to the plants of this genus.

Frequently, if these dilatations be examined with a lens,
numerous filaments may be observed issuing from them :
these are what Vaucher terms the young polysperms pro-
duced by the germination of the sporules, which are still
within the frond, and which developement of them is or-
dained to take place in all cases to such an extent as to
occasion the rupture of the dilatations, and consequent separ-
ation of some of the cortical cells from each other ; thus,
apertures are created, through which the sporules may pass
out, a condition essential to the perpetuation of the species.
The force with which this developement operates may be
appreciated when the cartilaginous nature of the frond is
considered.

It is only the middle and upper branches that are so
torulose, the lower being almost plain and cylindrical ; this
arising from the fact of the sporules having all escaped from
these, which are the oldest portions of the plant.

Bory's account of the structure of this genus appears
to contain some strange errors. " The Lemanice" he remarks,
" are articulated Conferva, whose contiguous joints are
united the one to the other by a solid interior filament, very
well represented by Vaillant (Bot. Paris, pi. iv. fig. 5.) in

F 3

70

the figure which he has given of one of the species of our
genus."

" The buds of the Lemania, sessile, naked, rounded, more
or less numerous, are situated at the points of junction of the
cells, which by their growth they render tumid. When
these gemmules come to cover or deform the plants they
appear to detach themselves from them ; they carry away
sometimes the joints which support them and elongate them-
selves to reproduce new Lemanice."

The above observations certainly do not apply to the
Lemania proper ; but Bory has included in the genus one
species at least (Chara batrachosperma, of which JBatracho-
spermum atrum is a synonyme) which does not belong to
it, and on this, distorted and irregular-looking bodies do
occur, which I take to be analogous to the " glomerules " of
other Batrachosperms ; in this species as in others of the
same genus the interior tube referred to by Bory would be
found.

" The Lemanice are very rigid plants and with a peculiar
and corneous appearance ; they crack under the teeth with a
taste which reminds one of that of fish."

" M. Thore of Dax first remarked, in the Conferva fiuma-
tilis of Linnaeus, a fact which is verified in the other species of
our genus. The recent filaments of this Lemania, presented
towards the flame of a candle, explode and extinguish the
candle. This phenomenon does not take place in dried
specimens. It is owing to some gas shut up in the con-
nections of the joints, and which, put in expansion by the
heat, presses against the walls and breaks them with an ex-
plosion. A remarkable movement of retraction is expe-
rienced in the fingers which hold by the two extremities the
filament experimented upon. As to the smell of the burnt
plant, although very peculiar, it cannot be compared to that of
animal substances submitted to the fire."

"I have not met with any Lemania in stagnant waters;
they grow in quick waters. It is in the pure fountains,
large rivers, in very rapid rivulets, that they appear to de-
light. Many, moreover, flourish especially in those places

LEMANIA. 7 1

where the current has the greatest force, such as in mill
sluices and the most impetuous falls of cascades.

" We have named our new genus Lemania. This name
comes from that of M. Leman, a modest naturalist, not less
learned in botany than in the other branches of science." —
Bory.

Kiitzing, in his " Phycologia Generalis," appears to have
studied this genus closely ; he there gives a beautiful, elabo-
rate, and accurate drawing of Lemania torulosa, from which
the figure of that species given in this work is chiefly derived.

1. LEMANIA TORULOSA Ag.
Plate VII.

Char. Frond nearly simple, incurved. Inflations of the stem
large, approximate.

Lemania incurvata, filamentis simplicibus, incurvatis, arti-
culis in centra turgidis, Bory, Annales du Musee, vol. xii.
p. 181. pi. xxi. fig. 1. Chantransia (torulosa} virescente-
nigrescens, filamentis subsimplicibus, articulis ovatis,
medio tumidis, Cand. Syn. 10. Chantransie en colliers,
Cand. Flor. fr. 2. p. 50. Conferva (torulosa) filamentis
filiformibus, torulosis ; geniculis contractis, annularibus ;
articulis ovalibus, infiatis. Roth. Cat. Bot. 1. 200.; Fl.
German, iii. 527. Conferva (torulosa) filis torulosis,
simplicibus, continuis, filiformibus, &c., Roth. Cat. Bot.
iii. 250. Conferva (verrucosa) anomalacea, incurva, no-
dis eminentibus, approximatis, verrucosis, Draparn. MS.
ined. Conferva (fiuviatilis) filamentis simplicibus, seti-
formibus ; geniculis crassioribus, angulatis, Syst. Nat.
xiii. 11. 1392. Conferva fiuviatilis var. a, Encyc. Met.
Die. No. 12. (The synonyme of Vaillant ought to be
excluded as also that in the " Flore Fra^aise." — Bory.)
Conferva nodosa var. a, Lam. Flor. fr. 1278. ix. Con-
ferva fiuviatilis nodosa, fucum emulans, Dill. Muse,
fig. 48. t. vii. Lemania torulosa, Ag. Spec. ii. p. 0.
Conferva fiuviatilis var. torulosa, English Botany, t.

F 4

72 LEMANEJE.

1763. ; Hook. Brit. Flora, ii. p. 322. ; Harvey, in Manual,
p. 119.

Hob. Mountain streams near Ludlow : Dillenius. Angle-
sea : Rev. H. Davies.

" It is now more than ten years since I observed, for the
first time, this species, and I have named it after the very
peculiar form and remarkable curvature of its filaments, Le-
mania incurvata. I believe that so very characteristic a
name ought to be maintained; that which other botanists
have since given to this plant applies equally to two orders
of Conferva.

" The Lemania incurvata abounds in certain rivers ; I have
above all observed it in the Dordogne, near the little town of
Sainte Foix. The fishermen bring it up from the bottom of
the river in their large nets. It has been confounded with
the following species, even by Linnaeus himself; the figures
47 and 48, given by Dillenius, and that of Vaillant, referred
to alike indifferently by their authors, prove this.

" From a little horny disc, fixed to the hard bodies which
support it, arise from six to thirty filaments, from one inch
to two inches and a half in length, curved in one direction,
perhaps by the continual action of the current, to which their
rigidity opposes itself in vain. Their colour is of a brownish
or reddish green, obscure or livid. They acquire in diameter
the greatest dimensions of all the Conferva.

" The joints are ovoid and thinned (amincies) at their point
of contact, while, in the following species, the contrary is
always observed. The Lemania incurvata is moreover shorter
and thicker, and the filaments but rarely branched." — Bory.

2. LEMANIA FLUVIATILIS Ag.
Char. Frond ramose. Inflations subdistant, oblong.

Lemania (corallina} filamentis subsimplicibus, articulis ob-
longis, extremitatibusturgidis, voLxii. pi. xxi. fig. 2.; Bory,
in Annales du Musee. Chantransia (jluviatilis) viridi-
HH/rescens ; Jilamentis subdivisis, cartilagineis ; articulis
teretibus, geruculis tumulis, Cand. Syn. 10. Chantransie

LEMANIA. 73

fluviatile Cand. Flor. fr. 2. 50. Potysperma fluviatilis
Vauch. Conf. p. 99. PL 1. fig. 3. et pi. x. fig. 1, 2, 3.
Conferva (fluviatilis) Jilis subramosis, setaceis, nodosis,
geniculatis ; geniculis torulosis, angulatis, 8fc., Roth. Cat.
Bot. iii. 304. Conferva fluviatilis fllamentis setaceis,
nodosis ; geniculis elevatis, brevibus, articulis oblongis,
cylindraceis, Roth. Cat. Bot. i. 201. ; Fl. German,
iii. 528. Conferva fluviatilis var. ft, Encyc. Met. Die.
No. 12.; Thore, Chloris, 441. Conferve rameuse var.
ft, Lam. Flor. fo. 1278. ix. Conferva (jftuviatilis) Jilis
simplicibus, setiformibus, rectis, geniculis crassioribus, an-
gulatis, Lin. Sp. 1635. Conferva fluviatilis, lubrica, se-
tosa, equiseti facie, Dill. Muse. viii. f. 47. Corallina
fluviatilis non ramosa, Vaill. Paris, p. 40. t. iv. fig. 5.
Nodularia fluviatilis Lyng. t. 29. Lemania fluviatilis
Kiitzing, Phycologia Generalis, p. 322.; Dillw. Brit.
Conf. PL ; Hooker, Brit. Flor. ii. p. 322. Conf. fluvia-
tilis, English Botany, t. 1766. Lemania fluviatilis
Harvey, in Manual, p. 119.

Hob. In the Winterbourne Stream, Lewes : W. Borrer,
Esq. In the stream at Hamsell, and at the Waterfall
at Harrison's Rocks in abundance : Mr. Jenner. Com-
mon in rapid streams about Aberdeen : Dr. Dickie.
Frequent in Ireland : Mr. Moore.

" The name of fluviatilis, adopted after Dillenius by
authors, does not well apply to a plant much less frequent
in rivers than any one of its congeners. The name, borrowed
from Sebastian Vaillant, better designates our Lemania, and
gives a very just idea of its bearing.

" The Lemania corallina is one of the most common of
Confervce ; it is frequently found attached to stones, and upon
stakes that are always covered with water, near mill-dams,
or against the sides of their channels. I have seen falls which
were quite covered ; the more rapid the current the more
the Lemania prospered. It becomes sometimes more than
half a foot in length, and of a considerable diameter. The
plant languishes or dies when any circumstance renders the
water in which it has grown stagnant.

74 LEMANE.fi.

"From a cartilaginous disc, strongly applied to foreign
bodies, proceed a great number of close filaments, elastic, of
a brownish green colour, and a little curved at the base ;
but they become more pale and straight in the remainder of
their length. These filaments are ordinarily from four to
seven inches in length. Some are entirely simple, the others
throw out here and there branches, or divide towards the
middle of their length.

" The internodes are oblong, from a line to a line and a
half, cylindrical, and inflated at their points of contact. Their
divisions are often but little apparent, and disappear towards
the base of the filaments, which appear continuous, cylin-
drical, and equal in diameter to a strong horse-hair.

" The surface of the filaments in old age is encrusted in
such a manner as not to become recognisable either by its
colour which changes, or by the destruction of the internodes,
which become confused and disappear." — Bory.

" I have seen this species growing near the mouth of the
Don, very luxuriantly, where it must have been exposed to
the action of salt or very brackish water." — Dr. Dickie
in lit.

" Let us then consider the Works of God, and observe the Operations
of his Hands ; Let us take notice of, and admire his infinite Wisdom and
Goodness in the Formation of them : No Creature in this sublunary
World is capable of so doing, besides Man, and yet we are deficient
herein : We content ourselves with the Knowledge of the Tongues, or a
little Skill in Philology, or History perhaps, and Antiquity, and neglect
that which to me seems more material, I mean, Natural History and the
Works of the Creation : I do not discommend or derogate from those
other Studies : I should betray mine own Ignorance and Weakness should
I do so ; I only wish they might not altogether justle out, and exclude
this. I wish that this might be brought in fashion among us ; I wish
Men would be so equal and civil, as not to disparage, deride and vilifie
those Studies which themselves skill not of, or are not conversant in ;
no Knowledge can be more pleasant than this, none that doth so satisfie
and feed the Soul ; in comparison whereto that of Words and Phrases
seem to me insipid and jejune." — Jiay.

75

FAM. IV. CALLITHAMNE,E.

4. TRENTEPHOLIA Ag.

Char. Frond affixed, ramose, articulated. Cells in single
series. Fructification corymbose, involucrate, and cap-
sular.

" Except for its freshwater habitat this genus does not
differ from the preceding section of Callithamnion, which in
the * Brit. Flora ' I ventured to unite to it. At Mrs. Griffith's
instance I now give up- this point, but must still observe
that Cal. Daviesii and T. pulchella, when the latter is well-
coloured, are scarcely distinguishable under the microscope."
— Harvey.

1. TRENTEPOHLIA PULCHELLA Ag.
Plate VIII. Fig. 2.

Char. Frond parasitic, tufted, blood-red, much branched.
Filaments equal, apices obtuse. Articulations four times
as long as broad. Capsules pedunculate, in clusters, and
ovoid.

C. chalybea Roth, Cat. Bot. iii. p. 286. tab. 8. fig. 2. C.
chalybea Dillw. Brit. Conf. t. 91. Conf. corymbifera,
E. B. t. 1996. and t. 2585. ; Harvey in Hooker's Brit.
Flora, p. 382. ; Harvey in Manual, p. 118.

Hob. On flints in Winterbourne Stream at Lewes, Sus-
sex : W. Borrer, Esq. On sandstones in a spring at
Ladsworth, near Midhurst, Sussex : Mr. Jenner. Clon-
mel : Dr. Allman. Hill of Fare, Aberdeenshire : Dr.
Dickie. Frequent in streams in Ireland : Mr. Moore.

" Professor Mertens first discovered the present delicate
species in the neighbourhood of Bremen, and communicated
it to Dr. Roth, who has published it with a good figure in
the third volume of his ' Catalccta Botanica.' Mr. Borrer

76 CALLITHAMNE^.

has since added it to the British flora, having found it at
Winterbourne Stream at Lewes, Sussex ; and to him and
Mr. Turner I am indebted for the specimen here figured.
It grows on flint stones in little tufts about a quarter of an
inch in length, and of a bluish green colour, glossy when
dry. The filaments, which are repeatedly branched, are
erect, straight, of equal height, and very flaccid and slender
throughout. The branches are placed at uncertain, gene-
rally considerable distances, from each other, and issue from
the stem so as to produce an obtuse angle, but immediately
curve inwards, and then rise in a more or less upright direc-
tion ; their disposition is far from regular, but they are fre-
quently disposed on opposite sides in alternate parcels of
two or three. The ramuli are always placed nearer to each
other than the main branches, and I have frequently ob-
served more than one proceeding from the top of the sanrj
joint ; they are blunt at their apices ; the dissepiments are
readily observable with a microscope, and divide the filaments
into perfectly cylindrical joints, of which the length is gene-
rally from four to six times greater than the diameter." —
Dillw.

To the above very accurate description of a most beautiful
production, it is necessary to add but very few words. The
single species of the genus Trentepohlia, like those of the
two preceding genera, seem to find pleasure in pure and
running waters, attaching itself to any substance favourably
placed in the current of the stream, and to which it can
firmly adhere. When in health the plant is of a blood-red
colour, a colour which, in decomposition, it readily imparts
to whatever it may be in contact with. This colour, how-
ever, is observed to change either by age or habitat, or
some other circumstance connected with its place of growth,
to a bluish grey, in which state it constitutes the Conferva
chalybea of Dr. Roth and Mr. Dillwyn. No difference can
be detected between the filaments of the two states, which
may therefore be concluded to be merely conditions of the
same Alga. The fructification, which adds much to the
beauty and elegance of the plant, is by no means rare.

77

FAM. V. CHARACEJL

Char. Stem dichotomous and jointed ; each joint composed
either as in Nitella of a single cell or tube, or as in Chara
of a single cell surrounded by other smaller contiguous cells,
which take a spiral direction ; each articulation more-
over is surmounted by a variable number of branches three
or four times jointed, which are arranged in the form
of a verticillum or whorl, and at the joints of which the
reproductive organs are situated : these are of two kinds,
consisting of nucules and globules. Circulation spiral, and
distinct in each cell.

Following the example of those more recent Algologists
who consider the Characece as Algce, I give this order a pro-
minent place amongst the British freshwater Alga, a position
to which they are well entitled, both on the ground of their
greater comparative complexity of structure, and of the high
interest attached to certain phenomena connected with their
history.

The phenomena more particularly alluded to in the pre-
ceding paragraph are twofold ; the first having reference
to the circulation in the cells of which the different spe-
cies of this order are composed, and the second to the ex-
istence of spermatozoa in the globules or male blossoms.
These phenomena are confined amongst the freshwater di-
vision of the Algce to the Characece.

In order that the nature of the circulation (which will first
be considered), carried on in the cells of the Characece, may be
more clearly understood, it will be advisable, previously to
entering upon its consideration, to give a general notion of
the structure of these curious productions.

The order Characece is divided into two genera, Chara
and Nitella. The main stems of the different species of

78 CHARACEJE.

Chara, which are all branched, consist of elongated cells
placed end to end, and tapering in size from below up-
wards ; surrounding these primary cells there are, in the per-
fect state of the plant, a number, in Chara vulgaris usually
eighteen, of smaller secondary cells : these take a spiral course
round the larger cell invariably from left to right. From
the upper extremity of each cell grow out nine arms or
smaller cells arranged in a campanulate manner; each of
these arms have four or five joints, from which issue the
organs of reproduction, to be described hereafter. From the
superior extremity of many of the cells also grow out branches,
and at the same time long and colourless branched articulated
roots are sent forth. The genus Nitella differs only from
Chara in the absence of the secondary spiral cells, and in
the number of arms which go to form each verticillum or
whorl.

The circulation in Chara was first noticed by Amici ; in
the two genera it does not differ materially, in both the course
is spiral ; the fluid, with its granules, passing obliquely and
slowly from left to right up one side of the cell, turning
round its extremity and descending in the same manner on the
other side. A circulation of the same character prevails not
only in the main cells of the stems and branches, but also in the
secondary spiral cells or tubes, some of which are occasionally
articulated or divided into other small cells, each, in like
manner, having an independent circulation.

Mr. Slack (Transactions Soc. of Arts, &c., vol. xlix. p. 1.)
long since observed, and the observation has been verified,
that the ascending current of the circulating fluid is always
in that half of each cell which is farthest from the axis of
the plant ; the descending, as a consequence, being confined
to the opposite half, or that which is nearest the axis. The
same observation Mr. Varley states to hold good in respect
to the roots, due allowance being made for the difference in
their direction, they, unlike the plant itself, taking a down-
ward course.

A deviation from the above-described circulation has been
noticed to occur in certain parts of Chara vulgaris by Mr.

CHARACE^E. 79

Solly, and has been described by Mr. Varley in one of his
excellent memoirs on Char a in the " Transactions of the Soc. of
Arts," vol. xlix. p. ii. This deviation occurs in many of the
cells which usually surround the seeds, and which are four
in number when complete. It occurs, see plate LXI. fig. 1.
of the present work, in those cells or sprouts surrounding the
seeds marked a, b, c, d, e, f, g, h, in which the sap has taken
a circular or cylindrical course round the axis. Mr. Varley
thus minutely describes this deviation.

." Fig. 2. (pi. LXI.) is an enlarged view of the sprout a. The
circulation is over to the right, as shown by arrows ; it thus
far agrees with the spiral course, which is always to the right.
Near the point by the top arrow, there is such an accumu-
lation as to form a ring or .thick mass very like a diaphragm ;
this mass keeps revolving on its own axis. Near the second
and third arrows the particles are more detached, each going
round in its own circle ; here the green studs, instead of being
arranged in a straight line, are slightly curved. Still lower
down, near the middle of the sprout, there is an inclined
elliptical circulation, shown by dots and arrows ; and from the
bottom, particles are seen rising nearly as high as the oval,
and descending again without appearing to follow any regular
course : these are shown by dots and arrows.

". Some of the particles in sprout (a) were of sufficient
size to be distinctly seen during the whole of their revolution,
which took place in about fourteen or fifteen seconds : this
observation was repeated by different persons, who nearly all
agreed as to the time of the revolution ; but in one of the
sprouts I observed three particles differing in their speed,
and occasionally passing each other. I counted their periods
by my own pulse ; one went round in nine beats, the next in
eleven ; these followed so nearly in the same track as to
move aside whilst passing; the third sometimes occupied
twenty beats, and at other times twenty-five in going round.
They all appeared to keep to the circumference, and therefore
the difference in their periods is more worthy of being re-
marked, as seeming to indicate that each particle had some
cause of motion independent of the fluid in which it moved."

80 CHARACE^5.

Various attempts have been made to determine the cause
of the remarkable circulation in Chara and Nitclla. The in-
sufficiency for this purpose of the well-known laws of endos-
mosis and exosmosis has been ingeniously shown by Mr. Slack
in a note inserted in the Second Part of vol. xlix. of the
" Transactions of the Society of Arts," that lamented inquirer
having ascertained that the circulation continued in all plants
in which it has been observed when the portion was immersed
in oil or mucilage, and in strong saline solutions, and even
when not in contact with fluid of any sort, but surrounded
only by the dry atmosphere.

In a letter addressed to the Royal Academy of Sciences,
of Paris, in the sitting of November 23d, 1829, by M. Du-
trochet, some highly interesting remarks occur relative to the
circulation of Chara. The discovery was made very many
years ago by Count Rumford, that water placed in vertical
tubes circulates. In order that the circulation of so transparent
a fluid may be the better appreciated it is requisite to suspend
in it some molecular substance, the best for which purpose M.
Dutrochet has found to be a few drops of milk, the specific
gravity of which is nearly equal to that of the water. Many
other substances will circulate in water, such as very fine
sawdust, amber reduced to powder, and rasped cork ; but
these being of greater specific gravity than the element in
which they are suspended, sooner or later subside to the
bottom of the tube.

M. de Bailif illustrated, by means of an apparatus con-
structed on this principle, the circulation which takes place
in the cells of Chara, &c. M. Dutrochet, however, in the
letter above cited, examines this curious physical phenomenon
more closely. He found that the efficient cause of the cir-
culation was caloric, that the rapidity of the motion depended
on the amount of caloric to which the tube and its contents
were subject, and that the direction of the current was go-
verned by the same agent, the ascending stream being placed
always on the side of the tube which received the most heat.
M. Dutrochet observed, moreover, that light exerted a power-
ful influence on the circulation, which influence was attri-

CHARACEJE. 81

butable to the caloric which accompanied its rays, and also that
mineral substances in solution accelerated its speed. The
caloric and the mineral substances in solution were supposed
to exert this power by causing the greater separation of the
molecules of the water, and thus increasing their mobility.
Pressure was found to have a contrary influence, and to re-
tard the circulation by, it was presumed, occasioning the
closer approximation of the molecules, and so impeding their
mobility. Viscid organic matter, such as gum, produced the
same effect, and for a similar reason.

The causes not favourable to the sustenance of this physical
circulation, therefore, are, the absence of caloric, or cold, and
of light, upon which it follows that the motion ought not to
take place during the night, pressure, and the solution of
viscid substances in the liquid ; all of which act in the same
way, viz. by impeding the facility of motion between the
aqueous molecules. On the contrary, the favourable causes
are all those things which act in an opposite way, by increas-
ing that facility.

A very curious fact is related by Dutrochet in reference
to the circulation of aqueous fluid in tubes. It is this : that
if a drop or two of acid, of alkaline solution, or a solution
somewhat saline be added to the water contained in a tube,
and which has had milk mixed with it, these substances, more
weighty than water, precipitate themselves, and become dis-
solved. " This solution being achieved, the water is no
longer susceptible of presenting the circulatory movement
by means of simple diffused light ; it only presents this move-
ment at its superior part, and this only when the tube is
exposed to the direct light of the sun, the continued action
of which on the tube for many hours can scarcely penetrate
the circulation to the depth of an inch in that water, whose
molecules have acquired a very extraordinary molecular fixity.
I consider this fixity as the result of a regular disposition of
the molecules of the liquid. Indeed, when one agitates this
liquid endowed with molecular fixity, it becomes immediately
susceptible of circulation under the influence of the simple

G

82 CHARACE^E.

diffused light. The agitation has changed, as it would a|«
pear, the regular order of the molecules of the liquid, and
their aggregation has become confused. In this last state
they enjoy a mobility of which they were deprived in their
state of regular position ; and it is to be remarked that water
so changed with a mineral substance in solution and agitated,
has more molecular mobility, and is more susceptible of cir-
culation than was the pure water before this solution."

With the following extract, this epitome of Dutrochet's
letter on the circulation of Chara may be concluded : —

" After having filled tubes with acidulated milky water
I have closed them with the lamp. This liquid being fit
for circulation, being unalterable, and not being able to lose
any thing by evaporation, it follows that being exposed to
the light it possesses the condition of a perpetual circulatory
movement, with nocturnal intermissions, and further, with a
winter intermission, which exists but when the temperature
is inferior to 5° R. One might say, metaphorically, that this
liquid is, during the night, in a state of sleep, and during
the day, in a state of wakefulness ; one might say also that
its repose in winter is a state of hibernation. It might be
supposed at first view that these phenomena bore some ana-
logy to the state of sleep and of wakefulness of plants, and
to their state of hibernation."

An experiment in reference to the circulation of the Cha-
racea may here be referred to, viz. that the application of a
ligature to the centre of a cell does not destroy the circulation
therein.

This experiment was originally made by Raspail.

A general description having now been given of the
structure and circulation of Chara and Nitella, a few other
particulars still remain to be noticed.

A delicate membrane lines the interior of each cell,
having little or no attachment to the one which constitutes
the proper cell membrane, and which is therefore easily
separable therefrom, save at the lateral colourless longitu-
dinal lines, which are formed probably by its attachment.

CHABACE^. 83

This membrane is studded over with a number of minute
granules, which impart colour and texture to the plant.
This inner membrane is represented in fig. 7. Concerning
these granules, Mr. Varley makes some curious remarks : —
" The minute green bodies always adhere to the membrane,
and never to the outer tube. In some specimens these
green bodies are so regular as to leave only a very narrow
and even partition, whilst in others, the green studs are very
scanty and irregular at the parting lines, appearing rather
scattered about, as shewn in fig. 11. In such places, if
the green bodies be patiently watched through a doublet
l-60th focus, they will be seen occasionally to expand and
contract, change their form, move a little round, then more,
and then go on to a whole turn or more ; move forwards a
little, and sometimes start off out of the field ; some I have
followed till they stopped behind stationary ones, and I have
seen some come into the field and be stopped ; also minute
darkish dots are seen running along between these studs,
and some of these would turn aside as by an eddy, and
stop between them. Again, whilst writing this, I have seen
some (where an open space had been made • by bending
or teasing the stem) move forwards, and then return ; three
or four separate ones came together laterally, then went
forwards close to the regular and undisturbed ones ; they
then, after stopping some time, came back, and parted a con-
siderable distance from each other, and with the motion of
others, they were lost to any further observation, and the
next day all the irregular ones had moved, and some parts
assumed a more regular arrangement." The singular move-
ments above described correspond precisely with those of
the Zoospores described in the Introduction, to which, in other
respects, one would not suppose them to be analogous.

Mr. Varley considers these green granules to be placed on
the external surface of the inner membrane, to which, from
their power of locomotion, they must be supposed to adhere
but feebly. The purpose which they serve in such a situation,

it is not easy to determine : were they adherent to the inner

G 2

84 CHARACE^.

surface of the membrane, their destination might be con-
jectured. The delicate and tender membrane itself might
be regarded as the matrix for the developement of these
granules, which, when mature quit it, and join the other
granular bodies contained in the circulating fluid, and the
nature of which is itself probably determined by their pre-
sence. That the granules studding the inner membrane do
in some way or other enter the circulating fluid, is rendered
highly probable by the fact that the majority of particles
which it contains bear a close resemblance to these granules.
Mr. Varley further remarks in reference to these granules,
that if any of them, situated in the middle part of a cur-
rent, be disturbed by injury, no effect is produced, the
stream passing on as before; but that if they be displaced
over the boundary lines, a communication takes place be-
tween the two currents ; a portion of the fluid near the
boundary line, instead of passing on to the end of the cells,
crosses over it into the returning current, and passes on
with it, a portion of the descending, in like manner, joining
the ascending and following its course. " I believe," says
Mr. Varley, " that in this case the fine membrane is not
wounded, but is probably loosened from its adhesion to the
ridge, the green vesicles only being removed or injured:
but it shows that there is a most intimate connexion be-
tween these vesicles and the circulation ; and they appear to
govern the circulation ; for in the case above stated, where a
clear space was refilled with green vesicles anastomosing
had taken place ; but when the spot was again coated with
vesicles, the anastomosing also ceased, the fluid having
again taken its direct course, coinciding correctly with the
track marked out by their arrangement. I am led to think
that any wound of the membrane would kill that whole cell,
by submerging the vesicles in the thick or the inner fluid, and
thus cutting off the continuity of their action, or by the
different fluids mixing and so destroying their action. The
fine membrane with the vesicles is seldom removed far
enough from the tube to shew the colourless space between

CHARACE^. 85

(though I have samples before me now that shew it) ; there-
fore the fluid which passes between the vesicles must be
very small in quantity, and is so limpid as to be difficult to
discover."

In what way the removal or injury of the granules, placed,
according to Mr. Varley, on the outer surface of the mem-
brane can influence or govern the circulation carried on
within that membrane, it is difficult to conceive. It seems
to me, that the anastomosing of the currents can only be
accounted for by adopting the view of Mr. Slack, relative to
the internal organization of the Characece to be mentioned
presently, or by supposing the internal membrane to be
ruptured in the situation pf the boundary line, thus permit-
ting an escape of the circulating fluids from the interior of
the membrane to its exterior, and so deranging the dis-
position of the granules.

Within the membrane which has been just described is the
proper circulating fluid of the plant, which, in full motion, is
dense and thick, though transparent, containing a variable
number of solid granules, which circulate with it in the"
course already indicated from left to right. The granules
do not, however, all move with equal velocity, or in a pro-
cession as it were.

Internal to this fluid, and occupying the centre or axis
of the cell is another fluid, almost quiescent, and usually free
from solid admixture. This is generally greater in quantity
than the former or circulating fluid.

" These two fluids being of different densities," accord-
ing to Mr. Varley, " do not when the plant is in health
mingle, and are not separated by a membrane. According
to Mr. Slack, however, a membrane does exist between the
different fluids, enveloping the central, and forming an
axis for the circulating fluid to revolve on, usually becoming
attached in the course of the longitudinal boundary lines,
thus separating the two currents of the circulating fluid
from each other. It can now be understood in what way
injury to this membrane, if it really exist, would occasion the

G 3

86 CHAKACE^E.

intermingling and anastomosing of the currents described by
Mr. Varley."

This membrane, which must be of exceeding tenuity, is,
however, in unhealthy states of the plant no doubt wanting.
In certain states of Chara, several large spherical masses
are noticed in the central fluid : these are supposed to consist
of portions of the innermost dense circulating fluid which
have become detached ; and it is by means of these that the
absence of the membrane can be demonstrated. The thick
circulating fluid does not seem to be visibly affected by
gravity, for it follows its usual course in whatever position
the cell may be placed : the spherical bodies, which are de-
scribed by both Mr. Varley and Mr. Slack, are, however,
sensibly affected by gravity : if the cell be placed horizontally
and one of these bodies be in the superior current, it will de-
scend, slackening its speed as it enters the middle fluid, revolv-
ing as it passes through it, and returning by the lower cur-
rents : then again, if the plant be reversed, the same globules
will again descend, and enter the former stream. The passage
of globules from current to current through the central fluid
proves that there is now no membrane surrounding it, and
also that the central fluid is lighter than the circulating.
Fig. 11. represents a cell containing several of these balls or
globules.

For the purpose of tracing and following the course of
these globules an apparatus, similar to Mr. Varley's vial
microscope, is necessary. Having now completed the con-
sideration of the circulation in the Characece, it remains
to treat of the reproduction of the order — a subject always
of the highest interest in productions belonging to the fresh-
water division of the Algce.

We will first describe the organs as they occur in Chara
vulgaris, and which will serve as the type of the whole order.

The branches which compose each whorl in Chara vulgaris
are usually nine in number, and consist of four or five cells,
the lower ones of which are surrounded by nine other smaller
cells, which pursue, like those covering the cells of the stems, a
spiral course. At the junction of the major cells with each other,

CHARACE^E. 87

and which are surrounded by the nine smaller spiral cells, arise
or are placed the organs of reproduction : these are of two kinds,
nucules and globules, which have been denominated male and
female ; the upper being regarded as the female and the lower
as the male apparatus. The female apparatus or nucule con-
sists of a seed-vessel, which is composed of a membranous and
brittle envelope, around which are wrapped five spiral cells,
surmounted or crowned by five smaller cells. The cells, it is
remarkable, pass from right to left, that is, in a direction the
reverse of the cells on the stems and branches, and contrary
also to the course of the circulation. (See pi. LXI. fig. 4.) In all
these cells circulation is carried on. The brittle envelope re-
ferred to may not be a real organized membrane. Each seed-
vessel, according to the observations of Mr.Varley and others,
contains but a single nucleus or germ, which has a proper
envelope: when young, it is of a green colour, the tubes
being colourless : as it ripens it becomes darker, and then
begins to fade away, and ultimately separates and disappears.
The seed or nucleus is then ripe, and ready to separate, con-
nected only by the brittle envelope, which is entirely soluble
in acids. When this is removed the nucleus or kernel appears
with its dark and shining skin, " which is flexible and tough
enough to bear squeezing out of shape." On the rupture of
this the contents issue forth, which are compared to wheat
flour by Mr. Varley. Such is a brief outline ofthe seed and
seed-vessels : the structure of the male blossom, if it may
be so termed, is more complicated. It is spherical and
situated beneath the seed-vessel, surrounded by its four
sprouts or cells. (See pi. LXI. fig. 4.) Although these globules,
as well as the seed-vessel or nucleus, are placed at the junc-
ture of the principal cells with each other, they do not arise
directly from these, but rest on a number of smaller cells,
which are there found, and which, as some of them present
phenomena, which are peculiar, and which are accurately de-
scribed by Varley in vol. iv. part 1., it will be well to notice
before following up the anatomy of the globule. The cells
which present these peculiar phenomena are, first, that upon
which rests the stalk of the globule ; secondly, that which sup-

G 4

88 CHABACEJS.

ports the stalk of the seed-vessel ; and thirdly and fourthly,
two other cells, which lie on each side of the cell, supporting
the stalk of the globule. " In ordinary tubes or cells," Mr. Var-
ley writes, " there are green vesicles regularly arranged on
the thin membrane which lines them, and the circulating fluid
appears thickened by innumerable particles, a little denser, or
not quite fluid, and with scarcely any colour. But in these
peculiar cells there are generally very few stationary green
vesicles, except about the angles formed by the adhesion of
other cells. The fluid within is very clear and limpid, with
many very equally sized green granules floating in it. Those
that are still, and those that are moving, appear to be the
same ; and some are seen to stop, and some stationary ones
are seen to break loose and go on : they are rather larger
than the orderly arranged green vesicles of other cells ; but
being loose, and the cells so glossy, they are seen very bright
and distinct. This is not all ; for they circulate round the
cells very quickly and freely, undergoing some extraordinary
influence; for they knock against one another, appear to
stick at some places, or as if they squeezed by, and then rush
on quicker : many, as they come near particular parts of the
cells, spin round most rapidly as they go on, different particles
turning in opposite directions ; and others only catch a slight
impulse to spin, suddenly turning round and back again, and
go on without spinning ; others, near the centre of rotation,
go round together, then start into a quick whirl, then vary
or slacken, and again start into a furious whirl, showing
considerable fluctuations in their motion ; and in the larger
rounds they appear to receive some impulse whenever they
touch that part of the surface which joins the arm, as though
they were slightly electrified." These motions precisely re-
semble those of the zoospores, and are doubtless voluntary,
performed, as in their case, by means of vibratile organs or
cilia.

We will now describe the globule itself: this, as has
already been observed, is spherical, with a light red nucleus,
the coating being made up of about eight deeply indented
triangular segments. (See plate LXI. fig. 4.) These con-

CHARACEJE. 89

tain a number of small red granules, to which the colour
of the globule is principally owing. Within these segments
are noticed, first, the stalk of the globule, which is pyri-
form, and rests upon one of the peculiar cells which have
been described. Upon the summit of this stalk rests a num-
ber of smaller spherical or pyriform cells : these occupy the
centre of the globule, and from them proceed a number of
large cells to be inserted into the segments which form the
coating of the membrane, and by means of which their seg-
ments are retained in their proper situation. These last cells
correspond in number with the segments, one going to each.
Lastly, interwoven together, and filling the interstices be-
tween the cells, are numerous fine articulated threads, to be
more particularly referred to hereafter.

No win the footstalks of the nucules and those of the globules,
as well as in the radiating cells attached to the segments, a
peculiar body or vesicle is noticed. This was first, I believe,
discovered by Mr. Yarley, but has since been noticed and de-
scribed by other observers; although its office has not yet
been determined. This vesicle is situated in the circulating
fluid of the cells, the course of which it follows, although
from its size it frequently projects some distance into the
central fluid.

In the stalk of the globule, and in those of the segments,
in addition to the transparent vesicle, there are membranes
studded with vesicles similar to those of the external and
ordinary cells, and in like manner arranged so as to show the
ascending and descending currents; but instead of being green,
as in the former case, they are bright red.

We now come to relate the most extraordinary circum-
stance, not without parallel, however, in the vegetable king-
dom, connected with the history of these most interesting
productions. The spaces between the stalks of the seg-
ments, it has been remarked, are filled up with entangled
filaments or vessels which appear ringed. The contents of
each division between the rings first appear angular, and sub-
sequently resemble a thread coiled up ; " after a while," to
adopt the language of the first discoverer of the fact, " these

90 CHARACEJE.

coils (see pi. LXII. fig. 3.) within the divisions become agitated ;
some shake or vibrate about, others revolve in their confined
places, and many come out, thus showing that they are
spirals of two or three coils, and then with an agitated motion
swim about. Now the field of view appears filled with life ;
great numbers of these spirals are seen agitated and moving in
all directions ; they all have a directive force, one end always
going foremost and never the other ; many stray a great way
out of the field ; these, by getting clear of each other, are
best to observe ; they do not quite keep their form as a stiff
spiral, but their foremost end seems to lash about ; and to
many are seen attached (see plate LXII. figs. 5, 6.) almost invi-
sible but very long fibres. These fibres were in quick undu-
lations, which rose in waves from the spiral to their farthest
end. It appears that these fibres cause many of the spirals
to entangle together, and thus bring them to a state of rest ;
therefore the separate ones were best to observe."

With a few other remarks this brief description of the
Characeas may be terminated. The spiral disposition of
organs seems to prevail almost universally throughout the
works of nature. The most superficial observer could not
be at a loss for a single moment to point out examples of it.
In the zoophytes this arrangement of parts is especially ob-
vious ; in no order of productions is it, however, more ap-
parent than in that which is under discussion. The tubes
which enfold the main cells are spirally disposed ; the cir-
culation in these cells follows a spiral course ; and lastly, the
cells of the seed-vessel are exactly, simply, and beautifully
spiral ; exactitude, simplicity, and beauty being the chief cha-
racteristics of the spiral disposition or formation.

The preceding pages embody an accurate and minute de-
scription of the different parts constituting the structure of the
order Characece, and of the different remarkable phenomena
presented in those parts ; so accurate, indeed, as to leave but
little to be desired in this respect : and yet, how much remains
to be solved and explained ! how deep is the mystery which
veils the right understanding of the different actions which
have been detailed ! The following questions may be pro-

CHARACE^E. 91

posed, but who shall answer them ? Is the globule really the
male apparatus? and are the spiral coils which may be
denominated animalcula the agents whereby the seeds are
fertilized? and if so, in what way do they effect this grand
and prime object ? what also is the nature of those numerous
particles contained in the peculiar cells whose motion seems
only to be regulated by individual will, and what is the office
over which the vesicles in the cells of the footstalks preside ?

M. Bischoff (Die Cryptogamischen Gewachse, Ire livr.,
1828) was the first to observe the animalcula of Chara.
Using a microscope of but feeble power, however, he did
not make out their origin. Afterwards Meyen gave very
imperfect figures of them in the " Annales des Sciences Na-
turelles," t. x. p. 319. pi: 10. 1838. Mr. Varley, however,
from whose excellent papers I have had occasion to draw so
largely, appears to be the first observer, who gave an ac-
curate, minute, and complete description of them in his paper
in the " Trans, of Society of Arts," published in 1834 ; a
paper, with the existence of which M. Gustave Thuret did
not seem acquainted when he published his excellent memoir
" Sur 1'Anthere du Chara" in the 14th volume, second series,
of the "Annales des Sciences Naturelles," 1840, as no allusion
is made to it therein, and the facts detailed do not differ in
any essential particular from those previously made known
by Mr. C. Varley.

M. Peyen has examined the Characea chemically. The
following are the more important of his remarks : —

" The orange-coloured vesicles (globules) which are seen on
the branches of Chara contain, as is known, cellules very
long and flexible. I have ascertained that their fine mem-
branes have the chemical composition of vegetable tissue,
while the substances enclosed by them present the azotized
composition proper to bodies enveloped in the young organs
of plants."

" These analytical results appear to me to be natural con-
sequences of the constitution of the reproductive organs of
Chara, such as M. Brongniart has indicated not only as to
the monospermic grain, but also relatively to the azotized

92 CHARACE.E.

substances contained in the vegetable membranes which are
related to the pollen of the male organ."

" These chemical facts should be in harmony with the ob-
servations of M. Meyen and those of M. Brongniart upon the
spontaneous movements of little bodies enclosed in the pollen.
(Ann. des Sc. Nat., Nov. et Dec. 1838.) The particles of
Brown are found in my experiments to have an azotized
quaternary composition."

The monospermic grain is composed chiefly, as was first
indicated by Raspail, of farina.

The affinities of the order Characece are by no means
striking or satisfactorily determined. In being composed of
tubular cells, and in the disposition of these they exhibit a
relation to the Confervoid Alga generally, in the arrangement
of their branches in whorls, and in the circumstance of the
primary being crusted with other secondary and descending
cells, they manifest a relationship with the Batrachosperms
in particular. In their organs of reproduction, and in cer-
tain other respects, they bear some resemblance to the Equi-
seta, I know not how exact however. The Characece are not
the only order of freshwater Algce possessing double organs
of reproduction : as, for example, Vaucheria. Linnaeus first
referred the Characece to the Cryptogamia, but subsequently,
regarding the globules as stamens and the nucules as pistils,
he removed them to Moncecia Monandria amongst flowering
plants.

The Characea are almost universally distributed : they are
found abundantly both in fresh and stagnant waters, in all parts
of the world. They form an important link in the economy
of Nature, in life purifying by the liberation of oxygen during
respiration, the impure and almost pestilential waters in which
they are frequently and especially encountered, and in death
yielding by their decomposition elements which impart fer-
tility to the soil, and render it fit for the growth and nourish-
ment of plants of an order higher in the scale of organization
than themselves, and of more direct utility to man, the destined
recipient of all Nature's bounties, and for whose benefit every
natural contrivance directly tends. Let this thought impress

CHARACE^l. 93

the heart with the conviction of the goodness of God towards
man, who often ungratefully omits to remember it, and
who therefore needs to be from time to time reminded of it.
The important part which the Characece take in the formation
of the earth's strata, geological investigation has made strik-
ingly and beautifully manifest, their fossil remains having
been found in great abundance in the freshwater strata
covering the chalk formation in the Isle of Wight, and in the
marls of Forfarshire, and other places — their remains con-
sisting of portions of the stems, but principally of the nucules
which Lamark mistook for the shells of testaceous animals,
and acting under this impression named them Gyrogonites.
The fossil remains found in the calcareous marls of Forfar-
shire have been identified as belonging to Chara hispida, the
same species still existing in a living state in great profusion
in the lakes which still cover portions of these marls.

The one grand purpose for which all cryptogamic vegetation
would appear to have been created, is the formation of soil
for the growth of productions more necessary to the wants of
man. First, the lichen, stunted and dry, but rich in salts,
appears on the face of the primordial rock. The rains of
Heaven descend upon it and moisten it, causing the dissolu-
tion of a portion of the rock itself: this it quickly imbibes
and retains in a more soluble form. It lives its allotted time,
then dies, and decomposes, liberating what it had derived from
the rock, together with the constituents of its own fabric. By
the continued and successive growth of the lichens, however,
a portion of the surface of the rock becomes hollowed out,
and a pool of water rests therein. The lichens now finding
this no longer a place fit for their developement, disappear.
Ere long, however, the sporules of a moss or a conferva light
upon this spot, and finding therein the circumstances requisite
for their growth, grow and flourish there for a period. Each
season they die also, and the quantity of their debris annually
increases, so that at last the pool is filled up : next in order
Equiseta, Carices, and Junci appear, and finally a soil is col-
lected, rich in the elements of fertility. The fungi assist much
in the formation of soil; but in a very different manner.

94 CHARACE^.

They require for their growth highly nutritious substances,
such as dead organic matter : this by their thalli, or thousand
rootlets, they quickly disorganize, appropriating a small por-
tion of it to their own nourishment, but allowing the return
to earth, to be again appropriated in some other form of tissue,
of by far the greater portion of those substances.

The Chares are frequently called Stoneworts, from the
quantity of calcareous matter with which they are often in-
crusted, or perhaps which they evolve, this property rendering
them agents still more important in the formation of soil.

5. NITELLA Ag.

Char. Plant more or less pellucid. Cells tubular, not in-
vested with a secondary layer of smaller cells. Globules
and nucules mostly on the terminal whorls, and axillary.

Of this and the following genus no figures are proposed
to be given, as their inclusion did not enter into the original
intention of the work. This is the less to be regretted, as very
good figures of the species are extant, especially those of
« Eng. Bot."

1. NITELLA TRANSLUCENS Ag.

Char. Stem elongated, Jlaccid, pellucid, glossy ; branches of
the whorls spreading, elongated. Nucules and globules
approximate, on the smaller ramuli scarcely bracteated.

Chara translucens, Eng. Bot. 1855, 2d ed. t. 1467, Hook.
Crypt Fl. part 1. p. 245. ; *Macreight, 278. ; Nitella
translucens Ag. Syst. Alg. 124.

This species grows in deep and stagnant ponds : it has been
found in several localities, but is by no means common. It
is the largest of our native species, and well adapted, from its
transparency, for microscopic examination, of which it has
often been made the subject. The whole plant is exceedingly
smooth and glossy, whence its name. The distance of the
whorls, and thickness and size of the branches, vary in differ-
ent specimens. Fructification met with from July to Sep-
tember.

NITELLA. 95

2. NITELLA FLEXILIS Ag.

Char. Stems repeatedly dichotomous, one to two feet long,
smooth, flaccid, somewhat glossy, and pellucid : borders of
the whorls compound, obtuse. Nucules and globules ap-
proximate, few, scarcely bracteated.

Chara flexilis, Eng. Bot. t. 1070. ; Eng. Bot. (2d ed.)
t. 1468., and fig. c to I, t. 1472. ; Smith, 1. 7. ; Hook.
Crypt. Fl. part 1. p. 245. ; Macreight, 278. Nitella
flexilis Ag. Syst. 124.

" Not unfrequent in ditches, lakes, and still waters. A
much weaker and more slender plant than the last, with the
branches of the whorls generally, but not always forked, or
divided into three or four segments, rarely all simple. Nucules
often solitary. It is never so glossy and bright in its hue
as N. translucens, and not uncommonly is found more or less
incrusted with calcareous matter, rendering the stems some-
what opaque : in this latter state it is N. opaca of Agardh."
— Eng. Bot., 2d ed.

3. NITELLA NIDIFICA Ag.

Char. Stems simple, below smooth, flaccid, somewhat glossy,
and pellucid : primary whorled branches simple, elongated ;
fertile ones numerous, crowded, proliferous. Nucules
and globules separate, bracteated.

Chara nidiflca, Eng. Bot. t. 1703., 2d ed. t. 1469. ; Smith,
1. 8. ; Hook. Crypt. Fl. part 1. p. 245. ; Macreight, 278.
Nitella nidiflca Ag. Syst. 125.

" A native of saltwater ditches in the South and East of
England. The simple much elongated branches of the pri-
mary whorls, and the crowded and proliferous character of
the fertile ones, form the chief distinctions of the species, the
globules and nucules not being always separate. I have
found the globule stalked, but that occasionally occurs in N.
flexilis, and it is not uniformly so in the present plant.

" It would be desirable to ascertain the effect of cultivation
in perfectly fresh water upon this species, as specimens of a

96 CHARACE^E.

Nitella, collected in the vicinity of Ely, seem to be inter-
mediate between it and N. translucens. The suggestion thrown
out by Sir W. J. Hooker that our native Nitellce may be all
varieties of a single species, as our Chares are perhaps of a
second, is far from improbable." — E. B. 2d edit.

4. NITELLA GRACILIS Ag.

Char. Stems smooth, glossy, pellucid ; branches of the whorls
compound, their segments acute ; the upper ones often all
fertile. Bracteas wanting.

Chara gracilis, Eng. Bot. t. 2140. 2d edit. 1470.; Smith, i.
9. ; Hook. Crypt. Part 1. p. 245. ; Macrcight, 278. Ni-
tella gracilis Ag. Syst. p. 125.

" Found in boggy pools in St. Leonard's Forest, Sussex :
in Llyn Idmel, North Wales ; and in Jersey. Pale green,
shining, very transparent. Fructification axillary in the di-
visions of the branches of the upper whorls ; generally one
nucule and one globule, side by side, sometimes separate, and,
according to Mr. Wilson, on different plants.

" A small, very delicate, and elegant species, but only
doubtfully distinct from N. flexilis" — E. B. 2d edit.

6. CHAKA.

Char. Plant more or less opaque, very brittle ; striated, often
spirally. Primary cells, excepting the ultimate ones of the
branches which are uncovered, invested by a layer of
secondary smaller cells, which take a spiral course. Glo-
bules and nucules regularly dispersed along the whorled
branches.

1. CHABA VULGARIS.

Char. Stem smooth, opaque, brittle, obscurely striated. Pri-
mary cells of the stems invested with about eighteen smaller
spiral cells ; those of the branches or whorls with about half
that number. Nucule bracteated. Bracts usually four,
much longer than the nucule.

CHAR A. 97

Chara vulgaris, E. B. 336. 2d edit. 1471; Smith, i. 6.;
Hook. Crypt., Part 1. p. 246.; Macreight, 278.; Agardh,
Syst. Alg. p. 128.

This is the commonest species of the whole genus : it is
met with in ponds, ditches, and slow streams, and is usually
of a yellowish green hue. The stems are sometimes seven
or eight inches long. Whorls about as long as the articula-
tions of the stem, the upper ones alone being fertile. This
Chara, from its great abundance, has most frequently been
the subject of microscopic observation, and amply has it re-
warded the labours of investigators.

2. CHARA HEDWIGII.

Char. Stem smooth, striated, opaque, somewhat brittle, elon-
gated. Branches of the whorls subulate ; fertile ones with
many whorls of short ramuli or bractece, of which the
longest are shorter than the fruit. Nucule ovate.
Chara Hedwigii, E. B. Suppl. t. 2762. 2d edit. 1472, in
part; Hook. Crypt., Part 1. p. 246.; Macreight, 278.

" Met with forming dense patches at the bottom of still
pools in several parts of the kingdom. Stems much longer
and more slender than in C. vulgaris ; and the whole plant of
a bright green colour, but sometimes partially incrusted;
rather flexible when freshly gathered : each joint appears to
be divided about the middle in consequence of the smaller
tubes, forming the wall, being articulated midway as well
as at the principal joints. Nucule much larger than its
accompanying globule ; about as long as, or rather longer than
the three or four apparent bractere which accompany it."
- E. B.

3. CHARA PULCHELLA.

Char. Stem smooth, striated, flexible. Branches of the whorls
subulate; the fertile ones with many whorls of short
ramuli or bractece, the longest of which are about the length
of the nucule. Nucule oblong.

H

98 CHARACE.E.

Chara pulchella, Eng. Bot. sup. 2824, 2d ed. 1473. Wai-
roth Ann. Bot. 184. tab. 2. C.pulchella globularis, Wallr.
FL Crypt. German, vol. 2. 108.

Found by Mr. Borrer in Sussex.

" Distinguished from C. Hedwigii principally by its more
flexible stems and more oblong nucules. When dry, it is
scarcely at all brittle, whereas C. Hedwigii is extremely so,
whence it is called C. fragilis by some authors."

Perhaps merely a variety of C. Hedwigii.

4. CHARA ASPERA.

Char. Stem very slender, scarcely brittle, obscurely striated
beset with scattered, spreading, or dcflexedbristles. Branches
of the whorls subulate ; the fertile ones with many whorls
of short ramuli or bractece, the two innermost longer than
the rest, bearing the globules or nucules which are
generally separate.

Chara aspcra, Eng. Bot. Suppl. 2d ed. 1474 ; Hook. Crypt.
Flor. Part 1. p. 246.; Macreight, 278.; Greville, Scot,
Crypt. Flor. 339. ; Agardh, Syst. Alg. 130.

" Found in bog pits, and still waters in several places in
the north of England and Scotland. Stem one or two feet
long, densely crowded, every where beset with acute, slender,
straight, spreading or deflexed bristles ; and having at the base
of each whorl a row of appressed bristles, connected in pairs,
of which one points upwards and the other downwards.

" Between the outer circle of tubes and central one,
in both the stems and branches, is found a green parenchyma,
arranged in lines alternating with the striae, and separated or
broken transversely at intervals, giving them a spotted ap-
pearance; globules and nucules solitary, often on separate
plants.

" I have had this species under cultivation in a glass jar for
several years, and although no nucules appeared at any time
upon it, young plants were copiously produced every spring."

CHARA. £9

5. CHARA HISPIDA.

Char. Stem more or less thickly covered with a calca-
reous crust, opaque, brittle, striated, spinulose, or hispid.
Branches of the whorls subulate ; the fertile ones with many
ivhorls of short ramuli or bractece, of which three or four
are larger than the nucule and globule that they accom-
pany.

Chara hispida, Eng. Bot. 463. 2d ed. 1475 ; Smith, i. 7. ;
Hook. Crypt. Part 1. p. 246. ; Macreight, 278. ; Ag. Syst.
128.

" Not uncommon in ditches, lakes, and turfy bog pools.
The stony incrustation is sometimes so thick as to give the
plant the appearance of a petrifaction, which in other habitats
is nearly wanting. Almost as foetid as C. vulgaris. It is
by far the largest of the true Charce in this country in its
ordinary form ; and, though varying in the thickness of its
stem and branches, can never be confounded with the slender
and more delicate C. aspera.

" A smaller variety is occasionally met with in which the
spinules are obsolete, or nearly so : the C. hispida ft' of
Agardh and Smith, /3 gracilis of Hooker, Eng. Bot."

6. CHARA LATIPOLIA.

" This fine species, which I have no hesitation in stating to
be new to Britain, occurred in great abundance in Belvidere
Lake, county Westmeath, where I collected it in August last.
The great size and semipellucid appearance at once struck
me as remarkable. The main branches are striated and
covered with raised rough points, as are the first joints of the
whorled ramuli, while the remaining portion consists only of
one pellucid tube, which is thicker than the lower joints, and
ends in a sharp point. The branches of the whorls are again
beset with smaller ramuli (not bracterc), in which respect it
differs from all our species in the opaque division. 1 regret
I could not find the species in fruit, neither globule nor

H 2

100 CHARACE^.

nucule was present ; though I examined hundreds of speci-
mens in various parts of the lake, where it sometimes
covered the bottom to the extent of many square perches ;
and what is singular enough, all the other species in the opaque
division occurred abundantly in the same lake, and were all
in fruit, each preserving its respective character." — D.Moore,
in <s Journal of Botany" p. 43.

The application of the specific name latifolia seems to be
peculiarly inappropriate to a plant which, strictly speaking,
has no leaves at all.

" God is said to be Maximus in minimis. We Men esteem it a more diffi-
cult Alatter, and of greater Art and Curiosity, to frame a small Watch than
a large Clock : And no Man blames him who spent his whole Time in the
Consideration of the Nature and Works of a Bee, or thinks his Subject
was too narrow. Let us not then esteem anything contemptible, or in-
considerable, or below our notice taking ; for this is to derogate from
the Wisdom and Art of the Creator, and to confess ourselves unworthy
of those Endowments of Knowledge and Understanding which he hath
bestowed on us. Do we praise Daedalus, and Archytas, and Hero, and
Callicrates, and Albertus Magnus, and many others which I might mention,
for their Cunning in inventing, and Dexterity in framing and composing
a few dead Engines, or Movements, and shall we not admire and magnifie
the Great Artfitovpyot Koffftov, Former of the World, who hath made so
many, yea, I may say, innumerable, rare Pieces, and those too not dead
ones, such as cease presently to move so soon as the spring is down ; but
all living, and themselves performing their own Motions, and those so in-
tricate and various, and requiring such a Multitude of Parts and sub-
ordinate Machines, that it is incomprehensible what Art, and Skill, and
Industry, must be employed in the framing of one of them ?" — Ray.

101

FAM. VI. BATRACHOSPERME.E.

Char. Algae gelatinous, moniliform, ramose, articulated,
verticillate, filaments of the verticilli dense, dichotomous,
and beaded, the inferior ones simple, descending, and
forming a sheath around the primary cells. Reproduction
consisting of glomerules scattered throughout the verticilli,
to which they are attached by a single filament or thread.

7. BATRACHOSPERMUM.
Char. Same as those of the family.

Derivation. From ^arpa^ps, a frog, and (nrsp^a, seed;
the species resembling frog-spawn.

Dillenius discriminated many species or varieties of this
genus in his " Historia Muscorum," under the name of Alga
lubrices. Linnaeus, however, after him, united them all into
one species, under the name of Conferva gelatinosa, in which
example he was followed by succeeding botanists.

Weiss first removed the Conferva fontana, nodosa, spermatis
ranarum instar, lubrica et viridis, of Dillenius from the genus
Conferva, perceiving that it possessed a structure much
more complicated than that of the greater number of the
species of that genus, which are for the most part exceed-
ingly simple, and placed it amongst the Characece, under the
name of Chara batrachosperma ; the term batrachosperma
implying the resemblance which Weiss noticed between the
Conferva which he examined, and the series of gelatinous
globules in which are enclosed the eggs of the greater part
of the Amphibia of the family of frogs.

If it was requisite that this species should be removed
from the genus Conferva, it soon became apparent that it
could not be permitted to remain with the Characece, and
the propriety of instituting a new genus for its reception
quickly became apparent.

" In the year 3," says Bory, " I established this genus
in my collection. I communicated it to my learned friend

H 3

102 BATRACIIOSPERME.E.

Draparnaud, and that skilful naturalist approved of it.
lloth, and after him Vaucher and Decandolle, have adopted it,
with the trivial name of Weiss, which has become general."

The Batrachosperms are highly flexible and mucous to the
touch, their lubricity arising in a measure from the presence
of innumerable lashes or cilia, terminating the branches,
which add also infinitely to the microscopic beauty of these
productions. Vaucher entertained the idea that they were to
be regarded as the stamina of the plant, and that they were
filled with a fecundating powder. This opinion would
appear to be mere conjecture, the only fact in support of
it being the deciduous character of the organs. Each
cilium is articulated in a manner similar to that of the
branches, of which they may be regarded as extensions.

The species of this genus inhabit mostly pure and run-
ning waters, being usually met with in fountains, wells, and
streams, the force of which is not considerable. They are
so exceedingly flexible, that they obey the slightest motion
of the fluid which surrounds them, and would seem almost
to be endowed with vitality; nothing can surpass the ease
and grace of their movements. When removed from the
water they lose all form, and appear like pieces of jelly,
without trace of organization, on immersion however the
branches again quickly resume their former disposition. They
adhere strongly to paper, and in drying frequently change
to some other tint, usually much deeper ; on being moistened
after long intervals, they recover much of their original
freshness ; and it is even asserted that, after having lain
in the herbarium for some years, when they are replaced in
water in a suitable locality, that they will vegetate as before.

The manner in which the glomerules are developed does
not seem to be well understood * ; each would appear to be
compounded of numerous cells, all having a single and
common attachment to the parent plant by means of a single
and slender thread ; from which they, when mature, separate,

* In the earliest period of their development they would appear to be
minute excrescences growing out of the walls of the cells, from which
finally they l)ecome entirely separated in most of the species of the genus,
but not in all, as in B. ntrnin.

BATRACHOSPERMUM. 103

or are thrown off. They would appear to partake more of the
nature of buds than seeds. When developing, each emits
numerous branches, which radiate in all directions.

Bory would seem to be the only observer who has studied
the species of this genus with that nice discrimination which
they require : in associating Batrachospermum atrum, however,
and some other species with the genus Thorea, he has
committed a great error. By a careful comparison of speci-
mens derived from the herbarium of Dillenius, which are
in the collection of M. de Jussieu, with others collected by
Roth, Mertens, and Draparnaud, Bory has succeeded in
ascertaining the correct synonymes of several species or varie-
ties, which had previously been quoted indiscriminately.

From the great number of specimens described in the
following pages, there are some, I fear, who will be dis-
posed to think that they have been multiplied on insuf-
ficient grounds: such an opinion I am sure will not be
entertained by those who have carefully studied the genus
for themselves, and who have had opportunities, as mainly
through the liberality of friends I have had, of comparing
a considerable number of specimens collected from widely
different localities together.

I suspect that the species of this genus are propagated
not merely by gemmae or glomerules, but also by Zoospores,
contained as in other Alga zoosporce in the cells, of the
aggregation of which these plants are composed.

The affinities of the genus are by no means direct, in their
lubricity, in the presence of cilia, and probably in their
reproduction by zoospores they bear a certain relationship
to the family Chatophorece.

a. Filaments exceedingly flexible.

1. BATRACHOSPERMUM BOMBUSINUM Bory.

Plate XIII. Fig. 3.

Char. Frond delicate, filaments sparingly branched, branches
simple. Cells much elongated. Verticilli minute, distant.

H 4

104 BATRACHOSPERME2E.

" Batrachosperma (bombusina) filamentis ramosis ; articulis
elongatis ; vfrticillis minutissimis, distantibus conoideis."
— Bory de St. Vincent, Annales du Museum, vol. xii.

Hob. Malahide near Dublin : Dr. Coulter.

" This beautiful plant grows in the Isles of France and of
Re-union. It covers pebbles in places exposed to the cur-
rents of great rivulets, particularly at the Great River and
the river of Saint Denis.

" Its colour is of the most elegant green ; but if the speci-
mens of this plant be not quickly prepared, they very soon
turn black upon the paper.

" From a principal filament from two to four inches long,
proceed many long slender loose branches, simple, or having
sometimes here and there scattered very small branches,
which are never divided. The articulations of the principal
stem, and of the larger branches are for the most part naked ;
their point of contact is dilated in such a manner as to
resemble the rods of bamboos.

" As to the verticilli, they are rounded, smaller than those
of the following species, composed of very compact branch-
lets. Their simple ramuli are likewise shorter than in the
other Batrachosperms ; three or four rounded joints compose
them : the ciliform appendage which terminates them is re-
markable. Some ramuli, shorter than those of the verti-
cillum, cover also the inferior part of the articulations, which
have the appearance of reversed cones." — Bory.

Bory's descriptions and figures of this species are so ac-
curate, as to leave no doubt either as to its specific distinct-
ness, or its identity with the plant collected by Dr. Coulter.

The exact correspondence of the specimens collected in the
Isles of France and of Re-union is remarkable with those found
in Ireland, and helps to confirm the opinion which I have
long entertained that the different species of the freshwater
division of the Alga are almost universally diffused.

BATRACHOSPERMUM. 105

2. BATRACHOSPERMUM HELMINTOSUM Bory.

Char. Filaments branched, pyramidal, naked below ; branches
simple, subpinnate, acute. Verticilli contiguous, com-
pressed.

Bory, in Annales du Museum, vol. xii. p. 316. pi. 2 9. fig. 2.;
Corallina pinguis, ramosa viridis, Vaill. Paris, 4to. tab. vi.
fig. 6.
Hal. New River, Cheshunt : A. H. H.

" There is no doubt but that Vaillant's plant is also
our plant : the figure which he has given of it is inferior ;
the disposition of the branches is badly given ; but the
tubercles in it are confounded. The extremities are subu-
late, and the author compares his corallina to a muscus jili-
cinus. I have moreover gathered the species in question in
the place in which the Parisian botanist has pointed out for
his habitat. I then discovered it for the first time upon the
rocks in the gloomy bosoms of very many freshwater foun-
tains situated in Brittany, beside the river Goesne, near the
city of Fougere.

" The stems of this beautiful species scarcely exceed two
inches in length. They are fine, and denuded at their base,
which appears yellow. Numerous branches proceed from it :
they are somewhat subulate, and diminish in length, in such
a way, that they incline from the extremities of the plant,
which gives to it a pyramidal appearance.

" The verticilli are compressed, voluminous, horizontal, and
so approximated, that they cannot acquire the globular form :
they become confused, and form around the stems a continuous
cylinder of mucosity. The diameter of this cylinder equals
often that of the plume of a little bird. The branches are
not less thick at their insertion. The colour of the plant is
obscure, of a bluish and uncertain green."

3. BATRACHOSPERMUM CONFUSUM Hass.
Plate XV. Fig. 1.

Char. Frond large. Filaments much branched. Verticilli
contiguous, subconfused, compressed above and below.

106 BATRACIIOSPERME;!:.

Conf. gelatinosa Dilhv. Brit. Conf. Bat. ludibundum (var.
confusum) Bory, In Annalesdu Museum, vol.xiv. p. 320.
pi. 29. fig. 3. no. 63. ; Gir. Chantrans. Mycros. p.[175.
pi. 25.

Hob. Lea well, Devonshire : W. H. Harvey. In a
small brook in Clive Wood, Swansea : Dillw.

Under the name of Batrachospermum ludibundum Bory de-
scribes seven different varieties of Batrachospermum : many of
these are indigenous to Great Britain, and several of them
doubtless, are distinct species, in which light the plant under
consideration ought to be regarded.

" Tliis variety is not rare ; it grows in the closed basins of
very pure and cold fountains. It there appears to choose
shady places. It is found in the holes of rivers, whose waters
carry no mud. I have observed it in France, in Spain, in
Germany, in Poland, and in Ducal Prussia.

" Of all Batrachosperms, this acquires the greatest dimen-
sions : its length is sometimes four inches and a half, its dia-
meter equal often to that of the culm of grasses. Its branches
appear also to be less obtuse than in the following varieties.
The globules or whorls are so approximated and so large
that they are often confounded together in such a manner,
as to be with difficulty distinguished in certain specimens
which have the aspect of Batrachosperma helmintosa. The
colour of the plant is of a mouse grey, agreeable by its trans-
parency. The large stems approach a little upon yellow.
These tints become of a beautiful violet by putrefaction.

" It is upon individuals of the variety which now engages
us that I made, for the first time, twelve years ago, an experi-
ment which ought to be known ; after having many times car-
ried from one locality to another stones bearing individuals of
this species, which continued to prosper in spite of the change
of habitation, I steeped many of them in lukewarm water,
afterwards in boiling, and no part of the batrachosperm ap-
peared, under the microscope, to have undergone the slightest
disorganization by these immersions, and certain sprigs replaced
in their native place continued to vegetate after these experi-

BATRACHOSPERMUM. 107

ments. I do not think that there exist other vegetables which
boiling water does not immediately disorganize ; there are not
others that can resist temperatures so opposite." — Bory.

This species differs from Batrachospermum helmintosum by
its stems, which are never denuded below, but always verticil--
late, and by its branches, which are more obtuse, less thick at
their insertion, and furnished with many secondary bran chlets.
I am not certain however that the B. helmintosum is anything
more than a variety, which the following may be also.

4. BATRACHOSPERMUM STAGNALE Hass.

Char. Frond yellowish green. Filaments thick, branched.
Whorls, distinct, slightly compressed, in the trunk confused.

Batrachospermum ludibundum (stagnale) Bory, Annales du
Museum, vol. xii. p. 325. pi. 30. fig. 5. Conferva fon-
tana, nodosa ; spermatis ranarum instar lubrica minor et
viridis, Dill. Muse. vol. xvii. f. 44. Conf. stagnalis,
globulis viridis, centibus mucosis. Chara batrachosperma
Weiss, Plant. Crypt. .

Hob. Cheshunt, Herts : A. H. H.

"Both (Cat. Bot. i. 126. No. 11. 187.) referred this last
synonyme of Dillenius to a variety (/3) of Batrachospermum mo-
niliforme: he has since regarded this variety (Cat. Bot. iii.161.)
as appertaining to his Conferva mutabilis, which is one of our
Draparnaldice ; but certainly the figure cited by Dillenius and
his phrase applies perfectly to the Batrachosperm which is
here under consideration, and cannot be applied to any other
plant. The rounded and very distinct globules, which the
English author represents, have no kind of resemblance to the
scattered tufts of the Conferva mutabilis of the German natu-
ralist. As to the figure 43. of the ' Historia Muscorum/ there
is no doubt that it represents the same plant as the figure 44.
There is absolutely no difference but in the length of the
branches, which proceeds from the age of the specimens repre-
sented. The stagnant variety of Batrachospermum ludi-
bundum has great resemblance in form and diameter to

108 BATRACHOSPERME^.

Batrachospermum confusum ; it is nevertheless shorter, but as
thick. Its whorls are round and distinct ; they are more ap-
proximated the one to the other in the large stems, about
which they are sometimes even confused. Their colour is a
greenish yellow, pale, and livid.

" This plant is found in ditches and in the most tranquil
fountains. I have even seen it in marshes fixed against
scirpes and stakes."

5. BATRACHOSPERMUM MONILIFORME Hass.

Char. Frond blackish brown. Whorls of the stems, distinct,
spherical, in the branches confused.

Batrachospermum ludibundum (nwniliforme) Bory, in loc.
cit. xii. p. 322. pi. 30. fig. 1. Conf. fontana, nodosa, sper-
matis ranarum instar lubrica major et fusca, Dill. Muse,
p. 36. t. vii. fig. 42. Chara (gelatinosa frondibus gela-
tinosis Jilamentosis : Jilamentis capillaribus tenuissimis.
Verticillis approximatis moniliformibus, Roth. Cat. i. 125.
Batrachospermum (moniliforme) Jilis ramosis ; ramis al-
ternis pollentibus, 8fc., I {nth. Cat. Bot. iii. 160. Batra-
chospermum moniliforme Vauch. Conf. 112. t. 1. fig. 5.
et tab. ix. fig. 4.

Hob. Plassey, near Limerick: W. II. Harvey. Upland
mountainous district 14 miles west of Aberdeen : Dr.
Dickie. Galway: M'Colla. Hill of Fare: Dr. Dickie.

" This variety is the commonest of all. It is frequently
met with in fountains, in rapid rivers, and even in waters
almost stagnant ; it is sufficient that they are pure. It
has some resemblance to the variety B. confusum; but it
is more slender, and its bearing is more elegant. Its stems
are very much divided, and from one to three inches long ;
the globules which cover them are round, distinct, and appear
to hold each other only by their poles. They are, however,
confused in the last branches, which resemble little worms.

" The colour of the B. moniliforme is deeper than that of

BATRACHO8PERMUM. 109

B. confusum ; it is also more solid, and changes less in dying :
it takes nevertheless sometimes a tint of pale violet or a
livid yellow."

6. BATRACHOSPERMUM PULCHERRIMUM Hass.
Plate XIV. Fig. 1.

Char. Frond violet grey. "Whorls spherical, distant, distinct

in the stems and branches.

Bory, in Annales du Museum, xii. 323. PI. 30. fig. 2.
Hob. Stream near Cheshunt : A. H. H. Near Tunbrigde

Wells : Mr. Jenner.

" The extreme elegance of form and of colour renders
this Batrachosperm remarkable ; its stems are rather more
branched than those of the variety (a) B confusum, and less
than those of (7) B. moniliforme, are from two to three inches
and a half long, slender, and of an intermediate diameter.
The globules are perfectly spherical, distant upon the stems
from each other the length of a ray, more approximate, flat-
tened, but always distinct in the branches.

" Its colour is a clear grey, approaching to a most agree-
able violet. This last tint becomes dominant in drying, and
passes sometimes to red."

This description applies closely to the plant, which I have
twice met with, in all respects save colour, my specimens
when recent being of a pleasant green, which in drying be-
came blackish — a tint which the specimens which I received
from Mr. Jenner likewise presented, and yet I can scarcely
consider them other than the Batrachospermum ludibundum
(var. pulcherrimum) of Bory.

7. BATRACHOSPERMUM VAGUM Ag.
Plate LXIII. Fig. 2.

Char. Filaments subdichotomous, much branched, everywhere
covered. Whorls horizontal, compressed, indistinctly con-
fused.

110 BATRACnOSPERME^E.

Batrachospcrmum turfosum Bory, in Annalcs tlu Museum,
loc. cit. Conferva gclatinosa var. vaga Roth, Bot.
i. 127. Batrachospcrmum moniliforme var. (8) vagum
Roth, Fl. Germ. iii. 482.

Udb. Appin : Captain Carmichacl. Summit of Snowdon :
Sir W. J. Hooker. Loch Phadrich, 2199 feet above the
level of the sea, Aberdeenshire, August, 1842 : Dr.
Dickie. Frequent in Ireland : D. Moore. Cromaglan :
IV. H. Harvey. Galway : Mc Colla. In the stream by
the wall near the entrance of the park by the road-side
from Rackham to Pulborough : E. Jenner.

" M. Thore, naturalist of Dax, first discovered this plant
in the environs of the city which he inhabits. I have
since met with it in peat holes of our southerly lands in
places where the water, although coloured, is pure ; it there
grows always at a certain depth, and rarely less than from
two to three feet.

" In no other Conferva is the number of the filaments so
considerable as in this. Their total diameter equals that of
the largest horsehair. They divide in every direction from
a little disc, ramify to infinity, observing remarkably well
the dichotomous disposition in their first division, their
branches becoming subsequently vague. Their total length
extends even to four inches.

" From their origin, even to their extremity, these filaments
are clothed with microscopic branches, so impacted that the
whorls arc not apparent in scarcely any direction : with a
simple lens they are not better discovered, from which it
might be supposed that one was observing a Thorea. It is
but towards the points of the branches that, by the assistance
of a strong lens, they are at last distinguished. These whorls
are very closely approximated, horizontal, compressed the
one upon the other, and becoming so confused as to form
around the filament, which is green or yellow, and very
flexible, a continuous down, mucous to the touch, sometimes
very pale, more frequently of a very agreeable bluish watery
green : this colour is moreover deep towards the point of the

BATRACHOSPERMUM. Ill

branches. As it grows old the plant turns yellow and is
discoloured."

The apices of the branches in young specimens are often
dilated, and all the filaments present in this state a greater
diameter, and a deeper colour, being usually glaucous green.

Some specimens of what I regard as a variety of this
species were sent me by Dr. Dickie. They differed from the
species in its ordinary condition in the fact of the lower whorls
of the main stems being distinctly moniliform.

8. BATRACHOSPERMUM ALPESTRE Shut.
Plate XIV. Fig. 2.

Char. Frond black, very mucous, much branched ; alternately
forming very obtuse angles with the principal Jilaments.
Whorls of the stems spherical, distinct, but approximate,
branches compressed.

Batrachospermum alpestre, Shuttleworth's MS.

Hab. River Lea, Cheshunt : A. H. H. Ireland : W. H.
Harvey.

It is now some three or four years since I first encountered
this species, from which time I regarded it as distinct from
any described British Batrachospermum, an opinion which
I was happy to have confirmed recently by the receipt of
a specimen marked B. alpestre Shuttleworth, and which
exactly accords with my own in all respects, except in being
much smaller. At the same time, Mr. Harvey, to whom
I was indebted for the authentic specimen of B. alpestre,
sent me a second example collected by himself, with the ob-
servation affixed to it, " very like B. alpestre, but I have
not examined it."

This species is easily recognised by the eye alone, either
in its recent or dried state ; in the former its size, great
lubricity, jetty black colour, and approximate, yet for the most
part exactly spherical whorls, are remarkable ; in the latter,
in which also the black tint is preserved, it may be distinguished
by the multiplicity of its branches, which are, except the pri-

112 BATRACHOSPERME.E.

mary ones, exceedingly short and irregular, and issue from
the main filaments almost at right angles, and by their non-
moniliform appearance. In drying, also, it shrinks consider-
ably. It is a well marked, but apparently not an uncommon
species. I am not able to refer it to any described by Bory.
My specimens were met with during the summer in a rapid
part of the river Lea, near Waltham Abbey, attached
to piles of wood, which they almost covered. The length
of some of them reached to four inches ; their great size,
the elegance of their movements, and their dark colour,
at once struck me, and made me desirous of securing speci-
mens, which it was not easy to do in consequence of the
depth at which they grew. I succeeded, however, in obtain-
ing a few at the imminent risk of immersion.

9. BATRACHOSPERMUM PROLIFERUM Hass.
Plate LXIII. Fig. 1.

Char. Frond grey, branches irregular, divaricate, beset
with short ramuli, which are pinnate. Whorls of the
stems approximate, compressed, almost confused, in the
pinnate branches, subdistant, distinct, formed of very J ew
Jilaments.

Batrachospermum moniliforme, B. proliferum, Carmichael.

Hob. Appin : Captain Carmichael.

I have seen but one specimen of this curious and in-
teresting species, for an examination of which I was in-
debted to Mr. Harvey : not the slightest doubt, however,
remains on my mind of its distinctness ; it is certainly no
less distinct than rare. Captain Carmichael, to whom algolo-
gists are deeply indebted, for numerous additions to both
the marine and freshwater divisions of the Alga, and whose
powers of observation were of a very high order, thus in his
MS. describes the plant in question. " Frond, solitary or
in small clusters, one or two inches long, irregularly branched ;
branches divaricate, curved or flexuous, opaque and very
dark coloured, beset with short ramuli, which issue out from

BATRACHOSPERMUM. 113

the joints among the whorls of eccentric filaments, and are
themselves beset with whorls ; colour grey."

10. BATRACHOSPERMUM RUBRUM Hass.
Plate XV. Figs. 2, 3.

Char. Filaments much branched. Branches divaricate, alter-
nate, ramuli broad, expanded. Whorls of the stems sphe-
rical, distinct, subdistant, large, those of the branches
altogether confused.

Batrachospermum moniliforme var., Penzance, June, 1839 :
Mr. Ralfs.

This is one of the most curious, at well as distinct species
of the genus. I have seen but a single specimen of the
plant, but this is quite sufficient to establish it as a species.
This specimen was sent to me, amongst other good things, by
my friend Mr. Harvey, and belongs to the Herbarium of
Trinity College, Dublin, to which Mr. Harvey, I believe,
has generously presented the whole of his collection of Algae.

Batrachospermum rubrum might possibly be mistaken for
Thorea ramosissima, on account of its mode of ramification, its
colour, which is bright red, and, above all, the expanded
branches, which are so like those of T. ramosissima, that if
it were not for the whorls on the main stems, the species
might readily be referred to the genus Thorea, an error
which even a microscopic examination of the plant would not
at once remove. If one of the whorls be submitted to the
microscope, it will be found to be composed, in part, of
slender filaments slightly beaded, and, in part, of other still
more slender threads, which are cylindrical, and from which
the first set of filaments would appear to arise, and both of
which are mixed together ; and again, if a portion of one of
the branches be examined from which the whorls have dis-
appeared, it will be seen to be composed almost entirely of the
exceedingly minute, and occasionally branched threads, with
here and there attached to them a single pyriform cell (see
fig. 3)., which is to be regarded either as the rudiment of the

i

114 BATRACHO3PERME.E.

ordinary beaded threads of which the branches are composed,
or as a capsule, but probably the former. It is thus seen
that this species is remarkable both in appearance and struc-
ture.

11. BATRACHOSPERMUM ATRUM Harv.
Plate XVI. Fig. 12.

Char. Filaments very much ramified. Whorls distinct, distant,
short) in the form of reversed cones, opaque ; inferior
portion of the articulations pellucid.

Lemania (batrachospcrmuni) jilamentis ramosissimis elon-
yatis ; nodis superne incrassato opacis, infernc alternatis
pellucidis, Bory, in'Annales du Museum, xii. 188. Ba-
trachospermum moniliforme (/3) detersum Ag., Hook.
Brit. Flor. Batrachospermum atrum Harv. in Manual,
p. 120. Conf. atra, E. B. t. 690.

This species is, perhaps, the most elegant of the genus ; it
grows generally in still, though pure waters. Although placed
by Bory in his genus Lemania, it cannot be said to have
any near structural relation thereto.

The articulations or internodes may be compared to re-
versed cones, the superior part or whorls being formed of a
few short, simple, subulate filaments, which are not beaded :
in these filaments the colouring matter chiefly resides, and it
is amongst them that the glomerules are formed : that portion
of each articulation, which is below the whorl, is transparent,
and beautifully exhibits the tubular and jointed structure of
the layers which invest the primary cells in all the species of
the genus Batrachospermum ; from many of these tubes, short
branches are given off, which have almost the appearance of
scales.

It is probable that there are several varieties of this species
which have all been confounded together. Bory describes
two, both of which, I believe, I have recognised.

a. SETACEUM. — Filament slender, long, ccerulescent. —
Bory, in Annales du Museum, xii. 188. pi. xxii.
fig. 3.

BATRACHOSPERMUM. 115

Chantransia atra, nigrcscens., Jtlamentis ramosis tenuis-
simis ; articulis longis teretibus ; geniculis, subrotundis
ciliatis, Cand. Syn. No. 120. Chantransie noir,
Cand. Flor. fr. 2. 120.

Hab. Ferring, near Arundel : Mr. Jenner.

" The filaments of this variety are exceedingly fine, and
often almost imperceptible. They dispose themselves with
grace upon paper; their internodes are a little oblong, and
less inflated towards their superior part than in the following
variety." — Bory.

/3. CAPALLINUM ? — Filaments somewhat thick, black. —
Bory, in loc. cit. pi. xxii. fig. 4.

Hab. Cheshunt Marshes : A. H. H.

e( The filaments of this variety are of the size of C/iara, a
little shorter than those of the preceding ; they appear firmer
and blacker.

" It dwells frequently with the large varieties of Conferva
gelatinosa of Linnaius, and appears to love to entwine itself
with it." — Bory.

" I have bestowed nearly all my attention upon our native Swiss
Plants ; for I had to pursue, at the same time, anatomy and the practice
of Physick : being unlike you the consecrated priest of Flora. I have
always cultivated Botany, in spite of all obstacles, since the year 1728,
when I accomplished a laborious journey of 200 leagues through the
Alps, on foot. I have since visited those mountains ten successive
times. But I am near-sighted, which is a great inconvenience. I have
laboured much at Mosses and such plants. I hope to settle a good many
doubtful matters, though many must remain undetermined. My family
are always finding fault with my pursuit ; but I do not repent. On the
contrary, I regret that I did not devote more of my time to these
things."

" Farewell my dear Linnasus, may you enjoy your health and your
botanical pursuits with every advantage for the prosecution of your
labours ! My studies and engagements, of a different kind, draw me un-
avoidably aside ; but my inclination always leads me to the charms of
Flora. To Botany I wish to devote my leisure, my old age, and my for-
tune." — • Haller to Linnmis.

i 2

116

FAM. VII.

Char. Algae gelatinous, ramose, composed of principal stems
and smaller filaments, for the most part ciliated. Re-
production usually by means of zoospores contained in the
filaments, but in some cases said to be capsular.

The species of this very natural family accord with the
preceding in being composed of two sets of filaments, in their
extreme lubricity, and in their branches terminating in long
ciliform appendages, to which, in a measure, their great
lubricity is attributable. They differ from it, however, in
the secondary branches not being whorled, in the absence of
glomerules, and of the fibrilhe surrounding the primary cells,
also in being of a light and beautiful green colour, which,
in drying, does not change to some other tint, as has been
seen to be the case in the BatrachospermecB.

The two families, likewise, agree in habit, the Ch&to-
phorece, like the Batrachospermece, dwelling in fresh and pure
water, such as that of fountains and slow streams ; but on
account of the delicacy of their structure they are not met with
in large rivers or streams, the force of whose current is
strong, and which would sweep them away and destroy them.

On certain species of the genus Chcetophora capsules have,
from time to time, been met with, but the occurrence of these
is exceedingly rare, and it cannot be supposed that the ordi-
nary and usual mode of reproduction is by means of these.
The true reproductive bodies in this family, as well in all
probability as in that of the Batrachospermece, are undoubt-
edly zoospores. If a specimen of Draparnaldia, D. glomerata
for example, be examined microscopically in its young state,
the main filaments will be seen to be quite cylindrical : at a
later period, however, the cells, of which these filaments are
composed, swell up, and the filaments then become beaded.
This inflation of the cells, which occurs in almost all the

CHJETOPHORE^:. 117

branched Algce, is indicative of the period of reproduction,
and terminates in the rupture of the individual cells, the
zoospores escaping through the apertures thus provided.
That this is the usual and true method of reproduction it is
easy to satisfy oneself in the following method. If a specimen
of Draparnaldia glomerata be kept in water, which ought not
to be renewed for a day or two, the cells will be observed to
separate from each other, and, floating on the surface of the
fluid, will be noticed a greenish pellicle : if a portion of this
be placed beneath the microscope, it will be found to consist
of a slimy material, in which are contained numerous green
globules of very minute size ; these, if watched for a day or
two, will be seen to take on the characters peculiar to the
species.

The following observations in M. Decaisne's Memoir on
the Classification of the Alga in the Annales des Sciences
Naturelles occur, which correspond closely with the views
already expressed in reference to the reproduction of the
genus Draparnaldia, and which I have long entertained.

" The Draparnaldia glomerata is composed, as it is known,
of a principal trunk formed by a series of large cells placed
upon each other, transparent, each occupied with a ring of
green matter, rather pale, mucous, and mixed up with amy-
laceous globules. The branches, which arise from the points
of junction of these cells, are themselves composed of articu-
lated ramuli, and terminated by a confervoid ciliform thread,
which, all united, produce the mucilage with which the plant
is found enveloped.

" At the period when it has attained its complete develope-
ment, the hairs are seen to detach themselves successively
from the last joint : afterwards the green substance enclosed
in each of the ramuli unites into little globules, which escape
one after the other by a rounded aperture 'pratiquees' upon
each of the cellules. These themselves become absorbed (se
resorbent) as soon as they are empty, so that at a period
more advanced, one finds of all the plant but a single filament
enveloped with mucus and filled with green globules.

" I believe that I am able to conclude from these observ-

I 3

118

ations that each of the cells of Draparnaldia glomerata ought
to be considered as a receptacle whence the reproductive
bodies formed at the expense of the green matter issue under
the form of rounded vesicles themselves being filled with
endochrome." — M. Decaisne, Memoire sur la Classification
des Algues, p. 314.

8. DRAPARNALDIA Bory.

Char. Filaments free, not immersed in gelatinous Jiuid.
Draparnaldia Bory, in Annales du Museum, vol. xii.
Charospermum Link, in Hort. Phys. 5. Batrachosper-
mum in part, Vauch. Hist, des Conf.

" It is to Draparnard that I dedicate this genus, which
forms the subject of this new memoir. Those who have
been acquainted with that naturalist, alone know all that
lie was capable of: active, indefatigable, he was fitted for
studies the most diverse. Wise and prudent, also timid in
his researches, he hastened not to publish ; he collected facts,
he matured them, he wished his works to be without re-
proach. Misfortunes and death have surprised him before
the execution of his projects, his career is closed before his
writings have established his reputation. Scarcely a few
phrases, escaped from his pen, and committed to paper, re-
main ; and the loss of treasures which he had collected in
his memoirs occasions the greater regret to those who loved
him for cherishing the sciences as he cherished them.

" I could doubtless have selected, amongst so many rare and
new vegetables which presented themselves to me in my
voyages, — I could have found, I say, some genus more ana-
logous to the beauties of his spirit, upon which to place the
name of Draparnard; majestic palm trees, brilliant with
vigour, reigning over the forest, should perpetuate his remem-
brance. But the modest manes of my friend, have they not
approved my choice ? They will smile on that which I have
done. May his name live amongst the Conferva, which were
Jiis dearest study ! " — Bory.

Jviitzing refers the genus Draparnaldia to his Ectospermea,

DR APARN ALDIA. 119

placing it immediately before Ectocarpus, and of course
assigning to it lateral external fructification. Certain
species hitherto associated with the genus Draparnaldia
Kiitzing has removed therefrom ; these are D. stellaris,
which may be identical with my D. condensata, and D. tennis,
and constituted a new genus for them, under the name of
Stygeoclonium : this genus is not even placed in the same family
with Draparnaldia, but in that of Ulothricece, of which Lyng-
bya zonata forms the type. The following are the definitions
of the family and genus.

" Ulothricece.

"Trichomatamucosatenerrima,cellulse coleogonimicae, sub-
stantia gonimica in fascias transversales disposita, postremo in
opseospermata hologonimica plerumque quadripartita trans-
iens."

" Stygeoclonium Ktz.

" Trichoma tenerrimum, ramosum, ramulis simplicibus
subulatis obsessum ; cellulae gelinea3 tenuissimse, abbreviatas ;
amyledise in fasciam transversalem collapse, tandem in opseo-
spermata quaternata turgida transeuntes."

I cannot myself think that any essential difference exists
between the reproduction of Draparnaldia tennis, &c. and
other Draparnaldics. I have myself occasionally observed the
quaternary division of the endochrome in the smaller branches
of, I believe, all the species of Draparnaldice : the circumstance
of the occurrence of this disposition in certain species of the
genus more frequently than others does not seem to me
to call for their separation from that genus altogether ; yet
Kiitzing has not merely formed a new genus for them, but
has referred this genus to a distinct family, — a family which
does indeed manifest a close affinity with Draparnaldia, but
which Kiitzing places in his arrangement at some distance
therefrom. The genus Lyngbya, of which L. zonata forms the
type of the family Ulothricece, accords with Draparnaldia in
the extreme mucosity and flexibility of its filaments, in pos-
sessing the second mode of growth of the cells, viz. that of
lateral developement, in the endochrome being arranged in

i 4

120 CILETOPHORE.E.

bands across the cells, and essentially in its reproduction. The
only real difference between the genera consists in the filaments
of the one being simple and those of the other branched. In
an arrangement, therefore, in which affinities are studied,
these two genera should be placed near to each other.

1. DRAPARNALDIA GLOMERATA Ag.
PL XIII. Fig. 1.

Char. Stem round, branched. Ramuli in tufts, ichich are
frequently alternate and always ciliated. Tufts divergent.

Hab. Everywhere common in slow streams and ditches,
adhering to stones, sticks, &c.

Draparnaldia (mutabilis) gelatinosa ; Jilamentis crassiusculis ;
ramis subpinnatis, obtusiusculis ; fasciculis breviusculis,
complicatis, Bory, in Annalcs du Museum, pi. 35. fig. 1.
Conferva mutabilis Roth, Cat. Bot. i. 197. Flor. Germ,
iii. 518. C. mutabilis Roth, Cat. Bot. iii. 282. C.fas-
ciculata Thore, Chlor. 444. Batrachosperme en houpe,
Vauch. Conf. 114. pi. xii. fig. 4. et 5. ; Cand. Flor.
Fr. ii. 59. Batrachospermum glomeratum Cand. Syn.144.
C. mutabilis, Eng. Bot. t. 1470. D. glomerata Harvey,
in Hook. Brit. Fl. p. 388. ; in Manual, p. 121.

This species differs in appearance greatly according to its
age and place of growth. The younger specimens are of a
herbaceous and delicate green, abundantly branched, and the
older ones often nearly denuded of branches and almost colour-
less, becoming so by the escape of the zoospores. When dried
on paper the differences between certain specimens of this
plant presented to the eye are so considerable that many
would regard them as varieties, and almost as species. A
microscopic examination would, however, at once remove
this supposition.

When first removed from the water, it presents the appear-
ance of a mass of coloured jelly without form or organization :
on immersion, however, its branches soon expand. Its fragility
is so excessive, that frequently its own weight when fresh is

DRAPARNALDI A. 121

sufficient to break it, and it is often a matter of considerable
difficulty to remove a specimen entire from the water for
preservation, each frond breaking as soon as the hand is placed
beneath it, and its own gravity is felt, and dividing into
many separate pieces, which are slowly carried away by the
gentle stream in which the species is usually found. It ad-
heres closely to paper, and does not undergo any considerable
change of colour in drying, it also recovers like the Batra-
ckospermece much of its freshness on being moistened. These
last remarks apply to all the species of the genera Drapar-
naldia and Chatophora.

2. DRAPARNALDIA PLUMOSA Ag.
Plate XII. Fig. 1.

Char. Frond subgelatinous. Filaments gracile, elongated.
Branches subpinnate. Tufts elongated, scattered, ap-
proximate to the branches, ciliated,

Batrachosperme en plume, Vauch. Conf. 113. pi. xi. fig.
2. and 4. ; Cand. Fl. Fr. ii. 59. Batrachospermum plu-
mosum, truncis elongatis ; ramulis cauli approximatis,
Cand. Syn. 143. Draparnaldia hypnosa Bory, in An-
nales du Museum, 405. pi. 35. fig. 2. D. plumosa Har-
vey, in Hook. Br. Fl. ; in Manual, 121. Conf. lubrica,
E. B. t. 2087.

Hob. Galway : McColla. Aberdeen: Dr. Dickie. Med-
hurst and Eastbourn : Mr. Jenner. Stream near Hod-
desdon : A. H. H.

This species is more slender, less gelatinous, and attains
a much greater length than Draparnaldia glomerata. It
lives also in purer and deeper water, is usually of a brighter
and more beautiful green, and, from being less gelatinous,
it is also less fragile. The mode of branching is different in
the two species; the tufts in that which is here described
are longer, more scattered, approximated to the branches, and
not as in the previous species divergent. It is an elegant
species. The cells of the stems are usually shorter, and rarely
so inflated or oval as those of D- glomerata.

122 CJELETOPHORE.E.

3. DRAPARNALDIA REPETITA Hass.

Plate XII. Fig. 2.

Char. Filaments branched, consisting of repeated series of cells,
each series composed of Jive or six cells, which decrease in
size from the first or lower cell to the last or upper one,
series oblique. Tufts dense, alternate.

Hassall, in Annals of Nat. Hist., August, 1842 ; also in
loc. cit. vol. xi. 428.

Hab. Cheshunt : A. H. H.

" I have only once met with the above species, and then
but in small quantity : it is therefore no less rare than it is
curious. Each series of cells is an epitome of the entire plant,
which consists but of an aggregation of such series. A
sketch of it was forwarded to Dr. Greville, who did not hesi-
tate to agree with myself in the opinion of its distinctness."

4. DRAPABNALDIA CONDENSATA Hass.
Plate XI. Fig. 1.

Char. Filaments of considerable size, sparingly branched.
Branches furnished with short cilia. Cells abbreviated.

Hassall, in Annals of Nat. Hist. vol. xi. p. 429.

This is one of the finest and most distinct species of the
genus. The only locality at present known for it is a large
fish pond opposite Mr. Bosanquet's school for girls in the
parish of Wormly, Hertfordshire. It differs from the two
preceding species in several respects. It is more sparingly
branched, the ramuli are never tufted, and the cilia rarely
prolonged: the cells are very short, usually broader than
long, and entirely filled with endochrome. The habit of the
plant is also different, dwelling in water less fresh, and its
colour in consequence is less vivid than in most other Dra-
parnaldice.

DRAPARNALDIA. 123

5. DRAPARNALDIA TENUIS Ag.
Plate XL Fig. 2.

Char. Filaments slender, ciliated, sparingly branched.
Branches usually simple and solitary, but sometimes sub-
fastigiate. Cells of the stems twice or thrice as long as
broad, those of the branches rather longer than broad.

Hob. Streams near Cheshunt : A. H. H. Reservoir, Ar-
drossan : Major Martin. Between Pembury and Tun-
bridge; Hawkhurst and Gondhurst, Kent: Mr. Jenner.

This is a much smaller species than any of the preceding,
is more tenacious, and an inhabitant of streams and rivulets,
the current of which is strong. Filaments very slender, four
to six inches long, irregularly or alternately branched, more
or less furnished with scattered or subfasciculate ramuli,
whose tops are either acute or drawn out into long setaceous
colourless points. Joints of the main filaments and ramuli
coloured or transversely banded. " At first the filaments are
enclosed in the manner of a Chcetophora in a common some-
what definite gelatine ; afterwards, on its bursting, they issue
from it like a Conferva, but are at all times very gelatinous."
— Harvey, Manual of Brit. Algoe, p. 122.

6. DRAPARNALDIA ELONGATA Hass.
Plate X. Fig. 3.

Char. Filaments very slender, ciliated. Cells fasciated, usually
three times as long as broad.

Hassall, in Annals of Nat. Hist, for August, 1842 ; also
in loc. cit. vol. xi. p. 4.

Hab. Cheshunt : A. H. H. Parkind : Major Martin.

The filaments in this species are finer than those of D.
tennis, and the cells longer. I have no doubt of its dis-
tinctness. It is a rare species, and I have only twice met
with it, once growing in a horse trough near Cheshunt.

124 CHJ2TOPHOREJE.

7. DRAPARNALDIA NAN A Hass.
Plate X. Fig. 3.

Char. Filaments highly mucous, very slender, sparingly
branched. Branches acuminate, not usually ciliated.
Cells rather broader than long.

Draparnaldia sparsa Hassall, in Annals of Nat. Hist. xi.
428. Conferva nana Dillw. Brit. Conf. t. 30.

Hob. Cheshunt and neighbourhood : A. H. H. Steven-
ston : Rev. D. Landsborough.

This is by no means an uncommon species during the spring
and early part of the summer, being found attached fre-
quently to dead leaves and sticks. In the fineness and mucosity
of its filaments, as well as in the shortness of its cells, it seems
to exhibit some relation to the genus Chcetophora (a bad name,
since the species of the genera Batrachospermum and Drapar-
naldia are likewise chcetophorous}. From D. tennis and D.
clongata it is distinguished by the absence of cilia, shorter
cells, and from the former again by its smaller size.

9. CHCETOPHORA Schrank.

Char. Filaments imbedded in a gelatinous matrix, which is
either globose or lobed, rarely plain and crustaceous ; ag-
gregated, branched, articulated, sometimes setaceous, and
issuing from a common base. Branches nearly colourless.
Kan i ul i coloured. Capsular fructification has only been
noticed in C. pisiformis, C. pellita, and C. tuberculosa.

Derivation. From %atT»7, a bristle, and fopsaj, to bear.

Chcelophora Schrank; Lyngb. p. 65, 66. ; Fl. Danica, 1. 1728. ;
Agardh, Syst. xix. ; Grev. Scot. Fl. t. 150. Rivu-
laria Bonnemais, in Jour. Physic, xciv. p. 176. My-
riodactylon Desv. in Jour. Bot. 1809, p. 307. Anhaltia
Schwahl, in Linnaea, ix. p. 127. t. 2. fig. 1. 2. Batra-
chospermum sp. Vauch. Conf. t. 12. f. 1, 2. t. 13.
fig. 1, 2.

CIUETOPHORA. 125

Through Draparnaldia tennis and D. nana there is an
easy and natural transition to this genus.

Imbedded in the gelatinous matrix, are usually, in the
older specimens, a number of stony particles ; these have been
supposed to be in some way or other connected with repro-
duction. Vaucher regards them as the ruptured cells of the
plant, and destined to reproduce the species.

1. CH^ETOPHORA DILATATA Hass.
Plate XIII. Fig. 2.

Char. Filaments much branched, fastigiatc. Extremities
dilated.

Hab. Ireland : Mr. Moore.

This species I discovered accidentally, mixed up with a
specimen of Nostoc muscorum. It is very remarkable.

2. CH.ETOPHORA ENDIVI^EFOLIA Ag.
Plate IX. Figs. 1, 2.

Char. Mucous matrix somewhat compressed, sub-dichoto-
mously branched. Primary branches frequently parallel;
apices of ultimate ramuli ciliated.

Batrachospermum fasciculatum Vaucher, Hist, des Conf.
d'Eau douce, p. 116. pi. xiii. fig. 1.; Harvey in Hooker's
Brit. Flor. ii. p. 389. Ulva incrassata, E. Bot. 967.
Chatophora endiviafolia Harv. in Manual, p. 122.

Hab. Common in streams.

" This Batrachospermum is more rare than the preceding
species B. moniliforme, B. plumosum, and B. glomeratum : it
is met with in slowly running waters, covering stones, to which
it is attached, under the form of a little green protuberance
irregularly lobed at its extremities. It is but little more
than a few lines in length, and about half as broad. It can
scarcely be distinguished with the unaided sight, but with
the microscope it appears curiously composed. If but a very

126 CHJETOPHORE^E.

small fragment be examined, it will be seen, with surprise,
that it is formed of an assemblage of principal filaments,
parallel, elongated, and which bear at their extremities sub-
divisions, very short, composed of three or four branches. The
white grains are here seen in great quantity, which proceed
from ruptured rings, and are destined to reproduce the plant,
so that it is difficult to doubt the destination of these grains,
even when this has not been confirmed by direct proofs.

" This Batrachosperm, without doubt, has not yet been
described, and it is necessary to observe, that it is difficult
to discern at first sight a Conferva in the gelatinous material
which forms it, but that which is obscure to the simple sight
becomes distinct to the microscope." — Vaucher.

Mr. Harvey, in his description of this species, compares the
mode of branching of the frond to stags' horns, a comparison
which conveys a very good idea of the appearance of this
beautiful object.

3. CH^ETOPHOEA TUBERCULOSA Hook.
Plate IX. Figs. 7, 8.

Char. " Gelatinous matrix, at first glabrous and firm, after-
wards much lobcd, fragile, and hollow. Filaments very
slender, ficxuous, hyaline. Ramuli coloured, palmate, fas-
ciculate" — Harvey.

Harvey, in Hooker's Brit. Flor. Rivularia tuberculosa, E.
Bot. t. 2366. Ch. tuberculosa Harvey, in Manual, p. 122.

Hab. Diana Pond, Bushey Park : A. H. H. Aberdeen :
Dr. Dickie. Neighbourhood of Manchester : Mr. Side-
botham. Barnett's Wood, near Tunbridge Wells : Mr.
Jenner.

" On sticks and aquatic plants in boggy pools. Fronds
bright green, an inch or more in diameter." — Harv.

It is doubtful as to whether this is to be regarded as
any thing more than a variety of the following species, C.
elegans, the Batrachospermum intricatum of Vaucher, or that
species much developed ; the softness and hollowness of the
matrix both resulting from the extraordinary developement.

CH^ETOPIIORA. 127

In English Botany the filaments are figured without cilia.
Kiitzing also figures them in the same manner : if this
character be permanent, then is the species doubtless a
good one.

The following observations, taken from the " Flora " for
1842, p. 513., were inserted in the " Annals" for June,
1843: —

" The fruit of Chcetophora appears hitherto to have been observed
only by Mr. Berkeley, who communicated specimens to Captain Car-
michael, who made a drawing from them ; which, with his other manu-
scripts, is in the hands of Sir W. J. Hooker. Mr. Berkeley also pub-
lished a figure of it in his " Gleanings of British Algae." Dr. Miiller of
Detmold has been so fortunate as to meet with similar fruit in Cfuz-
tophora tubsrculosa, and has given figures of it in the place cited above.
He has made, moreover, a very curious observation, viz. that the fruit is
accompanied by, and at length connate with, a red globule of a similar form
but smaller size, which he considers as the male fructification. As the
female capsule advances to maturity, the male approaches it, becomes
elongated, and at length is united with it, emptying the pollen globules
into the female fruit. This process being accomplished, it falls off.

" Whatever may be thought of this, his account of the developement
of the spores formed within the capsule, which are about five in number,
and disposed around an aperture occasioned probably by the pressure of
the male capsule, is not less wonderful. From each of the seeds a hyaline
thread is developed, formed of the globules which press forward from the
inside of the seed ; this at length becomes green, and consists of a very
tender hyaline tube filled with a moniliform row of globules. Finally,
the uppermost globule is elongated into a new tube, which is of a paler
green than the rest of the thread. The capsule is now no longer visible,
and the whole resembles a Rivularia, which soon assumes the form of
Chcetophora tuberculosa.

" The above observations are at least curious, and, if there has been no
error, are of much importance. We recommend them to the consider-
ation of some of our practical algologists, hoping that they may be able
to throw some light upon the matter."

4. CH^ETOPHORA ELEGANS Ag.
Plate IX. Figs. 3, 4.

Char. Mucous matrix subglobose, or lobed, rather solid,
green. Filaments subdichotomous. Ramuli fastigiate, the
apices produced beyond the gelatine and setigerous.

Batrachospermum intricatum Vauch. Hist, des Conf. d'Eau
douce, p. 117. pi. xii. figs. 2, 3. C. elegans Harvey,

128

in Hook. Brit. Flor. p. 389. ; also in Manual, p. 122.
C. clegans Ag.

Hob. On sticks, &c., in stagnant pools, common.

" No species is more easy to recognise ; it is formed of
gelatinous protuberances of all sorts of figures, and of a
diameter which varies from a point to an inch." — Vauclier.

5. CH^ETOPHORA PISIFORMIS Ag.
Plate IX. Figs. 5, 6.

Char. Frond subglobose, fleshy, green. Filaments sub-
dichotomous, obtuse. Sporidia globose, axillary. — Carm.

Harvey, in Hooker's Brit. Flor. p. 389. ; Berk. Alga3, 1. 1.

fig. 1. ; Grev. Crypt, t. 150.
Hob. In subalpine lakes.

Mr. Berkeley has discovered capsular fructification on this
species, and Kiitziug has figured similar capsules as belonging
to C. tuberculosa. The occurrence of these capsules must be
regarded as excessively rare, and therefore commonly con-
sidered as the only mode of reproduction possessed by species
which arc everywhere so abundant.

6. CH^ETOPHORA LONGJEVA Carm.

Char. " Frond indefinitely effused, incrusting, gelatinous,
green. Filaments subdichotomous. Kamuli produced pro-
liferous towards the apex." — Carm.

C. longava Harvey, in Hooker's Brit. Flor. ; also in

Manual, p. 123.
Hab. In a boggy stream at Appin : Captain Carmichael.

" Fronds, continuous, or so closely set as to have that ap-
pearance, of a delicate green colour, and more flaccid than
those of C. elegans, apparently from a deficiency of gelatine.
Filaments in all respects similar to those of other species,
excepting in being mostly proliferous."

I cannot regard this as a distinct species, and would refer
to it C. endivia-folia or C. tnbi>rculosa.

129

FAM. VIII. CONJUGATED.

Char. Filaments simple, equal, often conjugating. En-
dochrome mostly figured. Sporangia formed generally by
the union of the contents of two cells, either in different or
in the same filaments.

The Conferva, which we now propose to examine, are per-
haps the most curious of all their tribe. When viewed to-
gether, they form an exceedingly natural group, but one which
is defined rather by the enumeration of a number of cha-
racters than by one in particular.

Their filaments when examined with the microscope are
seen to be simple and of uniform diameter; they are for the
most part unattached, and in their young condition are
smooth and unctuous to the touch, and of a deep green colour :
they are formed of an assemblage of elongated cells placed
end to end, and all of them enclosed and held in union by
an investing membrane, common to all, the interior of these
cells being occupied, chiefly with endochrome, which is
variously disposed, sometimes in the form of spires and stars,
at others it completely fills their cavities : mixed up with this
endochrome, are observed numerous vesicles ; these being it is
presumed the unfertilized zoospores.

When the filaments have attained a certain age or period
of developement, most of the cells are seen to send forth a
little conical process, which unites with a similar protrusion
from a corresponding cell of a contiguous filament, an un-
interrupted passage of communication between the two cells
being thus established.

While this is occurring, the spiral tubes, if the species be
a Zygnema, become confused and coalesce in each cell, the con-
tents of one passing out through the passage of communication,
mingling with those of the other, and both uniting, are at
length moulded into a dark body of either an oval or circular
form, and enveloped in membranes ; and which Vaucher,

K

130 CONJUGATED.

M. Decaisne, and Mr. Jenncr regard as the true spores, but
which, Agardh declares, resolve themselves after a time into
zoospores, an opinion in which I concur, applying the term
sporangia to them.

The tubes of communication do not appear to issue from
any determinate point of each cell, but from that which lies
in nearest contact with a neighbouring filament ; the filaments
appearing to exercise a mutual attraction on each other : thus
a number will be given off in succession to corresponding
ones of a filament near to it on one side, while another set from
the same filament will unite with those of another coming
near to it in some other part of its length.

It is curious to remark that the cells in one part of the
same filament will part with their contents and remain
empty, while in another, they will be the recipients of the
contents of the cells of another filament.

This remarkable mode of union of the filaments, almost
without parallel in the vegetable kingdom, was first noticed
by Mullcr in a species which he named Conferva jugalis.
Miiller, however, did not entertain the slightest suspicion that
it was in any way connected with reproduction.

Since the time of the publication of Vaucher's " Histoire
des Confcrves d'Eau douce," in 1803, but little seems to have
been added to the information contained in that excellent
work in reference to this division of the Alga, in which the
phenomenon of union of the cells is shewn to belong to very
many species, which Vaucher for the most part has satisfac-
torily determined, notwithstanding the feeble power of the
instrument employed by him in their investigation. The
labours, however, which I have bestowed upon the fresh-
water Al(j(R have been rewarded with a few discoveries of
interest, one of which I shall now proceed to notice.

This relates to the fact, that certain species of Conjugated;,
l)clonging principally to the genus Zygnema, occur, in which
there is no union of the different filaments similar to that al-
ready described ; the sporangia being formed in these by the
concentration of the matter of two cells in the same, and not
as in the preceding casern different, filaments. This interest-
ing fact was first announced by me in a paper on the Zyyne-

CONJUGATED. 131

mata inserted in the 9th vol. of the " Annals and Magazine of
Natural History," p. 34. Since this paper was published I have
observed, in Dillwyn's " Synopsis of the British Freshwater
Algae," that a non-conjugating Zygnema has been described
accurately by Mr. Woods, under the idea of its being a variety
of Zygnema quininum. The accuracy of the description would
appear, however, to have been doubted, since we find no refer-
ence to the species, which is distinct, and not a variety of that
to which it was referred, made by subsequent writers on the
Alga. Mr. Harvey in his excellent " Manual " does not make
any mention of it.

In these non-conjugating Zygnemata the tubes of commu-
nication issue from the opposed extremities of the cells, and
not from the centre of the sides of the cells, as in the conju-
gating Zygnemata.

The analogy which exists between the conjunction of the
filaments of the Conjugates and the reproduction of animals
has led to the opinion being entertained by some that they
are animal and not vegetable productions. The erroneous
nature, however, of this view is easily proved by reference to
the non-conjugating species mentioned, these testifying that
the conjunction of the filaments is not an occurrence essential
to the perpetuity of the species, and that therefore no argu-
ments in favour of the animality of the Conjugates ought to
be founded on that circumstance. The union, however,
of distinct cells in the same filament might be regarded
as indicative of an animal nature ; but this view may be dis-
proved by reference to another genus of freshwater Alga, of
the vegetability of which there can be no question, viz. Vesi-
culifera, in which there is an union of the matter of two cells
in the same filament, though no tubular connection between
those cells. Now the analogy between the species of this
genus and the non-conjugating Zygnemata is too great to
permit of the opinion being entertained, that the former are
vegetables and the latter animals.

Some have accounted for the union of the filaments by
supposing that the entire of one filament contained fertilizing
and the other fertilizable material ; but this view is like-
wise shown to be erroneous by the occurrence of non-con-
ic 2

132 CONJUGATED.

jugating species. If two kinds of reproductive matter exist,
as most suppose, they must both be contained in the same fila-
ment in these species ; but even this view cannot be received
when it is known that certain species of the family Conjugates
occur in which there is not even a union of the matter of two
cells, but in which the sporangia are formed separately within
each ; as in Mesocarpus notabilis and Zygnema mirabilc.

It would thus appear that no argument can be deduced
from the conjunction of the cells in the same or different fila-
ments and the commingling of their contents in favour either
of the animality or sexuality of the Conjugates, and that the
phenomenon, remarkable as it is, is subservient to some se-
condary purpose in the economy of these productions.

The species of this group of Conferva may be found occa-
sionally in a state of conjugation during the entire of the
spring, summer, and autumnal months ; they are chiefly met
with, however, in this state in the spring. It is usually some
days after this union of the cells has been established, that the
slow emanation of the matter of one cell occurs, this trans-
ference being occasioned apparently by the mutual attraction
exercised by the contents of each cell on that of the one to
which it is joined ; this attraction, in correspondence with the
law of gravitation, being predominant in that cell which con-
tains the greatest bulk of matter ; and thus, I think, we may
account for the contents of a number of cells of one filament
passing to those of another set of cells of another filament,
the matter in them being more considerable in quantity.

Very soon after the contents of the cells have united, they
are seen to dispose themselves into a regular form, and in the
course of three or four days the sporangia are perfected, each
being invested with its two or three membranes.

For some time, not unfrequently extending to weeks after
the cells have conjoined, and the sporangia have become or-
ganized, the species docs not appear to undergo any further
change : at length, however, the tubes of communication
separate, the cells become disjointed, indicating the death of
the plant, respiration ceases, and the disunited fragments fall
to the bottom of the water, the sporangia being set free on the
entire disorganization of the plant or the zoospores bursting

CONJUGATED; 133

through the membrane which invests them, escape through
the open extremity of the communicating tubes.

When in a young condition, and before reproduction takes
place, the Conjugates are of a bright, beautiful, and shining
green colour, are highly lubricous to the touch, and the in-
dividual filaments are never entangled together, but placed
somewhat parallel. As soon, however, as a union of the
filaments has occurred, these characters are for the most part
lost. The rich green colour fades to a yellow tint ; the fila-
ments no longer glisten when removed from the water, or
feel slippery, but almost harsh and crisp under the fingers ;
they are now likewise much curled and twisted. The change
of colour is the result of diminished vitality, and the loss of
lubricity arises from the extension, amounting almost to ob-
literation of the sheath.

The Conjugates, with a single exception, dwell in waters
that are perfectly still, such as ponds, reservoirs, ditches,
pools, and extended marshes ; they are also, with a single
exception, unattached, roots not being necessary to them, for,
unlike the greater part of the Algs which have hitherto been
considered, and which are all provided with rootlike organs,
they incur no risk of being swept away by the force of the
river, stream, or cascade in which they delight to dwell.
The union between the filaments which is to occur, renders
a locality of the above description an essential to the very
existence of this family of plants, for without absolute
quietude of the water this conjugation would be frustrated.
In the only attached species with which I am acquainted,
and which dwells in flowing water, I have never detected
conjugation of the threads.

The Conjugates adhere strongly to paper, preserving their
shining appearance, but never their brilliant colours ; these
generally becoming almost black in drying.

The quantity of air or gas eliminated by the Confervas,
but principally by the Conjugates, in warm sunny weather
is very considerable. It is by means of the globules of air
given out by these plants in respiration, that such large
masses as are seen in the spring and summer months, covering
almost every pond and ditch, are sustained upon the surface,

K 3

134 CONJUGATED.

the globules becoming entangled amongst their filaments
render them specifically lighter than the water, and cause
them to crepitate under the finger when pressed upon. The
presence of these globules in warm weather causes the Con-
jugatea and other Conferva to present a vesicated or bullous
appearance, which the older algologists thought to be cha-
racteristic of a single species, which they named Conferva
bullosa : this appearance is now known to belong to a whole
host of Alga generically distinct — such is the progress of
scientific research and knowledge. Dillwyn, in his descrip-
tion of Conferva fracta, observes, that, "after being dried,
the Conferva lullosa have been used as wadding for stuffing
garments, and made into coarse household linen." Weiss, in
his " Plant® Cryptogamiae Florae Gottingenses," p. 23, relates,
that formerly the river Unstrut, after inundating a large tract
of country in Upper Saxony, on again retiring into its proper
channel, left a great quantity of Conf. bullosa, which having
been gathered and dried by the inhabitants, was used by them
for stuffing their garments ; but that it occasioned violent pains
in their limbs : it was also used for making coarse paper." On
some parts of the Continent serious injury has been done
to large tracts of country, by the deposit, on the subsidence
of the waters which have covered them for a period, of a
compact layer of these Conferva bullosa, which has pre-
vented the growth of the grass beneath, and thus deprived
the cattle of their food. So great an evil has this been
deemed of late years, that commissioners have been appointed
to investigate the nature of this deposit, and to endeavour to
devise some means to remove and prevent its re-formation.

M. Decaisne, in his " Memoir on the Classification of the
Algae," has, on grounds which, on mature consideration, I
cannot regard as satisfactory, separated this group from
Agardh's class of zoospores, in which I would retain it ; for
certain it is that one division of the group of sunspores of
M. Decaisne, viz. the true Confervea, are propagated by
means of zoospores.

The numerous species of this group resolve themselves
naturally into the genera Zygnema, Tyndaridea, Stanrocarpus,
Mesocarpus, and Mougcotia.

ZYGNEMA. 135

10. ZYGNEMA ^7.

Char. Endochrome arranged in spiral order within each cell.
Sporangia generally oval, and never lodged in the trans-
verse tubes of communication.

Derivation. From £wyo£, a yoke, and vrjjaa, a thread.
Spirogyra Link, Handb. iii. 261., Meyen, in Linna3a, ii.
410. Choaspis Gray. Salinacis Bory, in Diet. Class.
xv. p. 75. c. iv. t. 45. Conjugates sp. Vauch, Conf. d'Eau
douce.

The first of these genera is characterized by the endo-
chrome with its brilliant granules (which Miiller, in his sur-
prise on first discovering a species of the genus, likened to
precious stones), being arranged in a spiral form, the number
of spires being from one to eight.

The species of this genus admit readily of division into two
subgenera, in the one of which the filaments unite, and in
the other no conjugation takes place ; and each of these di-
visions allows of further analysis, founded on the conforma-
tion of the cells.

" In the first of these subdivisions, which for the most
part includes the long-celled species of the genus, such as
Zygnema elongatum and Z. quadratum, &c., the opposed ex-
tremities of all those cells which have attained maturity are
considerably inverted, and which inversion may be compared
to that of the finger of a glove (PI. xvn. fig. 4.) ; while in the
second, which embraces the short-celled examples, as Zyg-
nema maximum, Z. nitidum, and very many others, the cells
are not inverted, but touch each other by their plane surfaces.

" The form of this inversion is, in all the species in which
it occurs, identical and extremely regular, its circumference
being circular, and its base somewhat flat ; no membrane in-
tervenes between the spaces formed by this indoubling in
contiguous cells, which spaces therefore communicate directly
with each other.

" At the period of reproduction, and at no other, .one of
the two indented and opposed extremities of certain cells be-

K. 4

136 CONJUGATED.

comes everted and protruded into the cavity of the other.
(PL xvn. fig. 5.)

" The cause of this protrusion, and the reason why it only
occurs at the precise period of the reproduction of the cells,
are easily accounted for, and both arise from unequal internal
pressure of the contiguous cells on each other, which ine-
quality of pressure is produced by the emission of the endo-
chrome of one cell into a neighbouring cell either in the same
or different filaments ; thus, when a cell has discharged its
contents, its cavity is empty, and no resistance can be offered
by it to the protrusion of the inverted portion of the adjacent
cell or cells, replete as it or they may be with fluid and en-
dochrome. This explanation applies likewise to the fact, that
when a number of cells have either emptied themselves of
their contents, or have been the recipients of those of other
cells at the same time, no eversion takes place, for in this case
there is no inequality of internal pressure.

" But while a correct exposition may be given of the cause
of this protrusion and intromission, it is not so easy to offer
a satisfactoiy explanation of the purpose to be attained by it.
The eversion, doubtless, assists in effecting the dislocation of
the cells, and thus, reproduction being perfected, hastening the
destruction of the species and dispersion of the spores ; pro-
cesses, which, from the greater length of the cells and con-
sequent continuity of the enveloping sheath, would possibly
occupy, were it not for some special provision of the nature
indicated, a much longer time than in the short- celled species.
A subordinate and not unimportant use of this provision is, the
assistance which it affords in the determination of allied species.

" It is remarkable that no similar conformation presents
itself to our notice in the genera Tyndaridea and Mougeotia,
so closely allied to Zygnema, for in these the cells invariably
terminate by plane surfaces, which, however, may be either
everted or inverted to a slight extent.

" This peculiar formation of the cells of some Zygnemata
was first noticed by me in the spring of 1842, but its true
nature only became apparent to me in the early portion of
the present year. AVhen viewed through a low power of the
microscope, and in a Zygnema whose filaments are as yet

ZYGNEMA. 137

separate, it exhibits the appearance of two curved knife-
blades slightly approximating to each other at their apices,
near to which usually lies the divided spiral thread, and
strongly impressing the superficial observer, from the position
and aspect of these blades, with the idea that they are the
instruments which effect its separation, and reminding him of
the beautiful provision whereby the section of pollen granules
is accomplished.

" On transmitting a short time since a specimen of the
Zygnema quadratum, in a state of reproduction, to the Rev.
M. J. Berkeley and Mr. Ralfs, but unaccompanied by any
remarks in reference to the structure of the cells, both these
gentlemen noticed their peculiar conformation, and from the
former I received correct sketches of their appearances.

" The structure of the joints in Zygnema was long since
noticed in one species of the genus by Mohl, who thus de-
scribes it in his paper upon the multiplication of cells by
division, inserted in the * Flora * : — ' In Z. elongatum Ag.,
the dissepiments have a very peculiar structure, which I have
found in no other species. The terminal surface of each cell
is not even, but elongated into a blunt conical process. This
process can only be observed in its true state when two joints
are separated one from the other ; when, on the contrary, the
threads are unbroken the process is generally introverted like
the finger of a glove, and exhibits the form represented at
PI. I. fig. 8. a, b, c. This is the common condition, and in
most threads no joint is found otherwise constructed. But I
have now met with a single thread in which a part of the
articulations has the ordinary length, while another part has
joints only half as long. In these shorter articulations it
was normal that only the alternate dissepiments had the
structure peculiar to this species (so that by these dissepi-
ments the thread was divided into articulations of the ordinary
length), while, on the contrary, the intermediate dissepiments
exhibited the form usual in Conferva"

" The observation, that ' this process can only be observed
in its true state (that is, everted) when two joints are sepa-
rated, the one from the other,' is inaccurate, for the cells may
be separated and yet the processes inverted, the eversion of

138 CONJUGATED.

them having nothing whatever to do with the separation of
the cells, and never being in any case the result of it, but
depending, as explained already, upon unequal internal pres-
sure, and occurring chiefly at the period of reproduction.
The effect of the eversion is, as already observed, to occasion
the dislocation of the cells.

" Again, in every filament of those Zygnemata which ex-
hibit the inverted structure, cells may be observed terminating
in the ordinary manner of Conferva, viz. by plane surfaces,
the presence or absence of the inversion depending upon the
period of the formation of the dissepiments ; the older ones,
or, as observed in the beginning of tliis notice, the more
mature ones only presenting it. Thus it follows that the
opposed extremities of cells always exhibit the same structure,
and that this alternation in form supplies evidence the most
conclusive of the multiplication of cells throughout the entire
filament of a Conferva by division." *

It is in this genus that the radiated organ described in the
Introduction is best developed, and may be observed with
most advantage ; it is here also that the cruciform organs,
supposed to secrete the raphides, and the curved strings of
cytoblasts, before noticed, are most clearly seen.

Attention to the structure of the cells in the Zygnemata is
of the very first importance in the discrimination of species,
it being the only distinguishing character in some closely
allied species.

First Subgcnus. — Filaments conjugating.
* Extremities of the cells truncated.

a. Spires numerous.
1. ZYGNEMA OEBICULARE If ass.

Plate XIX. Figs. 1, 2.
Char. Filaments highly mucous, and of a light green colour,

* From a paper entitled " Observations on some Points in the Ana-
tomy and Physiology of the Freshwater Algae," by Arthur II. Hassall,
inserted in the " Annals and Mag. of Natural History," vol.xii. pp. 26 — 8.

ZYGNEMA. 139

their diameter and length being very considerable. Cells,
when in a state of conjugation, a little longer than broad,
prior to which, however, they are frequently not half so
long as broad; winding round the interior of these are
about eight spiral threads, the granules in them being small.
Sporangia almost circular, flattened.

Z. maximum Hassall, in Annals of Nat. Hist. vol. x. p. 36.

Hob. Cheshunt, Hertfordshire, and the country adjacent ;
Notting Hill : A. H. H. Waldron and Worthing : Mr.
Jenner. Graham Castle : Major Martin.

This is one of the finest as well as largest of all the Zygne-
mata hitherto described, the diameter of the filaments greatly
exceeding those of Z. nitidum, the Conjugata princeps of
Vaucher. It is found only in ponds and dykes whose waters
are deep and permanent, and it does not conjugate until near
the end of the summer. The only other Zygnema with which
it could possibly be confounded is Z. serratum, between which
and the present plant several well marked differences exist,
as will presently be shown. Two varieties of this plant were
described by me in the llth vol. of " Annals and Magazine
of Natural History," p. 432. both of which I now feel as-
sured are quite distinct. The first of these is Z. alternatum.

2. ZYGNEMA ALTEKNATUM Hass.
Plate XX.

Char. Filaments of the same diameter as those of the preceding
species. Cells rather longer than broad. Spires numerous,
granules small, conjugation alternate, that is, every second
pair of cells alone conjoin.

Hassall, Annals of Nat. Hist. vol. xi. p. 432. Zygnema
Decaisne, in Memoire sur la Classification des Algues,
An. des Scien. Nat.

Hob. Cheshunt, Hertfordshire. A. H. H.

This is one of the rarest species of the genus, and I am not
sure that I have ever met with it more than once. The mode
of conjugation of the cells, the alternate ones only uniting, is

140 CONJUGATED.

curious, and is confined to this and the following species.
The design of the interrupted conjugation is by no means
evident : it is remarkable, however, that the granules in those
cells, which remain disunited, decrease in size and become
almost colourless, while those of the conjoined cells increase
considerably, and darken in colour. This mode of conjugation
at least affords a decisive character by which it and the
following species may be known from all others hitherto de-
scribed. One fact is still wanting to complete the history of
this species, viz. the form of the sporangia, which might
possibly furnish an additional distinctive character.

3. ZYGNEMA INTERRUPTUM Hass.
Plate XXL.

Char. Filaments of considerable length, but less in diameter
than those of Z. orbiculare. Cells at the period of conju-
gation rather longer than broad : previous to this, however,
they are frequently not half so long as broad. Spires nu-
merous. Conjugation interrupted. Spire oval, equalling in
breadth the diameter of the cell but not producing any
inflation of it.

Hassall, in Annals of Nat. Hist. vol. xi. p. 432.
Hob. Cheshunt: A. H. H.

This also is a very rare species. I have only met with it
once, but then in very considerable quantity. It bears a
close resemblance to Z. alternatum, but differs from it in
having filaments which are considerably smaller than those in
that species. The granules or unfertilized zoospores are like-
wise largest in those cells which have conjoined.

4. ZYGNEMA SERRATUM Hass.
Plate XXIII. Figs. 1, 2.

Char. Filaments of nearly the same diameter as those of
Z. orbiculare, but less mucous. Cells longer than broad.
Spires varying from three to Jive in number. Granules
larger. Conjugation continuous. Sporangia broadly
ovate.

ZYGNEMA. 141

Hassall, in Annals of Nat. Hist. vol. xi. p. 432.

Hob. Cheshunt, very rare : A. H. H. Withyham : Mr.
Jenner.

The only species with which this can possibly be confounded
is Z. orbiculare, from which it may be readily distinguished by
the fewer number and serrated appearance of the spires, the
larger size of the granules, and the form of the sporangia,
which in Z. orbiculare are nearly spherical, and compressed,
while in Z. serratum they are broadly ovate. The filaments
do indeed resemble very closely in character those of Z. niti-
dum, with \Yhich, however, there is but little danger of con-
founding it, that species being altogether a much smaller plant.
It is very rare.

5. ZYGNEMA NITIDUM Ag.
Plate XXII. Figs. 1, 2.

Char. Filaments of muc h less diameter than those of Z. serra-
tum. Cells usually rather more than twice as long as broad.
Spires generally four in number. Granules large. Spo-
rangia acutely ovate.

Conferva jugalis Mtiller, Flora Danica. Conjugata princeps
Vaucher, Hist, des Conf. d'Eau douce, p. 64. pi. iv. fig. 1 .
F. nitidum Harv. in Manual, p. 143. ; Agardh's Systema,
Conf. nitidum Dillwyn, British Confervas, pi. iv. f. c. ;
Eng. Bot. t. 1656, in part.

Hob. Every where common throughout Great Britain
and Ireland.

This species is one of the best marked as well as most
beautiful of the tribe. Numerous other Zygnemata have
however doubtless been associated with it under the same
name.

Vaucher has the following observation upon it : — " Inde-
pendently of its size, it is distinguished from all others by a
coarser touch, a more shining appearance of tubes almost crisp,
and by its constant habit of raising its extremities out of
the water whenever it is immersed in the liquid."

142 CONJUGATED.

6. ZYGNEMA BELLE Hass.

Char. Filaments about a foot in lengthy with truncate extre-
mities ; of considerable though rather less diameter than those
of Z. nitidum, mucous, glossy, and of a deep and beautiful
green colour ; investing membrane of the cells very evident,
and transparent. Cells in the young filaments scarcely so
long as broad, but their length exceeds their breadth in
those which have conjugated ; round the interior of the cells
five or six loose spiral tubes may be faintly discerned ;
these contain the reproductive globules which are large, and
distinct, with a dark central nucleus. Sporangia oval some-
times almost circular, and flattened, lying in inflated cells,
the cavity of which they do not Jill.

Hassall, in Annals of Nat. Hist. vol. x. p. 37.

Hob. Essex, Hertfordshire, and in several places in Mid-
dlesex ; abundant : A. H. II. In the pond between
Ramslye Rocks and Broadwater Forest, and on Henfield
Common : Mr. Jenner.

This well-marked species is readily distinguished from all
others by the size of its filaments, the sporangia almost cir-
cular, and the inflated form of the cells. There is not a more
distinct or attractive species in the genus.

7. ZYGNEMA NEGLECTUM Hass.
Plate XXIII. Figs. 1, 2.

Char. Filaments of less diameter than those of Z. nitidum.
Cells rather longer than broad. Spires distinct, serrated.
Granules large. Sporangia oval, in some specimens, occa-
sioning a slight inflation of the cells in which they are
lodged.

Hassall, in Annals of Nat. Hist. vol. x. p. 37.

Hob. Neighbourhood of Cheshunt and other places ; com-
mon : A. H H. Vicinity of Tunbridge Wells and in
Kent : Mr. Jenner.

This species has doubtless usually been confounded with

ZYGNEMA. 143

Z. nitidum, of which the filaments are larger ; the spires
too, are generally but three in number, and the sporangia are
less acutely oval, frequently also producing an inflation of the
cells in which they are lodged.

8. ZYGNEMA CUKVATUM Ag.
Plate XXVI. Figs. 1, 2.

Char. Filaments nearly equal in diameter to those of Z. neglec-
tum. Conjugation angular. Cells three or four times as
long as broad, coalescing without the intervention of trans-
verse tubes. Spires about four in number, faintly indicated.
Sporangia oval.

Z. curvatum Ag. Conf. stritica, Eng. Bot. t, 2463. Harvey,
Hook. Br. Fl. p. 362., also in Manual. Mougeotia stritica
Kiitz. Alg. Dw. Sirogonium striticum Kiitz. Phyc. Gene-
ralis, p. 278.

Hob. Ditches in Henfield Level, Sussex, and pools on
Chy -an Hal Moor, near Penzance: Mr. Borrer. Ches-
hunt: A.H.H.

This species is remarkable for the direct conjugation of the
cells, they uniting with each other without the intervention
of tubes of communication, and it is the only species of the
genus which does so. By this junction of the cells with each
other, the filaments are bent at angles. The direct union of
the cells and angular flection of the filaments of this species
have induced Kiitzing to form a new genus for its reception
under the name of Sirogonium. Z. curvatum seems in some
measure to unite the genera Zygnema and Mougeotia, that it
is nothing more than a Zygnema, however, is proved by the
endochrome being disposed in a spiral order.

9. ZYGNEMA PELLUCIDUM Hass.
Plate XXV. Figs. 1, 2.

Char. Filaments of rather less diameter than those of Z. cur-
vatum, mucous, almost transparent. Conjugation parallel.
Cells six or seven times as long as broad. Spires indistinct,

144 CONJUGATED.

usually four in number. Sporangia circular, lodged in cells,
which are considerably enlarged for their accommodation.

Z. pellucidum Hassall, in Ann. Nat. Hist. vol. x. p. 37.
Hal. Cheshunt: A. H. H.

This is a very curious and beautiful species, and one by
no means common. I have only once been so fortunate as to
meet with it in a state of reproduction, in which condition it is
not possible to confound it with any other described species.

10. ZYGNEMA RIVULARE Hass.
Plate XXVII. Figs. 1, 2.

Char. Filaments seven or eight inches in length, usually at-
tached, and in diameter about equal to those of Z. pellu-
cidum. Cells varying in length from four to eight times
their diameter. Spires serrated, three or four in number.
Granules large.

Z. rivulare Hassall, in Annals of Nat. Hist. vol. x. p. 38.
Dill, t, 4. A. B.

Hob. In the Barge, New, and Lea rivers, near Cheshunt,
abundant : A. H. H. Cader Idris : Mr. Ralfs.

This is a very distinct species, and certainly not the
Conjugata adnata of Vaucher, the filaments of which equal
nearly those of Z. nitidum in diameter. I have never been
so fortunate as to find it in a state of reproduction. It would
not appear to be common, as I have not received it from any
other of my correspondents save Mr. Ralfs.

b. Spires two in number in each cell.

11. ZYGNEMA DECIMINUM Ag.
Plate XXIII. Figs. 3, 4.

Char. Filaments rather smaller than those of Z. neglcctnm.
Cells twice or thrice as long as broad. Spires two, crossing
each other. Granules large. Sporangia oval, obtuse, not
producing inflation of the cells in which they are lodged.

ZYGNEMA. 145

Conf. jugalis Dillw. t. 5. ; and C. nitida, t. 4. f, A. B. Z.
deciminum Harvey, 1. c. p. 362. ; also in Manual, p. 143.

Hob. Cheshunt and Epping Forest: A. H. H. In a
pond between Ramslye Rocks and Broadwater Forest ;
Henfield Common; and in a pond at Hill Park, near
Westerham, Kent : Mr. Jenner.

This is a very pretty species, and also very distinct, the
crosses described by the spires at once serving to distinguish
it from all others belonging to this division of the genus
Zygnema, Filaments frequently almost black.

c. Spires single.

12. ZYGNEMA QUININUM Ag.
Plate XXVIII. Figs. 1, 2.

Char. Filaments of rather larger diameter than those of
Z. deceminum. Cells longer than broad. Spire performing
about three revolutions in each. Sporangia acutely oval, not
producing inflation of the cells in which they are lodged.
Conferva porticalis Miiller, Nova Comment. Petropolitana,
pars 3. p. 90. Conjugata porticalis Vaucher, Hist, des
Conf. pi. 5. fig. 1. ; Dillw. t. 3. lower figure.
Hab. Everywhere common throughout Britain.

" This conjugata, already described and observed by
Miiller, is perhaps the most common of all those of the same
family ; its spires are formed of brilliant grains united by a
thread or a tube. Miiller compares them to porticos, since
in a certain state of their developement they have the form of
a semi-ellipse." — Vaucher. The specific name of quininum
bestowed upon them by Agardh is intended to express as well
as Miiller's of porticale, which ought properly to have been
retained on account of its priority, the form described by
each turn of the spires.

13. ZYGNEMA VARIANS Hass.
Plate XXIX. Figs. 1. 2, 3, 4.

Char. Filaments of somewhat less diameter than those of

146 CONJUGATED.

Zygnema quininum. Cells usually twice as long as broad.
Sporangia oval, and not usually producing any inflation of
the receiving cell.

Hob. Cheshunt and its vicinity : A. H. H. At Hawk-
hurst ; in a pond in a cottage garden between Broom-
hill and Speldhurst ; and by the road-side near Black-
boy's toll gate : Mr. Jenner. Graham Castle : Major
Martin.

" This common species was formerly (see * Annals and Ma-
gazine of Natural History,' vol. x. p. 35.) passed over by me
as a variety of Z. quininum, from which I am now perfectly
satisfied that it is specifically distinct. When a number of
cells unite in regular order with those of a neighbouring
filament, no inflation of any of these occurs; but it fre-
quently happens that several adjoining cells of a filament for
some reason or other do not unite, although the remaining
ones in that filament do ; in which case, those which have not
yoked themselves swell up, assuming a moniliform appear-
ance, and at the same time frequently emit blind and irregular
processes or prolongations, by which the cells manifest the
strong tendency which they have to conjoin themselves, but
which some cause, not evident, would appear to have frus-
trated. In some specimens, the number of inflated cells and
blind processes is but small, while in others the elongated
cells are more numerous than those which have united in the
ordinary manner of the Zygnemata." — MS.

14. ZYGNEMA ^STIVUM Hass.
Plate XXVIII. Figs. 3, 4.

Char. Filaments of less diameter than those of Z. varians.
Cells usually about four times as long as broad, but some-
times much longer, and occasionally shorter. Sporangia
oval, not producing any inflation of the cell in which they
are formed.

Zygnema (Bstivum Hassall, in Ann. Nat. Hist. vol. xi. p. 433.

Hab. Cheshunt : A. H. H. Wadhurst ; and Bury, near
Arundel : Mr. Jenner.

ZYGNEMA. 147

This species is distinguished from the former by the smaller
size of the filaments, greater length of the cells, and peculiar
zigzag disposition of the spiral thread ; it is not, however, a
very strongly marked species.

15. ZYGNEMA MALFOEMATUM Hass.

Plate XXX. Figs. 1, 2.

Char. Filaments nearly equal in diameter to those of Z. ces-
tivum. Cells about twice as long as broad, in each of
which a single spiral thread performs usually two revolu-
tions. Sporangia acutely oval, lying obliquely in the cells,
which are considerably distorted for their accommodation.

Zygnema malformatum Hassall, in Annals of Nat. Hist,
vol. x. p. 39.

Hab. Cheshunt : A. H. H. In a pond at Still Green,
and in the watercourse by the road side, near the Black -
boy's toll-gate : Mr. Jenner.

I hesitated at first to regard this species as distinct from
Z. commune ; I now, however, entertain no doubt of the fact.
It is a very pretty species, and not uncommon. The form
of the cells is very distinct from that of Z. commune.

16. ZYGNEMA CATEN^FORME Hass.

Plate XXX. Figs. 3, 4.

Char. Filaments a little finer than those of Z. malformatum.
Cells usually rather more than twice as long as broad.
Sporangia largely inflating the cells in which they are con-
tained, acutely oval.

Z. catenaforme Hassall, in Ann. of Nat. Hist. vol. x. p. 39.
Hab. Cheshunt : A. H. H. Between Yapton and Wal-
berton near Arundel : Mr. Jenner.

It is scarcely possible to distinguish the filaments of this

j. 2

148 CONJUGATED.

species from those of Z. commune before conjugation : after
this has occurred, the difference in the length of the cells and
the form of these is so obvious as not to leave any doubt of
its being distinct from that species. To this species ought, I
think, the Zygnema brevissimum, described by me in vol. x.
p. 40. of the " Annals of Nat. Hist." to be referred. I am still
not sure, however, but that it is distinct, yet fear to regard it
as such. The cells in it are scarcely so long as broad ; the
sporangia broadly oval, sometimes almost circular, their long
diameter being placed transversely in the cells, which are
frequently highly inflated.

17. ZYGNEMA COMMUNE Hass.
Plate XXVIII. Figs. 5, 6.

Char. Filaments about equal in diameter to those of Z. cate-
naforme. Cells usually three times as long as broad. Spo-
rangia acutely oval, not occasioning any inflation of the
cells in which tliey are formed.

Zygnema commune Hassall, in Annals of Nat. Hist. vol. x.
p. 39. ; Dillw. t. 3. upper figure, in part ?

Hab. Cheshunt : A. H. H. Framfield Common : Mr.
Jenner. Parkind Quarry : Major Martin.

This is a very distinct and regular species.

18. ZYGNEMA GRACILE Hass.
Plate XXX. Figs. 5, 6.

Char. Filaments of less diameter than those of Z. commune.
Cells usually four times as long as broad, and inflated on
the side which gives origin to the tubes of communication.
Sporangia acutely oval, not rendering the cells at all ven-
tricose.

Hab. Wanstead Flats, Essex ; Cheshunt : A. H. H.

Apparently a distinct species, known from Z. commune by
the smaller size of the filaments and lateral enlargements of
the cells.

ZYGNEMA. 149

19. ZYGNEMA FLAVESCENS Hass.
Plate XXX. Figs. 9, 10.

Char. Filaments of less diameter than those of Z. catenat-
forme. Cells usually four times as long as broad, and
slightly inflated for the accommodation of the sporangia,
which are oval.

Hob. Hertford Heath ; High Beech, Essex : A. H. H.
Several places in Sussex and Kent : Mr. Jenner.

The only species with which this could be confounded are
Z. catenaforme and Z. parvum, between which it is interme-
diate. It seems to prefer, like several other species of the
genus, the boggy pools of heaths, &c., to roadside ponds and
ditches.

20. ZYGNEMA PARVUM Hass.
Plate XXX. Figs. 7, 8.

Char. Filaments more slender than those of the preceding
species. Cells rather more tlian four times as long as
broad. Sporangia oval, generally producing a slight in-
flation of the cells in which they are formed.

Zygnema parvum Hassall, in Ann. Nat. Hist. vol. x. p. 41.

Hob. Cheshunt : A. H. H. In a pond between Ramslye
Rocks and Broadwater Forest : Mr. Jenner.

This is one of the smallest species of the genus ; it is not
uncommon.

** Extremities of cells inverted.

21. ZYGNEMA GREVILLEANUM Hass.
Plate XXXI. Figs. 1, 2.

Char. Filaments of rather less diameter than those of Z.
curvatum. Cells usually six or seven times as long as
broad, round the interior of each of which winds generally
one and sometimes two spiral threads. Sporangia broadly

150 CONJUGATED.

oval, lying in cells which are considerably inflated for
their accommodation.

Zygnema Grevilleanum, Annals and Mag. of Nat. Hist,
vol. x. p. 38.

Hob. Cheshunt and its vicinity : A. H. H. Framfield :
Mr. Jenner. Dolgelley : Mr. Ralfs. Turf Dyke, near
Ardrossan : Major Martin.

" To this~ fine species I have assigned the name of Dr.
Greville, author of the excellent ' Algae Britannicae,' as a
slight mark of personal respect, as well as an acknowledge-
ment of the eminent services rendered by that gentleman
to natural history."

22. ZYGNEMA IN^QUALE Hass.
Plate XXXIT. Figs. 1, 2.

Char. Filaments of smaller diameter than those of Z. Gre-
villeanum. Cells about Jive times as long as broad, and
enlarged on the side from which the tubes of communica-
tion arise. Sporangia oval.

Hob. Cheshunt: A. H. H.

This is not a common species. I have no doubt but that it
is distinct.

23. ZYGNEMA SUBVENTRICOSUM Hass.
Plate XXXII. Figs. 3, 4, and 5.

Char. Diameter of the filaments about equal to these of
Z. commune. Cells usually Jive or six times as long as
broad. Sporangia oval, occasioning the cells in which they
are placed to assume a ventricose form.

Zygnema ventricosum Hassall, in Annals of Nat. Hist,
vol. x. pp. 38, 39.

Hob. Cheshunt and its vicinity : A. H. H. Heathfield ;
in a pond near Boar's Head, Ramslye Rocks; and

ZYGNEMA. 151

Rackham, near Pulborough : Mr. Jenner. Dolgellcy :
Mr. Ralfs. Parkind : Major Martin.

This is a very distinct, as well as common species ; that
which I regard as a variety of it occurs at Wanstead Flats,
Essex, in which the filaments are somewhat finer, the cells
considerably longer, and the sporangia smaller. This may
be distinct.

24. ZYGNEMA LONGATUM Hass.
Plate XXXI. Figs. 3, 4.

Char. Filaments about equal in diameter to those of Z. sub-
ventricosum. Cells usually eight times as long as broad.
Sporangia not producing any inflation of the cells, in
which they are formed.

Conferva punctalis Miiller, Flor. Dan. pi. 1. no. 1. Con-
jugata longata Vaucher, Hist, des Conf. pp. 71, 72.
plate 6. fig. 1. ; Dillw. t. 3. upper figure in part? Z.
cequale Hassall, in Annals of Nat. Hist. vol. x. p. 39.

Hab. Cheshunt, rare : A. H. H. In a pond between
Pembury and Lamberhurst Quarter : Mr. Jenner.

I have but little doubt of the correctness of the synonymes
quoted ; the cells are never inflated. " II n'y a rien de plus
elegant et de plus gracieux au microscope que cette jolie
conjuguee." — Vaucher.

25. ZYGNEMA INPLATUM Hass.
Plate XXXII. Figs. 6, 7, and 8.

Char. Filaments of much less diameter than those of Z. sub-
ventricosum. Cells usually four, five, or six times as long
as broad. Sporangia elongated, and lodged in cells which
become considerably inflated for their reception.

Conjugata inflata Vaucher, Hist, des Conf. p. 68. plate 5.
fig. 3. Zygnema varians Hassall, in Annals of Nat. Hist.

vol. xi. p. 431.

I, 4

152 CONJUGATED.

Hob. Chcshunt and vicinity : A. H. H. Rusthall Com-
mon ; between Sharp's Bridge and Piltdown Common ;
Henfield: Mr. Jenner. Turf Dyke, near Ardrossan:
Major Martin.

I have now ascertained that the Zygnema varians described
by me in the " Annals of Nat. Hist." vol. xi. p. 431., is
the Conjugata inflata of Vaucher, a species which I have
been long anxious to identify. I have recently met with
what I shall describe as a variety of this species, but which
may possibly be distinct. It is characterized as follows : —

var. a. — Filaments of the same diameter as those of the
species proper. Cells eight or ten times as long as broad,
and enlarged on the side which gives origin to the tubes
of communication. Sporangia oval, long.

26. ZYGNEMA TENUISSIMUM Hass.
Plate XXXII. Figs. 9, 10.

Char. Filaments more slender than those of Z. inflatum.
Cells eight or nine times as long as broad. Sporangia pro-
ducing a slight iiiflation of the receiving cells.

Zygnema tenuissimum Hassall, in Annals of Nat. Hist,
vol. x. p. 41.

Hab. Cheshunt : A. II. H. Belmonden, Hawkhurst :
Mr. Jenner. Parkind : Major Martin.

This species bears a very close resemblance to the preced-
ing, from which it is chiefly distinguished by its smaller size.

Second Subgenus. — Filaments not conjugating.
* Cells not inverted.
a. Spires single.

27. ZYGNEMA ROSTRATUM Hass.
Plate XXXIH. Fig. 1.

Char. Filaments of somewhat larger diameter than those of
Zygnema nitidum. Cells from half to once as long as

ZYGNEMA. 153

broad, spires numerous, granules small. Sporangia
broadly oval, sometimes almost circular, lying obliquely
in the cells, which are not inflated.

Z. rostratum Hassall, MSS.

Ilab. Pond, near Hounslow : A. H. H.

A very fine species, the largest of all the non-conjugating
Zygnemata. It is very rare, for I have only once encoun-
tered it.

28. ZYGNEMA WOODSII Hass.
Plate XXXIII. Fig. 1.

Char. Filaments of somewhat less diameter than those of
Zygnema quininum. Cells usually about half or two-
thirds as long as broad. Sporangia oval, lying obliquely
in the cells, which are enlarged on that side from which
the tubes of communication proceed.

Z. Woodsii Hassall, MSS.

Hob. Cheshunt and neighbourhood : A. H. H. Several
places in Sussex and Kent : Mr. Jenner.

On looking over Dillwyn's " Synopsis of British Confervas,"
I was surprised to find under the head of Conferva spiralis
the following notice of the species just characterized : —

" Since the Introduction was printed, a curious specimen
of this species has been gathered by Mr. Home of Clapham,
and examined by Mr. Woods, who gives the following ac-
count of it. * The plant is a pale dirty green, nearly with-
out gloss, about the size of C. spiralis; when magnified the
length of the joints is seen to be about equal to their width,
or a little more, and the spiral tube is in most parts nearly
obliterated ; but the chief singularity of this plant is in the
connecting processes, which are uniformly at the ends instead
of as usual in the middle of the joints, and each of which
appears to unite with the process of the next joint of the
same filament. No indication of the conjugation of two
filaments is to be observed ; the dark globules appear only
when the two joints are thus connected, and the adjacent
one is invariably empty.' " — Synopsis, p. 60.

154 CONJUGATED.

The above Zygnema, which Mr. Woods has so accurately
described, is also the variety of Z. quininum (C. spiralis),
referred to by me in the 10th vol. of the " Annals," p. 35. I
have now, however, had numerous opportunities of examin-
ing it in all stages of its developement, and have no doubt
about the propriety of separating it from that species from
which it is distinguished by its finer filaments, and shorter
cells, as well as by the manner in which the sporangia are
formed ; characters which are constant.

29. ZYGNEMA ALTERNATDM Hass.

Plate XXXIII. Fig. 3.

Char. Filaments considerably finer than those of Z. Woodsii.
Cells usually two and a half times as long as broad.
Sporangia oval, not producing any inflation of the re-
ceiving cell.
Hob. Cheshunt: A. H. H.

I have seen this but once : it may possibly be but a variety
of the preceding species, although I can scarcely suppose that
it is so.

30. ZYGNEMA ABBEEVIATUM Hass.

Plate XXXIV. Fig. 4.

Char. Filaments about equal to those of Zygnema commune
in size. Cells once, or once and a half as long as broad.
Sporangia oval, small, not producing any inflation of the
cells in which they are lodged.
Hab. Cheshunt: A.H.H.

This also I have only once met with. It appears distinct,
however.

31. ZYGNEMA ANGULARE Hass.

Plate XXXIV. Figs. 1, 2, 3.

Char. Filaments at first straight, but at the period of repro-

ZYGNEMA. 155

duction becoming angulated, the angles being situated at
the junction of the cells and produced by the tubes of com-
munication. Cells usually three times as long as broad.
Sporangia oval, producing considerable inflation of the re-
ceiving cell.

Zygnema angulatum Hassall, in Annals of Nat. Hist,
vol. x. p. 41.

Hob. High Beech, Essex; and Cheshunt: A. H. H.
Mayfield, between Sharp's Bridge and Piltdown Com-
mon ; Barcombe and Framfield : Mr. Jenner.

The angular disposition of the filaments at the period of
reproduction is not peculiar to this species, the filaments
of most other non-conjugating Zygnemata being also angular
at that period. A variety of this species has occurred to
me, having cells only once and a half, or twice as long as
broad.

32. ZYGNEMA MALLEOLUM Hass.
Plate XXXIV. Fig. 5.

Char. Filaments of nearly the same diameter as those of
Zygnema parvum. Cells usually about six times as long
as broad. Sporangia producing considerable inflation of
the cells.

Hal. Cheshunt: A. H. H.

This would appear to be a distinct species, differing from
the following in the much greater length of the cells. The
empty cell taken in connection with the fruit-bearing cell
resembles somewhat in outline a hammer.

33. ZYGNEMA AFFINE Hass.
Plate XXXIV. Fig. 6.

Char. Filaments of nearly the same diameter as those of
Zygnema parvum. Cells usually twice or twice and a half
as long as broad. Sporangia oval, lodged in cells, which
are considerably inflated.
Hob. Cheshunt: A. H. H.

156 CONJUGATED:

I have only once met with this. If a condition of any, it
must be of the preceding species.

b. Sporangia formed in every cell.

34. ZYGNEMA MIRABILE Hass.
Plate XXXV. Figs. 1, 2, 3.

Char. Filaments equal to those of Z. commune in diameter.
Cells about six times as long as broad. Sporangia oval, at
first much elongated, and finally producing a slight in-
flation of the cells.

Z. mirabile Hassall, MSS.

Hob. Cheshunt and its vicinity : A. H. H. In the pond
between Tunbridge Wells Common and the Hurst
Wood ; in a pond at Burwash : Mr. Jenner.

This remarkable Zygnema I have repeatedly met with in
the state in which I have described it, and which I believe to
be its perfect condition. Mr. Jenner states that he is con-
vinced that the cells are united, but that the connecting
tubes are so frail as usually to be destroyed before the
specimen is examined. Mr. Jenner's observation, however, I
feel assured applies not to Z. mirabile, but to some other
species ; for had the cells at any period been united, they
would have been clearly indicated, even in the absence of the
connecting tubes, by the occurrence of empty cells in number
equal to those which contained sporangia. Now I have said
that in this species all the cells contain sporangia.

**

Extremities of cells inverted.
a. Spires two.

35. ZYGNEMA HASSALLII Jenner.
Plate XXXVI. Figs. 4, 5.

Char. Filaments of nearly the same diameter as those of
Zygnema Grevilleanum. Cells five or six times as long
as broad. Spires two, laxly disposed, and crossing each

ZYGNEMA. 157

other. Sporangia oval, large, and producing a considerable
inflation of the cells in which they are lodged.

Zygnema Hassallii Jenner, in Flora of Tunbridge Wells,

p. 182.
Hob. Cheshunt and Notting Hill : A. H. H. Sandhurst ;

near the rock at Washington ; and at Hellingly : Mr.

Jenner.

Mr. Jenner has done me the honour to assign my name to
the above species, which is one of the finest and most distinct
of the Zygnemata. I encountered it several times during the
spring and summer of 1842, but not having then met with
it in a state of reproduction, I regarded the filaments as those
of Z. Grevilleanum, which, however, are usually furnished
but with a single spire, and in which the form of the conju-
gated cells is so different.

b. Spire single.

36. ZYGNEMA QUADRATUM Hass.
Plate XXXVII. Figs. 1, 2.

Char. Filaments of rather less diameter than those of 7*yg-
nema Hassallii. Cells usually seven or eight times as long
as broad. Sporangia oval, large, and much elongated,
contained within quadrangular enlargements of the cells.
Tubes of communication prominent.
Zygnema quadratum Hassall, in Annals of Nat. Hist.

vol. x. p. 41.

Hob. High Beech ; Epping Forest ; Cheshunt ; and other
places : A. H. H. Pond at Ramslye : Mr. Jenner.

This is one of the most distinct as well as curious of the
non-conjugating Zygnemata. It is by no means uncommon.

37. ZYGNEMA INTERMEDIUM Hass.

Plate XXXVII. Fig. 3.
Char, Filaments of rather less diameter than those of Z. qua-

158 CONJUGATED.

dratum. Cells about five times as long as broad. Sporangia
oval, and producing a slight inflation of the cells.

Zygnema intermedium Hassall, in Annals of Nat. Hist,
vol. x. p. 41.

Hab. High Beech ; Cheshunt : A. H. H. Pond at Kams-
lye ; water-course by the road side at Wadhurst ; and in
a wet place in Tunbridge Wells Common : Mr. Jenner.

This very distinct species might be readily mistaken for
Zygnema angulatum, from which, however, it is at once dis-
tinguished by the inverted cells ; which cells also are longer.

38. ZYGNEMA DIDUCTUM Hass.
Plate XXXVII. Fig. 4.

Char. Filaments about equal in diameter to those of Z. inter'
medium. Cells eight or ten times as long as broad. Spo-
rangia oval, producing very considerable inflation of the
cells in which they are lodged.

Hab. Cheshunt: A. H. H.

There is but little doubt of the distinctness of this species.

39. ZYGNEMA VESICATUM Hass.
Plate XXXVII. Fig. 5.

Char. Filaments about equal in diameter to those of the pre-
ceding species, Z. diductum. Cells usually three times as
long as broad. Sporangia oval, producing a very consider-
able inflation of the cells in which they are lodged.

The chief difference between this and the following spe-
cies consists in the more considerable size of the filaments.

40. ZYGNEMA JENNERI Hass.
Plate XXXVII. Figs. 6. and 9.

Char. Filaments of less diameter than those of Z. vesicatum.
Cells usually three or four times as long as broad. Spo-

ZYGNEMA. 159

rangia oval, lodged in cells, which are considerably in-
flated.

Hab. In a wet spot by the road side between Dudsland
toll-gate and the Hall Farm, Mayfield ; in the pond at
Ramslye; in the watercourse by the road side near
Mark Cross, &c. : Mr. Jenner. Cheshunt : A. H. H.

To this species, which is certainly a distinct one, I have
assigned the name of Mr. Jenner, whose zeal and acuteness
in the cultivation of a knowledge of the freshwater Alga, as
well as in the pursuit of other departments of Natural History,
are so eminent. I could have wished that it had been more
worthy to have borne his name ; it has one advantage, how-
ever, over some others, which is this, that it is an abundant
species.

41. ZYGNEMA DUBIUM Hass.
Plate XXXVII. Fig. 7.

Char. Filaments rather more slender than those of Z. Jen-
neri. Cells Jive or six times as long as broad. Sporangia
oval, long, placed in cells, which are inflated for their
reception.

Hab. Between Sidley Green and Ninfield, near Battle :
Mr. Jenner. Near Wormly West End, Hertfordshire :
A. H. H.

This may be but a variety of Zygnema Jenneri.

42. ZYGNEMA MINIMUM Hass.
Plate XXXVII. Fig. 8.

Char. Filaments as slender as those of Z. tenuissimum. Cells
many times as long as broad. Sporangia oval, lodged in
much inflated cells.

Hab. Cheshunt: A. H. H.

This possibly may not be distinct, but prove eventually to
be the unconjugated state of Z. tenuissimum.

160 CONJUGATED.

11. TYNDARIDEA Bory.

Char. Endochrome disposed in the cells in a star-like form,
the stellate masses being double in each cell. Sporangia
usually circular, sometimes lodged in the cells, and occa-
sionally in the connecting tubes.

Derivation. Tyndaridce, the constellation so called of Cas-
tor and Pollux ; in allusion to the twin star-like masses
contained in each joint.

Stellulina Link, Handb. iii. 261. Agardhia Gray. Glo-
bulina Link, in Hor. Physic. 5. Lucernaria Rouss.
et Desv., Jour. Bot. i. 143. Tyndaridea et Led<B species
Bory, in Diet. Class. Conjugates, sect. 11. Vauch. pi. 6, 7.

The species of the genus Tyndaridea are distinguished by
the arrangement of the endochrome, which is in star-like
masses, two of which are contained in each cell, connected usu-
ally by a band or tube. Concerning the nature of these bodies,
numerous conjectures have been hazarded. It has been sup-
posed that the one represented the male and the other the
female, the sporangia resulting from their union : this con-
jecture, however, does not seem probable. This form, as well
as the beautifully spiral arrangement of the endochrome, in
the genus Zygnema, has doubtless been impressed upon these
plants by the Deity, in order that they might appear the
more attractive and more wonderful in the eyes of man.

The sporangia are usually circular, and lodged either in
the cells themselves, or in the transverse tubes. By this dif-
ference in the situation of the sporangia, the genus admits of
a natural division into two subgenera.

First Subgenus. — Sporangia placed in the cells of one or other

filament.

1. TYNDARIDEA CRUCIATA Hass.
Plate XXXVIII. Fig. 1.

Char. Filaments of considerable size. Cells once or once and
a half as long as broad, at first densely filled with en-

TYNDARIDEA. 161

dochrome, ichich near the period of conjugation exhibits a
somewhat stellate arrangement. Sporangia circular, not
producing any material change in the primary form of
the cell.

Conjugata cruciata Vaucher, Hist, des Conf. pi. vi. fig. 4. ;
pi. vii. fig. 2. p. 77.

Hab. Cheshunt: A.H.H.

I have but little doubt that this is the Conjugata cruciata of
Vaucher. It is the finest of all the Tyndaridea I have met
with. It is not common : and I have only once obtained it
with the sporangia formed.

2. TYNDARIDEA ANOMALA Ralfs.
Plate XXXVIII. Figs. 2, 3.

Char. Filaments smaller than those of T. cruciata. Cells in
the young state usually about as long as broad, densely
filled with endochrome, and invested with a broad and
very apparent mucous sheath; in a more advanced con-
dition the threads become narrower, the slteath smaller,
and the endochrome more scattered, and sometimes even
stellated ; finally, the sporangia are formed, which are
circular, and protrude slightly into the tubes of commu-
nication of the filaments.

T. anomala Ralfs, MSS.

Hab. Penzance and Dolgelly : Mr. Ralfs. High Beech :
A. H. H. In a boggy spot near Cross in Hand, oppo-
site to where the road branches to Hailsham ; Barcombe,
in Sussex, and Weston Bogs, near Southampton: Mr.
Jenner.

This remarkable and somewhat anomalous species was first
discovered by Mr. Ralfs, who submitted it to the examination
of several friends. For a long time, however, doubts were
entertained by many as to whether it really was a Tynda-
ridea or not ; doubts which I myself, in common with others,
for a period entertained, but which I was happily enabled to

M

162 CONJUGATED.

terminate by the discovery of a specimen in which perfect
sporangia were formed. The filaments, when dried on paper,
exhibit less gloss than the other species of the genus, and the
endochrome contracts but little. When the sporangia are
formed, but little difference can be detected between its fila-
ments and those of the following species. Where the species
does occur, it is ordinarily very abundant, destroying most
other Conferva with which it is in contact, by its more vi-
gorous growth. The highly developed mucous sheath, which
is so characteristic of the species, frequently presents waived
and irregular margins.

3. TYNDARIDEA LUTESCENS Hass.
Plate XXXVIII. Fig. 4.

Char. Filaments of nearly the same diameter as those of the
preceding species. Cells at first scarcely so long as broad,
and filled with endochrome; subsequently they become longer
than broad; and then the endochrome presents a partial
division, each division being somewhat stelliform. Sporangia
circular.

T. cruciata Harv. in Manual, p. 141.

Hob. Cheshunt and its vicinity : A. H. H.

This is the species which until lately I have regarded as
the Conjugata cruciata of Vaucher, to which in all, save
size, it bears considerable resemblance. It appears to be the
commonest species of the genus ; but I am not able to refer
it to any of Vaucher's species. Tyndaridea abbreviata, An-
nals of Nat. Hist., vol. x. p. 43, I am now inclined to think
is but this species with cells shorter than ordinary.

4. TYNDARIDEA BICORNIS Hass.
Plate XXXVIII. Fig. 5.

Char. Filaments more slender than those of the preceding
species. Endochrome divided into two masses, which are
united by a narrow band in the centre, each mass present-
ing two points or horns on its distant extremity. Sporangia

TYNDARIDEA. 163

circular, contained within the cells. Cells usually rather
more than twice as long as broad.

Tyndaridea bicornis, Annals of Nat. Hist. vol. x. p. 43.
Hob. Cheshunt and other places : A. H. H.

This species is by no means uncommon, and is certainly
distinct. A species described in the 10th vol. of the Annals
of Nat. Hist, under the name of T. interposita, ought, I think,
to be regarded as a variety of the species. Fig. 8. plate
xxxviu. may perhaps represent a species distinct from T.
bicornis. I have more than once met with it just as repre-
sented in the figure.

5. T. INSIGNIS Hass.
Plate XXXVIII. Figs. 6, 7.

Char. Filaments rather smaller than those of T. bicornis.
Cells twice as long as broad, and frequently curiously
distorted, that side of them which either has or is about
to unite itself with another, becoming remarkably protube-
rant. Sporangia circular, and partly lodged in the trans-
verse tubes.

Hob. High Beech, Wanstead, and other places : A. H. H.
Rusthall Common ; in a pool by the road- side between
Cross in Hand and Heathfield ; pond near Five Ashes,
Mayfield ; on Waterdown Forest ; Greatham and
Storrington Commons : Mr. Jenner.

This species, which sometimes presents an appearance so
remarkable, was first sent me by Mr. Jenner. It is by no
means uncommon, and I think certainly distinct from all
others with which I am acquainted.

6. TYNDARIDEA STAGNALIS Hass.
Plate XXXVIII. Fig. 9.

Char. Filaments more slender than those of T. insignis. Cells
about two and a half times as long as broad. Sporangia
M 2

164 CONJUGATED.

circular, extending into a portion of the connecting tubes.
T. stagnalis.

Hassall, in Annals of Nat. Hist. vol. x. p. 42.

Hab. Abundant on Hertford Heath and other places in

the counties of Hertfordshire and Essex: A. II. H.

Rusthall Common ; Waterdown Forest, and near Cross

in Hand.

This is a distinct and common species. Fig. 10. plate
xxxviii. may possibly be distinct from this.

Second subgenus. — Sporangia lodged in the transverse tubes.

7. TYNDARIDEA IMMERSA Hass.

Plate XXXIX. Fig. 3.

Char. Filaments of considerable diameter. Cells about once
and a half or twice as long as broad. Endochrome dis-
tinctly stellate. Sporangia large, circular, and partly im-
mersed in the cells.
Tyndaridea conspicua, Annals of Nat. Hist. vol. xii.

p. 187. pi. 7. fig. 17.
Hob. Wimbledon Common : A. IL H.

" This species bears considerable resemblance to Vauchcr's
figure of T. pectinata. I do not think, however, that it is
that species, for I presume that Vaucher employed the same
magnifying power to all his figures ; in which case the fila-
ments of T. pectinata would be almost equal in diameter
to those of Z. quininum, and consequently nearly as large again
as those of the present species." — Annals.

8. TYNDARIDEA CONSPICUA Hass.
Plate XXXIX. Figs. 1, 2.

Char. Filaments rather smaller than those of the preceding
species. Cells usually twice, or twice and a half as long as

TYNDARIDEA. 165

broad. Sporangia usually spherical, but sometimes oval,
and entirely confined to the transverse tubes.

Tyndaridea immersa, Annals of Nat. Hist. vol. xii. p. 188.
pi. 7. fig. 19.

Hob. Wimbledon Common : A. H. H.

A very rare species. I have seen it but once.

9. TYNDARIDEA DECUSSATA Hass.
Plate XXXIX. Fig. 6.

Char. Filaments of less diameter than those of the preceding
species. Cells usually two and a half times as long as
broad. Sporangia circular, and a portion of them immersed
either in one or other, or both cells.

T. decussata Hassall, in Annals and Mag. of Nat. Hist,
vol. xii. p. 188. pi. 7. fig. 18.

The species described by Vaucher, under the head of Con-
jugata decussata, would appear to be referrible to the next
genus, and not to Tyndaridea.

10. TYNDARIDEA KALFSII Hass.
Plate XXXIX. Figs. 4, 5.

Char. Filaments of less size than those of T. immersa. Cells
usually four times as long as broad. Sporangia elliptical,
their long diameter corresponding with the length of the
tube.

Hob. Penzance : Mr. Rolfs. Near Cross in Hand, oppo-
site to where the road branches to Hailsham, and on
Piltdown Common.

T. Ralfsii Hassall, in Annals of Nat. Hist. vol. xii. p. 188.
pi. 7. fig. 20.

" There is not a more beautiful or elegant species than
this in the genus, and I have much satisfaction in dedicating
it to Mr. Ralfs, its first finder, and a gentleman by whom

M 3

166 CONJUGATED.

our knowledge of the Alga has been so considerably aug-
mented." — Annals.

12. MESOCARPUS Hassall.

Char. Cells filled at first with endochrome, which subsequently
contracts, and assumes an irregularly spiral form.
Sporangia either circular or oval, and lodged in the trans-
verse tubes.

Derivation. From pscros, middle, and Kapjros, fruit.
Sphcerocarpus Hassall, in Annals of Nat. Hist. vol. xi.
p. 185. pi. 7. fig. 7. &c.

The genus Mcsocarpus, for which I first proposed the name
of Sphcerocarpus, to designate the position of the sporangia,
and which I now find to be preoccupied, differs from the
two genera already described in not having the endochrome
arranged in any definite and figured form. When the fila-
ments arc young, the endochrome occupies the entire cavity
of each cell ; as they grow older, however, spaces are left at
the extremities of the cells; and finally the endochrome
frequently contracts itself into a mere thread, irregularly
twisted. The sporangia are never placed in the cells, as in
all the species of the genus Zygnema, and in very many Tyn-
daridece, but invariably in the transverse tubes of commu-
nication which become dilated for their accommodation. The
species of this genus live in water, less pure than the Zygne-
mata and Tyndaridece, being mostly found in boggy and
ancient ponds, on commons, &c. ; and on this account they
are rarely so brightly coloured as are the species of those
genera.

1. MESOCARPUS SCALARIS Hass.
Plate XLII. Fig. 1.

Char. Filaments exceeding someivhat in diameter those of
Mougeotia gemiflexa. Cells about four times as long as
broad. Sporangia ova I, their long diameter being placed in
the direction of the diameter of the cells.

MESOCARPUS. 167

var. ft. — Sporangia circular.

Mougeotia scalaris Hassall, in Annals and Mag. of Nat.
Hist. vol. x. p. 45. pi. 7. fig. 7. Zygnema ordinarium 9
Berkeley's Gleanings. Sph&rocarpus scalaris var., An-
nals of Nat. Hist. vol. xii. p. 186. pi. 7. fig. 8.

Hab. England ; common, var. ft, Crowborough Warren :
Mr. Jenner.

This is one of the commonest as well as most distinct
species of the genus. I have encountered it repeatedly myself,
and have also received it from Mr. Jenner. Z. ordinarium
Berkeley is quoted as a synonyme with considerable doubt ;
but if that species be not the one above described, I am at
a loss to which of the other species of the genus described in
this paper it ought to be referred. The filaments in Meso-
carpus scalaris, as well as in the majority of the other species
of genus, are of a yellowish green, owing to the greater
impurity of the water in which they dwelt.

Plate XLII. fig. 2. represents what I shall here describe
as a variety of this species. The filaments are of the same
diameter, but the sporangia, instead of being oval, are spherical.
It is very probable that this is really a distinct species ; but
having seen it but once, I hesitate so to regard it.

2. MESOCARPUS INTRICATUS Hass.
Plate XLIII. Fig. 1.

Char. Filaments smaller than those of M. scalaris. Cells Jive
or six times as long as broad. Sporangia oval, rather
larger than those of M. scalaris, their long diameters being
placed in the direction of the width of the cells.

Sphcerocarpus intricatus, Annals of Nat. Hist. vol. xii.
p. 186. plate 7. fig. 9.

Hab. Broad water Forest : Mr. Jenner.

The only diiferences to be detected between this and M.
scalaris are, the smaller diameter of the filaments, and

M 4

168 CONJUGATED.

greater size of the sporangia ; but these are, I think, of a
sufficiently well marked character to justify its being ranked
as a distinct species. It has only as yet been found by that
indefatigable observer Mr. Jenner.

3. MESOCARPUS RECURVDS Hass.

Plate XLIII. Fig. 2.

Char. Filaments smaller than those of M. intricatus. Cells
six or seven times as long as broad. Sporangia circular.
Sphcerocarpus recurvus Hassall, in Annals of Nat. Hist,
vol. xii. p. 186. plate 7. fig. 10.

Hab. Penzance : Mr. Ralfs. Rackham Common : Mr.
Jenner.

" This species I first received from Mr. Ralfs, and some
two or three weeks afterwards it was sent me by Mr. Jenner.
I regard, it however, as the species figured by Dillwyn (Sup-
plement, plate C.), as M. genuflexa in a state of repro-
duction." — Annals.

4. MESOCARPUS DEPRESSUS Hass.

Plate XLIV. Fig. 1.

Char. Filaments rather larger than those of Mesocarpus
recurvus. Cells six or seven times as long as broad.
Sporangia oval, small, their long diameter being placed in
the direction of the length of the cells.

Sphcerocarpus depressus Hassall, in Annals of Nat. Hist,
vol. xii. p. 186. plate 7. fig. 11.

Hab. In a boggy spot near Cross in Hand, opposite to
where the road branches to Hailsham: Mr. Jenner.
Penzance : Mr. Ralfs.

" There can be no doubt of the distinctness of this species,
Avhich was procured by Mr. Jenner, some weeks before it
was found and transmitted me by Mr. Ralfs." — Annals.

MESOCARPUS. 169

5. MESOCARPUS NUMMULOIDES Ilass.
Plate XLV. Fig. 1.

Char. Filaments of rather larger size than those of Meso-
carpus recurvus. Cells about six times as long as broad,
not usually recurved. Sporangia circular, and smaller than
those of M. recurvus.

Sphcerocarpus nummuloides Hassall, in Annals of Nat. Hist,
vol. xii. p. 187. plate 7. fig. 12.

Hob. Hertford Heath : A. H. H.

This species approaches very closely to the following.

6. MESOCARPUS PARVULUS Hass.
Plate XLV. Figs. 2, 3.

Char. Filaments much shorter than those of Mesocarpus
nummuloides. Cells usually six times as long as broad.
Sporangia circular, small.

Mougeotia parvula Hassall, in Annals of Nat. Hist. vol. xi.
p. 434. ; Sphcerocarpus parvulus Hassall, Annals,
vol. xii. p. 187. plate 7. figs. 13, 14.

Hab. Hertford Heath, Epping, &c. : A. H. H. Near
Cross in Hand and Waterdown Forest : Mr. Jenner.

The larger figure of the two may represent a distinct
species.

7. MESOCARPUS OVALIS Hass.
Plate XLIV. Fig. 2.

Char. Filaments about equal in size to those of Mesocarpus
parvulus. Cells ten or twelve times as long as broad.
Sporangia slightly elliptical, their long diameter being
placed in the direction of the length of the cells.

Sphcerocarpus ovalis Hassall, in Annals of Nat. Hist,
vol. xii. p. 189. plate 7. fig. 15.

Hab. Hertford Heath : A. H. H. Penzance : Mr. Ralfs*

170 CONJUGATED.

" The sporangia, though elliptical, are not nearly so much
so as those of M. depressus, and the filaments not one half
so large." — Annals.

8. MESOCARPUS ANGUSTUS Hass.

Plate XLV. Fig. 4.

Char. Filaments very slender. Cells many times longer than
broad. Sporangia circular, very large in comparison with
the size of the filaments.
Sphcerocarpus angustus Hassall, in Annals of Nat. Hist.

vol. xii. p. 187. plate 7. fig. 16.
Hab. Penzance : Mr. Ralfs.

" This is a very distinct species, and for its discovery we
are indebted to Mr. Ralfs." — Annals.

Sporangia formed without union of the filaments, or com-
mingling of the contents of two cells.

9. MESOCARPUS NOTABILIS Hass.

Plate XL VI. Fig. 2.

Char. Filaments at first cylindrical, but subsequently be-
coming angulated, the angle of fiexion being situated in
the centre of each cell. Cells usually about eight or ten
times as long as broad, but frequently longer. Sporangia
non-symmetrical, a single one being placed in the angle
formed in each of the cells.
Mougeotia notabilis Hassall, in Ann. Nat. H. vol. x. p. 46.

Hab. Found in great abundance in some brick-fields near
Netting Hill: A. H. H.

I am unwilling to create a new genus for the reception of
this curious and anomalous production, and am induced to
refer it to Mesocarpus, on the supposition that were the fila-
ments in any case to conjoin, and sporangia to be formed,
that these would present the characters of the genus, and be
either spherical or oval.

MOUGEOTIA. 171

13. MOUGEOTIA Ag.

Char. Filaments coalescing usually without the intervention

of transverse tubes; no transference of endochrome, and

no formation of sporangia taking place. Conjugation a n-

gular.

Named in honour of M. J. B. Mougeot, a German botanist.

The genus Mougeotia corresponds with Mesocarpus, save in
the important fact that, although the filaments conjoin, there
is no transference of endochrome, and consequently no form-
ation of sporangia.

The following account of the genus Mougeotia was inserted
in the " Annals and Magazine of Natural History : " —

" The real nature of the genus Mougeotia does not hitherto
appear to have been at all understood, and consequently the
definitions given of it up to the present time are either erro-
neous or incomplete.

" Vaucher thus defines the genus Mougeotia : — * Conjugees
a tube interieur' And Agardh, as follows : — * Fila articulata
reticulata conjuncta, granulis absque ordine dispositis, fructibus
in angulis reticuli collocatis?

" The first of these definitions is imperfect, and the second
inaccurate, inasmuch as it contains a reference to perfect
fructification distinct from the granules or zoospores.

" The true and original species of the genus Mougeotia are
all characterized by the singular fact, that sporangia, which
Agardh calls the fruit, are never found in them as they are in
all other species of the conjugating tribe of Conferva. The
filaments do indeed unite, but no transference of the con-
tents of one cell into the interior of the other, and conse-
quently no formation of sporangia ever take place.

" This remarkable circumstance in the history of the genus
Mougeotia, resting as it does on long-continued and careful
observation of the species composing it, does not admit of the
smallest doubt ; and although not absolutely stated as a fact,
it is yet strongly implied by Vaucher in his description of Mou-
geotia gemiflexa, in which the following observations occur :—

" * This Conjugata has not presented to me the round

172 CONJUGATED.

globules of the other species of the same family ; on the con-
trary, the green matter which it incloses has appeared to
me to present nearly the same form, so that I know not how
the grain is formed, nor in what way the developement in this
species is brought about ; only I have remarked distinctly
three or four bright grains immersed in this green matter,
and I have seen in the month of April the cells separate
from each other and sink in the water, but I traced them no
further. Nevertheless, I have difficulty in believing that the
brilliant grains are not the germs.

" ' Since writing this description I have seen the germin-
ation of this Conjugata elsewhere in a manner very different
from all the others : the matter does not pass from one tube
to another neighbouring tube, but each cell itself furnishes
a single young plant, the interior tube which it was found to
enclose becoming a young Conjugata which was entirely con-
tained in the old tube, as it itself contains the plants which
are afterwards to become developed ; it issues by the ex-
tremity when it occupies the last cell, and by the sides when
it is found in one of the central cells.'

" With respect to the observations of Vaucher in reference
to the germination of the young Conferva while still within
the parent cell, I would observe that I have never witnessed
this singular developement, and can confidently assert that
this is not the legitimate or normal mode of developement of
the species of the genus Mougcotia, which is by zoospores, de-
veloped external to the cells, as in other Conferva."

1. MOUGEOTIA MAJOR Hass.

Plate XL. Fig. 1.

Char. Filaments of considerable size. Cells usually Jive times

as long as broad.
Mougeotia major Hassall, in Annals of Nat. Hist. vol. x.

p. 44.

Hub. Cheshunt : A. II. H.
Either this species and the following are subject to very

MOUGEOTIA. 173

considerable variation, or else several species, really distinct,
have been improperly referred to them. At one time, enter-
taining the latter opinion, I was induced to add three other
species to the genus ; but not finding, on subsequent examina-
tion, that these species were well established, I shall omit all
mention of them in the present work.

2. MOUGEOTIA GENUFLEXA Ag.
Plate XL. Fig. 2.

Char. Filaments of smaller diameter than those of M. major.

Cells seven or eight times as long as broad.
Mtiller, Acta Petropolitana, pars 3. p. 92. pi. 1. fig. 9.
Conjugata angulata Vaucher, Hist, des Conf. p. 79.
pi. 8. figs. 1, 2, 3, 4.

This interesting species is one of the commonest of the
whole tribe of freshwater Conferva, and there is scarce a
ditch in which it may not be found at all seasons of the year
The tubes remain connected for a very long time after con-
jugation, and this explains why it is that the species should
so constantly be found united. For Vaucher's account of its
reproduction see page 172.

14. ZYGOGONIUM Kutzing.

Char. Filaments of equal diameter, rarely branched. Cells
seldom conjugating ; transference of endochrome rare.
Sporangia none. Endochrome at first filling the cavity
of the cell. Zoospores scattered without order through the
colouring matter.

Derivation. From fyyos, a yoke, and ywvia, an angle.

This genus seems to me to be well established. At first
I felt disposed, on perceiving that the filaments of C. erice-
torum were occasionally branched, to refer the species to the
branched Conferva, acknowledging, at the same time, that in
many points it resembled the conjugating Alga. Subse-
quently, on finding union to have taken place between some

1 74 CONJUGATED.

of the filaments, I felt satisfied that its proper place was
with the Conjugates, and referred it to Mougeotia. This
reference did not, in all respects, seem satisfactory, for while
the true species of Mougeotia are almost constantly found
united, C. ericetorum is very rarely met with in that con-
dition. So rarely, indeed, as to make it apparent that the
species is reproduced independent of any union of the fila-
ments. The habit of C. ericetorum was so different from
that of the true Mougeotia, being more that of a Scytonema,
that I had determined to place it in a genus by itself ; a step
which, on looking over Kiitzing's " Phycologia Generalis,"
I found to have been already taken. Kiitzing thus accu-
rately defines the genus : —

" Trichomata simplicia vel subramosa, parenchymatica
hologonimica, primum viridis, deinde purpurascens ; cellulaj
cartilagineae, crispac, interdum didymae ; spermata nunc in
trabeculis, nunc lateralia, globosa."

1. ZYGOGONIUM ERICETORUM Kutz.
Plate XLI. Figs. I, 2.

Chat. Filaments not unfrequently branched. Cells usually
about twice as long as broad, rarely uniting, but frequently
emitting elongated and irregular processes, which are usually
to be regarded as rudimentary ramuli. Endochrome oc-
casionally becoming effused, generally from one cell into
an adjoining one in the same filament, but sometimes that
from both cells passes into a space formed between the two
utricles.

C. ericetorum Harv. in Hook. Brit. Flora, also in Manual,
p. 125. ; E. Bot. t. 1553. ; Grev. Crypt, t. 261. f. 1.

It has elsewhere been stated that I had been induced,
from the detection of ramuli on some of the filaments, to
consider Conferva ericetorum as referrible to the branched
Conferva. It would appear, however, on closer examination,
that while it certainly, by the not unfrequent occurrence of
ramuli, exhibits a degree of relation to those species, yet that
its affinities with the conjugating tribe are sufficiently strong

ZYGOGONIUM. 175

to make it apparent that- its proper station is with these, and
not with the branched species.

When a communication is about to be set up between two
cells in the same filament, the opposed extremities of those
cells are first seen to become slightly inflated, to point some-
what and then burst, effusing their contents sometimes into
a space which is formed gradually between the two cells,
but at others the endochrome of one cell passes directly
into the cavity of the other.

All the cells in a filament do not usually communicate
with each other at the same time, but at distant intervals ;
and around those cells between which a communication is
about to become established, the investing membrane is ob-
served to be thickened considerably, pointing out to the
observer those cells which either have, or are about to take
on, the characters of reproduction.

At one time I thought that the branches which I have so
often met with were spurious, and might have been formed
in the same manner as they sometimes are in M. genuflexa,
&c., viz. by the union of the extremities of certain filaments
at right angles with the cells of other filaments ; but this
idea was dispelled by observing, that in the specimens in
which the branches occurred most abundantly, no union of
cells in the regular way was to be met with.

The colour no less than the condition of the endochrome
varies considerably in this species. In some specimens the
filaments are of a bright green, in which case they have
always been found immersed in water ; while in others, and
more frequently, they are purple ; of which colour they in-
variably are when found spreading over swampy heaths.
Specimens of a beautiful green colour were recently sent me
by Mr. Jenner and Mr. Ralfs, and these, for some time,
puzzled me exceedingly.

I have no hesitation in referring to this species the C. pur-
purascens of Carmichael, and C. alpina Bory which is but an
aquatic condition of the plant, and strongly suspect that Conf.
tortuosa Dillw. (the Zygnema littoreum Lyngb., and C. per-
reptans Carm.) might be referred to it likewise.

176 CONJUGATED.

15. STAUKOCAKPUS.

Char. Sporangium cither square or cruciform, and lodyed in

the transverse tubes.
Derivation. From o-Tavpos, a cross, and icapTros, fruit.

" Certain square or cruciform species of conjugating Con-
ferva were doubtfully associated by Agardh with the genus
Mougeotia ; these species I learned long since had been sepa-
rated from it by Mr. Shuttleworth under the appropriate
generic appellation of Staurocarpus. Mr. Shuttleworth how-
ever did not, so far as I can learn, publish his opinion of the
propriety of establishing for these curiously formed species a
distinct genus, contenting himself with communicating his
views to some of his correspondents, of whom I may name
the following as being conversant with those views : — Mr.
Borrer, the Rev. M. J. Berkeley, and JMr. Ralfs. Within
these few days I have been informed by Mr. Berkeley that
Kiitzing has proposed this genus under the term of Stauro-
spermum in a sketch of a work on the Algoe, inserted in the
first number of the new series of " Linnsea." No account of
the genus is given by Kiitzing, but merely the name and an
enumeration of species belonging to it. Mr. Shuttleworth's
appellation I conceive to be much more appropriate and ac-
curate than that of Kiitzing, and have therefore ventured to
retain it ; for the word Staurocarpus applies to the fructifica-
tion generally, which is either square or cruciform, while
Staurospermum appears to me to specify the reproductive
granules or zoospores themselves with which each sporangium
is filled, and which are more or less of a circular form." —
Hassall, in Annals of Nat. Hist.

That Agardh entertained a very strong suspicion that the
square-fruited species ought to be separated from the genus
Mougeotia, will be apparent from the following observa-
tions : —

" Cetera species quoad fructum non satis cognitse, et
postea forsan separanda?, hue tantum ob habitum retenta?."

The genus Staurocarpus differs from Mougeotia in the facts
of the transference of endochrome and formation of sporangia,

STAUEOC ARPUS. 177

while from the genus Mesocarpus, hereafter to be described,
it is separated by the form of the sporangium.

But one species of this genus is described by British writers.
In a recent number of the " Annals " two others were added,
and I have now the pleasure of describing three other species.

1. STAUROCARPUS GLUTINOSUS If ass.
Plate XLVII. Fig. 1.

Char. Filaments of considerable diameter, highly mucous,
bluish green. Cells six or seven times as long as broad,
those being the longest which have conjugated. Sporidium
quadrangular, formed entirely by the transverse tubes.
Sporangia, when perfect, somewhat oval.

Mougeotia glutinosa, Hassall, in Annals of Nat. Hist. vol.

xxii. pi. 7. fig. 1.
Hab. Hertford Heath : A. H. H.

This is a very distinct and fine species, occurring abundantly
in boggy pools on Hertford Heath. Not unfrequently a
number of contiguous pairs of cells unite, forming arched
loops or links, separated from each other by the square
ovarium, which is the chief characteristic of the species.

2. STAUROCARPUS COERULESCENS Hass.
Plate XLVII. Fig. 2.

Char. Filaments of less diameter than those of Staurocarpus
glutinosus. Cells usually eight or ten times as long as
broad. Endochrome, when recent, ccerulescent ; when dried,
of a purple hue. Sporangia cruciform, large, and filled
with zoospores of a greenish colour.

Staurocarpus capucinus Hassall, in Annals of Nat. Hist,
vol. xii. p. 184.

Hab. Henfield : Mr. Borrer. Tunbridge Wells : Mr.
Jenner. Penzance : Mr. Ralfs. High Beech, Essex :
A. H. H.

N

178 CONJUGATED.

The colour of the filaments in this, as in other species,
wo.uld appear to be subject to considerable variety ; in their
youngest condition, the filaments are stated to be candescent ;
in their more advanced state, they are purple, and invariably
so when dried, exhibiting on paper, which they often stain,
some degree of gloss.

The Leda capucina of Bory, Mougeotia capucina of Agardh,
is probably identical with this species.

3. STAUROCARPUS QUADRATUS Hass.

Plate XL VIII. Fig. 1.

Char. Filaments of less diameter than those of the preceding
species, bluish green. Sporangia quadrangular.

Mougeotia quadrangulata Hassall, in Annals of Nat. Hist.

vol. xii. p. 185. pi. vii. fig. 3.
Hob. Cheshunt, and various places in the neighbourhood :

A. H. H. Ashdown Forest, and on Crawley Down, near

Turner's Mill : Mr. Jenner.

There is no difficulty in distinguishing this from all other
species hitherto recorded.

4. STAUROCARPUS VIRESCENS Hass.

Plate XL VIII. Fig. 2.

Char. Filaments smaller than those of St. quadratus,
usually of a grass green colour. Cells before conjugation
about eight or ten times as long as broad, but after that
period becoming much longer. Sporangia cruciform.

Staurocarpus affinis Hassall, in Annals of Nat. Hist,
vol. xii. p. 185. pi. vii. fig. 4.

Hob. Pool near Hoyden, Essex : A. H. H.

This species comes very near to St. quadratus, from which
it is distinguished by its somewhat finer filaments, and cru-
ciform sporangium, the sporangia in St. quadratus being
square.

STAUROCARPUS. 179

5. STAUROCARPUS GRACILIS Hass.
Plate XLIX. Fig. 1.

Char. Filaments more slender than those of St. virescens, and
usually of a green colour. Cells many times longer than
broad. Sporangia cruciform.

St. gracilis Hassall, in Annals of Nat. Hist. vol. xii. pi. vii.
fig. 5.

Hob. Penzance : Mr. Rolfs. "Waterdown Forest, Broad-
water Forest, Fisher's Castle, Crowborough Warren :
Mr. Jenner. High Beech, Hertford Heath, Wormley,
"West End, and Wanstead Flats, Essex : A. H. H.

This is an abundant species, and very distinct from any of
the others. It was found by Mr. Ralfs, Mr. Jenner, and
myself, within a few days of each other.

6. STAUROCARPUS GRACILLIMUS Hass.
Plate XLIX. Fig. 2.

Char. Filaments more slender than those of St. gracilis, and
usually of a green colour. Cells very many times as long
as broad. Sporangia cruciform, and about one half the size
of those of St. virescens.

St. gradllimus Hassall, in Annals of Nat. Hist. vol. xii.
p. 185. pi. 7. fig. 6.

Hob. Hertford Heath and High Beech : A. H. H. Kack-
ham Bogs, Parham Park, near Storrington, and Ash-
down Forests : Mr. Jenner.

This species I have myself met with several times, but did
not at first recognize its distinctness, of which, however, I
now entertain no doubt : and it was only on the receipt of a
beautiful sketch from Mr. Jenner, accompanied by remarks,
that I examined thoroughly into the matter, and satisfied
myself of its entire distinctness.

N 2

180

FAM. IX. CYSTOSPERME.E.

Char. Filaments simple, subulate, non-conjugating. Cells at
Jirst equal, subsequently here and there inflated or vesicular.
Sporangia formed by the union and condensation of the
endochrome of two contiguous cells of the same filament.

The impression which I first entertained respecting the Con-
ferva contained in this family was, that it would be sufficient
to regard them as constituting a new genus, referrible to the
Conjugates already described : subsequent reflection and exa-
mination have, however, convinced me that they should hold a
higher than a generic rank, and that the characters presented
by them are sufficiently distinctive to entitle them to the rank
of a separate family.

Their filaments are simple, slightly subulate, owing to
the cells growing laterally, or in diameter as well as in longi-
tude, usually attached, do not conjugate, are articulated or
jointed, and terminate in lanceolate extremities: in their young
condition the cells are uninflated ; subsequently, however, cer-
tain ones swelled up, this inflation being occasioned by the
transference into them of the contents of one of the adjoining
cells, and in these inflated cells, ultimately are formed, large
oval or circular bodies, similar to those of the Conjugates, both
in appearance and nature, and which therefore I in like manner
denominate sporangia.

In addition to these essential characters of this family, the
Cystospermcce are distinguished by other, though less obvious,
not less important characteristics. The filaments are of a
firmer texture than those of most other Confervce, they possess
comparatively but little flexibility, are not mucous, and con-
sequently do not exhibit that glossy appearance presented
by so many Conferva when removed from the water, and
which they retain when dried upon paper ; in all which par-
ticulars they stand in marked opposition to that numerous and

CYSTOSPERME^E. 181

important division of the freshwater Conferva, the Conjugates^
in the species of which the filaments are flexible, mucous,
and shining in the highest degree : in them, too, the fila-
ments never taper, but are always exactly cylindrical. More-
over, the articulations differ in the two groups : in the Cysto-
spermecB they are strongly marked, and when dried, become
contracted and dark, while in the Conjugates they are faintly
indicated ; and in dried specimens are often with difficulty
discoverable.

Such are the leading features of this interesting division
of the Conferva, and on a careful examination and estima-
tion of the many points of difference here enumerated be-
tween them and the Conjugate®, the tribe to which they most
closely approximate, there can be no doubt, I apprehend,
of the propriety of retaining them in a separate family.

The differences are too great to admit of their holding
merely a generic rank. The naturalness of the different
genera forming the preceding family may be readily per-
ceived, these passing through certain species, the one into
the other ; and all being allied by certain resemblances :
but how wide is the interval between any of these and the
group of Cystospermece !

The sporangia in the different species of Cystospermes are
produced in the same manner as in the non-conjugating
Zygnemata; that is, by the concentration of the contents
of two adjacent cells in the same filament, this being neces-
sarily always accompanied by the inflation of the receiving
cell, and the giving cell being constantly placed in com-
munication with the narrow end of the oyate inflated cell.

In all the Conjugates the endochrome is seen to pass through
tubes of connection between the cells, whether in different
or in the same filaments : in these, however, no such passages
exist, the contents of the cells escaping apparently through
a rent occasioned by some agency in their extremities. The
notice of this particular furnishes an additional distinctive
character between the two groups : but others still remain,
two of which may next be noticed.

The first of these relates to the presence of a peculiar and

N 3

182 CYSTOSPERME^E.

regular annulation of the enveloping membrane of the cells,
which would appear at a certain epoch to be intimately
adherent to the tissue of the cells themselves.

" The genus of freshwater Conferva which I have deno-
minated in a previous article Vesiculifera* r, in addition to the
characters indicated in the definition of it given therein, such
as the attachment, attenuation and slight mucosity of the
filaments of the species composing it, as well as the formation
of true spores by the intermingling and union of the contents
of two cells in the same filament, is particularly distinguished
by the presence of a peculiar and regular annulation of the
enveloping membrane of the cells, which would appear at a
certain epoch to be intimately adherent to the tissue of
the cells themselves." (PL xvn. figs. 7, 8.)

" This annular disposition of the sheath of the cells does not
occupy its whole extent, but corresponds only to certain cells
and determinate portions of those cells ; the cells around
Avhich it is disposed being those in which the spores are
destined to be formed, and the portion of these which it in-
vests being the extremities through which no endochrome
passes from the contiguous cells for the formation of the true
spores, or rather perhaps sporangia.

" The number of annuli which correspond to each fructi-
ferous cell varies according to the species, and is more consi-
derable in the long-celled species ; it would appear however to
be never less than two, or more than eight or ten, to each cell.

" The use of this interesting structure is much more apparent
than that of the provision already noticed as belonging to one
section of the genus Zygnema, and admits of a most satis-
factory explanation, it being manifestly designed to afford an
outlet to the imprisoned spores, which it may be supposed to do
in the following way. As soon as the species has reaehed its
maturity and the spores have become perfected, the annuli,
which are intimately united to the cells, contract, most pro-
bably from the arrest of growth and diminution of vitality

* This genus was first established by me in the " Annals and Maga-
zine of Natural History," vol. x. p. 385. ; it will be seen, however, that
the views here expressed differ in many respects from those therein stated.

CYSTOSPERME^E. 183

of the plant which occur towards the completion of the pro-
cess of reproduction, drawing along with them, and thus rup-
turing, the slightly elastic membrane of the cells. (PL xvn.
fig. 7.)

" Without some such beautiful and effectual provision, it
will be evident, on reflection, that the spores would have to
remain immured within their narrow cells for an indefinite
length of time, even until, perhaps, their vitality had ceased
and the cells had become their coffins ; for occupying, as the
spores do, but a portion of the space of the cells, and enve-
loped as they are in membranes, they can themselves, of
course, exert no influence in producing the rupture of the
walls of those cells.

*•' In all the Confervce with which I am acquainted, some
special means are provided for the escape of the spores or
zoospores, their liberation never being left to the sole agency
of decomposition of the tissue of these plants ; thus, in the
majority of the branched Conferva;, and in the species of the
genus Sphoeroplea as well as in many other Confervas, their
liberation is effected by the rupture of the cells in which
they are contained, which rupture is occasioned by the deve-
lopement of the zoospores while still inclosed within the cells ;
in Conferva (Microspora) glomerata a special aperture exists
for the escape of the zoospores at the period of reproduction,
situated at one side of the distal extremity of each cell ; in
the Conjugating tribe the zoospores pass out through the
openings of the connecting tubes of the cells, which, when
reproduction has been completed, separate from each other ;
and lastly, in the Vesiculiferce, as has been shown, a more
complicated provision exists for the egress of the spores and
zoospores.

" Of all characters whereby the Vesiculifera may be distin-
guished from other Confervoe, that derived from the corruga-
tion of the investing sheath is perhaps the most valuable,
from the circumstance not merely of its being confined to the
species of that genus, but from its constant presence in all
stages of their developement ; and not only is it interesting as
being indicative of a Vesiculifera, but also as pointing out

N 4

184 CYSTOSPERMEJE.

those cells, even in the young and but little developed Vcsi-
culifera, which are destined to carry the true spores when
the species shall have arrived at the perfection of its life."

Meyen, by whom this interesting structure seems first to
have been noticed, gives the following account of its charac-
ters in a species which he calls Conferva rivularis : —

" The annular structure appears worthy of notice, which
the upper end of many of the joints of the Conferva repre-
sented exhibits. This appearance is altogether analogous to
the annular structure observed in the horny coat of the
Campanularia. In those polypi also this structure appears
first at an advanced period of growth, as is the case with
the Conferva, and indeed in very different species of articu-
lated plants of this family. The formation commences with
a thickening of the membrane; the constrictions then ap-
pear, which are not spiral, but run in horizontal rings one
above the other. Sometimes it seems as if this ringed sub-
stance were an entirely new formation." — Meyen, Pflan-
zcn-physiologie, vol. iii. p. 451.

The above is the entire of Meyen's account of this cor-
rugated formation, which does not in all respects accord with
my own observations. The structure is, amongst freshwater
Algae, confined to the species of the genus Vesiculifera.

" The purpose to which the annular disposition of the horny
coat, of not merely the Campanularia but of most hydroid
Zoophytes, is subservient, is probably that of rendering their
polypidoms more flexible, and consequently less liable to
injury from the agitat-jon of the restless element in which
they dwell." *

The second particular refers to the central cytoblast or re-
productive vesicle, which, in the group of Cystospermcce, is
circular, whilst in one genus of the Conjugates, Zyynema, it
is somewhat quadrifonn, and furnished with tubular offsets.

It is at once apparent, that the mode of reproduction just
indicated, does not differ essentially from that first made
known by Vaucher, with reference to the Conjugates, and

* See Arniuls of Nut. Hist.

C YSTOSPERME^E. 185

especially in respect to those most interesting species which
I have described as producing true sporangia, without union
of the filaments.

This discovery of the identity of the mode of reproduction
of the two families of Conferva hitherto treated of, leads
necessarily to some general, and not unimportant conclusions.

Thus, it furnishes satisfactory evidence of the intimate
and general connection which exists between these two
families, which include such a considerable proportion of the
freshwater Conferva, whereby much light is thrown upon
the often canvassed and much disputed subject of the ani-
mality of the conjugating genera, for it proves, since in
reality a conjugation takes place for the formation of all
true sporangia, that both stand upon the same footing as
regards their animal nature, a fact, which hitherto has never
been suspected, the vegetable character of the Cystospermea
having long been considered as established, and that if those
species which exhibit the curious phenomenon of conjugation
are really animal, so are all the true Confervas ; thus, if these
should at any subsequent period be removed from the vege-
table kingdom to the animal, so ought, as an inevitable con-
sequence, all the other Conferva which I have included in
the group of Cystospermea,

But it appears to me that, from the fact disclosed of the
union and concentration of the contents of two cells in so many
Conferva, no argument can be deduced either in favour of
the sexuality or animality of the Conferva, numerous species
occurring, as already observed in the Introduction, in which
this curious phenomenon is wholly wanting.

For my own part, I trouble myself but little with the
disputes about the boundaries of the two great divisions of
the organised world, which forcibly remind me of the search
carried on by ancient philosophers, for days and years, after
the much-desired, but imaginary philosopher's stone, endowed
with such all-pervading influence, or the equally fruitless in-
quiry after perpetual motion, or any other of the wild chimeras
to which the minds of men have from time to time been
given. It is my belief, that no such rigid boundary exists ;

186 CYSTOSPEHME.E.

for in living nature there are no abrupt unsightly chasms ;
all is uniformity, transition, design.

To the group Cystospermea are to be referred all the true
Conferva; but before admitting any species as such, it is
necessary that it should undergo a rigorous examination ; for
we find placed among the Conferva proper many species having
no relation whatever with those near to whicli they are placed,
but are referrible to some others of the genera belonging
to the other divisions of the Conferva already established.
Thus C. alpina, C. purpurescens, C. zonata, C. punctata,
C> ericetorum, C. mucosa, are placed by Agardh the elder
and Harvey amongst the Conferva properly so called. The
first two, nevertheless, are Conjugatea, C. zonata and C. punc-
tata Spharoplea, and C. mucosa a Desmidium.

It may be thought by some, that instead of instituting a
new generic name, it would have been better to have reserved
for the species included under it the old appellation of Con-
ferva. To the adoption of this course, two objections pre-
sent themselves ; the first is, that it appears unadvisable
that the term Conferva should ever be employed merely in a
generic sense — that a wider meaning ought to be extended
to the word — that it should be employed in the same manner
as the term Zoophyte, and made to embrace the filamentous
division of the Alga; and the second is, that there is no
reason founded in right, why this term of Linnaeus should
be perpetuated in any other way than that suggested, he,
and all who have hitherto employed it, having had no defi-
nite ideas respecting the exact nature of the productions
which ought to be referred to it — Alga widely differing in
essentials having constantly been placed under it.

Five of the six species of Prolifera described by Vaucher
are certainly to be referred to the genus Vesiculifera, the
sixth C. glomerata is of an entirely different nature. So im-
perfectly and inaccurately, however, are those species de-
scribed and delineated, that it is impossible to identify them
with any degree of certainty. The following is Vaucher's
account of the reproduction of the genus Prolifera, which, it

CYSTOSPEKME^E. 187

will be seen, is not in all respects inaccurate, though still,
for the most part, very erroneous : —

" When the Proliferce are ready to reproduce, cylindrical
enlargements are seen to arise in the length of the filaments,
which one would take for knots, if the plants were not arti-
culated or chambered. These bourrelets, at first but little
apparent, soon increase in size, and finally become covered
with a pulverulent material, which is formed either by refuse
matter which floats in the liquid, and which has been re-
tained within the elevations, or of a material which is secreted
by the Conferva. When this powder has remained some
time upon the enlarged part of the stem, a number of fila-
ments are seen to issue from it, which form at first little
rounded heads. Unfortunately this powder at the same
time that it seems to favour the increase of the young Con-
ferva baffles greatly the observer. He is able to see but
little of the first developement of the plant, and in conse-
quence is not able to judge, whether it issues from the sur-
face of the enlargement or from the centre : whichever it
may be, the young filaments extend themselves round all the
circumference, where they form as it were a tuft of hairs.
Little by little their cells begin to be marked out ; soon their
tubes resemble in miniature those of the great ProHferce.
Lastly, they go and form elsewhere a new individual, like to
that from which they took their birth : but I acknowledge,"
says Vaucher, " that I have not seen this separation, although
I have no doubt but that it really takes place."

What Vaucher regards as the young proliferous offspring,
are doubtless to be regarded as parasitic growths, to which the
Conferva are peculiarly liable, more especially when they are
confined for a length of time in small vessels of water.

Two other species of this group have been referred by
Meyen to a genus Hempelia, which he instituted for them, a
genus even more erroneously defined than that of Prolifera,
already noticed.

"HEMPELIA. — Thallus simplex, membranaceus, septatus,
cequalis vel inacqualis. Fructus terminalis est, capsula sub-

188 CYSTOSPERME.E.

pyriformis, apice regulariter vel irregulariter dehiscens, et
sporas emittens. Spora? globosas, hyalinae, massa grumoso-
submucilaginosa infarcta?, utriculos irnplentes.

"H. mirabilis. — Fills inequalibus viridibus brevibus, septis
seini-pellucidis ; sporis e capsulis emissis ad fascicules con-
junctis ; utriculis cylindricis diametro dupli-triplo longioribus,
hinc inde ad globules tumescentibus, qui, secreti ab aliis
utriculis, ut animalcula infusoria, se movent et, rumpentes
eorum raembrana, sporas emittunt."

For the following translation of Meyen's remarks upon
the above species I am indebted to Mr. Kippist, to whom I
may take this opportunity of rendering my best thanks for
the kindness and readiness with which that gentleman has
always undertaken whatever could facilitate the progress of
this work : —

" This plant is found in a water-tank of one of the warmest
houses of the botanic garden at Bonn. I first observed it
in the beginning of January of the present year (1827). It
was at that time already in fruit, and during a period of
three and a half months, during which I have observed it, it
has continued quite in the same condition in which I at first
found it.

" It is a constant character of this Conferva, that the fruit
capsule appears at that end of the filament by which it is at-
tached to the side wall of the water-tank, and from the great
mass of spores scattered by the capsule, all the Confervas
which spring up at the same spot grow together into such a
heap that their basis appears of an almost uniform black,
from which the Confervas project in a radiating manner. I
have not yet succeeded in determining whether the threads
have first attached themselves to the wall of the tank, after
the formation of the capsule, or whether the last joint, by
which they, as it were, take root on the wall, may have
gradually assumed the form of a pear-shaped capsule, with
an extended neck. Even if in this latter case the explanation
of the structure of the capsule should present further diffi-
culties, I might still be able to explain them. I have but
very seldom been able to observe the streaming out from the

CYSTOSPEKME^E. 189

capsule of the masses of spores, which were surrounded by
a bright green granular mucilaginous mass, and thus were
held together in a ball. I have never been able to observe
in the interior of this mass any peculiar motion of the
spores, yet I have seen that during the discharge (Ausstro-
men) several seeds separated themselves from the principal
mass, and then exhibited a high degree of voluntary motion,
which often lasted a long time, and which still belonged to
them when they had distinctly increased in length, appa-
rently in order to produce new individuals : this occurrence I
have not actually been able to observe in this species, but I
hope that during this summer it will not escape me.

" The above-mentioned capsule is exhibited in very different
forms in the accompanying tables; it ordinarily presents a pear-
shaped figure, with a more or less elongated neck, which fre-
quently expands into the form of a funnel ; the breadth of the
capsule is greater at the base than that of the next joint. The
gradual developement of this organ, which I have not been able
to observe here, will be given with the following species. It
is however to be observed that the capsule, after the discharge
of the spores, separates from the filament, and then presents
the form which is to be seen in figures 8 and 9.

" The filaments are dissimilar, and, with advancing age,
the dissimilarity increases, so that, at length, the elliptical
form of an utriculus passes into a perfectly spherical one.
I had the good fortune to observe how such a spherical
utriculus separated itself, under my eyes, from the other
tubes ( Schlducheri), and, existing only for itself, moved, I
might almost say voluntarily, with incredible swiftness in all
directions. Figure 11. a and b show these detached spherical
utriculi ; and, whilst observing them , I succeeded, by blowing
on the object-bearer, in hastening this separation, and then
observed the free motion of the separated tube. With regard
to the structure of this organ, it is to be observed, that it is
usually as simple as that of the ordinary utriculus, whilst the
spherical cell is closely filled with masses of spores. In one
part, however, of the circumference of the sphere may be seen,
upon close examination, a transparent portion, like an affixed

1 90 CYSTOSPERME.E.

larger section of a smaller sphere, which, during motion, is
always directed forwards, while the entire sphere continually
revolves on its longer axis, and this with a wonderful rapidity.
At length I observed the fine skin of the organ to burst, and
with the discharge of the motionless spores, followed the death
of the animal life (der Tod des animalischen Lebens) of this
organ, and the plant appeared. It must also be observed,
that the mass of spores, which is discharged from this sphere,
is much more highly developed than that which escapes from
the capsule, since in the former they are little more than
vesicles, and scarcely present any thing of the grumous shiny
mass, which in the latter is very evident.

" In figs. 12. and 13. are displayed similar organs of irre-
gular form, whose origin it is very difficult to explain. If I
had not observed the springing up of this organ, as well as
its propagation (Fortpflanzung\ of which I shall speak here-
after, one might suppose it to represent the seeds, which here
appear to be a little more extended, and seated on the parent
plant, to be about to shoot out into young Conferva. This
idea is, however, entirely false, since such a mode of growth
occurs only in the inarticulate Conferva, and therefore in
Vaucheria. In conclusion, I must be allowed to assert that
this species has hitherto never been observed, since the dark-
green colour, the shortness of the filaments, and their lying
one upon another, are very striking characters ; yet we no-
where find them given." — Meyen, Kritische Beitrage zum
Studium der Susswasser-Algen Flora, No. 45., December,
1827.

Meyen's second example, H. polymorpha, seems to include
more than one species belonging to different genera.

The genus Hempelia is false both in fact and philosophy.
The capsule, upon which Meyen lays so much stress, is
nothing more than the first developed cell of the Conferva, or
transformed zoospore, and has nothing whatever to do with
the reproduction of the species. To imagine that it has, is
in the highest degree unphilosophical, for it is to attribute
that function, which is indicative of the perfection of the life
of an organic being, and which is the last for it to assume, to

CYSTOSPERMEJE. 191

the part of the plant first formed ; it is to invert in fact the
natural order of things

In the third volume of the "Memoires du Museum," 1817,
there is a paper by M. Leon le Clerk, on the genus Pro-
lifera. In this paper Vaucher's error in reference to growth
of the species by shoots is pointed out, and the formation
of circular bodies or sporangia noticed. M. Leon le Clerk was
not satisfied, however, that these bodies were formed by the
union of the endochrome of two cells, as they doubtless usually
are. " But it will be asked," he remarks, " what cause
determines the formation of the green matter into the globule
which we have described. To this question we frankly avow
our ignorance. We can only give the assurance that this for-
mation takes place without any kind of union with another
filament, as we had at first suspected from analogy to the
Conjugates. Perhaps, pre-occupied by the same analogy, one
might be led to suppose that two neighbouring divisions of
the same filament united their green matter to form the re-
productive globule. This supposition vanishes however upon
the slightest examination. The two divisions indeed bor-
dering on that which contains the grain present often the
green matter in its integrity, and if there be need for a fact
still more decisive, it has occurred to us often to meet with
not only two contiguous inflated cells, but three or four adjacent
cells all equally in fructification."

These two facts, mentioned by M. Leon le Clerk, do not
at all disprove the general rule, that the globules or sporangia
are formed by the union and condensation of the endochrome
of two cells. The correctness of the first statement is verv
questionable; it has never occurred to me to notice endo-
chrome in the cells on both sides of the sporangium, and I
am certain that where this body is perfectly formed the
greater portion of the green matter of the cells on one side or
other of it will invariably be found to have quitted that cell.

With regard to the second particular, viz. the occurrence
of more than one sporangium in contiguous cells, this I think
can scarcely be regarded as an exception to the rule, at least
it admits of explanation. The occurrence of two contiguous

1 92 CYSTOSPERME-ffi.

inflated cells occupied with sporangia or globules, is quite
consistent with the idea of these bodies being formed by the
contents of two cells, since each may be in contact on either
side with an inflated cell. In the very rare instances in which
three or four contiguous cells occur, I have never noticed
a perfect globule in each of these, and even if such ever exist,
each globule yet might be formed not indeed of the entire
contents of two cells, but still of a portion of the green matter
of two.

M. Leon le Clerk thus defines the genus Prolifera.
" Filamentis loculatis simplicibus, materia viridi granulis
fulgidis aspersa totaliter repletis. Singulo loculo, fructifica-
tionis tempore, propriis viribus in globulam suam efformante.
Isto globulo intense viridi ex loculo demisso novam plantam
emittente."

This definition of M. Leon le Clerk is exceedingly faulty.
It is not in each cell that the round globule is formed, but only
in occasional cells, or at most in alternate cells; and the asser-
tion that this globule really gives origin to a new plant, is
by no means established. Even M. J. Decaisne, who has
separated the Conjugates from the Algce zoosporce of Agardh,
does not state that he has witnessed their developement, but
infers this from the fact that the filaments of the Conjugates,
whether young or old, in the same species, invariably present
the same diameter, and thus, as he supposed, could not pro-
ceed from organs so minute as the zoospores.

M. Decaisne combats the idea of the disintegration of the
sporangia of the Conjugates and Vesiculifera into zoospores, by
the fact that their contents are at all times fluid. This argu-
ment is, however, by no means conclusive, the contents of
the cells of the Vesicutiferce, &c., are also generally fluid ; but
this fluid, when the proper period arrives, becomes fashioned
into distinct organs or zoospores, and the same may be the
case with the contents of the spores of the Zygnemata, as
asserted by Agardh.

M. Decaisne also repudiates the idea of a double mode of
reproduction ; the spores he regards as the true and only re-
productive bodies of those Algs which possess them ; but it

CYSTOSPERME^E. 193

is perfectly certain the usual and most frequent method of
reproduction of the Vesiculifera is by means of zoospores, and
this fact, of which I have so perfectly assured myself, leads
to adoption of one of the following views — either that the
large, oval, or spherical bodies of the Algce, comprised in M.
Decaisne's class of zoospores, are not in any way connected
with reproduction ; a view which can scarcely be regarded as
probable, and opposed to that entertained by M. Decaisne
himself; or that they as well as the zoospores do perpetuate
the species ; in favour of which view the evidence can scarcely
be pronounced sufficient to remove all doubt of its correctness.

Link has endeavoured to establish this genus under the
name of CEdogonium, which has been adopted by Kiitzing,
who thus imperfectly characterises it.

" Trichoma simplex, membranaceum, flaccidum. Cellulae
crelogonimicae, gonidia minutissima mobilia continentes. Sper-
matia solitaria globosa fusca, epispermo duplici hyalino cincta,
cellulis inclusa."

In this description no allusion is made to the mode of
formation of the sporangia, and none to the ringed apparatus
with which each fruit-bearing cell is provided.

Several other generic terms have been applied to certain
species of the genus Vesiculifera, such as Tiresias, Cadmus,
Zoocarpa *, &c. but all of them, so far as I can learn, are

* Respecting the genera CEdogonium, Tiresias, and Zoocarpa, I have
obtained the following information : — In the " Dictionnaire Classique,"
vol. xii. p. 78., Bory thus remarks on the genus CEdogonium. " The genus
proposed by Link under this name appears to be the same as that which
Vaucher named Prolifera, for which we have adopted the name of
VaucJieria. In the remarks on Vaucheria, Bory states that it was wrong
of De Candolle to change the name of Ectosperma, which he proposes to
restore, and to confer the name of Vaucher on the genus Prolifera, that
appellation being founded in error : and Guilleman in the 16th volume,
p. 268., of the same work, under the head of Tiresias, observes — ' Our
co-labourer, Bory de St. Vincent, has established and described a new
genus of the family of Arthrodece and of the tribe of Zoocarpece, in which
he indicates as the principal species the Conferva bipartita of Dillwyn
(a Tyndaridea ?). The characters of this genus have been explained in
this Dictionary, vol. i. p. 597 — 1822.' Since that time the genus has been
adopted by Fries, who has placed it amongst his Hydrophytes or Algae ;

O

194 CYSTOSPEKME.E.

founded upon a partial, imperfect, and often inaccurate know-
ledge, and therefore not admissible. If any of the older
terms should be retained for the genus Vesiculifera, it should
be by right of priority, — Conferva, for this genus hitherto
has been made to embrace various species of Vesiculifera, as
well as certainly a heterogeneous mass of other productions ;
but it seems to me that this genus ought to be abolished
altogether, and that the term Conferva should be used in a
more extended sense, and applied generally to any species of
the confervoid Alace, in the same manner as the word zoo-
phyte is now used. Kiitzing, in his " Phycologia Generalis,"
confines the genus Conferva to certain species of Sphceroplea,
and to the marine species of Conferva, with simple filaments,
such as Conf. cerea and its allies. Next to Conferva, Prolifera

and who observes that the Zoocarpea of Nees of Esenbeck, " Nov. Act.
Nat. Cur." an. 1813, p. 517., is the same genus. The same author
thinks that the greater part of the Prolifera of Vaucher, also the CEdo-
gonium of Link, ought to constitute part of the genus Tiresias. Of
Tiresias, Bory gives the following description : ' Filaments cylindrical,
the interior tube filled with green colouring matter, in which are de-
veloped hyaline corpuscles which separate from the filaments. This
colouring matter ends by becoming agglomerated in each cell into a
sphere or zoocarpe, of appearance similar to the gemma? of the Con-
jugate, and inert up to the moment when rupturing the cell by its
developement, and, putting itself in contact with the surrounding fluid,
it commences to move itself in different directions, and finishes,by swim-
ming freely about, leaving all broken and transparent as water the tube
which produced it.' The Conferva bipartite of Dillwyn is certainly a
species of Tiresias, in the vegetable condition of which the Cercaria
podura and viridis of Miiller are the Zoocarpes, which we have seen
after a certain period of liberty fix themselves by their divided extremities
upon the remains of vegetables, or even upon the filaments of other
Tiresias, and elongate themselves into a confervoid vegetable. This
state of elongation has been well seen and figured by Le Clerc, in his
excellent memoir on the Prolifera of Vaucher, as well as by Dillwyn
upon his Conferva genuflexa. It is surprising that these skilful naturalists
had not detected the metamorphoses of the Enchalis into that which they
call Conferva."

Both Bory and M. Leon le Clerc are in error in supposing that they
had witnessed the developement of the large oval or spherical bodies
formed by the concentration of the endochrome of two cells : what the
latter represents are undoubtedly the zoospores in different stages of
growth.

VESICULIFERA. 195

has the greatest claim to be retained : a name, however,
founded in error.

16. VESICULIFERA.

Char. Same as those of the family.
Derivation. From Vesicula, a vesicle, an&fero, to bear.

1. VESICULIFERA PRINCEPS Hass.

Char. Filaments of the same diameter as those of V. capil-
laris. Cells about once and a half as long as broad.
Sporangia circular, producing but a very slight inflation of
the fructiferous cell.

Isogonium capillare Kiitz. Phyc. Gener. 255. V. princeps

Hassall, in Annals, vol. x. p. 388.
Hob. Cheshunt: A.H.H.

This species I described in the Annals of Natural History,
vol. x. p. 388., under the name of V. princeps ; but not meeting
with it a second time, and fearing that it was not really dis-
tinct, I referred it to V. capillaris. I am now, however,
induced again to regard it as a distinct species, from the cir-
cumstance of its being described as such by Kutzing under
the name of Isogonium capillare, a subgeneric appellation, be-
stowed upon it on account of the sporangia not producing any
considerable inflation of the fruit-bearing cells, — a circum-
stance which scarcely called for such a distinction. The
figure given by Kiitzing accords closely with one made by
myself of the species long ago, and which I regret I have not
here introduced. The non or slight inflation of the cells will
distinguish it from all other described species.

2. VESICULIFERA CAPILLARIS Hass.
Plate L. Figs. 1, 2.

Char. Filaments of considerable diameter. Cells varying in
length from nearly twice to almost four times their dia-
meter. Sporangia large, circular, contained in distinct
inflations of the cells of an evidently ovate form.
o 2

196 CYSTOSPERME^.

Vesiculifera capillaris Linnasus? Hassall, in Annals of
Nat. Hist., vol. x. p. 389. V. princeps Hassall, in
loc. cit. Prolifera composita Vaucher, Hist, des Conf.,
p. 133. pi. 14. fig. 5.

Hob. Ponds near Netting Hill ; Cheshunt, and its
vicinity : A. H. H.

Whether the Vesiculifera, which is here regarded as the
Conferva capillaris of Linnaeus, be that species or not, there
can be no question but that it is the same plant as that con-
sidered as such by Agardh, as I have been able to ascertain
by the examination of an authentic specimen of Agardh's
C. capillaris var. B. alternata, contained in the Herbarium
of Dr. Greville. None of those who have noticed this
species were at all acquainted, however, with the true re-
production.

3. VESICULIFEBA CONDENSATA Hass.

Char. Filaments of more considerable diameter than those

of V. capillaris. Cells not so long as broad.
Vesiculifera condensata Hassall, in Annals of Nat. Hist.,
vol. x. p. 388.

Not having again met with this species since it was de-
scribed in the Annals, and never having seen it in a state of
reproduction, I am led to think that possibly it may be but
a variety of C. capillaris ; than which, however, the filaments
are thicker, and the cells much shorter. It was found ad-
herent to a wall reached by the tide in the Thames near
Barnes.

4. VESICULIFERA CRASSA Hass.
Plate LI. Fig. 1.

Char. Filaments fully equal in diameter to those of V. capil-
laris. Cells usually five times as long as broad. Spo-
rangia oval, generally solitary, but sometimes binary, con-
tained in cells of a slightly oval form, the length of which
about twice exceeds the diameter.

VESICULIFEKA. 197

Vesiculifera crassa Hassall, in Annals of Nat. Hist., vol. x.
p. 389.

Hab. In a pond at Wood Green, near Bury Green, vicinity
ofCheshunt: A.H.H.

The only species near to which this approaches is V.
Landsboroughi ; than which the filaments are much thicker
and the inflated cells shorter and less marked.

Having met with it now several times, I have not a doubt
of its being distinct from V. Landsboroughi.

5. VESICULIFEKA LANDSBOROUGHI Hass.
Plate LI. Fig. 2.

Char. Filaments of considerable diameter, but scarcely so
large as those of the preceding species. Cells at the period
of fructification, about Jive or six times as long as broad.
Sporangia oval, contained in inflated cells of an elongated
but not regularly oval form, these occurring usually singly
at intervals of three or four cells, but sometimes two are
juxta-posed.

Vesiculifera Landsboroughi Hassall, in Annals of Nat. Hist.,
vol. x. p. 389. Prolifera rivularis M. Leon le Clerc,
Mem. du Mus. t. 25.

Hab. Vicinity of Cheshunt, very rare : A. H. H. In an
old coal-pit near Stevenston, Ayrshire : Rev. D. Lands-
borough. Penzance : Mr. Ralfs.

I have much pleasure in dedicating this, one of the finest
species of the genus, to the Rev. David Landsborough, by
whom the merit of its discovery is shared equally with myself,
as an expression of my warm admiration of the zeal displayed
by that gentleman in the cause of natural science.

I have met with this species but sparingly myself, but have
received excellent specimens of it in a state of reproduction
from Mr. Landsborough, who aptly compares the form of
the seed-bearing cells to that of the " soldering of lead
pipes."

o 3

198 CYSTOSPERME^:.

6. VESICULIFEBA CUVIERI Hass.

Char. Filaments more slender than those of the preceding
species. Cells usually seven times as long as broad. Spo-
rangia oval, contained in inflated cells of an ovate form.

Vesiculifera prolongata Hassall, in Annals of Nat. Hist.,
x. 390. Prolifera. Cuvieri Le Clerc, Mem. du Mus.

Hob. Pond near Louton, Essex, and again near Enfield :
A. H. H.

This species is known from V. Landsboroughi by its finer
filaments, longer cells, and ovate form of the seed-bearing in-
flated cells.

" The inflations of Prolifera rivularis present an oval, whose
great diameter is never double the small. In the Prolifera
Cuvieri this enlargement is so much allongated that one
might distinguish it almost as well by the intensity of its colour
as by its size. In its state of greatest contraction its great
diameter is triple or quadruple that of the small. The same
proportion, but a little less marked, is observed between the
grains of the two Conferva."

7. VESICULIFERA LACUSTRIS Hass.
Plate LII. Fig 1.

Char. Filanlents nearly equal in diameter to those of V.
Cuvieri. Colls from three to five times as long as broad.
Sporangium oval, sometimes almost quadrangular, solitary,
occasioning no very considerable enlargement of the cell
in which it lies ; empty cell next the spore also inflated.

Vesiculifera lacustris Hassall, in Annals of Nat. Hist.,
vol. x. p.390.

Hob. In the New River reservoir, near Cheshunt, spar-
ingly, and other places in the vicinity : A. H. H.

V. lacustris differs from V. Borissii principally in being al-
together a more robust species, and in having shorter cells.

VESICULIFERA, 199

8. VESICULIFERA PALUDOSA Hass.
Plate LII. Fig. 3.

Char. Filaments of less considerable diameter than those of
V. lacustris. Cells usually three times as long as broad.
Sporangia oval, contained in inflated cells of the same
form.

Vesiculifera paludina f Hassall, in Annals of Nat. Hist.,

vol. x. p. 390.

Hab. Cheshunt : A. H. H. Framfield Common : Mr.
Jenner.

This species comes nearest to V. ciliata ; but the inflated
cells are of a different form. I know not whether this be the
species, described by me in the " Annals " as Vesiculifera
paludina, or whether that species be different from V. capillaris,
not having had opportunities of making any comparative ex-
amination of them.

9. VESICULIFERA PULCHELLA Hass.
Plate L. Fig. 3.

Char. Filaments of considerable diameter. Cells usually two
and a half or three times as long as broad. Sporangia
circular, contained in much iriflated cells, which are at first
oval, then circular, and lastly somewhat hexagonal.

Hab. Cheshunt ; Netting Hill : A. H. H.

This is a very fine species, seeking usually rather pure
water ; it is of an intense and beautiful green colour.

10. VESICULIFERA RALFSII Hass.
Plate L. Fig. 8.

Char. Filaments usually rather smaller than those of V. pul-
chella. Cells varying in length from twice to four times
their diameter. Sporangia circular, lodged in cells of an
hexagonal form.

o 4

200 CYSTOSPERME^E.

Vesiculifera pulchella var. Hassall, in Annals of Nat. Hist.,
vol. x. p. 390.

Hob. Cheshunt and its vicinity, especially Cheshunt Com-
mon : A. H. H. Penzance : Mr. Ralfs.

Subsequent examination has confirmed the suspicion ori-
ginally entertained that this species, which was first sent me
by Mr. Hull'-, was distinct from V. pulchella : the inflated
cells are smaller and more hexagonal than they are in that
species.

11. VESICULIFERA VAUCHERII Hass.
Plate L. Fig. 4.

Char. Filaments about equal to those of V. pulchella. Cells
usually two and a half or three times as long as broad.
Sporangia circular, lodged in cells which are very consider-
ably inflated and of an ovate form.

V. ventricosum Hassall MSS. Prolifera Vaucherii 9 M.

Leon le Clerc, loc. cit
Hob. Cheshunt: A. H. H.

This is a very distinct species, differing from V. virescens
in its circular sporangia, and highly inflated cells, and from
V. pulchella in the ovate form of the inflations, which in
the latter species are slightly hexagonal.

12. VESICULIFERA VIRESCENS Hass.
Pkte L. Fig. 5.

Char. Filaments equalling in diameter those of V. pulchella.
Cells once and a half or twice as long as broad, fasciated.
Sporangia ovate, contained in cells of the same form.

Vesiculifera virescens Hassall, in Annals of Nat. Hist.,
vol. x. p. 391.

Hob. Notting Hill, near London : A. H. H.

This species comes very near to the following, of which
possibly it may be but a variety.

VESICULIFERA. 201

13. VESICULIPEEA OVATA Hass.
Plate L. Fig. 6.

Char. Filaments about equal to those of V. virescens. Cells
three or four times as long as broad. Sporangia ovate,
occasionally circular, contained in inflated cells of an
ovate form.

Vesiculifera ovata Hassall, in Annals of Nat. Hist., vol. x.
p. 392.

Hob. Cheshunt : A. H. H. Turner's Hill and Heath-
field : Mr. Jenner.

This at all events is a very distinct species, if the preceding
one be not equally so.

14. VESICULirEKA CONCATENATA HttSS.

Plate LI. Fig. 3.

Char. Filaments thicker than those of V. ovata. Cells six
times as long as broad. Sporangium ovate ; cell next
the sporangium inflated.

Vesiculifera concatenata ? Hassall, in Annals of Nat. Hist.,
vol. x. p. 392.

Hob. Cheshunt Common and pond near Highgate:
A. H. H. In a pool between Hook Green and Lam-
berhurst, and at Peasmarsh and Henfield : Mr. Jenner.

Sometimes two or three sporangia occur contiguously to
each other. I am not quite sure that this is the species de-
scribed in the Annals by me as Vesiculifera concatenata,
but believe it to be so. There is not a more distinct species
in the genus.

15. VESICULIFERA BORISSII Hass.

Plate LII. Fig. 7.
Char. Filaments of nearly the same diameter as those of

202 CYSTOSPERME.E.

V. ovata. Cells from four to seven times as long as
broad. Sporangia oval, frequently of a golden colour,
usually solitary, but sometimes binary ; cells next the spo-
rangia inflated.

Prolifera Borissii M. Leon le Clerc, Mem. du Museum,
pi. 25. fig. 6. Vesiculifera aurea Hassall, in Annals of
Nat. Hist, vol. x. p. 392.

Hob. Wood Green, near Bury Green, vicinity of Ches-
hunt : A. H. H.

This is a very distinct species, as also a very beautiful ob-
ject under the microscope. There can be no doubt about the
synonyme of M. Leon le Clerc.

16. VESICULIFERA CILIATA Hass.
Plate LII. Fig. 2.

Char. Filaments smaller than those of V. pulchella, termi-
nated by long colourless cilia. Cells about three times as
long as broad. Sporangia oval, lodged in cells of the same
form.
Hal. Cheshunt: A. H. H.

The presence of cilia on the extremities of the filaments
renders this a very remarkable species, and one by which it
may be readily recognized. There is an evident analogy
between the genera Vesiculifera and Bulbocho2te, and through
V. ciliata there would appear to be an easy transition from
the one to the other.

17* VESICULIFERA DISSILIENS Hass.
Plate L. Fig. 7.

Char. Filaments of considerable diameter. Cells scarcely so
long as broad. Sporangia circular, contained in inflated
cells of the same form, and which are usually solitary.

Vesiculifera dissiliens Lyngb. et Ag.

VESICUL1FEKA. 203

Hob. Cheshunt : A. H. H. Turf Dyke, near Ardrossan,
Ayrshire : Major Martin.

The above is a very beautiful species under the microscope :
it is to be distinguished from all others by the shortness of its
cells. In the Herbarium of Dr. Greville I find a specimen of
this species, not indeed in a state of reproduction, put up by
M. Chauvin, and marked with doubt as Conferva dissiliens
Lyngb. It is certainly not the Conferva dissiliens, either of
Dillwyn's work, or of " English Botany," that of the latter
work being probably identical with Desmidium mucosum.

18. VESICULIFERA CAKDIACA Hass.
Plate LI. Fig. 4.

Char. Filaments of much less diameter than those of V. pul-
chella. Cells Jive or six times as long as broad. Sporangia
circular, placed in much inflated cells, which may be com-
pared to a heart inform.

Vesiculifera cardiaca Hassall, in Annals of Nat. Hist.,
vol. x. p. 391.

Hob. Pond near Netting Hill : A. H. H. In a pool
between Hook Green and Lamberhurst : Mr. Jenner.

This species would appear to be an uncommon one, for I
have only twice met with it.

19. VESICULIFERA CRISPA Hass.
Plate LII. Fig. 8.

Char. Filaments much more slender than those of V. ventri-
cosum. Cells usually three times as long as broad.
Sporangia circular, lodged in cells of an ovate form.

Vesiculifera crispa Hassall, MSS.

Hob. Cheshunt and vicinity : A. H. H. Between Wad-
hurst and Ticehurst, and between Ramslye Rocks and
Broadwater Forest : Mr. Jenner. Cannon Hill Quarry,
near Ardrossan, Ayrshire : Major Martin.

204 CYSTOSPERME^.

This is certainly a very distinct species, and one moreover
by on means uncommon.

20. VESICULIFEEA FASCIATA Hass.

Plate LIII. Fig. 6.

Char. Filaments of diameter about equal to that of V. crispa.
Cells usually three times as long as broad. Sporangia
circular, contained in cells of the same form.

Vesiculifera fasciata Hassall, in Annals of Nat. Hist., vol. x.
p. 392.

Hob. In a pond on Nazing Common, Essex : A. H. H.

This species differs from the preceding only in the shape of
the seed-bearing cells, which in V. crispa are somewhat ovate,
while in V. fasciata they are quite circular. It is possible
therefore that it is but a variety of V. crispa.

21. VESICULIFERA SPELZERICA Hass.

Plate LIII. Fig. 5.

Char. Filaments about equal to those of V. fasciata. Cells
usually once and a half or twice as long as broad.
Sporangia spherical, contained in enlarged cells of the
same form.

Vesiculifera sphcerica Hassall, in Annals of Nat. Hist.,

vol. x. p. 392.
Hal. Vicinity of Cheshunt : A. H. H.

This species differs only from the preceding in having
much shorter cells. I believe it to be distinct, however.

22. VESICULIFERA COMPRESSA Hass.
Plate LIII. Fig. 4.

Char. Filaments about equal to those of V. fasciata. Cells
twice or thrice as long as broad. Sporangia contained in
cells of a compressed ellipsoidal form.

VESICULIFERA. 205

Vesiculifera compressa Hassall, in Annals of Nat. Hist.,

vol. x. p. 393.
Hab. In a pond in Yorke's Brickfield, near Cheshunt :

A. H. H.

The inflations in this species resemble in form the knobs
of dumb-bells.

23. VESICULIFERA IN^QUALIS.
Plate LIII. Fig. 2.

Char. Filaments in a state of reproduction of very unequal
diameter. Cells varying in length, being sometimes four
or Jive times as long as broad, at others only three times ;
these variations occurring usually on different parts of the
same filament. Sporangia circular, lodged in cells which
present an hexagonal appearance, empty cell next the spore
larger than the rest.

Hab. Cheshunt : A. H. H. Rusthall Common and Bur-
wash : Mr. Jenner.

This appears to me to be a very distinct species ; it is sub-
ject, however, to considerable variation. It, as well as the
following, is very common, and both were procured by Mr.
Jenner, Mr. Ralfs and myself within a very short time of
each other.

24. VESICULIFERA ^QUALIS Hass.
Plate LIII. Fig. 3.

Char. Filaments of smaller calibre than those of the preced-
ing species, of equal diameter. Cells about six times as long
as broad. Sporangia circular, lodged in cells which are
broader than long.

Hab. Cheshunt : A. H. H. Kusthall Common and Del-
monden ; Hawkhurst : Mr. Jenner.

This as well as the preceding species is found in boggy
pools which retain the water for a long time.

206 CYSTOSPEEMEvE.

25. VESICULIFEKA FLAVESCENS Hass.
Plate LIIL Fig. 9.

Char. Filaments about equal in size to those of V. crispa.
Cells four or Jive times as long as broad. Sporangia cir-
cular, lodged in cells of the same form.

Hob. Penzance : Mr. Rolfs.

This species I have only received from Mr. Ralfs and Mr.
Jenner.

26. VESICULIFEBA AFFINIS Hass.
Plate LIIL Fig. 1.

Char. Filaments about equal in size to those of V. vernalis.
Cells./?ye or six times as long as broad. Sporangia cir-
cular, lodged in cells which are slightly ovate and protube-
rant at the sides.
Hab. Cheshunt : A. H. H.

Not an uncommon species, perhaps, but a variety of V.
vernalis.

27. VESICULIFERA IIEXAGONA Hass.
Plate LIIL Figs. 11, 12.

Char. Filaments somewhat stouter than those of V. aqualis.
Cells three or four times as long as broad. Sporangia cir-
cular, contained in inflated cells of an hexagonal form.

Hab. Cheshunt: A. H. H.

This is a very distinct little species, and not uncommon :
a variety occurs with filaments considerably finer. This may
also be distinct.

28. VESICULIFERA DUBIA Hass.

Plate LIIL Fig. 14.
Char. Filaments of the same size as those of V. hexagona,

VESICULIFERA. 207

uninflated. Cells usually Jive times as long as broad.
Sporangia circular, lodged in inflated cells of a somewhat
hexagonal form, but much larger than those of V. hexa-
gona.

Hob. Penzance: Mr. Ralfs.

This species approaches rather closely to V. hexagona, from
which, however, I think that it is distinct.

29. VESICULIFEEA MULLERI Hass.
Plate LIIL Fig. 10.

Char. Filaments more slender than those of V. fasciata. Cells
fully four times as long as broad. Sporangia spherical,
contained in inflated cells of a regularly globular form.

Vesiculifera Mulleri Hassall, in Annals and Mag. of Nat.
Hist., vol. x. p. 393.

Hob. Cheshunt : A. H. H. Rusthall Common and
Hawkhurst : Mr. Jenner.

This species is by no means common ; I have never met
with it but once.

30. VESICULIFERA Boscn Hass.
Plate LII. Figs. 3, 4, 5.

Char. Filaments slender. Cells about six times as long as
broad. Sporangia oval, contained in greatly enlarged cells
of the same form.

Prolifera Boscii M. Leon le Clerc, loc. cit. t. 25. f. 5. V.
elegans Hass., Annals, vol. x. Conf. tumidula, Eng.
Bot. 1670.

Hob. Henfield: Mr. Borrer. Rusthall Common: Mr.
Jenner.

There is not a more distinct or prettier species than this
in the genus.

I do not know whether figs. 4, 5. pi. 52. are to be regarded
as varieties of this or distinct species.

208 CYSTOSPERME^E.

31. VESICULIFEEA ALATA Hass.
Plate LIIL Fig. 8.

Char. Filaments scarcely exceeding those of V. Rothii in size.
Uninflated cells about six times as long as broad. Spo-
rangia oval, having their long diameter placed in the axis
of the diameter of the inflated cells, such bearing cells very
protuberant laterally.

Hab. Penzance: Mr. Ralfs.

This is one of the most remarkable species of the genus,
and the only specimens which I have seen of it are those
transmitted to me by Mr. Hull's.

32. VESICULIFERA ROTHII Hass.
Plate LIU. Fig. 7.

Char. Filaments rather more slender than those of the pre-
ceding species. Cells fully four times as long as broad.
Sporangia rather broader than long, contained in inflated
cells of the same form.

V. bombycina Hassall, in Annals of Nat. Hist., vol. x.
p. 394. Conf. bombycina Ag. Harv. Manual, p. 126.
Prolifera Rothii M. Leon le Clerc, Mem. du Mus.

Hab. Everywhere common.

Three or four cells sometimes occur in juxtaposition.

33. VESICULIFERA CANDOLLII Hass.
Plate LII. Fig 9.

Char. Filaments of about the same diameter as those of V.
crispa. Cells usually six times as long as broad. Sporangia
circular, contained in inflated cells which are somewhat
narrower at one extremity than the other.
V. vernalis Hassall, in Annals of Nat. Hist., vol. xi. p. 434.
Prolifera Candolli M. Leon le Clerc, Mem. du Museum,
t. 25. fig. 7.

BULBOCH^ETE. 209

Hob. Waltham Abbey and High Beech, Epping : A. H. H.
Rusthall Common : Mr. Jenner.

This is a distinct as well as common species. I have but
little doubt of the correctness of the synonym.

17. BULBOCHJETE Ag.

Char. Filaments attached, of equal diameter, branched. Cells
truncate, setigerous, the seta being rigid, elongated, and
bulbous at their bases. Reproductive bodies situated
either in inflated cells, when they are formed by the union
of the contents of two contiguous cells, or in the bulbous
portions of the setee, which become much enlarged for their
accommodation.

Derivation. From (3o\&os, a bulb, and %atT^, a bristle.

The reproduction of this remarkable genus has, until very
recently, been wholly unknown. M. Decaisne, in his Memoir
on the Classification of the Algas, contained in the numbers
of the " Ann. des Sciences Nat." for May and June 1842,
alludes to the mode of formation of the reproductive bodies
by the union of the matter of two cells in the same filament,
but does not appear to have noticed the second way in which
they are formed, viz. within the bulbous portion of the seta.
The observations of M. Decaisne and my own remarks appear
to have been made nearly at the same period.

" In the above account of the reproduction of the genus
Bulbochcete I have avoided using the term spore to designate
the condensed endochrome in the inflated cells, which presents
so much the appearance of a true spore ; for I conceive that it
is most probable that this separates, as in the other branched
species of Confervas, into numerous small reproductive gra-
nules.

" The genus Bulbochcete may be regarded as forming the
connecting link between the simple and branched freshwater
Conferva ; it agreeing with the Conjugates in the equality of
its filaments, with the Cystospermece in the union of the con-
tents of two distinct cells, and probably with the branched

210 CYSTOSrEUME^E.

species in the separation of the condensed endochrome in
the inflated cells into numerous reproductive vesicles."*

1. BULBOCH^TE SETIGERA Aff.

Plate LIV. Figs. 1, 2, 3, 4.

Char. Filaments dichotomousty branched, tufted. Cells
usually Jive times as long as broad.

B. setigera Harvey, in Hooker's Brit. Flor. ii. p. 350. ;
also in Manual, p. 121. Cow/1 vivipara Dillw. t. 59. ;
Hassall, in Annals, xi. p. 362.

Hob. Common in boggy pools.

Bulboch&te setigera has by most systematists been placed
in the same family of Alaee with Chcetophora and Drapar-
naldia, the presence of cilia on the filaments having been
the chief inducement so to do. It is certainly to be re-
garded as the connecting link between the branched and
simple freshwater Alga ; but it exhibits a closer relation to
Vesiculifera than to any genus of branched Conferva, it
agreeing with it in the mode of formation of the spores,
and in its rigid habit. The next genus to which it appears
closely allied is Cladophora, of which Cow/1 glomerata, C.
fracta, &c. are examples. This genus has the same rigid
character, though in a less degree, as Bulbochcete and Vesi-
culifera. In a natural arrangement, these genera should
follow each other somewhat in the following order : — Vesi-
culifera, Bulbochate, Cladophora, and then Coleochfete, Chce-
tophora, Draparnaldia, Sphceroplea, &c.

" On freshwater plants, &c., in lakes and ponds. Tufts a
quarter to half an inch high, forming dense villous tufts.
Filaments irregularly and slightly branched ; the branches
subalternate or dichotomous, either erect or recurved, jointed.
Joints three or four times as long as broad ; swollen up-
wards, from their upper part bearing a long inarticulate deci-
duous bristle, whose base is expanded, and half clasping the

* Hassall, in Annals of Nat. Hist. vol. xi.

BULBOCKLETE. 211

joints ; substance subgelatinous ; when recent, somewhat
horny ; when dry, colour dull greenish brown, fading to grey
in the herbarium. A curious plant of doubtful affinity ;
under the microscope, resembling a Sertularia set with herring
bones." — Harv.

This species is either very variable, or else several species
have been confounded together. I have noticed three varieties
or conditions : —

Var. 1. with cells three times as long as broad.

Var. 2. with cells once or once and a half as long broad.

Var. 3. filaments very small, cells five times as long as
broad.

" Mais la sexieme famille me parait bien plus obscure, et je ne 1'offre
aux naturalistes qu'avec repugnance. Cette reproduction par bourrelets,
toute conforme qu'elle parait aux loix de la nature, me cause toujours
quelque peine quand je 1'annonce. Elle me semble plutot devoir etre
considered comme un moyen surabondant, que comme une forme particu-
liere, qui distingue certaines especes. Et en effet en trouve peu de
plantes qui ne se multiplient de cette maniere, en meme temps qu'elles se
propagent par leur graines. Cependant jusqu'a present, je n'ai jamais
vu les Conferves de cette famille s'accroitre autrement, et d'autre part je
n'ai jamais vu les Conferves des autres families se multiplier de cette
maniere, j'en excepte cependant la Conferva glomerata Linmei, sur les
debris de laquelle j'ai quelquefois rencontre des brins verts, qui etoient de
nouveaux developpements. Je recommande done les prolif eres en parti-
culier aux observations des botanistes, pour qu'ils y cherchent des organea
sexuels, et qu'ils tachent de reconnoitre si, independamment des bour-
relets, elles renferment des graines. La Conferva rivularis est tres com-
mune et tres facile a observer ; les graines brillans dont elle se pourvue
doivent donner quelque souppon, et faire conjecturer que son organis-
ation est plus composee que je ne 1'ai dit. De mon cote, autant que
j'aurai du loisir et de la sante, je ne regarderai pas mon tache comme
achevee ; j'observerai cette famille plus attentivement que je n'ai fait
jusqu'a present. J'en isolerai quelques individus, et j'espere qu'aide des
lumieres que me fournira sans doute la publication de cet ouvrage, je
decouvrirai enfin la reproduction de cette famille, si du moins elle en a
une qui lui soit propre, independamment de ses bourrelets." — Vaitcher.

p 2

212

FAM. X. MONOCYSTE.E.

The reproduction of this family agrees precisely with that
of Chcetophora and Draparnaldia, and perhaps Batrachosper-
mum, which genera it would perhaps have been more natural
that it should have been made to follow.

It consists of three genera of freshwater Alga, Cladophora
Kiitzing (a genus synonymous with my genus Microspora),
Coleochcete, and Lyngbya.

In the species of this family we have no union and inter-
mingling of the contents of two cells, but each cell contains
all the requisites for the perpetuation of the species, viz.
zoospores and the fertilizing vesicles.

When the zoospores have been fertilized, the cells swell
up, the increase in the size of the cells being determined by
the developement of the zoospores, and which developement
proceeds to such an extent as to occasion the rupture of the
membranes of the cells, the zoospores escaping through the
apertures thus formed.

This inflation of the reproductive cells of the branched
Conferva and of the Lyngbya does not appear to have been
noticed by any other observer save Vaucher, and by him only
in the Batrachosperms ; and yet it is of frequent occurrence,
and affords a character whereby species may be often dis-
tinguished from each other, although at the same time it
changes the ordinary appearance of the species so much as to
lead sometimes to the description of specimens so altered as
distinct species ; and this has doubtless been the case with
Conferva fracta of the " Flora Danica," which is C. crispata
in a state of reproduction.

The species of this family are for the most part attached,
and present the double mode of growth described in the In-
troduction, viz. that of longitudinal and lateral developement
of the cells.

CLADOPHORA. 213

Sub-fam. i. CLADOPHOREJE.

18. CLADOPHORA Kutz.

Char. Filaments attached, much branched, not setigerous,

and not invested with secondary cells.
Derivation. From K\a&os, a branch, and <f>opso>, to bear.

This important genus I established in the " Annals of Nat.
Hist." vol. xi. p. 363., under the name of Microspora. Sub-
sequently finding the same genus to have been characterised
by Kiitzing in his " Phycologia Generalis," I have been in-
duced to adopt his generic name, it appearing to be the more
appropriate.

The genus should contain amongst the freshwater Conferva
C. glomerata and C. crispata, and the majority of the marine
branched Conferva. Conf. cerea and its numerous allies
should form another genus, agreeing in its reproduction
closely with Cladophora, but differing from that genus in
the simplicity of its filaments : this genus might be deno-
minated Aplonema.* The filaments when dry are destitute
of gloss, like those of the Cystospermece, and do not adhere
well to paper.

1. CLADOPHORA GLOMERATA.
Plates LVI, LVII. Figs. 1, 2.

Char. Filaments tufted, bushy ; somewhat riff id, bright green,
shining. Branches crowded, irregular, erect ; the ultimate
ramuli secund, subfasciculate. Articulations four to eight
times longer than broad.

C. glomerata Dillw. Conf. t. 13.,' Eng. Bot. t. 2192. ;
Manual, p. 134. Microspora glomerata Hassall, in
Annals, vol. xi. C. Brownii Harv. 1. c. p. 356. ; also
in Manual, p. 134. ; Dillw. Suppl. t. D. C. pulvinata
Brown, MS.; Wyatt, Alg. Dan. No. 225. C. (Bgagro-

* From &ir\oc, simple, and vi^a, a thread
T 3

214 MONOCYSTE^E.

pila, E. Bot. t. 1377. ; Dillw. Conf. t. 87. ; Harv. 1. c.
p. 357. ; also in Manual, p. 134.

Hob. C. glomerata, common in streams and wells. — C.
cegagropila, in lakes, rare. North Wales : Rev. M.
Dames. North of Scotland: Mr. Brodie. Prestwick
Car : Mr. Winch. Culmere Pool and Whitemore,
Shropshire : Rev. E. Williams. Cunnemara : Mr. Mac-
kay. — C. Brownii. On wet rocks, in a cave near Dunree,
North of Ireland : R. Brown, Esq. On shady rocks at
the entrance of a small cave beyond Black Castle,
Wicklow, where it is exposed to the dripping of fresh
water, and occasional overflow of the sea: W. H. Harvey.
Cornwall coast, near the Land's End : Mr. Ralfs.

This beautiful and abundant Conferva delights in pure and
running waters, attaching itself to stones, walls, and piles in
streams, rivers, and cascades, it being drawn out by the cur-
rent often to more than two feet in length. In the mass, it is of
a deep and refreshing green colour, which is occasioned by the
purity of the water in which it lives. Examined separately,
the filaments present a peculiar glistening appearance, rare
amongst freshwater Alga, though common to many marine
species. Not infrequently, the branches are beset with tufts
of ramuli, which, when the plant is floated out in water, give
it somewhat the appearance of a Sertularia, and increase
greatly its beauty. It is in this species that I have seen the
apertures situated on one side of the distal extremity of
the cells designed for the escape of the zoospores. Notwith-
standing that its usual resort is the stream and the waterfall,
it will flourish and increase in size amazingly for weeks and
months in a vessel, the water of which is occasionally re-
newed. I have thus kept it for many weeks, removing, when
by its growth it had filled the vessel, all but a small portion
of it ; this, however, speedily increased, and again filled its
dwelling-place. The tearing away of portions of the plant
in no way unpaired the vitality of the remainder, as from its
aggregation of minute cells, each the analogue of the other,
might a priori have been conjectured.

CLADOPHORA. 215

After the species has been thus confined for some time, if
it be examined with a glass, very many of the filaments
will be found to be invested with numerous smaller fila-
ments. These are the young of the plant derived from the
growth of the zoospores, which have attached themselves to
the parent filaments. It was the occurrence of a specimen
thus infected that induced Vaucher to place this species in
his genus Prolifera.

This species is the favourite resort of Diatoma vulgare,
which attaches itself to it by means of a distinct root-like
organ. The Diatoma frequently developes itself over the
filaments to such an extent as totally to obscure their rich
green colour. A brown no less rich is imparted to it by the
parasite.

The two following plants, old and established as the one of
them at least would appear to be, I regard as conditions of
Cladophora glomerata — viz. C. cegagropila and C. Brownu*
The microscope does not present any essential difference in
the structure of these supposed, though I believe erroneous,
species. The state of Cladophora glomerata (which has received
a distinct name even at the hands of the great Swede himself)
( C. cegagropila Linn.), I believe to be formed as follows : —
a specimen by the force of some mountain stream swollen by
recent rains becomes forced from its attachment ; as it is car-
ried along by the current, it is made to revolve repeatedly
upon itself, until at last a compact ball is formed of it, which
finally becomes deposited in some basin or reservoir in which
the stream loses itself, and in which these balls are usually
found.

The size of these balls varies from two to four inches ; they
are dense, firm, and spongy. Kiitzing has carried his idea
of this species to such an extent as to constitute for its re-
ception a new genus, taking for the generic name the old
specific appellation of cngagropila, and bestowing upon it the
specific name of its renowned discoverer Linnseus — j^Ega-
gropila Linncei. The term cegagropila is derived from its
resemblance to the balls that are found in the stomachs of
goats. The peculiarities of the second condition of C. glo-

p 4

216 MONOCYSTE2E.

merata (C. Srownii) arise from the sub-immersed habitat in
which it grows. Mr. Harvey thus describes C. Brownii : —
" This forms exceedingly dense, very rigid tufts, of a black
green colour when growing, but on having the water
expressed, and being held to the light, exhibits a beautiful
yellow-green tint. Filaments so matted together, that it is
difficult to separate a single thread. They appear to ori-
ginate in a mass of creeping, branched, densely matted fibres,
which form the base of the tufts. They are erect, from half-
an inch to an inch high, flexuous, very rigid and elastic ; the
branches few and nearly simple, almost always secund, very
erect. A very curious and distinct plant, having, to the
naked eye, a good deal the appearance of Vaucheria terrestris,
but totally different in structure. It is perhaps allied to C.
cegagropila. I have examined a specimen from Mr. Brown in
the late Mr. Templeton's herbarium, and find it to agree in
every respect with my Wicklow plant."

2. CLADOPHORA CRISPATA.
Plate LV. Figs. 1, 2.

Char. Filaments very tenacious and of variable diameter,
crisped, and entangled.

C. nigricans Dillw. Conf. Syn. 1. c. ; Harv. 1. c. p. 356.

C. crispata Sm. E. Bot. t. 2350 ; Harv. 1. c. p. 356.

C. Jlavescens Harv. 1. c. p. 356. ; E. Bot. t. 2088. ;

Wyatt, Alg. Darm. No. 224. C. fracta Dillw. Conf.

t. 14. ; E. Bot. t. 2338. ; Harv. 1. c. p. 356. Micro-

spora Hass. in Annals, vol. xi.
Hab. Everywhere common. Var. nigricans in a pond at

Wimbledon, Surrey : Mr. Dickson.

Three British species of Confervas appear all referrible to
this one : these are C. nigricans, C. fracta, and C. Jlavescens.
C. Jlavescens I take to be the young state of C. crispata,
while C. fracta is assuredly the mature or perfect condition
of the plant : it is also equally certain that the C. nigricans
of Dickson is merely a discoloured state of C. crispata.

COLEOCHJETE. 217

The suspicion also may, I think, be entertained, that C.
crispata itself is but a condition of C. glomerata, changed by
the difference of its place of growth — it growing for the
most part in still water, in deep ponds, and lakes. I have
often seen specimens, which it would be impossible to refer
with certainty to either species. A specimen of C. capillaris
in the Linnsean Herbarium, was referrible to this species, or
condition of one.

19. COLEOCEJETE Breb.

Char. " Frond disciform, oppressed, parasitic, formed of ^la-
ments radiating from a centre, generally conjoined. Fila-
ments articulated, dichotomousty branched, sending forth
in all directions from the upper surface of the cells cylin-
drical, truncated, lengthened, setigerous sheaths. Endo-
chrome green." — Breb.

Derivation. From KO\SOS, vagina, and %atT?7, seta.
1. COLEOCILffiTE SCUTATA Breb.

Plate LXXVII. Fig. 6.

Char. Filaments oppressed, conjoined, radiating, so as to
describe a disciform frond.

13 soluta. — Filaments radiating, prostrate, free.

Coleoch<Bte scutata Breb. Description de deux nouveaux
Genres d'Algues fluviatiles, Ann. des Scien. Nat., Jan-
vier, 1844, p. 25. pi. 2.

Hab. In stagnant waters and ditches, growing on sub-
mersed leaves and stems of aquatic plants. Autumn —
spring. Near Manchester: Mr. Sidebotham. Aber-
deen : Dr. Dickie. Near Clonmel : Prof. G. J. Allman.

" I have found this remarkable Alga in many places in
the environs of the town of Falaise. It grows closely applied
upon the leaves and stems of inundated and in part decom-
posed plants. I have gathered it principally upon Sparga-
nium natans, and upon the Potamogeton natans. Its lenticular

218 MOXOCYSTE^E.

fronds may be easily distinguished with the naked eye in
spite of their smallness, their green colour trenching upon the
discoloured parts of the plants upon which they are fixed.
At first sight one might be induced to believe that they are
but parts of those plants whose chromule has not been dis-
organised by the immersion which has discoloured their other
parts. These rosettes follow the forms of their supports. I
have seen them upon Conferva fracta ; they then embrace the
filaments in such a manner as to surround them with a sort
of ferrule or annular hood. A slight magnifying power of
the microscope is sufficient to show the elegant disposition of
radiating filaments which, by their approximation and lateral
union, resemble an areolated disc, which recalls to mind cer-
tain Pediastra belonging to the Desmidece.

" The fronds are roundish, from one to two, rarely three mil-
lemetres in diameter ; they are formed of filaments closely ap-
plied to the plant on which they grow, dichotomously branched ;
branches approximate, and as though soldered the one to the
other. The articulations or cells three or four times as long
as broad, often unequal, are furnished interiorly with a green
granular endochrome. On a great number of these articula-
tions is remarked a tubercular rounded projection or pro-
tuberance, from which arises a tubular filament, truncated a
little, dilated at the summit, from the interior of which issues
a long and very delicate thread. This part of the organiza-
tion of this Alga shows clearly that it ought to be placed in
the ChcetophoroidecB, and near to Bulbochcete. This setifer-
ous sheath is very caducous and difficult to perceive.

" At a certain period of the existence of Coleochate scutata
its disc is covered here and there with tuberculated masses of
endochrome, which one might regard as the formation of
spores, at a later period indeed, these little masses are con-
verted into groups of globules charged with the tube or seti-
ferous sheath which characterizes this Alga. In the first
period of its developement, the tubes terminate in a point,
from whence issues a long setaceous filament of great te-
nuity ; at a later period, the summit of this sheath is open,
and appears then truncated and slightly dilated.

LYNGBYA. 219

" About the globule which is at the base of this sheath, are
developed, in the form of a rosette, the first articulations of
the filaments, as is seen in^. 7. They are cuneiform ; some
slightly bi-lobed, give origin to two cells, and so determine the
dichotomy of the filaments.

" The variety, /3 soluta, which I have sometimes found
amongst examples of the ordinary type, might be considered
as another species on account of its filaments, which are not
depressed, and are free in their whole length, but certain
fronds of the ordinary type may be regarded as connecting
the two forms ; I therefore do not think that they can be
separated. I have always observed that the filaments of the
variety /3 do not preserve, in ramifying, a dichotomous dis-
position so exact as in Coleocheete scutata, &c."

In all those specimens of this most interesting production
which I have examined, the sheaths and cilia have been al-
together wanting. In some cases, however, the point of
attachment of the sheaths to the cells could be perceived.
The natural position of the genus is certainly near to Bulbo-
chcete.

Sub-fam. ii. ULOTHRICEJE.

20. LYNGBYA Ag.

Char. Filaments simple, subulate, and shining. Z6ospores

several in each cell, escaping through rents in the walls

of the cells.
Sphceroplea Berk. Ulothrix Kiitzing, Phyc. Gen. p. 251.

Sphceroplea Kiitzing, 1. c.
Name in honour of M. Lyngbye, author of an excellent

work on the Alga of Denmark.

The genera Lyngbya and Sphceroplea are undoubtedly
identical, and one of the terms must of necessity be sup-
pressed. Bangia also differs but slightly from the genus
Lyngbya, and its abolition seems called for. Kiitzing has
constituted a new genus for the reception of Conf. zonata
(SpharopleacrispaHerk.}, Ulothrix, preserving also the genus
Sphceroplea, the type of which he makes Conf. annularia Roth.

220 MONOCYSTKffi.

I cannot discover the necessity for the genus Ulothrix. Kiit-
zing's definitions of the genera Ulothrix and Sphavoplea are as
follow : —

ULOTHRIX — " Trichoma simplex, membranaceum, tener-
rimum, flaccidum; cellulae gelineae, tenuissimae, hyalinae, ach-
romaticae, abbreviatae: amylideae delicatissimae, virides, ple-
rumque granuliferae, primo extensae, dein paulatim in fascias
transversales contractae, tandem in opseospermata quatuor vel
plura hologonimica transeuntes."

SPHJEROPLEA. — " Trichoma parenchymaticum simplex,
cellulae tenuissimas membranaceae, substantia chlorogonomica
demum in spermatia transeunte repletae, spermatia primo
viridia deinceps miniate fusco : epispermio duplici, exteriori
filiformi, internum spiraliter investiente, cuncta in series longi-
tudinaliter digesta."

The endochrome in all the species of this genus in the
young condition is almost uniform ; subsequently, however, it
parcels itself into numerous zoospores in each cell. The
same remark applies to all the Algce, which are multiplied by
means of zoospores.

The species described in this genus might with some pro-
priety be divided into two subgenera, in the first of which
should be placed Lyngbya zonata, L. muralis, L. virescens, L.
Thompson!, and L. copulata, in which the filaments are almost
always attached, are of a delicate and fragile nature, of a deep
green colour, and delight in pure water; while in the second,
Lyngbya fioccosa, L. punctalis, and L. vermicularis, should
be ranged, these being distinguished by characters the very
reverse of those just enumerated, they being rarely attached,
tenacious, of a dull green colour, and inhabitants of impure
waters. In this division L.prolifica should also find a place.

1. LYNGBYA ZONATA Hass.
Plate LIX. Figs. 4, 5, 6 and 1, 2, 3.

Char. Filaments of considerable diameter. Cells usually
rather longer than broad, but sometimes shorter. Endo-
chrome at first quadrangular, not entirely filling the cavity

LYNGBYA. 221

of ike cell, but leaving a pellucid margin all around, sub-
sequently becoming globular and granular. Zoospores six
or eight in each cell.

Conf. zonata "Web et Morh. Conf. lucens Dillw. t. 47.
Conf. bicolor, E. B. t. 2288. Sphceroplea crispa Berk.
Glean. Algae, t. 3. fig. 1.

This species delights in pure and running water, it growing
luxuriantly in that of cascades and waterfalls. It is every-
where common throughout Great Britain. Considerable con-
fusion seems to have prevailed relative to this plant, several
observers having repeatedly described it under different names.
I have no doubt whatever of the correctness of the synonymes
quoted. The form of the cells in this species is somewhat pecu-
liar. They are not exactly cylindrical, but taper gradually
from each extremity towards the centre of the cell, the ex-
tremities, or angles of the cells appearing in consequence
prominent.

Two varieties of it have presented themselves to me ; the
one at Snaresbrook, Essex, in great quantity ; this agree-
ing with the species proper in all, save the length of the
cells, which are generally two and a half or three times as
long as broad ; the other in a stream at Wood Green, near
Cheshunt, in which the cells are cylindrical, completely filled
with endochrome, and not one third so long as broad. This
may be distinct.

2. LYNGBYA MUEALIS Ag.
Plate LIX. Fig. 7.

Char. Filaments of less diameter than those of Lyngbya
zonata, dark green, entangled. Cells very short, two or
three times broader than long.

Hob. On the ground in all damp situations early in the
spring.

This is a very distinct species, rendered interesting from
the peculiarity of its habitat. The diameter of the filaments

222 MONOCYSTEJE.

and length of the cells vary considerably, according to the
age of the plant.

3. LTNGBYA COPULATA Hass.
Plate LXXII. Fig. 14.

Char. Filaments very flexible, of about the same diameter
as those of L. muralis, adherent to each other for a con-
siderable portion of their length. Cells short.

L. muralis var. copulata Cann. MS.

Hab. Appin: Captain Carmichael. .

This is a very curious production, exhibiting some relation
in the adherence of the filaments the one to the other to
Calothrix mirabilis — than which it is not less wonderful.
It is very rare.

4. LYNGBYA VIBESCENS Hass.

Plate LX. Fig. 3.

Char. Filaments of about the same diameter as those of L.
punctalis. Cells usually somewhat beaded, rather longer
than broad. Endochrome not quite filling their cavities.
Hab. On stones, in a pond, near Wanstead Flats, Essex :
A. H. H. Penzance : Mr. Ralfs.

This species, except in the simplicity of its filaments, bears
a very close resemblance to the JDraparnaldice. Like the
species of that genus, it is of a beautiful green colour, fragile,
slippery to the touch, and delighting in pure and slowly run-
ning waters. The filaments are always attached, in which
respect it agrees with L. zonata.

5. LYNGBYA THOMPSON: Hass.

Char. Filaments attached, exceedingly slender. Cells once or
twice as long as broad.

Meloseira Thompsoni Harv. in Manual, p. 195.

LYNGBYA. 223

Hal. Growing on stones in a mountain rivulet at Bal-
lantrae, Ayrshire : Mr. W. Thompson.

This is clearly a Lyngbya, and the most minute species of
the genus with which I am acquainted. It is described as
forming " beautiful, glossy, dark green tufts."

6. LYNGBYA FLOCCOSA Hass.
Plate LX. Figs. 1, 2.

Char. Filaments of smaller diameter than those of L. muralis.
Cells at first cylindrical, subsequently beaded, rather longer
than broad.

Conf. jloccosa Ag. Conf. fugacissima Dillw. Supp., t. B.
C.fioccosa Harv. Manual, p. 126.

This species is very distinct and abundant, being found
in great quantities in almost all ponds, on heaths and bogs.
The filaments are rarely attached, are highly mucous and
tenacious. When kept in water it does not quickly pass to
decay. Specimens are often met with, which when placed
under the microscope appear quite colourless, the endochrome
having escaped from the cells.

7. LYNGBYA PUNCTALIS Hass.
Plate LX. Fig. 4.

Char. Filaments of less diameter than those of Lyngbya
Jloccosa, very mucous. Cells two or two and a half times

as long as broad, slightly contracted. Endochrome at
first quadrangular, not filling the entire cavity of the cell,

arranged usually in two separate masses, but sometimes

there is but one ; subsequently the cells becoming inflated,

the endochrome assumes a spherical form.

Sphceroplea punctalis Berk. Glean. Alg. t. 3. fig. 2. Conf.
punctalis Dillw. t. 51. Sph. punctalis Harv. in Manual,
p. 144.

224 MONOCY8TEJE.

Hob. High Beech : A. H. H. Penzance : Mr. Rolfs.
Bogs at Fisher's Castle : Mr. Jenner.

This very beautiful species is by no means common. It
inhabits generally ponds on commons and other exposed situ-
ations.

8. LYNGBYA VEKMICULARIS Hass.
Plate LX. Fig. 5.

Char. Filaments very mucous, tenacious, and of a yellowish
green colour, finer than those of the preceding species.
Cells twice or thrice as long as broad. Endochrome
rarely filling the cavity of the cell.

Hab. High Beech : A. H. H. Penzance : Mr. Ralfs.
Sussex : Mr. Jenner.

A common species in boggy pools.

9. LYNGBYA PBOLIFICA Grev.
Plate VIII. Fig. 4.

Char. Filaments exceedingly slender, entangled, purple, very
broadly effused, fioating.

Grev. Crypt. Fl. t. 303. ; Harv. 1. c. p. 370. ; also in Manual,

p. 160.
Hab. In the loch of Haining, Selkirkshire, October to

April: Dr. Greville.

" Plant extensively diffused, forming a floating stratum,
of a rich purple colour. Filaments extremely slender, en-
tangled, somewhat rigid, yet flexible, entirely destitute of
attachment, and free from any mucous layer. Annuli from
the minuteness of the filament almost inconspicuous." — Grev.

Note. — The following marine Alga I regard as members of the genus
Cladophora, — C. pellucida, C. rectangidaris, C. Hutchinsia, C.diffusa, C.
•n mil i. C. rupestris, C. Icetevirens, C.jftexuosa, C. gracilis, C. refracta, C.
(ilbidu, C. lanosa, C. uncialis, C. glaucescens, C. arcta, C. ceruginosa, and
C. riparia ; while in Aplonema I place the subjoined Conferva, — arenicola,
sutoria, Linum, crassa, implexa, idothrix, arenosa, melargonium, area, col-
labens, bangio'ides, Youngana, and clandestinu.

225

FAM. XL HYDRODICTYONE^E.

21. HYDRODICTYON Roth.

Char. Cells arranged in the form of a pentagon, an aggre-
gation of a number of these pentagonal meshes, going to
form an entire plant. Zoospores numerous in each cell,
and uniting together before the absorption of the parent
cell membrane.

Derivation. From vSoy>, water, and SIKTVOV, a net.

1. HYDRODICTYON UTRICULATUM Roth.

Plate LVIII.
Char. Same as those of the genus.

Harv. in Hook. Br. Fl. vol. ii. p. 359. Conf. reticulata,
E. B. t. 1687. ; Dillw. t. 97.; Vauch. Conf. d'Eau douce;
Harv. Manual, p. 140.

Hab. In ditches and pools in the midland and southern
counties of England. In a pond in the Botanic Garden
at Cambridge, where it has existed for many years :
Rev. Prof. Henslmv. Not found in Scotland or Ireland
hitherto.

Hydrodictyon utriculatum is one of the most remarkable
of the freshwater Alga. The credit of the discovery of the
singular reproduction of this species is due entirely to
Vaucher, whose account of it is so clear and well expressed
that I cannot do better than translate his remarks : — Each of
the fine filets (cells) which form the pentagon begins to swell
a little, principally at the extremities, then it is separated
from the others not by a rupture, properly so called, but by

Q

226 HYDRODICTYONE^:.

issuing from the interior of the membrane in which it was
contained, and which, without doubt, was open for the pur-
pose of its escape * ; and after this separation it floated on the
water under the form of a cylindrical cell. Soon it flattened
itself, and underwent an alteration, which I would com-
pare to that which the beginning of fusion produces upon
metals ; then it increased gradually in every direction, and,
the reticulations being cleared the one from the other, be-
came itself a new network, which one might distinguish
with the microscope. Soon the reticulations were to be seen
with the unaided sight, and at last each cell (or division of
the pentagon), was totally changed into a network entirely
like to that of which it made part. All these transformations
took place in the space of a few days, and at the end of two
or three months the young reticulated productions had acquired

the full dimensions of which they were capable

We have here then an example of reproduction more re-
markable perhaps than those heretofore observed."

" In conclusion, there is but little room to doubt that if the
sides of the reticulations of the network of the preceding
year be the networks of this year, the sides of the reticulations
of the present networks will also be the networks of the next
year, that each cell or fibre of the reticulations is itself the
network which shall develope itself on the second year, and
that the fibrilla of the principal fibre will be the network
which shall develope itself on the next year, and so on until
it please the Author of Nature to put an end to this deve1
lopement by destroying the species which presents it."

* Areschoug, who has published an excellent paper in Schlechtendal's
" Linnaea," for 1842, on the mode of growth of Hydrodictyon vtriculatum,
states that he has never been able to detect in this plant the enclosing
tube. Dr. Areschoug has made the interesting discovery of the exact
mode of formation of the minute network, viz., by the union of the
numerous spores while in the parent cell, previously to which they are
observed to be in lively motion ; the parent cell itself is absorbed, and
thus the new plant is eliminated according to Areschoug.

227

FAM. XII. SCYTONEME^E.

Char. Algae for the most part branched, rigid) or flaccid.
Cells globular or compressed. Colour either a dark olive
or a vivid oeruginous green.

The Alga described in this family form two very distinct
sections ; the first section embracing those species which are
characterized for the most part by a rigid cartilaginous habit,
globular cells, a black or olivaceous colour, being lustreless
in drying, and the second division including species which are
not of a rigid habit, but whose filaments are flaccid, cells usu-
ally cylindrical, and colour a vivid green. The species of this
last section Kiitzing makes the type of his order Paraspermece,
an order characterized by its lateral sporules, and including
Lyngbyaceee and Calothricece, families which follow in his
arrangement the Scytonemece.

Section i. STIGONEMEJE.

22. STIGONEMA Ag.

Char. Filaments tufted, branched, of irregular diameter, car-
tilaginous. Cells moniliform, arranged in transverse lines.

Derivation. From crrvywv, dotted, and vyfia, a thread.

There is scarcely any necessity for this genus: the species
described in it would form a natural section of the genus
Hassallia.

1. STIGONEMA ATROVIRENS Ag.
PL LXVI. Fig. 1.

Char. Filaments tufted, coarse. Branches slightly divided,
subacute. Rings mostly formed of three cells.
Q 2

228 SCYTONEME^J.

Conf. atrovirens Dillw. t. 25. Lichen pubescens, E. Bot.
t. 2318.; Harv. in Hook. Br. FL ii. p. 363. St. atro-
virens Harv. in Manual, p. 153.

Hob. On wet rocks forming the banks to the river
Diloris, near Neath, Glamorganshire: Mr. Dillwyn.
Mountainous district ; 14 miles west of Aberdeen : Dr.
Dickie. On wet rocks above the falls of Aberdylais,
Swansea : Gutch.

This species forms rigid lustreless and very dark tufts ;
the filaments are divaricately branched, the branches nar-
rower than the stem, and sometimes furnished with two or
three secondary ramuli. The larger divisions are dark brown
and opaque, the smaller vivid green, their terminations being
marked with transverse lines, which indicate the divisions into
cells. The dense cartilaginous sheath is most visible at the
terminations of the branches.

2. STIGONEMA MAMILLOSUM Ag.
Plate LXVI. Figs. 2, 3.

Char. Branches incrassated, spindle-shaped, the ^two inferior
thirds densely mamillose on all sides.

Bangia mamillosa Lyng. t. 25. ; Harv. in Hook. Br. Fl.
p. ii. p. 363. Stia. mamillosum Harv. in Manual,
p. 153.

Hob. Rocky bottoms of subalpine rivulets, Appin : Capt.
Carmichael. Eagle's nest, Killarney : W. H. Harvey.
Mountainous district ; 14 miles west of Aberdeen :
Dr. Dickie.

This forms continuous tufts several inches in diameter,
which are less rigid than in S. atrovirens ; the branches are
simple, their diameter being greatest in the middle, and beset
on all sides, for the two lower threads with mamillae of
various sizes, and the cells of which are always cylindrical,
and not moniliform. These mamillae as well as the upper

STIGONEMA. 229

third of the branches are frequently of a vivid green colour.
It is just probable that this species is but a condition of the
previous one, the differences observed being occasioned by its
moister habitat.

3. STIGONEMA PANNIPORME Harv.

Plate LXVI. Figs. 4, 5.

Char. Filaments dark brown, densely packed together, much
branched. Branches long, flexuous, obtuse. Cells an-
gular, in triple series.

Scytonema panniforme Carm. MS. ; Ag. Syst. p. 309 ?
Stiff onema panniforme Harv. in Manual, p. 154.

Hab. On rocks at the mouth of Spar Cave : Capt. Car-
michael.

" Patches indeterminate, crust-like, velvety. Filaments so
closely packed that only their tops are visible above the crust,
very tough when dry, gelatinous when moist, cohering
strongly together, much branched ; branches long and flexuous,
divaricating, cylindrical, quite obtuse, not tapered. Granules
ternate, very obvious in all the main branches, less distinct
towards the tips. This entirely agrees in external character
and ramification with the Scytonema panniforme of Agardh,
with an authentic specimen of which I have compared Car-
michael's specimen. The only difference I can perceive lies in
the generic character, and this I suspect depends on age, for
I find the apices of the branches simply striated, like a Cal-
othrix or Scytonema, and the smaller branches, for, at least,
part of their length, have the semi-punctate appearance of &
ocellatum ; and it is only in their larger and main branches
that the punctated character is clearly visible." — Harv.

4. STIGONEMA INTERRUPTUM Hass.

Plate LXIX. Fig. 2.

Char. Filaments thick, subulate, coriaceous, glaucous green,

Q 3

230 SCYTONEME.E.

cohering in tooth-like fascicles. Cells very short. Strise
strongly marked.

Calothrix interrupta Carm. MS. C. interrupta Harv. in
Hook. Brit. Fl. p. ii. p. 368. ; Harv. in Manual, p. 158.

Hob. On mosses and lichens, Appin : Capt. Carmichael.
Turk's Cascade, Killarney ; and Tobermorey in the Isle
of Mull: W. H. Harvey. Machynlleth, N. Wales:
Mr. Ralfs. Aberdeen : Dr. Dickie.

" Filaments about a line in length, of a glaucous green
colour, united into close erect tufts, spreading over the moss,
thick, tapering, cohering at the base, and sometimes through
their whole length. Internal mass here and there interrupted,
leaving short pellucid spaces resembling articulations. Strise
close and conspicuous."-- Carm. MS.

This species is certainly much more naturally placed in the
genus Stigonema than in Calothrix. Owing to the compact-
ness of the cells they do not exhibit the dotted or monili-
form arrangement of the other species — a difference surely
not generic. The colour is a light glaucous green.

5. STIGONEMA MINUTUM Hass.
Plate LXVII. Figs. 3, 4.

Char. Filaments minute, erect, rigid, jftexuous, fastigiate.
Branches short. Cells or rather sporules in the principal
filaments numerous, in the branches in single series.

Scytonema minutum Ag. S. minutum Harv. in Hook.
Brit. Fl. p. 365. ; Harv. in Manual, p. 155.

Hob. On rocks and crustaceous lichens ; common in al-
pine districts, Appin : Capt. Carmichael. Caroigataha
near Caher, and at Killarney : W. H. Harvey.

" Plant either spreading in a black suborbicular crust or
scattered in little tufts, filaments erect, minute, closely packed,
olivaceous ; branches irregular, obtuse, ascending." — Harv.

Not a very well marked species.

HASSALLIA. 231

23. HASSALLIA Berk.

Char. (t Branches increasing by the elongation and division
of a single cell." — Berk.

The above definition, like that of Scytonema, embraces only
the essential character of the genus, to it, other well marked
peculiarities maybe added; such'as the rigidity of the filaments,
the branches usually solitary, and the beaded form of the cells.
The genus therefore may otherwise be defined thus : —

Char. Filaments somewhat rigid, of unequal diameter.
Branches usually solitary, formed by the elongation and
division of a single cell. Cells distinctly moniliform, usu-
ally in a single series.

Kiitzing's genus Sirosyphon is thus specified : it includes
but a single species, and cannot be said to fulfil the intention
of the genus Hassallia.

" Trichomata parenchymatica ex cellulis gelineis in vagina
lamellosa, apice clausa longitudinaliter striatis, apice in arti-
culos epenchymaticos confluentes transeuntibus compositum.
Spermatia insterstitialia. Rami basi geniculati."

The above characters seem to me to be only of specific and
not generic importance.

The genus Hassallia was instituted by the Rev. Mr.
Berkeley a considerable time ago : that gentleman, however,
delayed publishing it, and conceived on the appearance of the
" Phycologia Generalis " that it was frustrated by Kiitzing's
genus Sirosyphon, which I cannot think that it is.

1. HASSALLIA OCELLATA Hass.
Plate LXVIL Figs. 2. 7. 6.

Char. Branches solitary, divaricating, slightly contracted at
the base. Cells beaded.

Conf. ocettata Dillw. t. D. Conf. ocellata E. B. t. 2530. ;
Harvey, in Hook. Brit. Fl. p. 364. Scytonema occllatum
Harv. in Manual, p. 154.

232 SCYTONEME2E.

Hob. Springs on the moors near Wolsingham, Durham :
Mr. Backhouse. In a bog on Tower Hill Common, near
Southampton : J. Woods, Esq. West Blanket Island,
Kerry : Mr. Andrews. Aberdeen : Dr. Dickie.

" It is composed of dense tufted masses of a dull brown,
except when held against the light, in which position they
appear of a horny or dirty orange hue. They are of a rigid
substance, and do not adhere to paper in drying. The co-
pious branches are irregular, wavy or curved, the ultimate
ones blunted, and many of them turned one way. The
greatest peculiarity of this species is that a chain-like row
of vesicles runs along the centre of the frond, each of which is
marked with a central dot, probably consisting of a mass of
seeds." — E. B.

2. HASSALLIA COMPACTA Hass.
Plate LXVIII. Fig. 3.

Char. " Filaments decumbent, branched, densely interwoven
into blackish tufts. Branches suberect, dichotomous, and
fasciculate within, furnished with transverse rings." —
Grev.

Scyt. compactum Harv., 1. c. p. 364. ; also in Manual, p. 154.
Hob. Moist rocks in the Pentland Hills : Messrs. Arnott
and Grevitte.

This species, with a specimen of which I have been kindly
favoured by Dr. Greville, does not differ very considerably
from H. ocellatum, and chiefly in the closer arrangement of
the sporidia. I am not certain that it is really distinct.

3. HASSALLIA TURFOSA Hass.

Char. Frond coriaceous, sparingly branched. Branches sub-
erect. Cells annuliform, rarely beaded. Sheath broad.
Dematium turfaceum Pers. Myc. Eur. vol. i. p. 68. ; Lk.
Sp. PL i. 134.; E. B. 2826. fig. 1.

HASSALLIA. 233

Hab. On heath, sphagnum, &c., on the Pentland Hills,
found by Dr. Greville.

" Forming a short brownish shaggy stratum, overrunning
the plants on which it grows. Threads suberect, giving out
in a proliferous manner short, very obtuse, branches of a beau-
tiful golden yellow brown. Two sometimes spring from the
same point. The walls of the threads are very thick. Spo-
rangia annuliform, green, composed of a compact grumous
mass, or divided, especially in the older threads, into a single
row of distinct oblong granules.

" This very beautiful Alga was communicated by Dr.
Greville to Sir W. J. Hooker, in whose Herbarium it is
marked by M. Klotzsch Dematium turfaceum Lk., which
there is every reason to believe is correct. Link appears to
have been acquainted with the plant merely from the short
notice of it by Persoon in the ' Mycologia Europaea.' Fries
tells us expressly, * Syst. Myc.' vol. ii. p. 603. ad not., that it is
an Alga. It is indeed a true Scytonema, which bears much re-
semblance to Petalonema alatum, though it wants the character-
istic feature of that very curious production. Radulum ater-
rimum of Fries, of which specimens are published in ' Scleromy-
cetes Suecise', and to which Persoon's var. cornutum is referred,
is altogether different, and truly a fungus." — M. J. B.

This beautiful species bears some resemblance to H. ocel-
latum and still more to H. compactum ; the cells, however,
are rarely beaded, as they invariably are in both those spe-
cies. It is no doubt distinct from either, the branches are
generally single.

4. HASSALLIA ? BYSSOIDEA Hass.
Plate LXVII. Fig. 5.

Char. Filaments minute, erect, simple, of equal diameter, fas-
ciculate, obtuse, forming, an unequal blackish crust. Striae
very close and evident.

Scyt. byssoideum Berk., Glean. Alg, t. 19. f. 1. ; Harv.
Hook. Brit. Fl. p. ii. p. 366. ; Harvey, in Manual.

234 SCYTONEMILE.

Hub. On the 'trunk of a living elm at Oundle, North-
amptonshire : Rev. M. J. Berkeley.

I doubt much whether this species be a true Hassallia.
It is much more like an Oscillatoria, the filaments being simple,
of equal diameter, regularly striated, and very brittle. The
only character which seems to unite it with Scytonema is its
erect habit. It might possibly be better placed in Kiitzing's
genus Symphosyphon: if not, it should perhaps form the type
of a new genus. The genus Symphosyphon is thus charac-
terized.

" Trichomata erecta vel adscendentia, vagina cartijaginea
multistriata (lamellosa) eaepe fasciculata, involuta, basi conflu-
entes, lateraliter concreta."

5. HASSALLIA ? LIMBATA Hass.
Plate LXVII. Fig. 6.

Char. " Filaments thick, Jlexuous, ceruginous, with a broad,
pellucid margin, loosely interwoven in a dense dull ceru-
ginous green stratum." — Grev.

O. limbata Grev. Crypt. Flor. Syn. p. 40. and t. 246.
(O. rupestris}. Scytonema (Brugineo-cinereum Kiitzing,
Phyc. General, p. 214. Ocellatoria limbata Harv. in
Hook. Brit. Flor. p. 375. ; also in Manual p. 164.

Hob. On perpendicular rocks, exposed to the trickling of
water, Pentland Hills: Dr. Greville.

On first examining an authentic specimen of this plant, I
was impressed with the idea that it ought to be referred to
the genus Scytonema, but from not discovering branches on
the filaments, I did not feel quite certain on this point.
Kiitzing having made the species the type of his genus Scy-
tonema, there can be but little doubt but that it really
belongs to the family Scytonemea. " Plant covering the face
of the rock for several inches together, and when old, peeling
off in rather large pieces. Externally it is mostly of a dull
and brownish green colour, but within more of a verdigris

SCYTONEMA. 235

green, differing in intensity in different parts; here and
there gelatinous and semi-transparent. Filaments thick for
their length, very flexuous, with a pellucid colourless limb,
equal in breadth to the coloured, striated portion, which is of
a pale verdigris green." — Grev.

24. SCYTONEMA Ag.

Char. " Branches increasing by the protrusion and division
of the central row of cells ." — Berk, in lit.

Derivation. From O-KVTOS, a skin, and vrj^a, a thread ; in
allusion to the toughness of the filaments.

The genus Scytonema has hitherto evidently embraced the
description of plants belonging to two distinct genera.

The above, therefore, is Mr. Berkeley's definition of the
genus Scytonema, as very properly proposed to be restricted
by that gentleman a considerable time ago. This concise de-
finition briefly describes the essential character of the altered
genus, but there are also others which serve to distinguish its
species from those which have hitherto been associated with
Scytonema, and which confirms the view adopted by Mr.
Berkeley of the necessity of forming two genera out of those
species. From the protrusion and division of the central
row of cells, it follows that the branches should frequently
be in pairs, and this is generally the case : the filaments,
also flaccid, of nearly equal diameter, are rarely moniliform.
The definition of the reconstructed genus Scytonema might
stand more fully thus : —

Char. Filaments flaccid, of nearly equal diameter. Branches
usually in pairs, and formed by the protrusion and divi-
sion of the central row of cells. Cells generally quadran-
gular, rarely if ever regularly moniliform.

Kiitzing, in his " Phycologia Generalis," has removed one
species from the genus Scytonema, S. ocellatum, and formed
for it a new genus Sirosyphon ; but still the genus Scyto-
nema of Kiitzing does not in the most remote degree cor-

236 8CYTONEME2E.

respond with the genus as defined by Mr. Berkeley or
myself, neither does his genus Sirosyphon answer to the
genus Hassallia, formed by Mr. Berkeley for those species
hitherto associated Avith the genus Scytonema, but which the
definition of that genus, as it at present stands, does not
embrace.

The following is Kiitzing's definition of Scytonema : —
" Trichomata vagina duplici, firma crassiuscula colorata
arete inclusa ramosa ; rami ex continuatione trichomatis in-
terni et prolongatione vaginae oriundi, non basi iis discreta.
Spermatia ex articulis intumescentibus progenita."

In the genus as thus characterised, Kiitzing includes the
following British species. Scytonema cerugineo-cinereum
( Ocellatoria rupestris, Grev. Scot. Flor. Turf. 246. ?), S. my-
ochrous, S. turfosum, and S. compactum. Now out of these
four species there is but one which could be received into
the genus Scytonema of Mr. Berkeley, and that one is Scyt.
myochrous. It is clear, therefore, that there is no correspond-
ence between the genus Scytonema of Berkeley and that of
Kiitzing.

1. SCYTONEMA HIBERNICUM Hass.
Plate LXVIII. Fig. 1.

Char. Filaments of considerable diameter. Cells about as
long as broad, issuing in pairs at right angles with the
stems.

Scyt. hibernicum Hassall, MS.

Hab. On a clayey bank, co. Antrim, Ireland: Mr.
Moore.

Of this beautiful species I have seen but a single specimen.
It was sent to me by Mr. Moore, with the name of Scyt.
ocellatum upon it, with which plant however it has no affi-
nity. The cells are of exactly the same form as in Scy.
myochrous, from which it differs principally in being alto-
gether larger.

PETALONEMA. 237

2. SCYTONEMA MYOCHROUS Ag.

Plate LXVIII. Fig. 2.

Char. Filaments of less considerable diameter, elongate, mostly
decumbent and flexuous.

Lyngb. t. 297. and £ ocellatum Lyngb. t. 28. Conf.
myochrous Dillw. Conf. 1. 19. ; E. B. t. 1555. Conf. mi-
rabilis, E. B. 2219. (not of Dillw.) Scytonema con-
textum Carmichael.

Hab. Various parts of Wales : Mr. Dillwyn and Mr.
Woods. Neighbourhood of Bantry : Miss Hutchins.
Crowborough Warren, and in Pressbridge Warren, near
Wych Cross : Mr. Jenner. Dolgelly : Mr. Ralfs.

This species differs from the previous one only in being
smaller in all its parts. I have no doubt of the correctness
of Scyt. contextum as a synonym, having, through the kind-
ness of Mr. Harvey, had an opportunity of examining an
authentic specimen. Carmichael thus describes it : — " Thi-
species occurs in a thin, closely matted blackish fleece, of ins
determinate extent. Filaments two or three lines in length,
simple, or rarely furnished with one or two branches,"
(which are occasionally geminate, as in S. myochrous}, " in-
terwoven into an almost inextricable stratum. Sporidia, when
visible, which rarely happens, globular and rather distant.
Besides the comparative shortness of the filaments, and the
more intimate contexture of the stratum, this species differs
from S. myochrous in becoming, when dry, of a light greyish-
green colour instead of black." — Carm. MSS.

25. PETALONEMA Berk.

Char. Frond composed of flat, branched or simple filaments,

the margins membranaceous and striate.
Derivation. From irsraKov, a leaf or lamina, and wjjta, a
thread ; in allusion to the singularly winged filaments.

238 SCYTONEME^E.

1. PETALONEMA ALATUM.
Plate LXVIII. Fig. 6.
Char. Filaments broadly membranaceous.

P. alatum Berk., Glean, of Alg., p. 23. t. 7. fig. 2. Oscilla-
toria alata Carm. Grev. Crypt. Fl. 222. ; Harv. in
Hook. Br. Fl. 378. ; Harv. in Manual, p. 168.

Hab. On wet calcareous cliffs, Appin : Capt. Carmichael.
Oban : Rev. M. J. Berkeley* Aberdeen : Dr. Dickie.

This highly curious plant forms a brownish or chestnut-
coloured stratum, subgelatinous. The filaments, which are
irregularly branched, central, consist of a coloured thread,
Avhich is distinctly annulated, and a broad colourless striated
sheath, obtuse at its extremity. The contrast between the
coloured and uncoloured portions of the filaments, and the
delicate stria) on the sheath, render this a very beautiful
object.

26. ARTHRONEMA Hass.

Char. Filaments simple, rarely branched ? of equal diameter,
divided into successive portions.

Derivation. From apOpov, a joint, and w)/j,a, a thread.

It is not without some hesitation that I have ventured to
constitute a new genus for the reception of this curious pro-
duction, which could not consistently I think be allowed to
remain with either Scytonema or Hassallia.

1. ARTHRONEMA CIRRHOSUM Hass.
Plate LXVIII. Fig. 7.

Char. Filaments of considerable size, stria close and evident.
Scytonema cirrhosum Carm. Tufts widely spreading, ^/a-
ments floating in bundles, spuriously ? branched ;
branches beset with fragments towards the top." -
Carm. MS.

ARTHRONEMA. 239

Harv. in Hook. Br. Flor. p. 366. ; Harv. in Manual, p. 155.

Hob. Borders of lakes at Lismore Island : Captain Car-
michaeL

" It occurs in continuous fleeces parallel to the water's
edge, of a deep chestnut colour when lying flat, dark olive
when floating. The fleeces are made up of small, contiguous
fasciculi of interlaced filaments. The filaments are from
half an inch to an inch in length, simple or spuriously (?)
branched, and prolonged by successive adhesions of portions,
seemingly of broken filaments, which at length coalesce and
form a knot at the points of adhesion. The transverse striae
are close and conspicuous." — • Carm.

Each filament, at regular distances, is obliquely divided :
these divisions are not formed by " successive adhesion of
portions," but by the partial separation into portions of a
single filament, the investing membrane or sheath remaining
entire.

Section ii. CALOTHRICE&.

" I have seen upon a Calothrix, gathered in the ponds of
water proceeding from the overflowing of the Seine, se-
condary oblong branches formed, which at first sight pre-
sented no difference of organization with that of the principal
tube. These branches presented transverse approximate in-
ternal divisions, and were filled with endochrome of a very
pale green tint. Shortly after their appearance, I have seen
the contents of these branches pierce the external envelope,
which it left empty and transparent, and issue under the
form of a tubular body, oblong, partitioned, obtuse at both
extremities like the principal filament. Unfortunately I
have not been able to follow their developement, because the
filaments themselves have become destroyed, or covered with
crystals resembling those of Chcetophora." — P. 333.

Mr. Dillwyn, in his " Introduction to the British Con-
fervas," makes some remarks of the same nature in refer-
ence to C. distorta.

240 SCYTONEMEJE.

27. TOLYPOTHRIX Kutzing.

Char. Filaments of nearly equal diameter, tufted, tenacious.
Branches few, continuous with the main filaments, an-
nulated at the base. Cells indistinct, rarely moniliform.
Sporules escaping at the extremities of the filaments.

Derivation. From Tohirn-v), wool, and Opi%, hair.

Kutzing, in his " Phycologia Generalis," has established
the genus Tolypothrix, which I here adopt. In the genus Ca-
lothrix Ag. Kutzing describes only C. mirabilis, a production
which differs essentially and generically from the proper
Calothrices, all of which Kutzing refers to his new genus.
A preferable arrangement I conceive would have been to
have constituted a new genus for the single species C. mira-
bilis, and to have allowed the Calothrices to have remained in
the genus in which they have been so long placed, and the
nature of which is so well understood by algologists.

a. Branches discrete.

1. TOLYPOTHRIX PUNCTATA Hass.

Plate LXIX. Fig. 3.

Char. Filaments somcichat irregular, very sparingly branched,
diameter considerable. Cells not quite so long as broad,
nucleated.

Hab. Under a cascade, co. "YVicklow : Mr. Moore.

This species is larger than T. distorta, and the filaments
less uniform ; the branches are rarely formed, and the cells
punctated.

2. TOLYPOTHRIX DISTORTA Kutz.

Plate LXIX. Fig. 4. r

Char. Filaments elongated, bluish green, forming large tufts,
mucous, somewhat rigid, branched. Branches erect,fiexuous.

Conf. distorta Dillw. t. 22.; E. Bot. t. 2577. C. distorta
Harv. in Hook. Brit. Flor. p. 369. ; Harv. in Manual,
p. 158.

TOLYPOTIIRIX. 241

Hal. Adhering to sticks, stems, &c. ; common.

This species forms tufts of from half an inch to an inch in
height, of a dark green hue, which on drying becomes of an
intense verdigris or blue green colour ; the filaments are slen-
der, and the branches elongated and simple.

3. TOLYPOTHRIX BERKELEYANA Carm.
Plate LXIX. Fig. 5. ?

Char. Filaments minute, bright grass green, flaccid, Jlexuous,
tufted. — Harv.

Calothrix Berkeleyana Harv. in Hook. Br. Fl. p. 367. ; also
in Manual, p. 157.

" Tufts scattered, about a line in diameter, of a vivid
green colour. Filaments twenty to thirty in each tuft, ra-
diating horizontally from a central point, exceedingly slender,
flaccid, tapering to a hyaline point, variously curved or flex-
uous. It comes very near C. confervicola ; but the filaments
are much shorter and more slender, and possess nothing of
the rigid, erect habit of that species." - — Carm. MS. cum
icone.

4. TOLYPOTHRIX NIVEA Hass.
Plate LXIX. Fig. 6.

Char. " Filaments exceedingly slender, rigid, white, forming
dirty yellow continuous tufts." •— Harv.

Conf. nivea Dillw. t. C. ; E. Bot. 2529. Cal. nivea Harv.
in Hook. Brit. Fl. ; also in Manual, p. 157.

Hob. In sulphur springs, Yorkshire and Durham : Dr.
Willan. Near Darlington: Mr. W. Backhouse. Plentiful
in sulphur springs, Llanwrtyd, and other similar springs
in Great Britain : Dillw.

" Dr. Willan assures us that this species is found below
the spring no further than as the water retains the sensible

R

242 SCYTONEME^I.

sulphureous properties, as if the hepatic gas were necessary
to its production and nourishment." — Dillw.

5. TOLYPOTHRIX KUFESCENS.

Plate LXIX. Fig. 7.

Char. Filaments minute, spreading in a thin slimy purplish
stratum.

Calothrix rufcscens Carm. ; Harv. in Hook. B. Flor. p. 368. ;
Harv. in Manual, p. 158.

Hob. On rocks under the spray of cascades, Appin: Cap-
tain Carmichael.

" Crust or stratum of indefinite extent, and so thin as to
seem a mere discoloration of the rocks until the finger is
passed over it, when a certain sliminess detects the presence
of the plant. Filaments half a line in length, and so slender
as to appear mere lines under the highest power of the com-
pound microscope." — Carm. MS.

b. Branches adherent to the main filaments.

6. TOLYPOTHRIX DILLWYNII Hass.
Plate LXVIII. Figs. 4, 5.

Char. Filaments tufted. Branches subulate, adherent to the
principal threads nearly their whole length. Striae about
a diameter from each other.

Scytonema Dillwynii Harv. et Ralfs' MS.
Hab. Dolgelly: Mr. Ralfs. Moist rocks, co. Antrim:
Mr. Moore.

This species was named by Harvey Scytonema Dillwynii,
under the impression that it was the Microcoleus ? Dillwynii
of his " Manual," and the Conf. vaginata of Dillwyn, t. 99.
which it is difficult to conceive from Dillwyn's description
that it really is. I felt much inclined to place this plant by

CALOTHRIX. 243

itself in a distinct genus, and perhaps this would have been
the correct course ; it is, however, more naturally associated
with the genus Tolypothrix than with Scytonema. It forms
little tufts two or three lines in height.

28. CALOTHRIX.

Char. Filaments of equal diameter, branched by apposition.
Derivation. From KO\OS, beautiful, and 0pi$;, a hair.

1. CALOTHKIX MIRABILIS.
Plate LXIX. Fig. 1.

Char. Filaments tufted, ceruainous, black, articulated. Striae
distant about the half of a diameter from each other, dis-
tinct.

Conf. mirabilis Dillw. t. 96. Calothrix atroviridis Harv.
in Manual, p. 159. ; Harv. in Hook. B. Flora, p. 369.

Hob. On mosses and in small streams, rare. Stream
which runs through the wood at Penllegare, near
Swansea : Dillwyn. — C. atroviridis in spring wells, near
Penzance : Mr. Ralfs. Aberdeen : Dr. Dickie.

Having had opportunities of examining, through the kind-
ness of Mr. Dillwyn and Mr. Harvey, authentic specimens of
Conf. mirabilis and Calothrix atroviridis, I have no hesita-
tion in declaring that the two plants are identical. There
is a close resemblance between C. mirabilis and Lyngbya
copulata, which species ought not to be far removed from each
other in a natural arrangement.

244

FAM. XIII. OSCILLATORE.E.

The family of Oscillatorece, limited to the genera Oscillatoria
and Microcoleus, is one of the most distinct and remark-
able of the divisions of the Alga. The majority of the
species are characterized by the minuteness of then* fila-
ments, the equality of their calibre, and their mathematical
rectitude or straightness ; they are still further distinguished by
the brevity of their cells, the ease with which these separate
from each other, the wonderful rapidity of their growth, the
surpassing brilliancy of their colours, and lastly, by a peculiar
oscillation, upon which feature their generic name has been
founded, but with regard to which I can myself perceive
nothing extraordinary, although the phenomenon is certainly
peculiar to this family — nothing indicative, as most suppose,
of a sensitive or animal life. The explanation to be given
of this oscillation of the filaments I consider to be partly of
an external, and entirely of a physical character. It has been
stated that the filaments of very many species of Oscillatoriay
and indeed of all those which present the phenomenon of
oscillation, are remarkable for their straightness or rectitude,
which is due to a certain degree of elasticity belonging to
them, and which leads to the effort on their part, whenever,
as on being placed for observation on the field of the micro-
scope, must be the case, they are bent or put out of a straight
line, to recover that position which is natural to them. T^is
elastic property of the filaments, currents almost impercep-
tible in the liquid in which they are immersed, and perhaps
unequal attractions amongst the filaments themselves, are
causes amply sufficient to explain any motion which I have
ever witnessed amongst the OscillatoritB, and which motion I
cannot help thinking to have been misunderstood and exag-
gerated to such an extent, as to throw around these plants an
unnecessary degree of mystery.

OSCILLATORIA. 245

Upon the reproduction of this family, and some others
which follow, no very precise observations appear to have
been made. Vaucher remarking the ease with which the cells
or " rings " separated from each other, supposed them to be
multiplied by means of these. This separation, however, is
probably merely to be regarded as a preparatory step, the
true reproduction being by means of zoospores.

Gerod Chantrans * makes some observations upon the re-
production of the Oscillatorice. He states that when an
Oscillatoria has reached its complete developement, it emits
from its cells a granulated powder, each grain of which
increases insensibly until finally it becomes developed into
a perfect plant. In this account, Gerod Chantrans has not
swerved far from the truth.

The species of this family are found under very different
circumstances ; upon the moist earth, in stagnant, still, and
running waters; in medicinal waters, and in such as are
absolutely hot and almost boiling. They are, with very few
exceptions, highly mucous to the touch, and in some kinds
the filaments are imbedded in a mucous nidus.

The brilliancy of their colours has been noticed. The
tints are various, shades of bright and beautiful greens, many
presenting a metallic or aeruginous cast, of violet, purple,
dark brown and glossy black.

No description of a species can be considered perfect, un-
less it be taken from an examination of specimens, both in
the recent and dried state, the characters not being identical
in these conditions.

A monograph on this family, the result of two or three
years' patient and careful observation, is much needed.

29. OSCILLATORIA.

Char. Filaments simple, even, elastic, closely striated, and often
lying in a mucous matrix.

Derivation. From oscillo, to vibrate.

* Recberches Chimiques et Microscopiques sur les Conferves, &c.
Paris, an x.

K 3

246 OSCILLATOREjE.

Kiitzing's definition is as follows : —

" Trichomata libera, basi vaginata, ex vagina longe prore-
pentia, vaginae achromatic® tenerrimae, simplices, utrimque
opertae liberae, nunquam coalitae."

Kiitzing makes a genus for the reception of the Oscittatoria
autumnalis Ag., of which Conf. decorticans of Dillw. is a
synonym. The genus is as follows : —

Phormidium.

" Trichomata libera, basi vaginata, ex vagina prorepentia,
vaginae achromaticae, simplices (non lamellosae), apertae, latera-
liter in membranam plus minus ve continuam coalitae."

I can offer no opinion on this genus, but I cannot perceive
in what the Conf. decorticans (Dillwyn) differs generically
from other Oscillatorice.

a. Filaments brittle.
1. OSCILLATORIA LIMOSA Ag.

Plate LXXI. Fig. 2.

Char. Filaments brittle, straight, large. Stratum rich dark
green, glossy, and gelatinous. Striae strongly marked and
close.

O. limosa Harv. Hook. Br. Fl. p. 374. ; Harv. Manual,
p. 162. (Not of Grev. Flor. Edin. p. 303. ; or Hook.
Scot. Fl. part ii. p. 79.)

Stratum of a rich dark and acruginous green colour, send-
ing out from its edges long radii equally or in bundles ; it is
also glossy, even in the dried state. Filaments when recent
of equal diameter, but in the dried condition they are seen to
be variously twisted and furrowed, and the striae to be much
less conspicuous. The furrowing and consequent irregularity
of diameter of the filaments in dried specimens, affords not
unfrequently a distinguishing character between nearly allied
species. Mr. Harvey remarks that this fine species is ap-
parently alluded to by Dillwyn in his description of Conferva

OSCILLATORIA. 247

fontinalis, t. 64. ; but the figure is more like O nigra. In
drying it adheres closely to paper. From O. major it differs
in the much greater diameter of its filaments, and darker
colour. It is therefore intermediate between these species.

2. OSCILLATORIA MUCOSA Hass.

Plate LXXI. Fig. 1.

Char. Stratum gelatinous, dark, aruginous green, glossy.
Filaments large. Striae subdistant.

Hob. Floating in a pond like a little dusky cloud ;
Stevenston : Rev. D. Landsborough.

This species agrees with the previous one in all its characters,
save in the arrangement of the striae. The filaments are of
the same diameter, of the same gelatinous habit, and present
the irregular and furrowed appearance when dried of O.
Umosa : the only difference between the two species is in the
striae, which are twice as distant in this as in O. Umosa.

The only specimen which I have seen of this species is
that sent me by the Rev. D. Landsborough. There can be
no doubt entertained of its distinctness.

3. OSCILLATORIA CINEREA Hass.

Plate LXX. Fig. 4.

Char. Stratum of a dull (Bruginous green colour. Filaments
large. Striae close, very evident.

Hob. In a pond on Stanstead Common, Essex.

This is a fine and well-marked species. The diameter of
the filaments is equal to that of the two preceding Oscilla-
torics, but they are infinitely less mucous, and the stratum
when dried is not in the least glossy, neither do the filaments
collapse or become wrinkled in drying, but preserve the same
equal diameter in the dried as in the recent state. The
species, judging from Carmichael's description, seems to
come near to the Oscillatoria littoralis of that observer.

B 4

248 OSCILLATORE.S;.

4. OSCILLATORIA TENUIS Ag.
Plate LXXII. Fig. 1.

Char. Stratum rich dark green, very thin, gelatinous, with
short rays. Filaments pale green, straight. Striae sub-
distant, evident.

Grev. Edin., p. 303. ; Harv. in Hook. Brit. Flor. 374. ;
Harv. in Manual, p. 163. O. limosa Hook. Scot. ii.
p. 79. Conf. limosa Dillw. t. 20. O. viridis Johnst.
Berw. Flor. p. 264.

Hab. Common in ditches.

" In muddy ditches, at first resting at the bottom, but gra-
dually rising in bullated strata to the surface, common ; stratum
extensive, glossy when dry, in which state it fully preserves
its colour. Filaments, of half the diameter of those of O. li-
mosa, pale green; striae distant and indistinct. It adheres
strongly to paper." — Harv. The stratum of this species
exactly resembles that of O. limosa, and the filaments, like it
also, contract somewhat in drying ; they arc, however, two
or three times smaller ; the striae more distant, and not so
strongly marked.

5. OSCILLATORIA CYANEA Ag.

Char. " Glaucous blue. Filaments simple, entangled, cylin-
drical, even, with a deciduous coat. Joints obsolete, about
as long as broad." — Sin.

Harv. Hook. Br. Fl. p. 374. Conferva cyanea, E. B.
t. 2578. ; Harv. Manual, p. 163.

Hab. Damp walls on the inside of several Suffolk churches ;
at Icklingham and Hengrave ; also in Lincolnshire : Sir
Thomas Gage, Bart.

" On the wall it is conspicuous for its light sky-blue colour,
like some sort of mucor. Under a high magnifier, and
when moistened, it is found to consist of minute, even, simple,
entangled threads, one five hundredth part of an inch in dia-

OSCILLATOKIA. 249

meter, coated with a frequently interrupted covering of a
dull glaucous green hue, under which the thread itself ap-
pears of a lighter glaucous bluish colour, very even in thick-
ness and surface, consisting of scarcely distinguishable joints,
about as broad as they are long." — Sm.

6. OSCILLATORIA ^EKUGESCENS Drum.

Plate LXXII. Fig. 2.

Char. Stratum of a fine deep green, highly gelatinous ; when
dried, cBruginous blue, and glossy. Filaments slender,
opaque green. Stride evident.

Drummond, in Ann. Nat. Hist. vol. i. p. 1. ; Manual of
Brit, Alg. p. 163.

Hob. Lakes of Glaslough, co. Monaghan, Ireland: Dr.
Drummond. Farnham : Mr. Jenner. Bottom of pools
near Stocket, Aberdeen : Dr. Dickie.

" Filaments exceedingly slender, opaque green ; conglom-
erated in large toughish glutinous masses, in sheltered, calm
situations, and rarely floating on the surface ; in more open
exposures, broken into innumerable fragments, and suspended
like cloudy flocculi in the water. Stria numerous, at dis-
tances of about half a diameter from each other. Oscillatory
movement often lively. Colour when dried, a beautiful
aeruginous blue ; adheres strongly to paper, exhibiting a glossy
surface. Filaments expanded by moisture so as to seem re-
cent, and sometimes resuming the oscillatory motion." —
Dr. Drummond.

This species may at once be distinguished when dried from
all others by the peculiarly dense and waxen appearance of
the stratum, which also exhibits numerous fissures. The fila-
ments are smaller than those of O. tenuis, and the striae closer.
They are likewise brittle, and when dried break up into very
short pieces, which are not of uniform diameter.

250 OSCILLATORE^E.

7. OSCILLATORIA PULCHELLA Hass.

Plate LXX. Fig. 5.

Char. Filaments thick, straight, brittle, vivid green. Striae

close, very conspicuous.

Hab. Bottom of pools near Stocket, Aberdeen: Dr.
Dickie. Cheshunt: A.H.H.

The filaments of this fine species are more robust than those
of O. virescens and the striae closer. The only other described
species with which it could be confounded is O. spadicea,
which it resembles in the closeness and strength of the striae ;
but the filaments in O. pulchella are rather finer and much
more brittle.

8. OSCILLATORIA VIRESCENS Hass.

Plate LXXI. Fig. 9.

Char. Stratum terrestrial, of a light aruginous green colour.
Filaments of considerable diameter, pale yellowish green
straight, brittle. Striae subdistant.

Hab. Cheshunt, Herts : A. H. H. Between River Head
and Chipstead, bankside : Mr. Jenner.

This would appear to be a distinct as well as a fine species.
The filaments are longer than those of O. tennis, and more-
over preserve their diameter in drying. Striae nearly a dia-
meter of the filaments apart, conspicuous.

9. OSCILLATORIA THERMALIS Hass.

Plate LXXII. Fig. 3.

Char. Filaments small, green. Striae straight, brittle, sub-
distant, very evident.

Hab. In a stream of hot water, Stevenston : Rev. D.
Landsborough.

The filaments of this species are as slender as those of O.

OSCILLATORIA, 251

terebriformis, but of a different colour, and the strife are much
more evident.

10. OSCILLATORIA SPLENDIDA Grev.

Plate LXXII. Fig. 8.

Char. Stratum bright ceruginous or bluish green, thin, with
short rays. Filaments arachnoid, straight or curved,
Striae wholly invisible.

Grev. Flor. Edin., p. 304. ; Harv. Br. Flor. 375. ; Harv.
Manual, p. 164. O. membranacea, O. amphibia and
O. elegans Ag.

Hab. In tubs of water in the stove of the Botanic Garden,
Edinburgh : Dr. Greville.

This is the most slender of all the Oscillatorice. The
stratum exactly resembles in colour and appearance that of
either O. limosa or O. tennis, from which it may be imme-
diately detected by the microscope. Agardh has described
this species under no less than three different names, as I
have ascertained from an examination of authentic specimens
in the Herbarium of Sir "W. J. Hooker.

11. OSCILLATORIA AUTUMNALIS Ag.

Plate LXXII. Fig. 7.

Char. Stratum of a deep ceruainous green, with a metallic
lustre, very lubricous. Filaments very slender. Strise
subdistant.

O. autumnalis Ag. Syst. p. 62. ; Grev. Flor. Edin. p. 305. ;
Harv. 1. c. p. 376.; Harv. Manual, p. 165.

Hab. Appin : Carmichael.

, The filaments of this species are very slender, not being
more than twice the diameter of those of O. splendida. They
cohere closely, and are usually very much broken when ex-
amined under the microscope. Stride not very evident, sub-
distant.

252 OSCILLATORE*:.

12. OSCILLATORIA MUSCORUM Ag.

Plate LXXII. Fig. 12.

Char. Stratum dark ceruginous green, shortly radiating, creep-
ing over mosses. Filaments thickish, pale blue green.
Striae distant.

O. muscorum Ag. Syst. p. 375.; Harv. Hook. Br. Flor.
365. ; Manual, p. 164.

Hab. On Hypnum ruscifolium in rapid streams : Captain
Carmichael.

" Stratum three or four inches in extent, closely inter-
woven with the branches and leaves of mosses, of a bluish
green colour, and slightly lubricous. Filaments a line or two
in length, variously curved, and radiating. Striae at the
distance of a diameter from each other." — Carm. MS. Fila-
ments brittle, about equal in diameter to those of O. turfosa,
and when examined in the dried state, usually found to be
much broken up, with the striae all but invisible.

b. Filaments Jlexuous, coriaceous.

13. OSCILLATORIA CORIUM Ag.

Char. " Stratum thick, subcoriaceous, opaque, dull brownish,
streaked with pale green. Filaments yellowish, slender.
Striae indistinct, distant." — Harv.

O. corium Grev. Flor. Edin., p. 303. ; Harv. Hook. Br. Fl.
p. 377.; Harv. Manual, p. 166.

Hab. On the rocky bottoms of alpine rivulets.

" Stratum thick, tough, dull brownish ; occasionally
streaked with pale green, which in some varieties is the pre-
vailing colour, slightly glossy when dry; filaments slender.
In some situations it radiates in fascicles from its whole upper
surface ; in others, it is found almost denuded of radii, and
forming a compact leathery stratum." — Harv.

OSCILLATORIA. 253

14. OSCILLATORIA TURFOSA Carm.

Plate LXXII. Fig. 6.

Char. Stratum pale verdigris green, glaucous, with an ochra-
ceous substratum. Filaments slender, curved. Striae
distant.
O. turfosa Harv. in Hook. Br. Flor. ; Harv. in Manual.

Hub. On floating sods in old turf pits. Appin : Capt.
Carmichael. Near Dolgelley : Mr. Rolfs.

11 This species grows in a thick intensely green layer, over a
tough slimy ochre-coloured substratum. It entirely enveloped
the sods, some of which were a foot and a half in diameter.
Filaments very slender, more or less curved, and mostly hya-
line at the point." — Carm. MS. The filaments are nearly
equal in size to those of O. muscorum, from which, however,
they may be distinguished by their greater tenacity and
length. Sometimes the endochrome is discharged from a
portion of a filament.

15. OSCILLATORIA SUBFUSCA Vauch.
Plate LXXII. Fig. 9.

Char. Stratum dull greyish brown, somewhat streaked ivith
green ; soft, green, fragile. Filaments very slender.
Striae inconspicuous.

O. subfusca Vauch. Hist, des Conf. ; Lyngb., t. 26.;
Harv. in Br. Flor. 377.; Harv. in Manual, p. 166.

Hob. Rocks and stones in sub-alpine rivulets.

Stratum " soft, slimy, void of tenacity, wrinkled ; of a
dusky grey colour." — Carm. It differs from O. corium
" chiefly in being more gelatinous and fragile." — Harv.
The filaments are very slender, long, much curved. Striae
in the dried specimens wholly invisible.

254 OSCILLATOKEJi.

16. OSCILLATOKIA VIOLACEA Johnst.

Plate LXXII. Fig. 10.

Char. " Mass gelatinous, dark purple. Filaments very
slender} straight, without perceptible, transverse stria, laid
on a thin, compact, greenish substratum." — Johnston.

O. violacea Johnston, Berw. Fl. p. 264. ; Harv. in Hook.
Br. Flor. p. 377. ; Harv. in Manual, p. 166. Oscillatoria
rubiginosa Carmichael, MS.

Hab. Rapid streams near Berwick upon Tweed: Dr.
Johnston. On stones in the bottoms of rivers, co. An-
trim : D. Moore. Appin : Capt. Carmichael.

When dry, the filaments of this species assume a blackish
green cast, with an evident gloss. The filaments are thicker
than those of O. subfusca, but do not, like those of that spe-
cies, preserve their calibre in drying : they are also more
brittle. Striae in the dried specimens almost invisible, at a
distance usually of about two diameters from each other.
Dr. Johnston considers this to be the " Conferva mucosa con-
fragosa rivulis innascens " of Dillenius.

17. OSCILLATORIA RUPESTRIS Ag.
Plate LXXII. Fig. 11.

Char. Stratum blackish green, thick, opaque, extremely tough.
Filaments rigid, brittle. Striae almost imperceptible ', at
distances of about half a diameter.

Ag. Syst. p. 63. ; Harv. Hook. Brit. Fl. p. 377. ; Harv. in
Manual, p. 166. O. tenax Carm. MS.

Hab. On the precipitous face of cascades. Appin : Capt.
Carmichael.

" Stratum extensive, slimy, remarkably tough and elastic,
black on the surface, ash-coloured underneath: when dry
blackish green. Filaments pale green, straight, or variously
curved, radiating, but not equally in all directions." — Carm.
MS. The dried stratum of this species resembles in colour

OSCILLATORIA. 255

that of O. muscorum, than which, however, it is much more
tough and elastic : the filaments likewise are much smaller.
They are intermediate in diameter between those of O. sub-
fusca, and O. violacea, differing also from both in some other
respects. They are more brittle than those of O. subfusca,
though like those of that species they preserve their diameter
in drying, which is not the case with O. violacea. The striae
are close, and tolerably evident.

18. OSCILLATORIA SPADICEA Carm.
Plate LXXI. Pig. 5. and Plate LXXII. Fig. 5.

Char. Stratum very thin, spreading. Filaments yellowish
brown, thick, variously curved and twisted. Striaj con-
spicuous, and very close.

O. spadicea Harv. Hook. Brit. Fl. p. 378. ; Harv. in
Manual, p. 167.

Hob. On damp mossy earth ; rare. Appin : Capt. Carmi-
chael. Ireland : Mr. Moore. Cheshunt : A. H. H.

" It occurs in a very thin dark green stratum, spreading to
the extent of several feet, and is hardly to be distinguished
from the mossy earth on which it grows. Filaments short,
straight, curved, or spirally twisted, radiating in all directions,
and possessed of all the movements peculiar to the tribe." —
Carm.

c. Stratum blackish ; filaments brittle, not coriaceous.

19. OSCILLATOKIA NIGRA Vauch.

Plate LXXI. Fig. 3.

Char. Stratum black ; when dry bluish black, with long radii.
Filaments pale bluish green, thick. Stride very distinct
and close.

Hook. Scot. ii. p. 79. Conf. fontinalis Dillw. t. 64.
O. limosa, Grev. Edin. p. 303. O. nigra Harv. in
Manual, p. 165.

256 OSCILLATORE^S.

Hob. Ditches and ponds ; common.

" Stratum extensive, blackish, with a shade of green; when
dry, blue black, very rapid in its growth and sending out
long vividly oscillating rays. Dillwyn's figure of Conferva
fontinalis answers to this species pretty correctly." — Harv.

20. OSCILLATORIA CONTEXTA Carm.

Plate LXXI. Figs. 7. 4. 6.

Char. Stratum glossy black, strongly striated. Filaments
somewhat thick, pale green. Stria? subdistant, evident.

O. contexta Harv. Hook. Brit. Fl. p. 376.; Manual, p. 165.

Hob. On moist ground. Appin: Capt. Carmichael.
Cheshunt : A. H. H. Sussex : Mr. Jenner.

" Stratum of indefinite extent, three feet and upwards,
exceedingly thin, and peeling off in large flakes in dry
weather, of a deep but shining black colour, scored or striated
in all directions. These striae are caused by thick fasciculi of
filaments, shooting out either parallel to or across each other,
changing their course from time to time, and sending off la-
teral fasciculi. The filaments are rather thick, about a line in
length, straight, or variously curved, of a greyish green colour,
and they radiate with great rapidity. A portion of the stra-
tum, not more than a line in diameter, placed in a watch-glass
filled with water, overspread the whole area of t\c glass with
filaments in the course of a night." — Carm. MS. This is
a very distinct as well as fine species. The gloss of the stra-
tum is equal to that of satin, and the filaments are in calibre
not less than those of O. tennis, from which species it is dis-
tinguished chiefly by its colour. The filaments do not con-
tract in drying.

21. OSCILLATORIA CARMICHAELI Hnss.

Plate LXXI. Fig. 8.
( 'liar. Stratum black, destitute of gloss, thin, brittle. Fila-

OSCILLATORIA. 257

ments slender, straight, brittle. Striae subdistant, scarcely
perceptible.

O. nigra Carmichael, MS.

This species differs only from the following in the absence
of gloss on the filaments ; a difference which is, in all pro-
bability, of specific importance.

22. OSCILLATORIA TEREBRIFORMIS Ag.
Plate LXXII. Fig. 4.

Char. Stratum terrestrial, bluish black, glossy. Filaments
slender, straight, brittle. Striae scarcely evident.

O. terebriformis Ag.

Hab. Marshy places, Aberdeen, Nov. 1839 : Dr. Dickie.
Sussex: Mr. Jenner. Netting Hill: A. H. H.

A very abundant species.

23. OSCILLATORIA DECORTICANS Grev.
Plate LXXI. Fig. 10.

Char. " Stratum smooth, glaucous green, membranaceous.
Filaments very slender, curved, pale bluish green. Striae
distant" — Harv.

Grev. Flora Edin. p. 304. C. decorticans Dillw. t. 26. ;
Harv. Manual, 164.

ft corticola. — Stratum blackish green. See PI. LXXI. fig. 4.
O. corticola Carm. MS.

Hab. Damp walls, rotten timber, often on pumps, &c.
Common. — ft "on the trunk of an old sycamore where
the rain water trickled down : " Capt. Carmichael.

Stratum membranaceous, not very gelatinous, peeling off in
large flakes, and imperfectly adhering to paper ; filaments very
minute. I strongly suspect that the O. contexta of Carmi-
chael is identical with Greville's O. decorticans, the ft variety
is altogether different.

8

258 OSCILLATORE.&.

d. Filaments brown, brittle, not coriaceous.
24. OSCILLATORIA DlCKIEI HdSS.

Plate LXXII. Fig. 13.

Char. Stratum light chestnut, gelatinous, glossy. Filaments
long, straight, brittle, rather thick. Striae visible, sub-
distant.

Hob. Pools of fresh water near the sea, Aberdeen : Dr.
Dickie.

The colour of this species is so peculiar as at once to dis-
tinguish it from all others which have been described. This
colour is preserved in drying ; the filaments are of nearly the
same -diameter with those of O. tennis, but they preserve their
calibre when dried. Several fine specimens of this plant
were sent me by Dr. Dickie, and which have undergone no
change since they have been in my possession, now some
weeks.

e. Filaments collected into close erect tufts.

In the species of this division of the genus there would
appear to be an evident transition to Rivularia, the filaments
in one, O. lucifuga, and perhaps in the others, being subulate,
and which circumstance induced me, as well as its erect
habit, to place that species in the genus Rivularia. I am now
satisfied that it should either remain in the division of the
genus Oscillatoria in which it has been placed by Mr.
Harvey ; or that Kiitzing's Symploea ought to be adopted for
the reception of the species of this division of Oscillatoria.
Kutzing thus defines the genus :

Trichomata adscendentia vaginata in fascicules erectos, basi
confluentes, coalita ; vaginae ex membrana simplicima, hyalina,
(nee striatae nee lamellosae) formatae.

25. OSCILLATORIA FRIESII Ag.

Char. Stratum bright green, bristling with the elongated, erect,
tooth-like fascicles of filaments.

OSCILLATOR1A. 259

Scytonema Bangii Lyngb. Dan. t. 28. Oscillatoria Bangii
Carm. MS.; Grev. Edin. p. 303. Q. Friesii Harv.
Hook. Brit. Fl. 373.; Harv. in Manual, 162.

Hob. On mosses in shady subalpine situations, near Edin-
burgh : Dr. Greville. Appin : Capt. Carmichael. Kil-
larney : W. H. Harvey. Co. Kerry : Mr. Andrews.

" Stratum two or three inches broad, bright aeruginous
green. Filaments closely interwoven into erect, elongated,
tooth-like fascicles, an inch or more in height, pale green;
under the microscope annulated within, with a broad limb or
border. Well marked by its erect spinulose habit." — Harv
The filaments in the dried state are flaccid, long, and apparently
of equal diameter. Striae scarcely conspicuous, rather close,

26. OSCILLATOKIA LUCIFUGA Harv.

Plate LXV. Figs. 5, 6.

Char. Stratum blackish green, bristling with minute tooth"
like fascicles of filaments. Filaments subulate.

Calothrix lucifuga Carm. MSS. ; Harv. Hook. Br. Flor.
p. 373. ; Harv. Manual, p. 162.

Hob. " On the decayed trunk of an alder, lying in a ravine,
and buried under a heap of rubbish," at Appin : Capt.
Carmichael.

" Stratum spreading, dull, blackish green, bristling all over
with minute erect fascicles about one-third of a line high.
Filaments thickish, flexuous, strongly agglutinated together,
annulated within, pale yellowish. Almost like the last species
in miniature " (Harv.), of which it may be but a variety.

27. OSCILLATORIA TENUISSIMA Ag.

Char. " Dark green, ascending, tufted. Filaments simple,
cylindrical, even, without any visible joints." — Harv.

O. tenuissima Sm., Eng. Bot. t. 2584. ; Harv. in Hook. Br,
Fl. 373.; Harv. in Manual, p. 162.

260 OSCILLATOREJE.

Hob. In the celebrated warm waters of Bath, spreading
rather unequally in broad velvet-like patches, of a dark
green colour : Rev. H. Dames.

(t The irregularity of its appearance arises from the fila-
ments being collected together into little ascending tufts,
apparently rooted in the muddy deposit of the water. Each
tuft proves, on examination, to consist of simple uniform even
filaments, crowded together and quite pellucid, and equally
destitute of joints and branches : their diameter is not more
than the eighth or tenth thousandth part of an inch." — Sm.

30. MICROCOLEUS Desmar.

Char. Filaments simple, straight, brittle, closely striated, in
bundles, and enclosed within broad, membranous, and
branched sheaths, from the apices of which they protrude.

Chthonoplastus Kiitzing, Phyc. Gener. p. 197.
Derivation. From pucpos, small, and KO\SOS, a sheath.

This is an exceedingly beautiful and interesting genus ; the
younger branches or sheaths usually enclose but two or three
filaments, while the older contain as many as fifty or sixty :
it is difficult to conceive in what way the filaments become
multiplied within the sheath, unless it be by a longitudinal
division of them.

1. MICROCOLEUS REPENS Harv.
Plate LXX. Fig. 3.

Char. Fronds terrestrial, decumbent, radiating, branches diverg-
ing, curled and twisted, gradually tapering to the extre-
mity. Filaments large. Striae subdistant, evident.

Oscillatoria chthonoplastes ft Harv. in Hook. Br. Fl. ii.
p. 373. Oscillatoria repens Ag. Syst. p. 61. Conf.
vaginata, Eng. Bot. t. 1995. Vaginaria vulgaris Gray,
Br. Fl. i. p. 280.

'

MICROCOLEUS. 261

Hob. " On the naked soil by road-sides, frequent : "
Harv.

" This forms a dull green decumbent slimy stratum. The
frond consists of numerous curled branches, diverging from
a centre in a starry manner, and gradually tapering from a
broad base to a fine point, containing numerous deep green
filaments, which radiate and oscillate from the tips, and on
laceration issue in bundles." — Harv.

2. MICROCOLEUS ANGUIFORMIS Harv.
Plate LXX. Fig. 1.

Char. Filaments smaller than in the preceding species.
M. anguiformis Harv. MSS.
Hob. Saltwater marshes.

This, although a very distinct species, is a doubtful fresh-
water production, and perhaps had better to have been al-
together omitted from this work. The Alga of our salt-
water marshes require a separate study.

3. MICROCOLEUS GRACILIS Hass.

Plate LXX. Fig. 2.
Char. Filaments very slender.
Hob. Near Aberdeen: Dr. Dickie.

This is another salt marsh Microcoleus. I detected it
amongst some Alga sent me by Dr. Dickie. It is a distinct
and pretty little species.

" Plants, as well as animals, excite the curiosity and interest of the
observer, first, by diversities, which distinguish parts and properties and
species ; and by similitudes, which lead to the assemblage of species into
groups, or genera and classes, &c. : secondly, by grace or beauty of form
or colour ; thirdly, by analogies, or affinities of relation, traceable, more
or less remotely, throughout all the works of the Creator." — Duncan.

s 3

262

FAM. XIV. RIVULARE^:.

Char. Frond usually gelatinous, lubricous, and definite, in
which are embedded filaments often fiagelliform, simple, or
spuriously branched, kilted below, the hilts being formed
of an enlarged cell, connected to the filaments by a narrow
neck, and filled with endochrome. Sheaths in which the
filaments are enclosed, sometimes saccate below, above at-
tenuated and open.

No very exact observations have as yet been made upon
the reproduction of this family. Do not the enlarged cells
which terminate the base of the filaments correspond in
function with those of the Nostochinece f In the setigerous
elongation of the filaments a resemblance to Chcetophora is
manifested. Certain species exhibit a relation to the Scyto-
nemece.

31. RIVULARIA.

Section i. RIVULARIA Roth.

Char. Frond wart-shaped, rarely encrusting, coriaceous. Fila-
ments close, set firmly, adherent, spuriously branched,
radiating.

Linkia Lyngb.

1. RIVULARIA PISUM Ag.

Char. Frond globose, smooth, shining, dark green. Filaments
dichotomous, firmly united.

Harv. in Hook. Br. FL vol. ii. p. 392. ; Berk., Glean. Alg.
t 2. p. 2.

Hob. On aquatic plants in subalpine streamlets, Appin:
Captain Carmichael. Cheshunt Common : A. H. H.

RIVULARIA. 263

"Fronds a line in diameter, scattered or confluent, of a dark
green colour and fleshy firmness. Filaments radiating from
the base, dichotomously branched and alternate, the apices
free." — Carm. I have no hesitation in referring all the
British specimens which I have seen of this species to Rivu-
laria botryoides, and these again to R. granulifera, which spe-
cies I consider R. Pisum to be in the earliest period of its
developement, and Rivularia botry aides that species in the
middle period of its growth.

The following is Carmichael's description of R. botryoides,
which, like the preceding, is found attached to stones, &c., in
streamlets.

" Fronds about a line in diameter, hemispherical, wrinkled
and cartilaginous, scattered or running together like a bunch
of grapes. Filaments cohering firmly, obscurely striated,
dichotomous. Colour., when ' fresh, black ; on drying, darkly
ferruginous." — Carm.

2. RIVULARIA GRANULIFERA Carm.
Plate LXV. Figs. 1. 4.

Char. Frond large, convex, becoming hollow underneath,
fleshy, lubricous, brownish olive, often including stony
particles, never petrified. Filaments slender, firmly ad-
herent, furnished with a broad sheath.

Harv. in Hook. Br. Fl. p. 393. ; in Manual, p. 151.

Hob. On cliffs exposed to the trickling of water, common,
annual, Appin : Captain Carmichael. — Var. botryoides
in streamlets, attached to rocks and stones, co. Antrim :
Mr. Moore.

" Fronds from a line to half an inch in diameter, often con-
fluent, convex, and at length concave underneath, fleshy,
dusky olive green, and extremely slippery. Filaments rather
thick, repeatedly dichotomous. In the substance are gene-
rally enclosed a number of stony particles. This species
comes nearest in size and form to R. calcarea, but is never
like that petrified with calcareous matter ; and it is moreover

s 4

264 RIVULARE^:.

an annual plant, whereas the other exists for several years."
— Carm.

A microscopical examination of these two plants will not
only make it evident that the two are specifically distinct,
but also most probably generically so.

Section ii. RAPHIDIA Carm.

Char. Frond gelatinous, subglobose, bullated. Filaments
few, Jlagelliform, simple, moniliform within, scattered
through the gelatine, or radiating from a central point.

1. RAPHIDIA ANGULOSA Hass.
Plate LXIV. Figs. 1. 4.

Char. Fronds gregarious, roundish, gelatinous, hollow, of a
bright chestnut colour when recent, changing to dark olive
in drying. Filaments large, often produced into a long
and curved setigerous point. Sheath broad, often angular.

Rivularia angulosa Roth, Harv. in Hook. Br. Fl. p. 394.;
and in Manual, p. 153. Ulva pruniformis, E. B. t. 968.
Raphania natans Carm. MSS. cum icone.

Hob. Attached to aquatic plants in ponds and still waters,
or floating on the surface, Appin : Captain Carmichael.
In a pond on the common east of Lewes and Burwash
Road, near Easton Green : W. Borrer, Esq. Swansea :
Mr. Rolfs. Cheshunt Marshes : A. H. H. Near Cas-
cades, co. Antrim : Mr. Moore.

" Fronds gregarious, often confluent, one fourth to three
fourths of an inch in diameter, roundish, gelatinous, vesicular,
and when detached, rising to the surface of the water with
the velocity of an air-bubble. Filaments at the distance of 4
or 5 diameters from each other, radiating in all directions from
the centre of the vesicle ; rising from a colourless globule,
inflated for about one-third of their length, thence tapering to
a long slender often curved point. Internal mass mouiliform,
occupying about one half the diameter of the inflated part of

RIVULARIA. 265

the filament. Colour pale chestnut, inclining to olive." —
Carm.

2. RAPHIDIA VIRIDIS Hass.
Plate LXIV. Figs. 3. 2.

Char. Frond very mucous, soft. Filaments small, elongated.
Sheath not evident.

/3 marginata. — Filaments rather smaller. Sheath evident.

Hob. Near Manchester : Mr. Sidebotham. Aberdeen :
Dr. Dickie.

This Raphidia is very distinct. It was sent me by Mr.
Sidebotham of Manchester put up in fluid. The filaments
are not one half so large as those of R. angulosa, but much
longer ; the sheath in it could not be detected. In the variety
/3 the sheath was quite apparent, and I at first was induced to
regard it as altogether different : it is safer however to consider
it merely as a variety of R. viridis, or as that species in its
perfect condition, the sheath in the specimen sent by Mr.
Sidebotham, and which had been put up some time in fluid,
having probably become decomposed.

Section iii. LITHONEMA Hass.

Char. Fronds indefinite, truly ramose. Bases of the fila-
ments not manubriated. Filaments petrified.

Derivation. From \i0os, a stone, and vrjfMi, a thread.

1. LITHONEMA CALCAREUM Hass.
Plate LXV. Fig. 2.

Char. Fronds large, orbicular, convex, afterwards aggregated
into a broad spongy crust zoned within, at length petrified.
Filaments slender, adherent, and dichotomously branched.

R. calcarea Sm., E. B. t. 1799. ; Harv. in Hook. Br. Fl.

p. 392. ; also in Manual, p. 150.
Hab. On rocks and stones in streamlets and the borders of

subalpine lakes.

266 RIVULAKE^C.

" Fronds one fourth or half an inch in diameter, circular or
slightly convex, sometimes greenish, but oftener of a dark
chestnut colour. After a time, they run together into a flat
spongy crust, of indefinite size. On the smooth face of a
rock exposed to the trickling of water, I found a sheet of it
upwards of a foot in diameter. When broken the crust ap-
pears zoned within, so as to indicate the age of the plant,
each zone being equal to a year's growth. At this age, it is
always more or less stony, from the absorption of calcareous
matter." — Carm.

2. LlTHONEMA CRUSTACEUM HdSS.

Plate LXV. Fig. 3.

Char. Crust very thin, widely spreading. Filaments attenuated
at the base, fastigiately branched above the middle.

Rivularia Crustacea Carm. MS. R. Crustacea Harv. in
Hook. Br. Fl. p. 393. ; also in Manual, p. 151.

Hob. On rocks exposed to the spray of cascades, in the
hill streams at Appin : Captain Carmichael.

" Crust of no determinate extent, extremely thin and slimy,
black. Filaments one fourth of a line in length, attenuated
at the base, fastigiately branched above the middle of an
olive green colour." — Carm.

This species, although decidedly congeneric with L. calca-
reum, may at once be distinguished from it by vhe fastigiate
division of its filaments.

" If you detect any mistakes of mine, I rely on your superior know-
ledge to excuse them; for who has ever avoided errors in the wide-
extended field of Nature ? Who is furnished with a sufficient stock of
observations ? I shall be thankful for your friendly corrections, I have
done what I could myself." — Linnaeus to Holler.

267

FAM. XV. NOSTOCHINE.E.

The Nostochinece form one of the most natural and beauti-
ful of the families of freshwater Alga. The filaments are
simple, of uniform diameter, elegantly moniliform, resembling
strings of pearls, in the highest degree flexible, and of ex-
ceeding lubricity. The species of which it is composed
naturally arrange themselves into two divisions : in the one
the filaments are free, and in the other imbedded in a mucous
matrix, which sometimes assumes a definite form.

At intervals, in the course of the filaments, are observed
cells larger than those which compose the thread itself: these,
in the genus Anabaina are more or less of an oval or elongated
form ; while in the genus Nostoc they are exactly spherical.
They are generally supposed to be connected with reproduc-
tion ; but hitherto no precise observations have been made
upon them. In most, and perhaps in all the species of Nostoc,
many of these enlarged cells are scattered singly and de-
tached throughout the mucous matrix : they have doubtless
become separated from the filaments of which originally they
formed a link.

If a Nostoc in the first period of its developement be ex-
amined, it will be observed to consist of a single moniliform
thread, short, and but little curved, immersed in a mucous
nidus. In each of the fully developed specimens of most of
the Nostocs, however, threads innumerable present themselves.
Now the question arises, in what way are those threads mul-
tiplied ? First, and chiefly I conceive, by the separation or dis-
location of the enlarged cells, whereby each filament is divided
into other shorter filaments ; and in the second place, probably
by the growth of those vesicles themselves ; but on this point
nothing positive is known. Independently of these two modes
of multiplication of the threads in each frond, no other con-
ceivable method exists. The filaments in every example of a

268 NOSTOCHINE^.

true Nostoc, whether young or old, present one uniform dia-
meter ; there are no gradations of size. It cannot therefore be
supposed that the threads are increased in number by the
effusion of the minute contents of the cells.

The multiplication of the threads in a frond having been
as it seems to me satisfactorily accounted for, the manner of
the formation of new fronds remains to be determined. When
a Nostoc has arrived at the full and last period of its develope-
ment, the pellicle formed by the inspissation of the mucous ma-
trix bursts : the mucous contents and the filaments are effused :
these last become disarticulated, so as to form short fragments,
each of which retains about it a portion of mucus, so that in
this state it corresponds with a Nostoc in the first period of its
developement. In this mode of multiplication, remarkable as
it is, there is nothing generically peculiar. A Conferva multi-
plies itself occasionally by the disarticulation of the filaments.
The only difference between the case of the Nostoc and the
Conferva is, that the process in the first is natural, and in the
second artificial. While, however, the separation of the pri-
mary filaments accounts amply and satisfactorily for the mul-
tiplication, not only of the threads of a frond, but also for
the increase of a number of the fronds themselves, it falls
short of explaining the first developement of the first thread.
The species of the genus Nostoc, like the freshwater Alga in
general, are short-lived : in the course of a few months they
pass through the stages of their developement ; they die, dis-
appear ; the filaments themselves are destroyed ; arid then are
seen no more until the advent of another season. It is plain,
therefore, that the true mode of reproduction of the species of
this family is something more than a mere separation of the
filaments into fragments. It is now, that in my view we
learn the real nature of the enlarged vesicles : these are the
true reproductive bodies, at the season not proper for their
developement, lying concealed in the earth, awaiting their
appointed time to start into growth, activity, and life —
all else of the plant, the mucus and the filaments, utterly
perishing.

In the " Annales des Sciences Naturelles," third series,

NOBTOCHINE^E. 269

tome ii., there are some interesting observations on the re-
production of Nostoc verrucosum by M. Gustave Thuret, of
whose accurate and skilful researches I have already had oc-
casion to avail myself in the Introduction.

" When the plant has arrived at its full developement, the
external pellicle, formed by the thickened mucilage, breaks,
and permits the escape of the green jelly, which is composed
of mucilage and threads. These last scatter themselves in the
water the more easily, that they are endowed at that time with
a spontaneous motion, analogous to that of the DiatomacecK.
This curious phenomenon has been already observed by
Vaucher, who believed he had found it, although much more
evident in all the other Nostocs. In spite of the assertion of
that conscientious observer — in spite of the earnestness with
which he sought to generalise this fact (Hist, des Tremelles,
p. 215. et suiv.), it is difficult to compare movements at least
equivocal, with mobility so evidently spontaneous, which the
threads of the Nostoc verrucosum possess. Perhaps it is not
without some interest to remark on this subject, that the
spontaneous movements, the locomotion, are again met with
under different forms, in the Algce, which, like the Nostocs,
live in running waters — in the Oscillatoria, in the spores of
Vaucheria, the Confervece, &c., and that this faculty appears
to be a condition of their station.

" To observe well this phenomenon in the Nostoc verru-
cosum, the most simple way is to place in a plate filled with
water some fine specimens freshly gathered. At the end of
two or three days the external skin breaks, the threads ex-
pand in the water, and form at the bottom of the plate, or
on the surface of the liquid, a green scum, nearly like that
of the Oscillatoria. If then you have recourse to the mi-
croscope, you observe that the threads, originally very long,
and winding in a thousand ways, are divided into a number
of fragments of unequal lengths, all nearly straight, or
scarcely bent, which move in the direction of their lengths,
and seem to creep upon the surface of the object glass. The
larger globules are detached and immoveable ; no increase
of magnifying power or mode of clearing, no re-agent, no

270 NOSTOCHINE^E.

coloured infusion betrays the presence of vibratile ciliae;
and we cannot believe that the threads turn on themselves,
because the granulations of the green matter do not change
place during the progression. I have seen threads of
three seeds move, but never a single seed. If you continue
to observe for some days, you will see the thread become
immoveable, increase in size, at the same time develope the
mucilage with which they are surrounded as with a transparent
sheath. Soon the seed enlarges considerably, and divides to
form two others, but sideways, and not in the direction of
the length of the threads.

" This formation is repeated many times, and it would seem
natural to seek in this circumstance the origin of new
threads. Unfortunately the increase of the number of grains,
by diminishing the transparency, prevents one following the
increase with the same facility. Their confused mass fills
entirely the young Nostoc, which is developed in a very irre-
gular manner, and takes a variety of forms. It is but later
when the mucilage is most abundant, when the seeds are less
crowded in the interior of the Nostoc, that you begin to
distinguish the threads."

The Nostochinece of the first section are mostly of a lively
and exquisitely delicate green colour. They are wonder-
fully prolific, increasing to such an extent frequently as to
impart their beautiful colour to extensive tracts of water,
as also do occasionally certain species of Oscillator-ice. One
species described by Mr. Thompson, Anabaina f tpiralis, and
which I have named in honour of its discoverer, Spirillum
Thompsoni, imparted its colour to the entire of an extensive
lake, Ballydrain, which extends over about twenty acres of
ground near Belfast* The Oscillatoria cenigescens of Drum-
mond in like manner imparted its rich green colour to an
extensive lough in the north of Ireland, Glaslough, whose
waters seemed greened as though by the reflection of trees, f

* For an interesting paper, by Mr. Thompson, on this Alga, see
" Annals of Nat. Hist." vol. v.
See Annals Nat. Hist. vol. i.

NOSTOCHINE^. 271

Leaving the limits of our own country, MM. Engelhardt and
Treschel have described a minute Alga, which they have named
Oscillatoria rubescens, and which tinges with a red colour
the lake of Morat, in Switzerland, assuming sometimes a
very beautiful arrangement, depending upon the motion of
the water in which it is immersed.*

But it is not in fresh water merely that the productions of
this family are found; they likewise have been noticed to
occur in vast quantities in the sea, in different parts of the
world ; and it has been ascertained that the Red Sea owes its
name to the periodical developement of a species of this
family, the Trichodesmium Ehrenbergii Montagne. The
name of Ehrenberg has very properly been appended to
this species by Dr. Montagne, that illustrious naturalist
being not merely the first to describe the species, but also
the first to discover and record the important and wonderful
fact that to a production in its individual parts so minute and
insignificant, the Red Sea owes its name and appearance.
This interesting discovery, however, of Ehrenberg was for
many years overlooked, the account of it having been pub-
lished in a work not devoted to natural history, but to
chemical science, " Annals of Poggendorf." The following
translation cannot fail to interest : —

" During the year 1823," observes M. Ehrenberg, " I made
a stay of many months at Tor, upon the borders of the Red
Sea, close to Mount Sinai. On the 1 Oth of December I there
saw the surprising phenomenon of the^blood-red colouration
of all the bay which forms the port of that city. The high
sea, without the boundary of the corals, preserves its ordi-
nary colour. The short waves of a tranquil sea bring upon
the banks during the heat of the day a mucilaginous matter
of a blood-red colour, and deposit it upon the sand, in such a
manner as that in the course of a good half hour all the bay
with the receding tide is surrounded with a red border of many

* Notice sur la matiere qui a colore en rouge le lac Morat, en 1825, par
De Candolle, dans les Memoires de la Societe de Physique et d'Histoire
Naturelle de Science, 1825, vol. ii. with fig.

272 NOSTOCHINE^E.

feet in depth. I removed from the water some specimens with
glasses, and carried them to a tent which I had near the sea.
It was easy to perceive that the colouration was due to little
tufts, scarcely visible, often greenish, and sometimes of an
intense green, but for the most part of a deep red : the water
upon which they floated was always colourless. This very
interesting phenomenon, sufficient to afford a reason for the
etymology of the name which this sea has received (an ety-
mology up to the present time always buried in complete
obscurity) — attracted all my attention, and I examined it at
leisure with all the care of which I was capable. During
many days I observed also the colouring matter with the
microscope : the tufts were formed of little bundles of fila-
ments of an Oscillatoria ; they were fusiform and elongated,
irregular, having rarely more than the diameter of a line,
and were contained in a sort of mucilaginous sheath; but
neither the filaments taken separately in each fleece, nor
the fleeces themselves resembled each other. When the
sun shines in the horizon, I observed, moreover, that these
last maintained themselves upon the surface of the water
in the glasses which I had brought with me, and that
during the night, and when I shook the vessel, they reached
the bottom. Some time afterwards they remounted to the
surface.

" The phenomenon of the Red Sea was not permanent, but
periodical. I observed it three other times, the 25th and
30th of December, 1823, and the 5th of January) 1824."

The same phenomenon of the colouration of the Red Sea,
although on a scale infinitely more surprising, has occurred
also more recently to other observers, especially to M. Evenor
Dupont, a very distinguished advocate of the Isle of Mau-
ritius, who also accurately determined, as did Ehrenberg
previously the cause of this colouration, although he had no
knowledge but that the discovery was entirely new to sci-
ence, and which he found to be an Alga, which Dr. Montagne
has ascertained to be identical with that described by the
Prussian naturalist.

The letter of M. Evenor Dupont is so very circumstantial

NOSTOCHINE^E. 273

and satisfactory, and corroborative of Ehrenberg's account,
that its introduction cannot but be approved of. It is ad-
dressed to his friend M. Isidore Geoffroy-Saint-Hilaire.

" My dear Friend,

" You demand of me certain details in reference to the
circumstances in which I gathered the Cryptogamic plant
which I sent you from the Red Sea, and which you told me
appeared a new species. They are as follow : —

" The 8th July last (1843) I entered into the Red Sea
by the Strait of Babelmandel upon the steam-boat the At-
alanta, belonging to the Indian Company. I demanded of
the captain and the officers, who for a long time navigated in
these latitudes (parages) what was the origin of this ancient
name of the Red Sea ; if it was owing, as some have pre-
tended, to sands of that colour, or, according to others, to
rocks. None of these gentlemen could reply to me; they
never, they said, remarked any thing to justify this denomi-
nation. I observed then for myself as we advanced : whether
the ship approached by turns the Arabian coast or the African
coast, the red was in no part apparent. The horrid moun-
tainous barriers which border the two banks were uniformly of
a blackish brown, except where in some places the appearance
of an extinct volcano had left long white streams. The
sands were white, the reefs of coral were white also ; the sea
of the most beautiful caerulean blue. I had given up the
hope of discovering my etymology.

" On the 15th of July the burning sun of Arabia awoke
me suddenly by shining all at once, from the horizon without
spot, and in all its splendour. I turned myself mechanically
towards the window of the poop to seek a remnant of the
fresh air of the night before the ardour of the day had de-
voured it. What was my surprise to behold the sea tinted
with red as far as the eye could reach ! Behind the ship,
upon the deck, and on all sides I saw the same phenomenon.

" I interrogated the officers anew. The doctor pretended
that he had already observed this fact, which was, according
to him, produced by the fry of fish floating on the surface ; the

274 NOSTOCHINE-ffi.

others said that they did not recollect having seen it before.
All seemed surprised that I should attach such interest to it.

" If it be necessary to describe the appearance of the sea, I
should say that its surface was covered with a compact stratum
of but little thickness, but of a fine texture, of a brick red,
slightly tinged with rouge ; sawdust of this colour, of ma-
hogany, for example, would produce very nearly the same
effect. It seemed to me, and I said at the time, that it was
a marine plant. No one seemed of my opinion ; so with a
pail tied at the end of a rope I was able to gather, with one
of the sailors, a certain quantity of the substance : this with
a spoon I introduced into a white glass bottle, thinking
that it would be the better preserved. The next day the
substance had become of a deep violet, and the water had
taken a pretty pink tinge. Fearing that the immersion
would hasten the decomposition instead of preventing it, I
emptied the contents of the bottle upon a piece of cotton (the
same which I remitted to you). The water passed through it
and the substance adhered to the tissue. In drying it became
green, as you actually saw it. I ought to add, that on the 15th
of July we were by the side of the town of Cosseir ; that the
sea was red the whole day ; that the next, the 16th, it was the
same until near mid-day, the hour at which we found ourselves
before Tor, a little Arabian village, the palms of which we per-
ceived in an oasis on the border of the sea, below the chain of
mountains which descends from Sanai, even to the sandy shore.
A little after mid-day, the 16th, the red disappeared, and the
surface of the sea became blue as before. The 17th we cast
anchor at Suez. The red colour had consequently showed itself
from the 15th of July, towards 5 o'clock in the morning, up
to the 16th, nearly an hour after mid-day; that is to say,
during thirty-two hours. During this interval the steam-
boat, making eight knots an hour, as said the sailors, had
traversed a space of 256 miles, or 85 leagues and a third.

" In the different works relative to Egypt and the Red Sea
which I have had occasion to read, I do not recollect to have
found mention made of a similar fact : it appears to me,
nevertheless, but little probable that it has not been ob-

NOSTOCHINEJE. 275

served by others. I reproached myself for not having ques-
tioned the Arabian pilot whom we had on board, and who
for twenty years traversed that sea. This idea unhappily
presented itself too late.

" If it should be in your opinion worth the pains, I would
demand new observations of the surgeon or officers of the
Atalanta, for it would be easy for me to write to them by
way of Alexandria.

" Believe me, my dear Geoffroy, &c.

" EVENOB DUPONT."

Numerous other navigators and naturalists have noticed the
colouration of different portions of the ocean, but these for
the most part have not determined the exact nature of the
cause, most of them attributing the phenomenon to minute
animals. Crustacea and Molluscce. Two English naturalists,
in describing it, have distinctly stated the cause to be an
Alga, the species of which, however, they did not determine.
The first of these, Mr. Darwin, observed the phenomenon
in the Atlantic ocean near Brazil, and not far from the Isles
of Abrolhos. The other, Dr. Hinds, of H. M. ship Sulphur,
encountered the same Alga at the same spot in which it was
originally discovered by Mr. Darwin, and again observed it
in the month of April 1837, while at anchor at Liberty, near
San Salvador, upon the western coast of America, latitude
14° north. Mr. Hinds on both occasions remarked that the
plant emitted a strong and penetrating odour, and many
persons on board experiencing an irritation of the eyes, fol-
lowed by an abundant secretion of tears, attributed the af-
fection to the presence around the ship of the Alga. Mr. Hinds
took the precaution to preserve specimens of his plant, some
of which were entrusted to Mr. Berkeley for publication,
who forwarded them to Dr. Montagne, who ascertained that,
though belonging to the genus Trichodesmium, the plant was
specifically distinct therefrom, and named it T. Hindsii.

I have been led, in having introduced the above account of
the colouration of the waters of the sea, to depart from the
strict limits of this work. The phenomenon is, however, so

T 2

276 NOSTOCHINE^E.

analogous to what has been observed, though of course on a
scale much smaller in portions of freshwater, that the one
can scarcely be considered complete without a reference to the
other, and both are of the highest interest. In the " An-
nales des Sciences Naturelles," 3d Series, t. ii., there is an
able and elaborate memoir by Dr. Montagne, one of the first
Cryptogamic Botanists of Europe, " Sur la Phe*nomene de
la Coloration des Eaux de la Mer Rouge," which contains
a great number of references to works in which mention
has been made of the phenomenon of the colouration of the
sea.

The sudden and periodical colouration of vast extents of
the sea, has been, to uninformed minds, in early times, a sub-
ject of superstition and dread, these appearances having been
regarded by the ignorant as Divine manifestations of anger
or impending calamity ; and that they should have been so
regarded in days in which natural science was all but un-
known, is scarcely surprising. The true explanation of the
cause of these sudden and remarkable appearances, while it
removes all feelings of superstition or dread, does not banish
those of amazement and admiration which indeed supplant
them.

The following appropriate observations in the memoir of
Montagne, already referred to, occur : —

" The singular phenomenon of the colouration produced on
the surface of the Red Sea, — a colouration in which we
have seen the waters themselves do not participate, has
been, each time that it occurs, a new subject of astonish-
ment for the people who have witnessed it. It cannot be
doubted, moreover, that the jugglers and charlatans, after
having probably calculated in advance its periodical return,
made use of it to govern the multitude by the menace
of an approaching calamity, of which they failed not to pre-
sent this sign as the undoubted precursor. It is also to a
cause, if not altogether similar, at least very analogous, that
is to be attributed, according to many naturalists, in the
number of whom figures M. Ehrenberg, those rivers, waters,
and lakes changed into blood in one of the plains of Egypt, —

SPIRILLUM. . 277

an explanation which M. Morren considers somewhat hazard-
ous, although not improbable. As to the phenomenon of the
Red Sea, by the fact that its extent has impressed apon it a
character of majesty calculated to affect strongly the imagin-
ation of the vulgar, it ought to produce still more sensation.
Since now we know the origin of it, if we compare together
the immensity of this phenomenon, and the infinite smallness
of the being which produces it, one cannot divest oneself
from a profound sentiment of admiration for the Omnipotence
which effects such great ends with such feeble means."

Section i.
Filaments not enclosed in gelatine of a definite form.

32. SPIRILLUM Ehr.
Char. Filaments spiral, ceruginous green.

1. SPIRILLUM JENNERI Hass.
Plate LXXV. Fig. 5.

Char. Filaments rather thick, each being usually composed of
about eight or ten regular spiral coils. Striae distant, per-
ceptible.

Hob. Tunbridge: Mr. Jenner.

This is the finest species of the genus. I have not seen a
pure specimen, those sent me by Mr. Jenner being mixed
up with different species of Oscillatorice.

2. SPIRILLUM RUPESTRE.
Plate LXXV. Fig. 6.
Char. Filaments slender, regularly spiral.
Oscillatoria spiralis Carm.

Hab. On rocks by the seaside where the birds are in the
habit of resting, Appin : Capt. Carmichael.
T 3

NOSTOCHLNE.&.

" It spreads over the dry naked earth. Stratum several
feet in extent, firm, coriaceous, of a glossy black colour, void
of lubricity. Filaments about half a line in length, twisted
like a corkscrew, radiating in all directions." — Carm.

When dried, the filaments lose their regularly spiral
character.

3. SPIRILLUM MINUTISSIMUM Hass.

Plate LXXV. Fig. 8.

Char. Filaments excessively small, describing usually about
three turns.

Hab. Ireland : Mr. Moore.

This exceedingly minute species I received from Mr. Moore.
The spiral character of the filaments is retained in drying,
which is not the case in the previous species. I was much sur-
prised to notice, when examining a portion of a specimen
which had been preserved for a considerable time, that the
filaments were in lively movement, turning round and round
repeatedly, and with exceeding rapidity.

4. SPIRILLUM THOMPSON i Hass.

Plate LXXV. Fig. 7.

Char. Threads rather large, moniliform. Globules of equal
size throughout their entire length.

Anabaina f spiralis Thompson, Annals of Nuc. Hist. vol. v.
Hab. Ballydrain Lake, near Belfast : Mr. Thompson.

" The specimens obtained were invariably of similar
breadth, and rarely presented more than four spiral turns, and
when of this size were one fiftieth of an inch in length. The
species at first, when mingling with the water, is of a dark
green colour ; when in calm weather it ascends to the surface
in separate particles, it appears pale green ; when it does so
en masse (the earliest symptom of decay), it is of a pale blue ;
and in the last stage of decomposition, ferruginous. Having
on the 27th September brought home in several phials spe-

APHANIZOMKJSON. 279

cimens of what I had presumed to be this plant in all its
stages (i. e. from its first to its last appearance as a colouring
matter), I was much pleased to have the conjecture verified
by microscopical examination. A portion taken from the
surface when it appeared pale green was, under the mi-
croscope, of as dark a hue as in July, whilst the blue and fer-
ruginous colours exhibited different stages of decomposition.
When in the most perfect state in which the plant has
occurred to me, the globules appear entirely filled with
granules ; but when very highly magnified are each found to
be surrounded by a hyaline membrane. The blue and ferru-
ginous tufts exhibited generally its empty globules and the
escaped granules scattered all about; but the former were
seen in every state from full to empty ; some had granules
only in the centre, others were half full, and some separate
globules were entirely filled with the granular mass.

" When two of the spiral portions come in contact, they
have an elastic power, by which they can, though slowly,
disentangle themselves and separate from each other, a fact
which I witnessed in various instances ; but under such cir-
cumstance only did I ever perceive any motion in this Alga."

" In some respects the Anab. spiralis resembles the Anab.
impalpabilis Bory, as described in the " Encyclopedic Metho-
dique ; " but its dull green unlustrous hue on paper is quite
opposed to that of the species just named, which is described —
Preparee sur le papier, ou on a facilite son developpement,
elle est de la teinte la plus brillante, tirant sur celle de 1'oxide
du cuivre, et luisant comme si on 1'eut enduite d'eau de
gomme." Besides, were this species of the exact spiral form
of that under consideration, this character would not I con-
ceive have been unnoticed in the description." — Thompson.

33. APHANIZOMENON Morren.

Char. " Filaments simple) cylindrical, flexile, membranaceous,
glossy, articulated, cohering together in fiat lamella1,, lance-
olated at the apex, straight, or here and there inflated, full
of green matter, oscillating spontaneously, falling into
pieces." — Morren.

T 4

280 NOSTOCIIINE^E.

Derivation. From a/favi^o^evov, a vanishing thing.

" It is evident that this genus unites the true Conjugates
to the Zygnemata by a union well marked in the latter, but
being a simple soldering in the Aphanizomena : it relates the
Conjugates with the Laminarice of the sea by the form of the
lamella, which results from the soldering of the threads : it
establishes an analogy between the OscillatoricB and the Con-
fervas, by demonstrating that a movement of reptation, of
swimming, or of oscillation, may appertain also to the organi-
zation as of the Conferva as to that of the OscillatoricB, in
which the characters of animality are supposed to be recognised:
the inflated vesicles unite the Aphanizomena to the Conferva
vesicata of Agardh, and the cells as well as the organization
of the threads themselves maintain with the true Confervce
relations so clear, that it would be improper to place other-
wise than amongst them this new genus." - - Morren.

The true position of the genus is undoubtedly amongst the
No&tochinecB, uniting them with the OscillatoricB. The ana-
logies indicated by Bory are more imaginary than real.

1. APHANIZOMENON INCUKVUM Morren.
Plate LXXVI. Fig. 6.

Char. Lamella plain, whitish green, incurved. Threads
cohering. Cells from two to eight times as long as broad.

Morren, in memoir read before the Royai Academy of
Brussels, in Dec. 1839: Thompson, in Annals of Nat.
Hist. vol. v. p. 82. ; Harv. in Manual, p. 145.

Hab. In sheltered creeks, floating on the surface ; Bally-
drain Lake : W. Thompson, Esq. Grand Canal docks,
near Dublin : Professor G. J. Allman. In the pond of
the Dublin Zoological Gardens : Miss Ball.

" Towards the middle of the month of May, up to July, the
waters of the lakes, the ponds, and the basins which surround
the country houses in Flanders are noticed to present tufts
of a whitish green, and of a size which varies from that of a

ANABALNA. 281

little pea to that of a melon. These tufts, which appear afar
off cloud-like, are placed at a distance, the one from the other.
One would consider them immovable ; but seen nearer, they
enjoy a veritable power of locomotion which allows of their
being met at all heights in the waters. I have observed this
year again a prodigious quantity of it at Gentbrugghe, near
Gand." — Bory.

Mr. Thompson, who was the first to notice in Ireland this
species, observes, in his remarks on it in the " Annals of Natural
History," loc. cit. — " In Ballydrain Lake I have, both in 1838
and 1839, remarked its presence on very calm days, for it is
only at such times visible during the month of July, August,
and September, and then it appears in the most sheltered
creeks only, floating in patches of various dimensions."

It has not yet been found in Great Britain.

34. ANABAINA Bory.

Char. " Filaments frequently elegantly moniliform, curved,
invested with mucous matter, and having a vermicular
motion resembling that of worms." — Bory. Reproduction
consisting of sporules contained in enlarged cells, the form
and size of which varies according to the species.

Derivation. From ava, up, and ftcuva), to mount.

" Their movement exhibits a relation with that by means
of which the earthworms move from place to place ; they are
progressive, and the curves which they describe are of extreme
slowness. It is by this ambulatory faculty principally that
the aquatic species elevate themselves to the surface of the
water, traversing the length of Conferva and the remains of
vegetables, mount to the surface of reeds and carices, pene-
trate the slime and the Oscillatorice, which they surmount in
such a way that they merit the uame derived from the
Greek, by which we have proposed to designate them."

The remarks of Bory in the above quotation appear to me to
be somewhat fanciful and overstrained. I much doubt whether
this mounting upwards of the Anabaina partakes in any de-

282 NOSTOCHINE.E.

gree of a voluntary character, and whether the explanation
given of the elevation to the surface of the waters of almost all
the Confervas is not sufficient to account for that of the Ana-
baincB. The explanation alluded to is the fact that during
respiration a gas is eliminated, the globules of which be-
coming entangled in their filaments, renders them specifically
lighter than the water, and so causes them to ascend.

1. ANABAINA FLOS-AQILE Bory.
Plate LXXV. Fig. 2.

Char. Filaments large, beautifully moniliform, and variously
curved. Reproductive cells numerous, elongated, and for
the most part curved.

Nostoc Jlos-aqutB Lyngb., Dan. p. 201. t. 68. Anabaina
Jlos-aquoK Bory ; Hudson, Flor. Ang. p. 604. ; Light.
Scot. p. 999.; Harvey in Manual, p. 186.

" This species attracted my attention when tinging with
its delicate green hue the margin of the smallest (?) of the
lochs Maben- in Dumfries-shire, or that nearest to Jardine
Hall (on the road from the village of Lochmaben), as I drove
thither on the 15th of August, 1838. The day was calm and
bright. My specimens tinge the paper with a verdigris
colour, and are quite dull, or wanting in any lustrous ap-
pearance. This species is introduced here on account of its
having been erased of late years from the British Flora.
Hudson and Lightfoot included it without assigning to it
any British station or locality." — Thompson. The repro-
ductive cells, which, as noticed in the definition of the
species, are curved to accommodate themselves to the various
curvatures of the threads are mostly solitary, and I have
never observed more than two contiguous to each other.

2. ANABAINA LICHENIFORMIS ? Bory.

Plate l^XXV. Fig. 4.
Char. Filaments not moniliform, minute, but little curved.

SPHJBltOZYGA. 283

Reproductive cells of various sizes, oval, and occurring
in series.
Bory, in Diet. Class, d. Hist. Nat. vol. i. p. 309.

Hob. Neighbourhood of Dublin : Dr. Allman. County
Wicklow : Mr. Moore. Sussex : Mr. Jenner.

There is no species hitherto recorded with which this can
possibly be confounded. The form of the reproductive cells,
the various size of these and their occurrence in chains or
series serving to mark it from all others.

3. ANABAINA IMPALPEBRALIS ? Bory.
Plate LXXV. Fig. 3.

Char. Filaments minute, not moniliform, but little curved.
Reproductive cells large and quadriform.

Bory, in Diet. Class, d. Hist. Nat. vol. i. p. 309.
Hob. Under a waterfall, co. Wicklow : Mr. Moore.

This is also a very distinct species ; the reproductive cells
are large, elongated, and in the form of a parallelogram, with
the angles slightly rounded; they are also usually solitary,
rarely in pairs. It dries without gloss.

4. ANABAINA CONSTRICTA Hass.
Plate LXXV. Fig. 9.

Char. Filaments very slender, not moniliform. Reproductive
cells much elongated, mostly solitary, small.

Hob. On mosses, Cheshunt : A. H. H.

This species bears some resemblance to the preceding ; the
reproductive cells are, however, not nearly so large as in it,
and are slightly constricted in the centre.

35. SPH^EROZYGA Ag.

Char. Stratum gelatinous, in which undulate articulated
unbranched threads with quadrangular joints, joined

284 NOSTOCIIINE^E.

here and there to a spherical cell, which is sometimes
terminal.

1. SPH^ROZYGA JACOBI Ag.

Char. Threads radiating, lonely, disposed in gelatine.
Sphcerozyga Jacobi Berk., in Eng. Bot. t. 2826. fig. 2.

Hob. Northamptonshire : Rev. M. J. Berkeley. Cromlyn
Bog : J. W. Gutch, Esq.

This species would appear from the description to belong
to Anabaina or Aphanizomenon. I have never seen it.

36. TRICHORMUS Allman.

Char. Frond free, of undeterminate figure, consisting of simple,
minute, moniliform, curved threads, with articulations of
uniform size, immersed in a gelatinous matrix.

Derivation. From Spi};, hair, and opfios, a necklace.

" From Anabaina of Bory Saint Vincent the present
Alga, as well as that of Mr. Thompson {Anabaina ? spiralis},
differs in the uniform size of the articulations, Bory's genus
being characterised by larger globules occurring at distinct
intervals in the series." — Allman*

Although strongly inclined to agree with my excellent and
early friend Dr. Allman, as to the validity of the genus Tri-
chormus, I am still not altogether satisfied respecting it, the
suspicion resting on my mind that the T. incurvus Allm.
might possibly be an Anabaina in a young stage of its
developement, the reproductive enlarged cells not having as
yet manifested themselves. This, however, is but a suspicion,
against which may be urged the fact that in veritable Ana-
baina the globules are invariably found interrupting the
uniformity of the filaments.

* " On a New Genus of Algae, belonging to the family of the Nosto-
chineaj." By G. J. Allman, A.B., L.R.C.S.J., Secretary to the Dublin
Microscopical Society. Annals of Nat. Hist. vol. xi. p. 161.

MONORMIA. 285

1. TEICHORMUS INCURVUS Allm.
Plate LXXV. Fig. 1.?

Char. " Plant either diffused through the water or collected on
the surface. Filaments of a pea-green colour, crowded
together confusedly in a gelatinous matrix, variously curved,
but never regularly spiral, assuming, when dried, a fine
verdigris-green colour without lustre." — Allraan.

Allman in Annals of Nat. Hist. vol. xi. p. 163.

Hob. In the Grand Canal dock, Dublin, October: Dr.
Allman.

The only authentic specimen which I have seen of this
species was so much injured that I was not able to make an
examination of it in the least satisfactory. A specimen, how-
ever, sent me by Mr. Thompson, collected by that gentleman
and found floating on the surface of Lough Neagh, at Shane's
Castle, marked Anabaina jlos-aquce, accords so well with the
description and figure given by Dr. Allman of T. incurvus,
that scarcely a doubt remains as to the propriety of regarding
Mr. Thompson's plant as that species, see PI. LXXV. fig. 1.
From the true A.fios-aqua Mr. Thompson's specimens differ
in the less considerable dimensions of the filaments, and in
the absence of the enlarged cells.

Section ii.
Filaments invested in a mucous matrix of a definite form.

37. MONORMIA Berkeley.

Char. " Frond branched, composed of a single moniliform
thread, following the ramifications, immersed in gela-
tine^ — Berk.
Derivation. From p,ovos, one, and oppos, a necklace.

This genus scarcely differs from Nostoc, between which and
Anabaina it forms a clear link.

286 NOSTOCHINEJE.

1 . MONORMIA INTRICATA Berk.

Plate LXXV. Fig. 11.

Char. Filaments scarcely moniliform. Reproductive cells
infrequent, globular, in series.

Monormia intricata Berk., Gl. of Alg. p. 46. t. 18. ; Harv.
in Manual, p. 185. Nostoc intricatum Meneghini, Mo-
nographia Nostochinearum Italicarum, p. 122. with

%•

Hob. In ditches of the marsh to the south of Frindsbury
Canal, near Gravesend, in great abundance in June,
1832 : Rev. M. J. Berkeley.

" Forming small roundish gelatinous masses, floating
amongst different species of Lemna in fresh water, but probably
within the influence of the tide, and also amongst Enteromor-
pha intestinalis, and even within the frond in brackish water.
The plant is at first of an olive yellow, gradually assuming a
greener tint, and when dried of a deep verdigris. Very gela-
tinous, delicately branched; the branches very flaccid. Under
a high magnifier the whole plant is evidently composed of
gelatine, in the centre of which runs a single moniliform fila-
ment, following the ramifications, and in its progress curling
to and fro repeatedly across the thread, the joints being
nearly globular. The specimens from the interior of En-
teromorpha are paler, and have often longer joints amongst
the globular ones." — Berk.

In the authentic specimen which I have examined of this
beautiful production, the articulations of the threads them-
selves could scarcely be called moniliform, althougn the large
reproductive cells were distinctly so.

38. NOSTOC Vouch.

Char. Frond definite, gelatinous or coriaceous, globose or lobed,
filled with curled beaded simple filaments. Reproduction
consisting of enlarged spherical cells placed irregularly in

NOSTOC. 287

the course of the filaments, from which finally they become
separated.

" This name is unexplained : it was first used by Paracel-
sus, and adopted by Vaucher for the present group, which
before that time was included in Tremella" — Harv.

1. NOSTOC VARIEGATUM Moore.
Plate LXXIV. Fig. 3.

Char. Frond terrestrial, expanded, gelatinous, livid, variable
in shape. Filaments rather distant. Cells oval, and
variable in size.

Harv. in Manual, p. 183.
Hob. Ireland : Mr. Moore.

" This singular plant I first collected in 1836, growing on
the face of a moist bank over which water trickled. When
recent it formed a soft gelatinous mass, of a livid colour,
bearing the closest resemblance, both in substance and co-
lour, to those gelatinous Medusae which are cast ashore along
the coast, and called by the country people * fallen stars.' I
again collected it on the same spot in 1838, when I sent Dr.
Greville specimens, who thinks it different from any thing
he knows, and coming nearest to Nostoc commune." —
Moore's MS.

If I had acted on my own convictions in reference to this
species, I should have removed it to the genus Anabaina, to
which it seems more properly to belong than to Nostoc. In
the genus Nostoc there is an exact similarity in all the fila-
ments ; in the species under consideration, a considerable
want of uniformity is observed, some being composed of cells
larger than those of others, as may be seen by the figure, in
which particular it resembles Anabaina, as it does also in the
diffused or unlimited mucous matrix, in which the threads
are imbedded, and in the oval form of the enlarged or repro-
ductive cells.

288 NOSTOCHINE^E.

2. NOSTOC COMMUNE Vaucll.

Plate LXXIV. Fig. 2.

Char. Frond terrestrial, expanded, membranaceous, plaited,
waved, or curled; olive green, shining, and irregular in
form. Filaments thick, beautifully moniliform. Repro-
ductive cells large, either attached to the filaments, or lying
scattered throughout the frond.

Nostoc commune Vauch., Hist, des Conf. p. 223. pi. xvi.
f. 1. Tremella Nostoc, Eng. Bot. t. 461. Tremella ter-
restris Dill., Muse. p. 52. t. 10. f. 14. ; Harvey in
Manual, p. 183. ; Meneghini, Monographia Nostochine-
arum Italicarum.

Hob. " Gravelly soils, garden walks, rocks, pastures, &c. ;
very common in autumn and winter."

The filaments are large, exactly moniliform, flexuous, and
copious, with here and there an enlarged reproductive cell of
an exactly spherical form. These enlarged cells occur either
in the course of the filaments, are terminal, or lie detached in
the mucous matrix of the frond. Some writers have laid
great stress, in their descriptions, upon the fact of these
globules being so frequently terminal. This position of them
has nothing to do with the developement of the species, but
arises from the thread of which they formed a link having
separated from one side of them — a step preparatory to their
being altogether cast off by the filaments.

" In prima tantum hujusce speciei aetate deprehendenda
eat interior substantia aquosa-gelatinosa, qua cito elapsa
frons excavata potius quam vesicaeformis eificitur, stratum
enim periphericum, ratione habita cavitate interiori, multo
crassius est in caeteris omnibus speciebus." — Menegh.

The only species with which there is any danger of con-
founding Nostoc commune are, N. cceruleum and N.foliaceum.
The filaments of N. commune correspond in size and appear-
ance very closely with those of .2V. cceruleum, but the external
characters are altogether distinct ; the contrary is the case
with N. foliaceum, the external characters resembling those

NOSTOC. 289

of N. commune, but the filaments are different, being much
smaller in size, although, like those of N. commune, distinctly
moniliform.

3. NOSTOC FOLIACEUM Ag.
Plate LXXVI. Fig. 2.

Char. Frond membranaceous, erect, plaited, olive green.
Filaments slender, copious, moniliform. Enlarged globuli
numerous.

Nostoc foliaceum Ag., Syst. p. 19. ; Harv. in Hook. Br.
Flora, ii. p. 399. ; Harv. in Manual, p. 1 84. ; Meneghini,
Monographia Nostochinearum ttalicarum, vol. v. p. 18.
serie ii. delle Meinorie della E. Academic delle Scienze
di Turino.

Hob. On clayey ground kept constantly damp by the
oozing of water, Appin : Capt. Carmichael. Ireland :
Mr. Moore.

" This species is easily distinguished both by its appearance
and station from Nostoc commune, to which it seems similar,
as respects certain external characters. It never swells up
into the form of a vesicle ; the structure, altogether uniform,
extends as a membrane, and rises up by moisture into plicated
lobes : it grows on stones, and is evolved, the winter scarcely
being ended, when Nostoc commune has not yet appeared." —
Menegh. The difference in the size of the filaments of Nostoc
commune and N. foliaceum is perhaps the only character
whereby the two species can at all times be discriminated,
the threads being much smaller in the latter species.

4. NOSTOC SPHJERICUM Vauch.
Plate LXXVI. Fig. 5.

Char. Frond small, globose, densely aggregated, solid, smooth,
olive green, watery within. Filaments small, moniliform.

Nostoc sphcericum Vauch., Conf. p. 223. pi. xv. f. 2.

u

290 NOSTOCHINE^E.

Ulva pisiformis Hudson. Conf. pisum, Flor. Dan.;
Harv. in Hook. Brit. Flor. p. 400. ; Harv. in Manual,
p. 185. ; Meneghini, Monographia Nostochinearum,
p. 110.

Hab. In rivulets and fountains, attached to stones, &c.
Appin : Captain Carmichael. Pools near Barmouth and
Llyn Coron, near Anglesea : Mr. Ralfs. Co. Wick-
low : Mr. Moore.

" Fronds from half a line to two lines in diameter, globular,
firm, smooth, solid, heaped on each other like a parcel of small
shells. Internal filaments rather thinly scattered through the
mass." - — Carm.

" This species dried and again moistened sometimes emit a
most grateful violet odour, as though it were a species of
Chroolepis, and such as no other Alga of the family of Nos-
tochinecB presents." — Menegh.

The filaments are moniliform, and exactly correspond with
those of Nostoc foliaceum in size, the young state of which
species, as it agrees with it also in habit, it may eventually
prove to be.

5. NOSTOC VESICARIUM D. C.

Char. " Frond globose, plicated, greenish yellow, the internal
viscid mucus escaped, vesicceform, cartilaginous. Filaments
curved, slender, with cells twice as large, thickly interspersed
and terminal." - - Menegh.

D. C. Flor. Fr. vol. iii. ; Harv. in Hook. Br. Flor. p. 399. ;
Harv. in Manual, p. 184.; Ag. Syst. p. 19. ; Meneghini,
Monographia Nostochinearum, p. 108.

Hab. Road-side, near Perth : G. A. W. Arnott, Esq.

" The diameter of the frond varies from a millimetre to an
inch. The colour in the smaller fronds obscurely green, verges
in the larger to a yellowish brown. Substance firm, cartilagin-
ous, including a fluid viscous juice : afterwards, the gelatinous
substance having escaped, empty, vesicaforin, membranaceous;

NOSTOC'. 291

threads moniliform, in the interior substance very lax, in the
external stratum much more curved than in Nostoc commune,
smaller in diameter, they scarcely attain three millimetres ;
but the larger spherical globules, twice as thick, abound, and
sometimes form tracts more or less long, no smaller globule
occurring between. In adult specimens the threads are vari-
cose wherever they occur." — Meneghini.

6. NOSTOC VERRUCOSUM Vauch.
Plate LXXV. Fig. 1.

Char. Frond attached, large, subglobose, in the beginning solid,
externally subcoriaceous, within gelatinous, at length hol-
low, vesicceform, verrucose, brownish green ; when dried
ceruginous. Filaments dense, slender, almost cylindrical.

Nostoc verrucosum Vauch., Hist, des Conf. Tremellafluvi-
atilis Dillw., Muse. ; Harv. in Hook. Br. Fl. p. 400. ;
also in Manual, p. 185. ; Meneghini, in loc. cit. ; Thuret,
in Annales des Sciences Naturelles.

Hab. On stones in Alpine streams ; Aberdeen : Dr.
Dickie.

This species may be distinguished from most others of the
genus by the nature of the filaments, which are almost cylin-
drical. The species with which it is most likely to be con-
founded is Nostoc pruiniforme, the filaments of which resemble
it closely, but are considerably larger ; in other respects the
two species are widely different, being estranged in form,
habit and consistence.

7. NOSTOC PRUINIFORME Ag.
Plate LXXVI. Figs. 3, 4.

Char. Frond unattached, solitary, globose, smooth, olivaceous,
gelatino-coriaceous, within watery. Filaments somewhat
thick, almost cylindrical.

Ag. Disp. p. 45. ; Berk. Gl. p. 48. t. 19. f. 2. ; Lyngb.

u 2

292

Hydroph. p. 200. t. 68 a. ; Harv. in Hook. Br. Fl. p. 399. ;
also in Manual, p. 184. ; Meneghini, loc. cit. p. 114.

Hob. In freshwater pools near the coast ; rivulet near
Torquay : Sir W. J. Hooker. Appin : Captain Car-
michael.

" Fronds unattached, scattered at random in the clefts of
the rocks, globular, smooth, olive-green, diaphanous, from \ to
1^ inches in diameter, the larger ones generally compressed,
hollowed, and sometimes ruptured." — Carmichael.

The filaments, as remarked in the description of the pre-
ceding species, resemble those of Nostoc verrucosum in all, save
size, being larger than in that species. The reproductive cells
are rarely produced.

8. NOSTOC MUSCORUM Ag.
Plate LXXIV. Fig. 4.

Char. Frond tuberculate, subcoriaceous, variable in shape.
Filaments much curved, moniliform, exceedingly slender.

Ag. Disp. p. 44. ; Ag. Syn. p. 132.; Syst. p. 19. ; Harv.
in Hook. Br. Fl. p. 399. N. mnscorum Harv., in
Manual, p. 183. N. microscopicum Carm., MS.; Harv.
in Manual, p. 184. ; Meneghini, Nostochinearum Italica-
rum, p. 1 1 9.

Hob. N. muscorum, on calcareous rocks, and the mosses
which cover them, Appin : Captain Carmichael. — N.
microscopicum, on exposed calcareous rocks among
mosses, Appin: Captain Carmichael. Near Youghal:
Miss Ball. Wilderness, near Clonmel : W. H. Harvey.
Clayey banks, co. Antrim : Mr. Moore.

I have examined several of Carmichael's specimens of this
Nostoc, and compared them with others of Nostoc micro-
scopicum Carm., and I entertain no doubt of the specific
identity of both. All the specimens which I have received
of the former have consisted not of single fronds, but of an
aggregation of numerous smaller fronds of various sizes and

NOSTOC. 293

forms, most of them being spherical but many of them angular.
The filaments are minute, much curved, and the cells are
spherical or slightly oval. It is one of the most distinct and
beautiful species of the genus. In the smaller specimens,
there is but a single thread, which curves in an elegant manner
throughout the frond.

9. NOSTOC C^ERULEUM Lyngb.

Plate LXXVL Fig. 11. Plate LXXV. Fig. 10.

Plate LXXIV. Fig. 1.

Char. Frond solitary, small, globose, solid, fluid within, at
length vesicular, mostly pale blue, sub-pellucid. Filaments
large, elegantly moniliform, much curved.

Nosloc cceruleum Lyngb., Hydroph. p. 201. No. 6. 768. /3;
Grev. Crypt. Fl. t. 131. ; Hook. Brit. Flor. p. 400. ;
Harv. in Manual, p. 185. ; Meneghini, Monographia
Nostochinearum Italicarum, p. 111.

Hob. In flowing water or in very moist places attached to
mosses, near Calender : Dr. Greville. Co. Antrim ; near
Wicklow : Mr. D. Moore. Pass of Lerry : Dr. Greville.

This species in its dried state might be readily passed over
as Nostoc commune in the first period of its growth, the fila-
ments of N. cceruleum according exactly with those of that
species. Notwithstanding the difference in its colour, and
perhaps in its habit also, I am not perfectly assured that it
is really distinct. The larger size of the filaments will serve
to distinguish it from Nostoc sphcericum, . which in form it
resembles, as well as the difference in its colour, and its
greater mucosity, which causes it to adhere closely to paper.

«

10. NOSTOC MACROSPORUM ? Menegh.

Plate LXXIII. Figs. 1, 2.
Char. Frond minute, solid, spherical, ceruginous green.

•294: NOSTOCHINE^K.

Filaments curved, thick, almost cylindrical, with here and
there an enlarged spherical cellule.

N. crassisporum Menegh., Consp. Alg. Europ. p. 7. ; et ^V.
macrosporum, Monographia Nostochinearum Italicarum,
p. 116. pLxiv. fig. 2.

Hob. Ireland : Mr. Moore.

Meneghini describes the frond of his N. macrosporum as
being polymorphous; in my specimens it was regularly
spherical. Meneghini's description, however, in other respects
accords so well with my examples that there scarcely a doubt
can exist as to their identity with the N. macrosporum.

" But different objects stimulate different minds to inquiry. Perhaps
the contemplation of the vegetable kingdom may be suited to the varied
conditions of more persons than the investigation of the animal structure ;
for plants, abundantly bordering our paths, are more readily procured for
the purposes of analytical examination, attract more continual attention
in our moments of leisure by many trivial allurements, and give little or
no shock to the most irritable sympathies during dissection. The vege-
table kingdom, as a manifest part of a universally concatenated system,
presents unquestionable traces of the great Intelligence which has planned
and constructed the whole. These traces appear so singularly diversified
through every part of the great sphere of human observation, that the
conclusion is irresistible, that such diversity has been especially intended
as a final cause to awaken admiration in beings of duly adapted intelli-
gence, to stimulate feelings made to be in harmony with such display of
beauty and of glory ; with a purpose to obviate all doubt, to evoke con-
tinual rapture, and to elevate the soul of man through transitions of fear
and wonder and awe to adoration and to divine love, which is said to be
the perfection of all wisdom." — J. S. Duncan's Botanical Theology.

295

ALG.E GLOBULIFERvE.

FAM. XVI. ULVACEJE.

Char. Frond gelatinous, saccate, tubulose, or membranaceous.
Cells either spherical and scattered singly throughout the
mucous frond irregularly, in pairs, in fours, or multiples
of that number ; or polygonal, and crowded together.

THE species of the family Ulvacece appear, so far as the
freshwater examples are concerned, to require a separation
into two sections : the first including the genera Ulva, at least
the single freshwater species of that genus Ulva bullosa (of
the marine species, I have no exact knowledge), Tetraspora,
Hydrurus, and Merismopedia ; the second, the genus Entero-
morpha. In the first, the cells are small, and spherical, being
imbedded at considerable intervals from each other in the
mucous frond ; in the second, the cells are large, polygonal,
and attached firmly to each other, the mucous nidus having
disappeared.

The reproduction of this family does not appear to have
been satisfactorily determined. In Agardh's memoir on the
propagation of the Algce, referred to so often, the following
remarks occur : —

" My father advanced the opinion that the cellules disposed
often in fours were the seeds, which was contradicted by
Lyngbye. Greville in the work cited above * observes, that
from three to four granules are disposed in the cellules of the
frond, but he pronounces not upon the function which ought
to be attribute^ to these granules. In this uncertainty, some
observations on the movement of the globules of Tetraspora
lubrica, should easily decide the question ; but no person

* Algae Britannicae.

u 4

296 ULVAXJE^K.

having as yet observed the act itself of their disjunction
from the membrane, it has not been ascertained whether it
was the cells themselves or that which they contain which
escaped from it. That which is certain is, that the sporules
of this plant are not more naked (an opinion advanced by
M. Gaillon) than those of any other Ulvacea.

" The Ulvacece properly so called are composed of cells some-
times arranged in a single layer, which constitutes an elongated
tube entirely empty, sometimes disposed in two layers, com-
pressed the one against the other, and forming a flat mem-
brane more or less extensive. Their sporules are lodged in
these cells, and issuing by a pore situated on the surface, they
offer the same phenomenon of locomotion which we have seen
to belong to the preceding families.

" Their movement is more slow and in the cellules straighter
than amongst the Confervece. Their beak is not so pointed,
and is not near so well separated from the body ; but never-
theless it is always the thinnest end of the oviform bodies
which is foremost during the movement. The sporules are
five or six in number in each cellule ; in some of them there
were two or three which were much smaller than the others,
a difference which is also observed in the Confervece, but in a
manner less apparent.

" Finally, it is only in the Viva dathrata that I have ob-
served the complete developement of these sporules. The ger-
mination (if one may so name a phenomenon analogous to that
act in more perfect plants) consists in this species of a longi-
tudinal expansion, during which the green matter insensibly
transforms itself into transverse bands. In this state one
might easily take the young plant for a species of Conferva,
but soon the bands being divided longitudinally, and so become
disposed in two series, one cannot longer mistake it."

Section i.
Granules simply imbedded in the frond.

39. ULVA Linn.
Char. Frond gelatinous, saccate or membranaceous. Cells

ULVA. 297

scattered through the frond either singly, in pairs, or in
fours.
Name supposed to be from ul, water, in Celtic.

1. ULVA BULLOSA Roth.
Plate LXXVIII. Fig. 13.

Char. Frond very delicate, somewhat gelatinous, at first sac-
cate, afterwards becoming expanded into a broad waved
or torn floating membrane.

Eng. Bot. t. 2320.; Hook. Brit. Flor. vol. ii. p. 312.; Harv.

in Manual, p. 171.
Hob. In stagnant freshwater ponds and ditches.

Fronds clustered, at first fixed, afterwards floating, very thin
and gelatinous, of a pale green colour, becoming yellowish.
Cells in the fully developed plant single, and equally diffused
throughout the lamina. If this disposition of the cells be not
constant, and if in the young condition of the frond they are
ever arranged in fours, as I believe to be the case, then I think
that this species can scarcely be regarded as distinct from
Tetraspora lubrica. The size of the cells is the same in both.

2. ULVA CRiSPA Light.
Plate LXXVIII. Fig. 12.

Char. Fronds terrestrial, saccate, firm, densely tufted,

plaited and wrinkled, of a roundish form. Cells arranged

in fours, crowded.
Ulva crispa Lightfoot. Grev. Alg. Brit. p. 175.; Hook.

Brit. Flor. vol. ii. p. 312. ; Harvey, in Manual, p. 171.

Ulva furfuracea Horncastle. Grev. Crypt, t. 265. ;

Hook. Brit. Flor. p. 312. ; Harvey, in Manual, p. 171. ;

E. B. t. 2754.

Hob. On damp ground, rocks, thatched roofs , &c. ; very
common, winter and spring ; rocks near the sea : Appin :
Captain Carmichael. On the walls of King's College,
Cambridge: Rev. M. J. Berkeley. Several places near

298 ULVACE^E.

Limerick : W. H. Harvey. Near Ballycastle : Mr. D.
Moore. Roger's Tower on Castle an Dinas, near Gul-
vall ; and Bosigran Castle, near Morvah ; in both places
on granite : Mr. Borrer. Dublin Bay : Mr. Moore.
On damp shaded walls, on the ground ; frequent, near
Tunbridge Wells : Mr. Jenner. Walls of Chesterton
church, near Cambridge : Rev. Prof. Henslow.

Having carefully examined numerous specimens which have
been sent me under the names of Ulva crispa and Ulva fur-
furacea, and not being able to detect the slightest difference in
the microscopic characters of these, I do not hesitate to unite
the two supposed species.

The specific denominations of crispa. and furfuracea arc
both well expressive of the appearance of this species : the cells
are densely crowded together in the frond, so as indeed to
leave very narrow interspaces between the groups of cells,
which are usually composed each of about sixteen cells,
disposed in fours, and which from the compression one against
the other are rendered somewhat angular. The different
groups of cells are not disposed usually in linear series.

3. ULVA CALOPHYLLA Spreng.
Plate LXXVII. Fig. 1.

Char. Frond densely tufted, plane, linear, ligulate, attenu-
ated at base, often stipitate, longitudinally striate, each
stria marked with a series of bi-quaternate granules.

Hook. Brit. Flor. vol. ii. p. 312. Bangia colophylla Carm.,
in Grev. Crypt. FL, t. 220.

Hab. On damp stones, rocks, &c. ; Lismore Island,
Appin : Captain Carmichael. Near Limerick : W. H.
Harvey. Dublin : Mr. Moore and Dr. G. J. Allman.
North of Ireland : Mr. D. Moore. Oswestry : Rev. J.
Salwey.

" This forms a bright green thin stratum. Frond minute,
three or four lines long, linear, strap-shaped, obtuse, tapering
at base, or suddenly contracted into a cylindrical stipes, much

I

MERISMOPEDIA. 299

waved and curled, very variable in breadth. Granules qua-
ternate, closely covering the frond, set in longitudinal lines, of
which two or more (sometimes half a dozen) form the breadth
of the frond ; interstices colourless." — Harv.

Kiitzing makes a new genus for this species under the
name of Prasiola.

4. ULVA BINALIS Hass.
Char. Cells large, in twos.

I have not studied this species with sufficient attention to
pronounce decidedly whether it is distinct or not ; the ar-
rangement of the granules by twos would seem, however, to
be remarkable, and to render it very probable that it really is
so. This species would appear to be referred to in the fol-
lowing remarks of Vaucher's " Hist, des Conf." p. 238. " It
is not impossible but that other species of freshwater Ulvcs
exist independently of those which I have described. I have
myself met with some others which have appeared to me to be
different from the two first ; one in particular, the grains of
which were disposed two by two, and not four by four ; but I
pass them by under silence, because I am not assured whether
they are species or only varieties."

40. MERISMOPEDIA.

Char. Frond increasing by spontaneous division, laminar,
quadrangular.

Derivation. From /u,fptcr/ioy, a division, and TrsBtov, a
fetter or chain.

1. MERISMOPEDIA PUNCTATA Meyen.
Plate LXXXIV. Fig. 6.

Char. " Green, corpuscles imbedded in a crystalline mem-
brane, and nearly the T^ of a millimetre in size, polypary,
quadrangular, flattened, sometimes twice as broad as long,
equalling from the T^ to ^ of a millimetre, and containing
sixteen simple corpuscles, either binary or quaternary" —
Ehr.

300 ULVACE.E.

Merismopedia punctata Jenner, in Fl. of Tunbridge Wells.
Gonium tranquillum Ehr., Die Infus. p. 57. t. iii. f. 3.

Hab. Ashdown Forest, Cold Bath Spring, &c. : Mr.
Jenner.

I am not at all acquainted with this pretty production ; it
doubtless, however, belongs to the family of Ulvacece, and
my Ulva binalis may possibly be identical with it.

41. TETRASPORA Link.

Char. Frond either tubular, inflated, or flat, gelatinous.
Cells mostly arranged in fours.

Derivation. From rerpa, four, and <nropa, a seed ; hi allu-
sion to the arrangement of the cells.

This genus seems to me to be wholly unnecessary : it ought
either to merge into Ulva, or else several species now asso-
ciated with that genus should be removed from it and placed
in Tetraspora. All the characters of the genus Tetraspora
may be found in one or other species of Ulva, and especially
that of the quaternate arrangement of the granules, or perhaps
more strictly speaking, the cells, from which the generic de-
nomination is derived.

1. TETRASPORA LUBRICA Ag.
Plate LXXVIII. Fig. 10.

Char. " Frond quite simple, tubular, subgelatinous, waved
and serrated."

Harv. in Hook. Brit. Flor. vol. ii. p. 313. ; Harvey, in
Manual, p. 176.

Hab. Hellesdon, Norfolk : Sir W. J. Hooker. Appin :
Captain Carmichael. Castlemartyr, Cork : Miss Ball.
Malahide : Mr. Moore. Aberdeen : Dr. Dickie. In an
old quarry above Cromlyn Bog, Swansea : J. W. Gutch.
Tuubridge Wells : Mr. Jenner.

The freshwater Ulvacece have not as yet been studied with

TETRASPORA. 301

the attention which they require. I do not feel at all cer-
tain that either this species, or Tet. gelatinosa are really dis-
tinct from Ulva bullosa : at all events, it is certain that in
Ulva bullosa in its young state the frond is saccate or tubular,
and the granules arranged in fours : neither can any difference
be detected in the size of the cells in these supposed species :
all which circumstances lead to the suspicion that they are
but states of the same production. If the observation of
Vaucher be correct that the granules or cells undergo an in-
crease of size at the period of the complete developement of the
frond, and just before it passes to decay, then it would seem
that no certain character can be derived from their size, unless
the condition of the species as to age be likewise ascertained.
The frond of T. lubrica is stated to be larger than in the
following species, less gelatinous, with a more distinct mem-
brane and of a deeper colour. The tube finally ruptures, and
becomes membranaceous, with an irregular outline.

2. TETKASPORA GELATINOSA Desv.
Char. Frond ovate, inflated, and very gelatinous.
Hook. Br. Fl. p. 313. ; Harv. in Manual, p. 176.
Hob. In freshwater streams attached to aquatic plants ;
Newcross, Killarney : W. H. Harvey. Botanic Garden,
Belfast : Dr. Drummond. Malahide : Mr. Moore.

" Frond exceedingly lubricous and gelatinous, but firm,
delicately waved, and plaited, of an oval outline. Sporules
bright green, or arranged in fours or scattered." — Harv.

3. TETRASPOKA FLAVA Hass.
Plate LXXVIII. Fig. 11.

Char. Frond when dried yellowish. Cells very minute.
Hob. Rocky rivulet, co. Antrim : Mr. Moore.

This species at all events would appear to be distinct, the
cells being two or three times smaller than those of the two
preceding TetrasportB.

302 ULVACE^E.

42. HYDRURUS Ag.

Char. Frond gelatinous, cylindrical, branched, solid, filled
with scattered, oviform bright green granules.

Derivation. From vSwp, water, and ovpa, a tail.

1. HYDRUKUS DUCLUZELII Ag.

Plate LXXVII. Fig. 3.
Char. Frond very gelatinous, branched, plumose.

Ag. Consp. Crit. Diat. p. 27. Batrachospermum Myosurus
Ducluz. Palmella Myosurus Lyngb., Dan. t. 68. ; Harv.
in Manual, p. 180.

Hob. In alpine rivulets, on stones, &c. In the river
Walkam, near Tavistock : Mr. Ralfs. Meary, Devon :
Rev. W. S. Hore.

" Root scutate, blackish, rather hard. Fronds clustered,
solid, very gelatinous, 2 — 6 inches long or more, 2 — 4 lines
in diameter, cylindrical, freely waving in the water, atte-
nuated towards the apex, branched ; branches scattered,
alternate, elongate, slender, beset with other more slender,
short ramuli. Gelatinous mass pellucid, viscid, colourless
under the microscope, without apparent margin, unless as
the granules imbedded within its substance indicate such ;
these are globose, green, formed in the stem and primary
branches, most densely set in the ramuli, especially towards
the margin. Colour of the recent frond brownish-olive, or
dark brown, in drying, green ; of the granules both recent
and dry, green.

" The odour, in a recent state, is very offensive, and as
Lyngbye remarks, only to be submitted to by an algologist.
In a dry state it shrinks much, and most closely adheres to
paper. Having only seen this very interesting plant in a dry
state, I have thought it better to copy the above description
from Lyngbye. Our specimens, so far as they can be exa-
mined, well agree with his figure. The affinities of the genus
are doubtful. By Agardh it is now placed near Schizonema,

ENTEROMOKPHA. 303

to which its offensive smell certainly allies it. But the form
and appearance of the granules are so totally unlike the frus-
tules of any diatomaceous plant, that, for the present at
least, I retain it near Palmella, to which it seems to me
about as much allied as Chcetophora endivicefolia to the shape-
less species of that genus. If a true diatomaceous plant, it
ought, as Agardh suggests, to form the type of a new series,
of which, perhaps, our Cymbella l&tevirens might represent
the lowest form." — Harv.

There is not the least question but that the Hydrurus
Ducluzelii is not a diatomaceous plant, and it is equally clear
that it is an undoubted member of the family of the Ulvacece,
in some measure connecting Ulva with Enteromorpha. The
granules are oviform, precisely resemble zoospores, with
which in function it is difficult to conceive that they are not
identical, the thin being transparent.

Section ii.
Frond reticulate.

43. ENTEROMOKPHA Link.

Char. Frond tubular, hollow, membranaceous, and of a reti-
culate structure. Fructification consisting of three or
four granules aggregated in the reticulations.

Derivation. From svrspov, the entrail, and /j,op<j>r], a form
or appearance.

1. ENTEROMORPHA INTESTINALIS Link.

Plate LXXVII. Fig. 2.
Char. Fronds elongated, simple, inflated, often floating.

Grev. Alg. Brit. p. 179.; Wyatt, Alg. Dar. No. 80.
E. B. 2756. ; Harv. in Hook. Brit. Flor. p. 313. ; et in
Manual, p. 174. E. lacustris Hassall, in Trans, of Lin-
ntcan Society.

Hob. In ditches. Common, summer and autumn.

304 ULVACE^S.

" Fronds often two feet or more long, and from a line to
two or three inches in diameter, tapering at base, at first
fixed by a minute root, afterwards detached and freely floating,
inflated, variously waved or curled, of a full green colour,
fading to yellowish, and finally white." — Harv.

" In the earliest stage of their developement, the tapering
filaments consist of a single series of cells placed end to end.
Each of these cells afterwards becomes bisected by a longitu-
dinal line, and other lines subsequently appear, so that the
original cells are ultimately divided into several, each of
which, in its turn, enlarges, and is in like manner divided.
From the continued growth and unlimited division of the
cells the filaments increase to an indefinite size, soon lose
their original confervoid character, present a reticulated ap-
pearance, and, instead of being attenuated, become cylindrical
and hollow.

" In each cell or articulation of the filaments, and when
these arc not thicker than a horse hair, a dark central nucleus
is gradually developed, which, there can be no doubt, under-
goes repeated division in the same manner as the reproductive
globules of the Ulvce. These nuclei often germinate while
still enclosed within the cells in which they were developed,
and while the parent filament retains all its freshness and
vigour, and give rise to the pointed and tapering filaments
first described ; which, in this state, after the rupture of the
parent cells, and while their bases are fixed within them, one
filament in each, bear a strong resemblance to a parasitic
Conferva.

" This developement, division and growth of cells and repro-
ductive bodies, appears to be going on continually and suc-
cessively, so that most specimens of the plant present ex-
amples of each different stage of its formation.

" The Enteromorpha intestinalis would appear to have a
twofold relation to the Confervas in its young articulated
filaments, and to the Ulvce in its reproduction from globules
which undergo repeated division. The tautology of the
specific name is objectionable, and that of lacustris might be
substituted for it." — Hass.

BOTRYDUM. 305

44. BOTRYDUM Wall.

Char. " Plant a spherical vesicular receptacle, filled with a
watery fluid, dehiscent at the apex, terminating below in
radiating tufts of fibres." • — Grev.

Derivation. From ftorpvs, a bunch of grapes, which the
clustered fronds somewhat resemble.

1. BOTRYDUM GRANULATUM Grev.
Plate LXXVII. Fig. 5.

Grev. Alg. Brit. p. 196. t. 19. ; Hooker's Brit. Flor. 321.
Tremella granulata, E. B. t. 234. Conf. multicapsularis
Dillw. t. 71.? Gongoseira clavata? Kiitzing, Phy. Gen.
p. 281.

Hab. On damp clayey ground, dried up ponds, &c.
Common.

" Fronds minute, densely clustered on the surface of the
ground, spreading in patches. Vesicle containing a watery
fluid, in which a few granules are sometimes found. In dry
weather the upper part of the vesicle collapses, when they
become cup-shaped." — Harv.

Kiitzing I believe has not included in his " Phycologia Ge-
neralis " the genus Botrydium : he has constituted, however,
a new genus for the Conf. multicapsularis of Dillw., under
the name of Gongoseira. This genus he places amongst the
ProtonemecB, which is probably the position which this curious
production ought to occupy.

" Thus natural history blends with primitive tradition and record,
affording to our faith a basis of previous probability, with evidence on
every side, in our paths, our fields, our gardens, our woods ; in cultiva-
tion and in the desert ; in every fibre, root, stem, leaf, flower, or fruit,
demonstrating the omnipotent all-sustaining omnipresent God." — J. S.
Duncan's Botanical Theology.

306

FAM. XVII. PALMELLE^E.

Char. Frond consisting of a gelatinous colourless fluid, in
which are immersed numerous globules, containing the co-
louring matter.

45. PALMELLA Lyngb.

Char. " Frond mucous, indefinite, enclosing hyaline globules,
in which the colouring substance, continuous, and never
granular, is situated. Granules fast evolved in the
mucous substratum of the frond, at length constituting new
globules.'1'' — Meneghini.

Derivation. From Tra\fjMs, vibration ; in allusion to the
gelatinous nature of the frond.

" This genus differs from all the other genera of Nosto-
chinece, especially in its frond, which, from the beginning, is
indefinite. In other species the frond preserves its defined
form during the entire course of its existence, or at least in the
beginning describes a certain form with peculiar limits. But
in this, the frond never can possess a definite form, on account
of the nature of its generation and evolution ; for the globules
living in the mucous substratum of the frond, otherwise
very similar to those of other Nostochinece, differ as much
as possible from all others, in the fact of the colouring matter
in them never becoming granular, and that, because the gra-
nules from which new globules proceed are neither evolved
nor undergo evolution in the interior of the maternal globules ;
for these are either altogether resolved into mucus, or pour
out the mucous substance which they contain, which sub-
stance not being covered with an involucre, is indefinitely
diffused, and is circumscribed only by external circum-
stances. But in this mucosity minute punctated points or
granules appear, which little by little are evolved, and at
length attain to the dimensions of the parent globules. The

PALMELLA. 307

form, therefore, of the frond is necessarily indefinite. By
reason of the absence of the vesicles nourished in the interior
of the larger globules, the material included in the globules
is altogether continuous, fluid, and never granular. At length,
when effused, the presence of dots or minute granules dis-
persed through the mucous substratum afford distinct cha-
racters whereby the genus may be easily distinguished by
microscopic examination.

In the genus Palmetto,, as limited by himself, Meneghini
describes two species, Palmella cruenta and P. montana.
The first of these Meneghini takes for the type of his genus
Palmella, and to this only do his observations in any mea-
sure apply. The other species seems to me to be of a nature
altogether different, indeed scarcely congeneric. In P. cruenta
the grains or cells are loosely scattered through the mucous
matrix, and their contents are usually, as Meneghini describes
them, uniform and homogeneous. In P. montana, P. Ralfsii,
P. virescens, and P. grumosa, the cells are collected into little
clusters, and their contents are nucleated. Meneghini, there-
fore, would not appear to have studied the second species of
his genus P. montana, which, as well as the other species
Palmella Ralfsii, P. virescens, and P. grumosa, ought, in all
probability, to be included in a distinct genus. Palmella cruenta,
on the one side, evidently bears a close relation to Protococcus
nivalis, from which indeed it principally differs in the fact
of the globules being distinctly immersed in gelatine, while
in P. nivalis they are free. P. montana, &c., on the other
hand, exhibits a relation almost as close to Hcematococcus, from
which genus it differs in the same manner as Protococcus
nivalis and Palmella cruenta differ. The globules of Hcema-
tococcus sanguineus exhibit the same nucleated appearance as
do those of P. montana^ P. Ralfsii, &c.

x 2

308 PALMELLE.E.

1. PALMELLA CRUENTA Ag.
Plate LXXX. Fig. 5.

Char. Frond indefinite, crustaceous, expanded, blood-red,
tuberculate, filled with subangular hyaline globules, and
" very minute punctiform scattered granules"
Tremella cruenta, E. Bot. t. 1800.; Grev. Crypt. Flor.
p. 205. ; Hook. Brit. Flor. vol. ii. p. 396. ; Harv. in
Manual, p. 179.

Hob. On damp walls, chiefly such as are whitewashed ;
often in cellars. Glasgow : Sir W. J. Hooker. On
damp walls near the ground at Mayfield and elsewhere,
frequent : Mr. Jenner.

" The red spots in the beginning irregularly orbicular,
quickly becoming confluent, attached to earthy particles, to
stones, and other extraneous substances, form a widely ex-
panded crust, which, on the application of moisture, swells
up, and then especially resembles coagulated blood. By
drought their young frond grows dusky and disappears ; but
more evolved, it dries up, and is more intensely coloured ; it
cracks, curls up, and falls in pieces. Rainy weather con-
tinuing, and other Algce being evolved amongst it, especially
Oscillatoria autumnalis and Microcystis atrovirens, it be-
comes green, and at length black. If the crust be kept
immersed some hours in water, it swims on the surface
like a thin pellicle. A morsel of this subjected to the
microscope presents hyaline globules, subangular, and adorned
with a faint cameous tint, which are so closely heaped toge-
ther, that at first sight they appear to form a cellular mem-
brane. Nevertheless they are not joined by any adherence,
as is evident from the fact that they recede from each other
under the object glass itself with the slightest pressure. The
mucous, colourless substratum and punctiform granula or
lesser globules, more intensely coloured, then come into sight.
Moreover, a fragment of the frond itself, first submerged in
water, submitted to microscopic examination, manifests the
same organs, though less appressed, and the mucous sub-
stratum, endowed with more consistence, is detected."

SOKOSPORA. 309

46. SOROSPORA Hass.

Char. Cells nucleated, associated in clusters.

Derivation. From a-wpos, a cluster or mass, and crrropa, a
seed.

1. SOROSPORA MONTANA Hass.

Plate LXXIX. Fig. 1.

Char. Frond between coriaceous and gelatinous, irregular,
much and variously lobed, curled, dark purple. Granules
crowded, in clusters composed of six or eight granules each.

P. alpicola Lyngb., Hydroph. p. 2067. ap. 69. Ulva mon-
tana Light., Scot. Flor. p. 973. Ulva montana Hud-
son, Flor. Ang. p. 652. Ulva montana Withering, Ar-
rangement of Br. PI. vol. iv. p. 122. ; Smith, E. B.
t. 2193.; Harv. in Hook. Br. Flora, p. 396., also in
Manual, p. 179.

Hob. On mosses and lichens on the summits of rocks. On
the mountains of the Isle of Skye, and west coast of
Scotland ; Glen Cateol : Dr. M( Culloch. Lying on the
ground but not attached to it, in stony moist places on
Goat Fell, Arran : Sir W. J. Hooker.

According to Lightfoot, this is the " Mountain Dulse " of
the Scotch.

" On the mountains of Arran this lies unattached among
loose wet stones, covering them in a straggling manner to a
considerable extent. Each frond is an inch or an inch and a
half in diameter, flattish, somewhat orbicular, between co-
riaceous and gelatinous ; when dry almost horny, of a deep
but dull purple colour, much lobed and curled, like some Gy-
rophora, filled with crowded clusters of granules, which, if
minutely examined, are found to be arranged mostly in fours."
— Hook.

x 3

310 PALMELLEJE.

2. SOROSPORA RALFSII Hass.
Plate LXXIX. Fig. 3.

Char. Frond minute, thin, gelatinous, hyaline, somewhat areo-
late; each areola containing 2 — 8 large, globose, blood-red
granules.

Palmella Ralfsii Harv., in Manual, p. 179.

Hob. Spreading over mosses on Cader Idris : Mr. Ralfs.

"Fronds a few lines in diameter, gelatinous, somewhat
areolate, or as if composed of numerous small vesicles massed
together, each of which contains 2—4 or eight large blood-
red granules, which are much larger and of a far deeper colour
than those of P. montana." — Harv.

In the specimens which I have examined of this species,
the granules in each cluster have been usually not less than
six or eight, and between the clusters faint divisions of the
mucous matrix may be discerned, which increases still further
the resemblance which this and the preceding plant bear to
Hcematococcus, and especially Ham. sanguineus.

3. SOROSPORA VIRESCENS Hass.

Plate LXXVIII. Fig. 8. a.
Char. Frond green. Cells in clusters, nucleated, globose.

Of this species I have seen but a very small fragment ;
there can be no doubt, however, I think, of its distinctness :
each cell is imbedded in a distinct cavity of the mucous
matrix, the outline of which may be distinctly traced subse-
quent to the removal of the cells.

4. SOROSPORA GRUMOSA Hass.
Plate LXXX. Fig. 7.

Char. Frond widely expanded, clotted, brick-red, floating.
Globules usually binate, globose, blood-red, and surrounded
by a narrow pellucid limbus, occasionally aggregated.

COCCOCHLOR1S. 311

Palmella grumosa Carm., MS. P. grumosa Harv., in
Manual, p. 180.

Hob. On a rock at the sea side in a small cavity filled
with rain water at Appin : Captain Carmichael. West
of Ireland: M'Colla.

This species would appear to be somewhat anomalous,
agreeing, in the fact of the globules being immersed in a dis-
tinct gelatinous matrix, with the genus Palmella, and according
with Hamatococcus in the circumstance of these being sur-
rounded with a pellucid margin, and also in its reproduction :
not, however, that it is ascertained that the reproduction of
S. grumosa is really distinct from Hcematococcus. It there-
fore connects these two genera closely with each other. In
drying the brick-red colour of the frond changes to a dirty
green, with a slight degree of gloss upon its surface.

47. COCCOCHLOKIS Spreng.

Char. Frond mucous, definite, at a later period often effused,
in which are imbedded the globules, filled with matter mostly
green and granular, to be converted into vesicles replete
with globules, and producing new fronds.

Derivation. From KOKKOS, a berry, and ^Xto/ooy, green.

The following observations on Coccochloris, which would
appear to be a tolerably well established genus, occur in Mene-
ghini's " Monographia Nostochinearum," pp. 57, 58.

" Globuli, in substrato mucoso nidulantes, materie granulari
farciuntur. Non tamen omnes ad evectiorem evolutionem
perveniunt ; nonnulli enim tantum majores dimensiones con-
sequuntur, eorumque interior substantia in distinctos globulos
confirmatur ; globuli hujusmodi propagatione inservientes vel
ad superficiem tantum frondis reperiuntur vel inordinate et
sparsae in quacumque frondis regione evolvuntur. In primo
illo casu a fronde matricali facile extricantur et totidem
novas frondes constituunt quibus ita definita forma semper
inest; in secundo vero primordia ilia novarum frondium a

x 4

312 PALMELLE^E.

mucoso frondis matricalis substrate obvoluta et impedita
extricari nequeunt et ibidem evolvuntur usque dum tandem
eodem dissolute et evanido libere disseminantur. In primis
illis frons, tota vita perdurante, semper definita remanet : in
his primum definita quidem est, sed ab initio usque effunditur
et dissolvitur. Differunt itaque Coccochlorides a Palmellis, in
eo quod granula in sinu globulorum ipsorum gignuntur et
evolvuntur, proptereaque frons definita hie necesse inest, dum
illaB eodem necesse carent; et quamquam serius in multis
quoque Coccocliloribus frons ipsa effundatur, origine tamen
summopere ab ilia Palmellarum differt. Ita ut Palmellce Proto-
coccos in muco indefinite nidulantes representant, sic Cocco-
chlorides a Chlorococcis in fronde mucosa definita inclusis
efformataj dici possunt."

1. COCCOCHLORIS PROTUBERANS Spreng.

Plate LXXVI. Fig. 7., and PI. LXXXII. Figs. 6, 7,
8, 9, 10.

Char. Fronds green, gelatinous, soft, irregularly lobed, spread-
ing, confluent. Globules elliptical, generally more obscure
towards the centre. Vesicles of various sizes, spherical or
elliptical, constantly surrounded with a diaphanous margin.

Ulva protuberans Smith, E. B. t. 2583. Palmella protu-
beransGrev., Flor. Edin. p. 323.; Crypt. Fl. t. 243. f. 1.
Palmella protuberans Ag., Syst. p. 14. ; Hook. Br. Fl.
vol. ii. p. 396. ; Harv. in Manual, p. 176. Coccochloris
protuberans Spreng., Syst. Veg. vol. iv. p. 373. Palmo-
gloea protuberans Kiitzing, Phy. Gen. p. 176.

Hab. Sussex, spring to autumn : Mr. Borrer. Camsie
Glen, near Glasgow : Sir W. J. Hooker and Dr. Greville.
Pentland Hills : Dr. Greville. On the ground at Crow-
borough Warren : Mr. Jenner. Co. Wicklow : Mr.
Moore.

" The fronds in the beginning roundish, of very variable
magnitude, quickly run into a mass more or less extensive,
investing surrounding bodies or spreading over the naked soil.

COCCOCHLOR1S. 313

Its substance, in the beginning watery and pellucid, becomes
at a later period firmer and more intensely green. The frond
itself, subjected to the microscope, differs very considerably
in the different states of its developement. When it is green
and firm, the globules scarcely vary at all in dimensions, but
generally stand at the one hundred and twenty-fifth part of
a millimetre in the greatest diameter, and their form always
oblong, varies from elliptical to irregularly angular. Their
interior substance appears obscurely granular, and is always
more opaque in the centre. The vesicles are variable in form
and magnitude ; the smaller are mostly spherical, the larger
elliptical, all constantly surrounded by a hyaline border.
The smallest of all only differ from the other globules in
their spherical form and diaphanous margin; and the most
nevertheless attain the fiftieth part of a millimetre in dia-
meter, and the largest have the twentieth part in their
greatest diameter. The larger these are, the more manifestly
granular is the structure of the interior substance: when
enclosed they scarcely equal the thousandth part of a milli-
metre. The diaphanous margin is equally manifest both in
the smaller and greater vesicles, and preserves the same pro-
portion. In the more delicate fronds, and those having less
consistence, being almost watery, the mass itself is constituted
of a colourless thin mucus, in which the oblong cylindrico-
elliptical, or rarely spherical globules, reaching from the two
hundredth to the one hundredth part of a millimetre in their
greatest diameter, hyaline or diluted green, scattered here and
there, appear, with areolae intensely green, presenting a definite
suborbicular, or but irregular form, constituted of firmer and
more intensely coloured mucus, and filled with subrotund
globules, varying in diameter, from the thousandth to the
two hundredth part of a millimetre, and surrounded with a
narrow diaphanous margin. Intermediate forms are some-
times noticed, in which the mass itself, more diluted and
watery, gradually disappears, and the green areolae increased
in size, and at length confluent, assume finally the characters
of the older fronds." - — Menegh.

314 PALMELLE^E.

2. COCCOCHLORIS MU8CICOLA Menegh.
Plate LXXVIII. Figs. 3 a. 3 b.

Char. " Frond mucous, indefinite, very slender, investing mosses,
blackish green ; the smallest globules perfectly spherical,
.green, generally germinate. Vesicles elliptical, the larger
entirely filled with lesser globules, and not surrounded with
any margin"

P. hyalina, B. muscicola Harv., Manual, p. 177.
Hab. Aberdeen : Dr. Dickie.

"The mucous pellicle, blackish green, shining, covers exten-
sively mosses, and at the same time includes with our Cocco-
chloris, Oscillatoria autumnalis and Nostoc lichenoideum, the
Coccochloris globules scarcely measuring the three-thousandth
part of a millimetre, imbedded in a soft and easily yielding
mucus, in which are mixed, scattered elliptical vesicles, varying
in dimensions from the hundredth to the twenty-fifth part
of a millemetre, entirely filled with smaller globules closely
heaped together. The vesicles themselves are seen to be
constituted of a very slender membrane, which embraces them,
but not presenting a diaphanous margin, and which by lacera-
tion is scarcely to be perceived : when the membrane has been
ruptured, the contents of the globules escape into irregular
angular heaps. The vesicle from which the globules have
proceeded is not apparent : this however is certain, that the
globules are not surrounded by any peculiar membrane.

" The vesicles effused into irregular areolae resemble the
beginnings of new fronds, which, evolved in the mucous matrix,
and quickly becoming confluent, form a mucous pellicle. Hence
the frond is said to be indefinite, although, in the beginning,
as in all other species of this genus, it is definite. This spe-
cies agrees in habit with Coccochloris protuberans, but in
structure and microscopic characters it exhibits greater affi-
nity with Coccochloris parietalis, as will be shewn hereafter."
In drying, it leaves but a mere stain upon the paper, most
evident at the margins of the frond.

COCCOCHLORIS. 315

3. COCCOCHLORIS HYALINA Menegh.
Plate LXXVIII. Figs. 2 a. 2 b.

Char. Frond gelatinous, cylindrical or globose, solitary, sub-
hyaline ; internal globules globose, very minute, green.

Palmella hyalina Lyngb. ; Grev. Scot. Crypt. Fl. t. 247. ;
Harv. in Hook. Brit. Flor. p. 397. ; Harv. in Manual,
p. 177.

Hab. Bogs at Fisher's Castle, Tunbridge Wells : Mr.
Jenner.

Lyngbye describes this species as .follows : — " Mass gela-
tinous, cylindrical, solitary, solid, floating on the surface of
water, an inch or two long, colour commonly watery, pel-
lucid, except as regards that which is owing to the internal
granules, which are of a delicate green colour. Substance in
the highest degree lubricous, adheres, in drying, to paper."
Brebisson, however, states that it attains to the remarkable
size of one or two feet in length, and from six to eight inches
in thickness.

" Specimens communicated liberally by Cl. Brebisson
and Lenormond are five inches long, and although closely
adherent to paper, yet manifest greater solidity of the super-
ficial stratum over the internal substance. For being lacer-
ated by compression, they exhibit the interior effused sub-
stance hyaline, and the exterior pellicle more intensely
coloured and opaque, and divided into irregular fragments.
In the interior substance uniform, very minute globules are
imbedded, scarcely measuring the two thousandth part of a
millemetre ; but the exterior pellicle is constituted of globules
somewhat larger, covering a diameter of the two hundred and
fiftieth part of a millimetre, in which oblong vesicles, alto-
gether filled with minute globules, from the twentieth to the
twenty-fifth part of a millimetre long, are mixed."

What appears to me to be at least a variety of this
species was sent to me by the Rev. M. J. Berkeley. The
fronds were globose, but smaller and less solid than those of
C. hyalina in its usual state, and the globules larger. See
PL LXXVIII. fig. 5.

316 PALMELLE^i.

4. COCCOCHLORIS DEPRESSA Menegh.
Plate LXX VIII. Figs. 4 a. 4 b.

Char. " Fronds subhemispherical, depressed, green. Granules
globose or irregular." — Berk.

Palmella depressa Berk., Glean, p. 19. t. 5. f. 4.; Harv.
in Manual, p. 178.

Hob. Growing on an old pump at Cotterstock, North-
amptonshire, and constantly moistened by the dripping
of the spout.

" The irregular granules, some of them larger than others,
and many being agglomerated together, and comprehended
in a common integument, as depicted by the author, have
led to this generic collocation of this species. The comparison
also which the author of this species instituted with the
Palmella terminalis Ag. appears to sustain this opinion." —
Menegh. When dried the frond is destitute of gloss.

5. COCCOCHLORIS MOOREANA Hass.
Plate LXXVIIL Figs. 1 a. 1 b.

Char. Fronds large, globose or lobed, of a rich dark ceru-
ginous green colour, unaltered in drying, and of firm
substance. Globules oval, small, tolerably uniform in size
and shape.

Palmella Mooreana Harv., in Manual, p. 178.
Hob. In a boggy hole at Shane's Castle, the seat of Lord
O'Neill, near Lough Neagh : Mr. D. Moore.

" The fronds are of an irregular globose form, about an
inch in diameter, tuberculated, and inclining to become hollow
in the centre when old, at which time it floats on the sur-
the colour is dark green, and the substance firm, resem-
bling that of an animal's liver." — Moore's MS. The rich
jeruginous green colour of this species, resembling that of
many OsciUatorice, affords a character whereby at once this
species may be distinguished from all its congeners. The

COCCOCHLORIS. 317

fronds adhere closely to paper, present considerable gloss,
and retain the freshness and depth of their colouring when
dried.

" I have much pleasure in ascribing it to its acute dis-
coverer Mr. D. Moore, curator of the Royal Dublin Society's
Botanic Garden, who has added so many interesting plants
to the Irish Flora." — Harv.

Having only had the opportunity of examining dried spe-
cimens, I am not able to give the measurements of the
globules and vesicles ; I have, however, been able to ascertain
sufficient of the species to render it quite certain that the
reference to the genus Coccochloris is correct. The same re-
mark applies to the other species which I have placed in
that genus.

6. COCCOCHLORIS EIVULARIS Hass.
Plate LXXYIII. Figs. 6 a. b.

Char. Fronds hemispherical, tuberculose, often confluent,
bright green when recent, turning to brown in drying.
Globules small, globose, scattered.

Palmella rivularis Carm., MS. P. rivularis Harv., in Hook.
Brit. Flor. p. 397. ; Harv. in Manual, p. 177.

Hob. In a mountain streamlet, attached to rocks and
stones, Appin: Captain Carmichael.

" Fronds one fourth or half an inch in diameter, hemi-
spherical, tubercular, firmly adhering, sometimes cohering
into a broad crust. Granules small, globular, scattered.
Colour vivid green. It bears a striking resemblance to Chce-
tophora tuberculosa" — Carm. MSS. In drying it shrinks
considerably, and fades to dirty brown.*

* In a specimen which I have lately examined of this species, I dis-
tinctly perceived divisions in the mucous substance ; a certain number,
usually two, of the granules, as in the genus Hamatococcus, being invested
with a separate portion of the general substance. It is probable that this
structure belongs to all the species of the genus, and possibly of Ulva also,

318 PALMELLE.E.

7. COCCOCHLORIS GREVILLEI Hass.
Plate LXXVIII. Figs. 7 a. b. 8.

Char. Fronds minute, densely crowded, globose or somewhat

lobed, green, decidedly gelatinous.
a Granules elliptical.
/3 Granules small, globose.

7 Frond smaller, more hyaline, and with larger globose
granules.

Berk. Glean. Br. Alg. p. 16. t. 5. f. 1. ; Harv. in Manual,
p. 177. Palmella botryoides Grev., Crypt. Fl. t. 243. f.
2.; Harv. Hook. Brit. Fl. 1. c. p. 396. — /9. P. botryoides
Lyngb., Dan. p. 205. —7 Berk., Glean, t. 5. f. 2.

Hob. On heathy places, moist situations, frequent : 7 on
decaying stems of Asparagus officinalis ; in a hotbed :
Rev. M. J. Berkeley.

" Fronds minute, densely crowded, globose, green, com-
posed of pale green jelly, in which are numerous darker gra-
nules, elliptic in var. a ; in var. yS globose, and accompanied
with smaller globose granules, collected more or less into
little rounded heaps, the longest of which are of the size of
the larger granules. After it has been dried, the jelly is
nearly colourless, and the granules are scattered, and all of
the same size." — Rev. M. J. Berkeley.

It is evident from the preceding description that more than
one species is included under the name of Palmella Grevillei.

Note. I have since paid further attention to the subject of the division
of the mucous matrix into vesicles or cysts in Coccochloris, and I now
find that this structure is to be met with only in certain species of the
genus, and that it cannot be detected in any of the species figured in this
work. The species, therefore, with the frond thus divided, connect Cocco-
chlorisviith Hamatococcus, and scarcely differ from thoseof the latter genus.

It is still probable that the structure really does belong to all the Coc-
cochlorides, but that the extreme delicacy of the organization of some of
the species prevents its detection. Ramifying throughout the substance
of the fronds of all the species may be observed numerous slender
branched tubes, which may either be parasitic growth, or else form part
of the organization of the fronds ; and in the latter case they may be pre-
sumed to be connected with respiration.

319

FAM. XVIII. PROTOCOCCE^E.

Char. Stratum indefinite, friable, formed by an aggregation
of distinct globules, tohich, not being immersed in gelatine,
and not enclosed by a common investing membrane, are
readily separable from each other on the. application of
moisture.

48. BOTRIDINA Breb.

Char. " Frond gelatinous, globose, at a later period entirely
constituted of vesicles enclosing granules ; at length the
internal vesicles being absorbed, and the outer cellular
membrane defined, including granules imbedded in mu-
cus."

Derivation. The diminutive of ftorpv?, a bunch.

Obs. " Cl. Brebisson humanissimis literis observationes
suas communicavit, quibus innixus novum hoc genus pro-
posuit, has ipsas maxima pro parte et nos ipsi veritate
apprime respondentes invenimus. In hoc tamen nostra differt
sententia, quod granula secundum Cl. Brebisson in alveolis
tantum periphericis sita, nobis contra in alveolis cum peri-
phericis turn interioribus initio nidulari videantur, sed alve-^
olis sine vesiculis illis interioribus serius resorptis, et peri-
phericis tantum iisdemque vacuis, membrana efformatur
globules jam evolutos et propagatione aptos muco obvolutos
includens. Nomen a Cl. Brebisson propositum, legibus
glossologiae non omnino concisum, delere ausi non sumus."
— Meneghini.

This genus resembles somewhat in structure the compound
pollen granules of many plants.

Note. The Anacystis furfuracea Menegh., a production very different
from the Palmetto, furfuracea Berk., with which Meneghini supposed it
identical, and one coming near to Botridina, is a British Alga. I have
more than once met with it.

320 PROTOCOCCEJE.

1. BOTRIDINA VULGARIS Breb. in lit.

Plate LXXXI. Fig. 2.

Char. " Fronds small, spherical, aggregated, often confluent,

green, solid, with minute globose or subangular globules"
" Nostoc botryoides Ag., Syn. p. 135. Palmella botry aides
Lyng., Hydrop. p. 205. No. 6.; Ag. Syst. p. 14. No. 5.;
Grev. Scot. Crypt. Fl. t. 5. No. 243. ? P. Grevillei
Berk., Glean, vol. i. p. 16. t. 5. f. 1. — ?" — Meneghini.
Botridina vulgaris Meneghini, in Monograph. Nosto-
chinearum.

" The fronds of various sizes, rarely surpassing the head
of a pin, of a subspherical form, aggregated in considerable
quantity, cover the stems of mosses with a pulverulent
blackish green stratum, which Agardh first well delineated.
The granules in the beginning solitary, here and there affixed
subspherical or slightly angular, scarcely equal in their
greatest diameter the five hundredth part of a millimetre ;
gradually they increase in size, and when they have arrived
at the two hundredth part of a millimetre, they manifest an
internal granular substance ; at a later period having acquired
a form exactly spherical, the internal substance is seen ag-
gregated or collected into the centre, and the granules sur-
rounded by a pellucid margin. Again they increase in size, and
the interior granules are seen converted into vesicles filled with
lesser granules. These vesicles increased in number and mag-
nitude, the greatest dimensions of the frond being attained,
occupy its entire substance, and at length the diaphanous
margin disappears. The whole frond is then constituted of
vesicles closely heaped together, and enclosing in the centre
granules. The primitive membrane, enclosing in its midst
the interwoven or cellular structure, is so closely united with
the peripheral stratum of vesicles, that it can in no way be
separated from it. The last developement having been ac-
complished, the peripheral stratum of vesicles altogether looses
its granules : whether these disappear by absorption, or escape
outwardly, I have never been able to perceive. In this man-

H^EMATOCOCCUS. 321

ner the frond again obtains a diaphanous margin, but different
from that with which in the beginning it was surrounded." —
Menegh.

49. H^EMATOCOCCUS Ag.

Char. Cells spherical or oval, of various sizes, each invested
with one or more concentric vesicles 'Or membranes, mul-
tiplied either by division or by granules formed within the
parent cells.

Derivation. From al/j,a, blood, and KOKKOS, a berry.

Agardh has evidently included in his genus Hamatococcus
productions generically distinct; as, for example, H. sanguineus
and Hcem. or properly Protococcus nivalis : he therefore would
appear not to have entertained any precise ideas in reference
to his genus beyond the fact of the contents of the cells of
some of the species being of a red colour. Meneghini in the
memoir so often referred to, limits the genus ffcematococcus
to one species, the H. nivalis of Agardh, a production which
assuredly does not differ even specifically from the Proto-
coccus nivalis of the same author, and constitutes a new genus
Microcystis for the reception of H. sanguineus and its allies,
the adoption of which, as H. nivalis Ag. cannot be allowed
to remain in that genus, is rendered unnecessary.

Of the two terms Hcematococcus and Microcystis, the latter
is by far the more applicable, the former being in some de-
gree objectionable, inasmuch as it is founded on the colour of
the globules, a colour confined to a limited number of the
species of the genus. Meneghini thus defines his genus
Microcystis : —

" Frond mucous ; in the beginning definite, at a later period
effused, including globules clothed in vesicles and multi-
plied by a quaternary division or by granules evolved
within, constituting so many new fronds."

" Each globule, in the same way as those of the Pleurococci,
shrinks from its involucre, and then appears to be clothed
with its proper vesicle. A process of this kind is frequently

Y

322 PROTOCOCCEJE.

repeated, and hence arise so many concentric vesicles en-
closing the small globule in the centre.

" Frequently the globule, having shrunk from its proper
envelope, is divided into half, and each half, having shrunk
from its investing vesicle, again is divided into two parts, and
this occurs many times in succession. At length, the vesicles
being torn or converted into mucus and absorbed, the glo-
bules themselves formed by division are poured out into the
common mucous substratum. At other times the primitive
globules, or more frequently the internal substance of the
second, the usual division being suspended, passes into very
minute granules, and the involucre of the globule itself con-
verted into mucous substance, gives birth in the same man-
ner to new globules. The frond in the beginning indeed
definite, nevertheless speedily becomes confluent, and inde-
finitely expanded. This genus, therefore, differs only from
Coccochloris in the division of the globules, which likewise
manifests an affinity to Pleurococcus" — Meneyhini. •

The species included by me in the genus H&matococcus
admit of division into three subgenera. They embrace also
the genera Microcystis and Pleurococcus of Meneghini, to dis-
tinguish which genera I can find no satisfactory character.

First Subgenus. — Globules appendaged, that is, each termi-
nates or is imbedded in the extremity of a distinct mucous
prolongation, the mass of the plant being formed princi-
pally of these mucous prolongations.

The term Ouracoccus might be applied to the species of this
subgenus.

a. Mucous prolongation plain. Granules invested with a
single vesicle.

1. H^MATOCOCCUS ALLMANI Hass.
Plate LXXX. Fig. 3.

Char. Globules elliptical, large, blood-red, surrounded by a
single diaphanous margin.

H^MATOCOCCUS. 323

Hob. Dropping Well, Knaresborough : Prof. G. J. Allman.

The globules of this species resemble in size and form
those of Coccochloris murorum, a species which might indeed
be referred to the genus Hcematococcus, it differing from
Ham. Allmani only in colour, and in so far as I can ascer-
tain, the absence of the mucous appendages. If these ever be
present in Coccochloris murorum, then there can be no doubt
of the generic identity of the two plants.

Not being able to find that this plant has as yet been re-
corded, I have great pleasure in naming it after my friend
Dr. Allman, from whom alone I have received the plant. The
specimens sent, although very fine, were not altogether free
from admixture, being mixed up with examples of Ham.
Hookeriana. It was on an examination of these specimens
that I first discovered the mucous appendages, of which I
immediately apprised Dr. Allman, who wrote to me as fol-
lows : — " Many thanks for your information. Your ob-
servation on the structure of the Alga I sent you is most
interesting. Though I distinctly enough detected a peculiar
organization in the gelatinous flesh in which the capsules of
the Alga with red granules are imbedded, I saw nothing of
the singular arrangement you mention. Your observation is
certainly most interesting and original. I am longing to exa-
mine the Alga, now that you have directed my attention to
the curious fact you mention." The granules vary much in
size in this as well as in all other species of the genus H&ma-
tococcus. The Hcem. sanguineus of Kiitzing may possibly be
referrible to this, or perhaps more probably to the Hcem. cryp->
tophila, as it is described as having elliptical granules.

2. PLEMATOCOCCUS MUROKUM Hass.

Plate LXXXI. Fig. 4.

Char. Granules elliptical, aruginous green, free, surrounded

by a band, pellucid limbus.

Coccochlorum murorum Grev., Scot. Crypt. Fl. t. 6. No.
325. Microcystis mellea ? Menegh., loc. cit. t. xii. fig. 2.
Hob. Scotland : Dr. Greville. Ireland : Mr. Moore.

T 2

324 PROTOCOCCE.E.

The cells of this species precisely resemble those of H.
Allmani in form and size, the only difference being that of
colour, and the absence of the mucous elongations. It ought,
assuredly, to be regarded as congeneric with H. Allmani.
In a specimen from the herbarium of Sir W. J. Hooker, the
granules were not, as in other specimens which I have exa-
mined, exactly cylindrical, but somewhat pointed at one
extremity.

May 14. 1845. — I have just detected mucous appendages
in this species similar to those of H. Allmani.

3. HvEMATOCOCCUS CRYPTOPHILA HttSS.

Plate LXXX. Fig. 1.
Char. Granules blood-red, small, usually oval.

Palmella ? cryptophila Carm., MS. cum icone. Hcema-
tococcus sanguineus, in part, Harv. in Manual, p. 181.

Hob. On a stalactitic incrustation lining the vault of a
cavern in a quartz rock, Appin : Captain Carmichael.

This forms wide patches, externally of a brick-red colour,
but within whitish, breaking up easily into the numerous
separate portions of which each mass is formed. The reason
of the red colour being confined to the external surface of
the crust results from the structure and mode of develope-
ment of the species of this genus. The colour resides alone
in the granules : these terminate the superior extremity of
the mucous prolongations, which are colourless, and arranged
almost entirely side by side. The granules or cells are several
times smaller than in H. Allmani.

b. Mucous prolongations transversely corrugated or ringed.
Granules 1 — 2 in each cell, spherical. Vesicles numerous.

4. H^MATOCOCCUS INSIGNIS Hass.

Plate LXXX. Figs. 6 a. 6 b.
Cliar. Granules very large, spherical, blood-red.
Hob. England.

ILafiMATOCOCCUS. 325

This very fine species I have never met with in any con-
siderable quantity. Scattered isolated globules I have fre-
quently met with, and these occasionally attached to a closely
corrugated or ringed mucous appendage. Each globule is
usually surrounded by a single vesicle or ring : in some
globules, however, there are as many as four or five en-
closing vesicles.

5. H^EMATOCOCCUS HoOKERlANA Berk, and Hass.
Plate LXXX. Fig. 4.

Char. Granules very small, spherical, blood red, surrounded
by one or more investing membranes or vesicles.

Hab. On a chalk cliff at Mundley, Norfolk : Sir W. J.
Hooker. Dropping Well, Knaresborough : Dr. Allman.

Shortly after noticing this species in beautiful condition,
mixed up with H. Allmani, but which had altogether escaped
the notice of Dr. Allman, I received a dried specimen of
this plant, accompanied by a description and remarks on the
ringed organization of the mucous appendages from the Rev.
M. J. Berkeley, to whom it had been communicated for exa-
mination by Sir W. J. Hooker. Specimens of H. Allmani and
H. Hookeriana were then sent to Mr. Berkeley, who satisfied
himself of the identity of Dr. Allman's specimen with that
transmitted to him by Sir William Hooker. The only differ-
ence between the specimens collected in habitats so widely
different was, that in the former the transverse corrugation
of the sheath was the more conspicuous.

The Rev. M. J. Berkeley, in his first letter, thus speaks of
it: — " I have just received the enclosed from Sir W. J. Hooker.
It does not agree with any of Meneghini's species of Micro-
cystis. There is a very curious appearance in some parts as
if the old vesicles were chained together." In a second com-
munication, Mr. Berkeley adds — " I have not had time to ex-
amine your Alga till to-day : it is certainly the same as Sir W.
Hooker's, but far finer ; the threads are three or four times
as long. I still fancy my theory, as to their origin, is right."

T 3

326 PROTOCOCCEJE.

Second Subgenus. — Mucous appendage wanting. Granules
one, two, or four, in each cell.

Obs. It is possible that subsequent research may prove
that one or more of the species of this section should be re-
ferred to the first subgenus.

a. Investing vesicles numerous.

6. H^MATOCOCCUS RUPESTRIS HttSS.

Plate LXXXIL Fig. 1.

Char. Granules spherical, olive green, single, sometimes binate,
very small, each enclosed in several distinct enveloping
vesicles.

Palmella rupestris Lyngb., Hydroph. p. 207. t. 69. D.
P. rupestris Ag., Syst. p. 13. Microcystis rupestris Kiitz.,
Linnrv:i. p. 374. No. 9. Microhaloa rupestris Kiitzing,
Phycologia Generalis, p. 169.; Harv. in Hook. Br. Flora,
ii. 397. ; also in Manual, p. 178. ; Meneghini loc. cit.

Hob. On moist overhanging cliffs, Appin : Capt. Car-
michael. Aberdeen: Dr. Dickie. On moist conglo-
merate sandstone caves near Cushendall, co. Antrim :
Mr. Moore.

" Frond hyaline, gelatinous, yellowish green, easily broken
up, about an inch in diameter, shapeless, rough; pellucid,
more dense in the centre and elevated ; when dried, collapsed ;
blackish, cartilaginous, fragile. Subjected to the micro-
scope, it appears constituted of hyaline subspherical vesicles,
enclosing yellowish green, spherical or slightly oblong glo-
bules, usually undivided. Solitary globules, magnified with
glasses less powerful, are seen free and naked ; by means of a
more powerful microscope, almost all are perceived to be
clothed with a proper cyst, larger vesicles enclose smaller,
and the whole frond appears areolated, the hollow areolae con-
taining solitary or binate globules. The vesicles, general as
well as partial, duplex, triplex, or multiplex, and that without

H^MATOCOCCUS. 327

any perceptible order, commonly present concentric circles,
generally approximated, evident to the light. But the quater-
nary type, both in the distribution of the vesicles and glo-
bules, is generally preserved. The diameter of the globules
is constant at the two hundredth part of a millimetre ; that of
the vesicles varies from the hundredth to the twenty-fifth part
of a millimetre.

" At a more advanced period of growth, some globules be-
come thicker, and manifestly include a granular substance,
the partial vesicles at the same time becoming dissolved, and
disappearing. Towards the circumference of the frond are
often noticed globose, elliptical, or irregularly lobed areolae,
which are seen to be gelatinous, and all filled with very mi-
nute granules scarcely the fiftieth part of a millimetre in size.
It appears, therefore, that each one of the larger vesicles, the
partial vesicles included by it being absorbed, the globules
having been converted into granules, is changed into a new
frond. As often as a fragment of the frond is compressed be-
tween plates of glass, the oblong gelatinous bodies enclosing
very small granules, which we regard as new and incipient
fronds, and which are always present in great abundance, are
lacerated, their contents poured forth, and they then cover
the other parts with the thin mucus with which they are
themselves enveloped; and from this C. Kiitzing appears
to have asserted that the vesicles were enfolded, the green
stratum enclosing very minute granules. It is yet remark-
able that the multiplied and concentric vesicles escaped the
celebrated Kiitzing and the acute Lyngbye." — Meneghini.

7. HJEMATOCOCCUS GKANOSUS Harv.
Plate LXXXI. Fig. 6.

Char. Crust widely spreading, granulated, pale green. Cells
polymorphous, formed of two or three vesicles, and each
containing one, two, or four green, large, elliptical granules
with distinct hyaline borders.

Y 4

328 PKOTOCOCCE^C.

Palmclla granosa Berk., Glean. Brit. Alg. ii. p. 19. Mi-
crocystis granosa Meneghini, 1. c. p. 85.

Hab. Growing in great abundance on sub-immersed
Hypnum stellatum, in the bogs bordering on Whittlesea
Mere, summer : Rev. M. J. Berkeley. Aberdeen :
Dr. Dickie. Broadwater Forest : Mr. Jenner.

" Pale green, or when preserved in the herbarium, with a
pale brownish tint. Growing in large masses of no certain or
distinct form, but broken into many angular faces, having a
very granulated appearance, and crumbling beneath the fin-
gers. The whole plant is made up of sub-elliptic, hyaline,
colourless, jelly-like bags, containing from two to four green
elliptical granules, which in some lights appear as if sur-
rounded with a pellucid border." — Berk.

Meneghini makes the following remarks on this fine spe-
cies : " Hie auctor monet speciem hanc praeter colorem Hee-
matococco sanguineo Ag. simillimam esse ; et ejusdem affini-
tate cum Palmella rupestris animadvertens limites generum
Haematococcus et Palmella incertos esse demonstrat, summo
nempe acutnine novi generis Microcystis instituendi necessi-
tatein praesenserat."

b. Usually but one investing membrane or vesicle.

* Granules from one to eight.
8. H^MATOCOCCUS ALPESTRI8 HttSS.

Plate LXXXI. Fig. 3.

Char. Globules of very variable size, often large, rarely
concentric, containing one, two, four, or eight, but usually
two or four small, spherical, dark green granules.

Pleurococcus glomeratus ? Menegh., loc. cit. t. v. f. 2.
Hab. Wales: Sir W.J. Hooker.

On looking over the splendid collection of Alga forming
part of the herbarium of Sir W. J. Hooker, I noticed a

H^EMATOCOCCUS. 329

specimen of a dark olive compact substance two inches in ex-
tent, marked Tremella. This, on examining with the micro-
scope, I soon ascertained to belong to the present genus, of
which it forms a remarkable species — one remarkable for the
size of the vesicles, the smallness of the enclosed granules, and
for the absence in general of concentric rings or vesicles.

** Granules mostly numerous in each cell.
9. HZBMATOCOCCUS SANGUINEUS Ag.

Plate LXXIX. Fig. 2.

Char. Smaller cells spherical, containing usually one or two
granules ; larger, often angular, and filled with numer-
ous blood-red, circular, and nucleated, granules.

Hamatococcus sanguineus Ag., Icon. Alg. Europ. No. xxiv.
Palmella ? sanguinea Ag., Syst. p. 15. ffcem. sangui-
neus, in part, Harv. Manual, p. 181.

Hob. On shady rocks at Tobermorey in Mull: W. H.
Harvey.

Mr. Harvey in his " Manual " has included in his Hcemato-
coccus sanguineus two species, the one being the Palmella?
cryptophila of Carmichael, the other, in all probability, the
true H. sanguineus, a production which would seem to be as
rare as it is strikingly beautiful, it only having as yet been
discovered in one locality by Mr. Harvey, to whom I am in-
debted for the specimen from which my figure is taken. The
smaller cells are quite spherical, and contain but a single
blood-red granule, a wide pellucid border produced by the
thickness of the single vesicle which encloses it surrounding
the granule: the larger attain a very considerable size, are
mostly angular, and include a very considerable number of
large spherical granules, each of which is occasionally sur-
rounded by a transparent vesicle, in which state each separate
granule is to be regarded as a distinct young frond enclosed
in the parent cell.

330 PKOTOCOCCE^:.

10. H^MATOCOCCUS FRU8TULOSUS Harv.

Plate LXXXI. Fig. 1.

Char. Crust widely spreading, friable, dark grey. Cells large,
roundish, containing numerous, very minute, scattered
granules.

Palmella frustulosa Carm., MSS. cum icone. Hcematococ-
cus frustulosus Harv., in Hook. Br. Fl. p. 395. ; also in
Manual, p. 181.

Hab. On irrigated cliffs, perennial, Appin : Capt. Car-
michael.

Capt. Carmichael thus briefly describes this fine species : —
" It occurs in the form of a greyish black fragmentary scurf
On the slightest pressure it separates into corpuscles of va-
rious forms, but mostly spherical, hyaline : under the micro-
scope, surrounded by a membranous envelope, and including
several granules."

The granules are very minute, spherical, not usually sur-
rounded by vesicles, and very numerous, the larger cells en-
closing as many as one or two hundred granules.

11. H^MATOCOCCUS ARENAEIU8 HttSS.

Plate LXXVI. Fig. 10.

Char. Cells spherical, rather small, containing spherical
green granules, varying in number from one to ten, but
usually there are five or six.

Hab. Tunbridge Wells Common : Mr. Jenner.

This species approaches rather closely to the preceding, but
yet may be easily distinguished from it. The cells or fronds
of H. arenarius are much smaller, contain fewer granules,
although these are larger than those of H. frustulosus.

*** Granules frequently binate or quaternate.

The granules in all the species of the genus Hcematococcus
are increased by division, the division not usually extending

ILEMATOCOCCUS. 331

to the outer membrane. The cells, the youngest of all, con-
tain but a single granule : as the developement proceeds, this
becomes divided into two other granules, and these are again
subdivided, and so on the process of multiplication proceeds,
in some cases, as in H. sanguineus and H. frustulosus, to a
much greater extent than in other species.

12. ILEMATOCOCCUS BINALIS Hass.

Plate LXXXII. Fig. 2.

Char. Cells large, elliptical, green, each containing mostly two

semi- elliptical granules.
Pleurococcus thermalis $ Menegh., loc. cit. t. iv. fig. 3.

Hob. Cheshunt : A. H. H. Aberdeen, mixed up with
other Algae : Dr. Dickie.

This species is very distinct. Some of the cells contain
but a single granule, others two, and these are by far the
most numerous ; others again, four granules. The species I
suspect is by no means uncommon.

It is not unlikely that this is an appendaged species.

13. HLaEMATOCOCCUS FURFURACEUS Hass.
Plate LXXXII. Fig. 4.

Char. Cells small, spherical, or somewhat angulated. Granules
often associated in pairs,

Palmella furfuracea Berk., Glean. Alg. p. 18. t. 5. f. 3. .P.
furfuracea Harv., in Manual, p. 178.

Hab. Forming a thin mealy stratum of a light yellowish
green, on the walls of a large frame at Milton, North-
amptonshire : Rev. M. J. Berkeley. Limestone rocks,
co. Antrim : Mr. Moore.

" Fronds aggregate, diffuse, irregular, granulated, rather
rigid, under the knife, falling down into a mass of minute

332 PROTOCOCCEJE.

more or less rounded granules with scarcely any appearance
of jelly." — Berk.

The Anacystis furfuracea would appear to be an entirely
different plant.

14. ELEMATOCOCCUS LIVIDUS HttSS.

Plate LXXXII. Fig. 5.

Char. Crust of an indefinite extent, and livid colour. Granules
spherical, green, small, solitary or binate, and frequent,
quaternate, the quaternate granules being contained in
spherical cysts.

Palmella livida Carm., in Grev. Flor. Edin. P. livida
Harv., in Manual, p. 178. Microcystis livida Meneghini,
Monographia Nostochinearum Italicaruin, p. 74, 5.

Hab. " On overhanging cliffs, covering them to an indefi-
nite extent with a dirty black scurf: " Captain Car-
michael. Found on limestone rocks near Poilballintrea,
co. Antrim : D. Moore.

The solitary and binate granules which constitute by far
the greatest portion of the plant are not enclosed in cysts,
and therefore do not appear to be surrounded by a trans-
parent limb or border. The granules however when asso-
ciated in pairs or multiples of that number are always enclosed
in a distinct cyst or vesicle, and occasionally it happens in
this as in other species of this division of the genus Hcemato-
coccus, that each of the contained granules is also furnished
with a distinct envelope.

Mr. Moore writes of this species : — " This singular substance
covers the overhanging limestone rocks to a great extent,
sometimes as much as several hundred yards together. When
fresh, it looks like a blackish brown, gelatinous substance,
giving the rocks on which it grows the appearance of being
covered with pitch. On places where it becomes dry by
exposure to the sun, it is very friable, and on being touched
crumbles down to a powder. Under the glass it is found to

H^EMATOCOCCUS. 333

]be composed of excessively minute granules, pellucid in the
centre with darker edges. Is it a Palmella?"

15. HJEMATOCOCCUS JERUGINOSUS Hass.

Plate LXXXIL Fig. 3.

Char. Stratum aruginous green, firm. Granules minute,
mostly solitary, and not enclosed in cysts, somewhat angular,
occasionally in their ultimate developement associated in
pairs or multiples of that number and contained in a
globose vesicle,

Palmella aruginosa Carm., MS.
Hab. Appin : Captain Carmichael.

Of this species, remarkable for the richness of its colour, I
found a specimen in the herbarium of Sir W. J. Hooker. In
its microscopic character, it resembles somewhat H. lividus,
but is altogether a smaller plant.

16. ILEMATOCOCCUS THERIACUS HttSS.

Plate LXXVIII. Fig. 9.

Char. Granules excessively minute, mostly solitary and sphe-
rical, but occasionally enclosed in cysts,

Hab. Rievaulx Abbey, Yorkshire : Dr. Allman.

This is the most minute species of the genus. Dr. All-
man, who alone has noticed it, compares its appearance to
that of inspissated syrup.

17. H^MATOCOCCUS VULGARIS HttSS.

Plate LXXXI. Fig. 5.

Char. Cells many-cysted, of various sizes and forms. Gra-
nules angular, numerous in each cell, often repeatedly
divided into fours.

Pleurococcus vulgaris Menegh., Consp. p. 20. Chlorococcum
vulgare Grev., Scot. Crypt. Fl. vol. iv. No. 262.

334 PROTOCOCCEJE.

Hob. On walls, trees, &c., Cheshunt : A. H. H. Appin :
Captain Carmichael.

Although this species is somewhat peculiar in its deve-
lopement, not the slightest necessity exists for its removal
from the many-cysted species of the genus Hcematococcus. It
is impossible to make too rigid an examination and analysis
of plants of this order, but the utmost care is required in
forming a right estimate of the value of the differences dis-
closed by a rigorous examination, for if every small difference
be too highly regarded, we shall soon have genera as nu-
merous as species. The figure given in this work is chiefly
taken from that of Meneghini's " Monographia."

18. KEMATOCOCCUS MICROSPORUS Hass.

Plate LXXVI. Fig. 8.

Char. Cells angular, adherent to each other, and each occu-
pied with usually four minute slightly oval green granules.

Hab. Uckfield Sandrocks, Sussex : Mr. Jenner.

This is a distinct enough little species. I have only seen
the specimens of Mr. Jenner, who sent it me as " Palmella
protuberans" The granules are always enclosed in cells,
which are strongly adherent to each other, and never sepa-
rate.

19. H^MATOCOCCUS MINUTISSIMUS HttSS.

Plate LXXVI. Fig. 9.

Char. Globules spherical. Granules excessively minutet
green.

Hab. Mixed up with H. furfuraceus. Ireland : Mr.
Moore.

The granules in this species are even smaller than those of
Hcem. microsporus, and are much more numerous in each
cell than in that species.

PROTOCOCCUS. 335

50. PROTOCOCCUS Ag.

Char. Plant consisting of aggregated, naked globules, filled
with minute granules, and sessile on a gelatinous trans-
parent mass.

Derivation. From Trparos, first or primary, and KOKKOS,
fruit ; from its elementary organization.

" Agardh states that the globules of his Protococcus are
perfectly simple, or consist merely of a hyaline cellule en-
closing an uniform coloured mass, and he regards our British
plant as a different species, belonging to Hcematococcus.
Having minutely examined a specimen from Agardh himself,
submitted to me for that purpose by Dr. Greville, and find-
ing exactly the same compound structure as in our British
specimens, I do not hesitate to pronounce the two plants
identical." — Harv,

1. PKOTOCOCCUS NIVALIS Ag.
Plate LXXX. Fig. 2.

Char. Globules exactly spherical, very minute, fine purple-
red. Gelatinous mass pale, spreading.

Grev. Crypt Fl. t. 231. ; Ag. Je. Alg. Europ. t. 21., and
Ham. Grevillii Ag., 1. c. t. 23. ; Harv. 1. c. p. 395. Pal-
mella nivalis Hook., in Parry's 2nd Voy. App. Uredo
nivalis Bauer, in Journ. of Science and Arts, vol. vii.
p. 222. t. 6.

Hob. On the borders of the lake of Lismore, spreading
over decaying leaves, &c. : but in greater perfection on
the calcareous rocks, within the reach of occasional in-
undation : Captain Carmichael. Near Miltown Malbay,
on schist ; Limerick, on limestone ; and about Dublin
on granite. In most cases slightly inundated. — W. H.
Harvey.

This curious little plant, which, under the name of Red
Snow, has excited so much interest among botanists, is usu-

336 PROTOCOCCE^.

ally found in this country in the form of a thin, stain-like
stratum on the surface of rocks, or investing decayed vege-
table substances with a purplish crust. On examination
under the microscope, it is found to be composed of innu-
merable spherical bodies, seated upon a gelatinous substra-
tum. The globules are of various sizes, probably depending
upon age. At first they are furnished with a wide pellucid
border, and contain a deep red homogeneous mass. As they
increase in size, this border gradually becomes narrower, and
at length altogether disappears, while the internal mass,
which at first was simple, becomes broken into numerous
distinct granules or seeds, which are finally discharged. Red
snow, we are informed by Professor Agardh in his interesting
memoir on the Protococcus *, was first observed by Dr. Saus-
sure in the year 1760, on Mount Beven, in Switzerland, and
subsequently so frequently among the Alps, that he was sur-
prised how such a phenomenon should have escaped the
attention of other travellers, especially Scheuchzer. Ra-
mond found red snow on the Pyrenees, and the botanist
Sommerfeldt in Norway. At the beginning of the century
it was noticed on several of the mountains of Italy, along
the Apennines; and in March, 1808, the whole country
round Cadore, Belluno, and Feltre was covered in one night
to the depth of twenty centimetres with a rose-coloured snow,
a pure white snow having fallen before and after, so that the
coloured snow formed an intermediate stratum. The same
fact is recorded at the same time in several other Italian
localities. Still red snow excited little attention among
botanists, and had not obtained a place in our scientific
arrangements until Captain Ross discovered it in Baffin's
Bay, covering tracts of some miles in extent, and penetrating
in some places to the depth of ten or twelve feet. The spe-
cimens brought home by this celebrated traveller were sub-
mitted to Mr. Bauer and Mr. Brown, to be examined

* Nova Acta Phys. Med. Academiae Cas. Leop Car. Nat. Cuv. vol xii.
p. 737. Translated in Grev. Crypt. Fl. vol. iv. sub. t. 231.

PROTOCOCCUS. 337

botanically, the latter of whom, with his usual acuteness,
decided that it was " Algarum genus ? ? Confervis simpli-
cibus et Tremellas cruentee quodammodo affine ? ? " The
" local habitation " thus assigned, has been acknowledged
by all succeeding botanists ; and Agardh has completed its
history by giving it " a name." — Harv.

" It is to be observed, that the same wisdom which ordained the vege-
table creation for the use of feeding and healing the body, hath applied
it also to a moral and intellectual use, for the enlarging of our ideas, and
the enlightening of our understandings. It joins its voice in the universal
chorus of all created things, and to the ear of reason celebrates the wis-
dom of the Almighty Creator. As the heavens, from day to day and from
night unto night, declare the glory of God, so do the productions of the
earth ; all trees and herbs, in their places and seasons, speak the same lan-
guage, from the climates of the north to the torrid regions of the south,
and from winter to spring and the harvest. Happiest of all is he, who,
having cultivated herbs and trees, and studied their virtues, and applied
them for his own and for the common benefit, rises from thence to a
contemplation of the great Parent of good, whom he sees and adores in
these his glorious works. The world cannot shew us a more exalted
character than that of a truly religious philosopher, who delights to turn
all things to the glory of God ; who from the objects of his sight derives
improvement to his mind, and in the glass of things temporal sees the
image of things eternal. Let a man have all the world can give him, he
is still miserable, if he has a grovelling, unlettered, undevout mind ; let
him have his gardens, his fields, his woods, and his lawns, for grandeur,
ornament, plenty, and gratification, while at the same time God is not in
all his thoughts ; and let another have neither field nor garden ; let him
only look at nature with an enlightened mind ; a mind which can see and
adore the Creator in his works ; can consider them as demonstrations of
his power, his wisdom, his goodness, his truth : this man is greater as
well as happier in his poverty, than the other in his riches. The one is
but little higher than a beast, the other but little lower than an angel." —
Rev. W. Jones of Nayland.

338

ALGJE FIGURATJI.

FAM. XIX. DESMIDE.E.

Char. Algae rarely filamentous, bipartite, of a ^figured out-
line, highly mucous.

WE have arrived at length at the consideration of a most
ntercsting group and family of freshwater Alga, the essential
characteristics of which are the beautifully figured forms
and bipartite composition of the fronds of the numerous
species of which it is composed.

The Desmidece have been the subject of considerable dis-
cussion respecting their animal or vegetable nature : the
question is now, however, all but settled in favour of their
vegetability. Amongst the advocates of their animal nature
may be mentioned the names of Ehrenberg and Mr. Dal-
ryrnple : the observations of the latter, however, were con-
fined almost exclusively to the genus Closterium.

Ehrenberg rested the claims of the Desmidea to ani-
mality upon the mode of their increase by self-division, a
method of multiplication which it is now known belongs to
all the Algce, and which, therefore, cannot be allowed to have
any weight in the decision of the point in question. Mr. Dal-
rymple, however, in his memoir on the Closteria*, adduces
several\ther reasons for regarding them as animals, two only
of which apply at all to the other genera of Desmidea, the
remainder being alone applicable to Closterium : — these are,
first, the fact that the inner delicate membrane, which lines
the outer symmetrical, and usually crescentic covering, con-

« See "Annals of Nat. Hist," vol. v. p. 415.

DESMIDE^E. 339

tracts forcibly on the application of certain reagents, the
action of which cannot be considered as purely chemical;
and second, that iodine does not detect the presence of starch
in the cells. The former observation is equally applicable
to the tender membrane which lines the cells of true Con-
ferva, while the latter remark is wanting in accuracy, for
it is only when the Desmidece are very young, and before
the contents of the cells assume a granular appearance, that
iodine does not make manifest the presence of starch ; subse-
quently, however, when the endochrome has become granular
and vesicular, starch is readily detected by means of iodine,
it turning the large vesicular granules of a blue colour.

Meyen advocated the vegetability of the Desmidea, and
was the first to detect the presence of starch in the cells, but
the accuracy of his remarks has been doubted ; they are now,
however, fully confirmed by Ralfs, Jenner, and the majority
of recent algologists.

The DesmidecB, I conceive then, are to be regarded as
vegetable productions, agreeing with the Conferva proper, of
whose vegetability there can be no question, in the following
particulars.

1st. Probably in the elementary composition of the cel-
lular tissue.

2d. In the undoubted presence of starch in the cells.

3d. In the multiplication of cells by division.

4th. In their reproduction.

The reproduction of this family has been stated by some
writers to be threefold. I am disposed to think, however,
that there is but one essential and true mode of reproduc-
tion. The three methods by which the Desmidece are stated
to be multiplied are, first, by the division of the cells ;
second, by bodies analogous to zoospores ; and third, by
true spores, formed as in the Conjugates, by the union,
intermingling, and condensation of the contents of two
distinct individuals. To the family Conjugates indeed the
DesmidecB would appear to be more nearly related than to
any other. The first cannot be regarded as a true mode of
reproduction ; it is but a continual growth, repetition, and

z 2

340 DESMIDEJS.

multiplication of cells; and while it effects the increase of
the individuals of a species, does not provide against the ex-
tinction of that species when it shall have reached the ter-
mination of the brief existence allowed to it. Moreover, the
cells resulting from the bisection of other primary cells have
no periods of juvenescence and growth ; they are produced
at once fully developed and perfect in size and organization.
It is the nature, on the contrary, of a true reproduction, that
the bodies or organs by which it is effected should be at first
minute, and subsequently pass through successive stages of
devclopement. The second method is assuredly the usual and
legitimate mode of reproduction, viz. that by bodies analogous
to zoospores, while in the third the organs resulting from the
union of two individuals are probably to be regarded in the
same light in which Agardh viewed the similar bodies of the
Conjugates, viz. as receptacles in which the zoospores are
stored, and destined, as I think, not for immediate but for
future use, that they are in fact hibernacula, designed to
preserve the contained propagules until the vicissitudes and
rigour of winter shall have passed away.

The formation of sporangia has been noticed to occur in
nearly all the genera of the family of Desmidea, and it is
probable that it occasionally occurs in all of them. By
Ehrenberg it has been noticed in different species of the
genus Closterium, by Brebisson in Desmidium, by Ralfs in
his genus Tetmemorus, and in Staurastrum. In the Cylin-
drocystis Brebissoni, a production placed by Meneghini
amongst the Nostochinece, but which seems to me to belong
to Desmidece, union of the cells has been observed, and it is
most probable that this union is followed by the formation of
sporangia.

So much for the reproduction of the Desmidea: a few
words may be added upon their growth. It has already
been stated in the definition of the family that certain species
of Desmidece are filamentous. The filaments of these in-
crease in length though not in number by the continual
division of the cells, as do other filamentous Alga; but
in the Desmidea, which are not formed of filaments, the

DESMIDIUM. 341

growth of cells is different, and approaches rather more
closely to a true reproduction, which, however, it is not.
Each of these Desmidia consists of two portions, or cells, fre-
quently contracted at their points of junction. These seg-
ments, when they have arrived at maturity, separate from
each other, and from the open extremity of each a little
mucous pouch extends : this imperceptibly increases in size,
and finally assumes the form and characters of the originally
formed segments. This mode of formation of cells is highly
curious, and it is one which may be accounted for by refer-
ence to the form and constitution of two portions of those
DesmidecK which present it.

Another fact, not as yet alluded to, has been advanced in
support of the animality of the Closteria by Mr. Dairy mple :
this is the presence in each extremity of Closterium of a
distinct organ or vesicle which contains a number of active
and revolving molecules. But moving and revolving par-
ticles are met with in many undoubted Alga, and, therefore,
their presence in Closterium cannot be considered as decisive :
moreover, no such organ presents itself in any other genus
of Desmidece, the proofs of the vegetability of which may
be regarded as decisive, and to which the Closteria are too
evidently related for the idea to be entertained that the one
are animal and the other vegetable productions.

The Desmidecs are found in old boggy pools, the waters
of which are not periodically dried up, but which are per-
manent for several years. They do not usually float on the
surface, but are found in cloud-like masses near the bottom.
They are best removed on pieces of linen, on which, if
moistened regularly, they may be preserved unaltered for
several days.

Section i.
Frond filamentous.

51. DESMIDIUM Ag.

Char. Frond filamentous, simple, spirally twisted, fragile,
articulated and angular ; mature cells bipartite ; angles
z 3

342 DESMIDE2E.

mostly bicrenate. Endochrome frequently bipartite, in
the transverse view stellate, not filling entirely the cavity
of the cells. Reproduction by bodies analogous to zoo-
spores.

Derivation. From Sea-os, a bond.

a. Filaments with two angles.
* Mucous sheath very evident.

1. DESMIDIUM CYLINDRICUM Grev.
Plate LXXXIII. Figs. 1, 2.

Char. Filaments stout, somewhat compressed, with two bi-
crenate angles. Crenatures strongly marked. Cells
rather longer than broad, connected by a thickened border,
mucous sheath very evident. Endochrome four or Jive
rayed.

Grev. Scot. Crypt. Flor. t. 293.; Desmar, n. 1110.; Harv.
in Manual, p. 196. Didymoprium Grevillei Kiitzing,
Phyc. Gener. Desmidium cylindricum Ralfs, in An-
nals, vol. xi. p. 378. pi. viii. fig. 1.

Hob. Scotland : Dr. Greville. At the bottom of shallow
pools and ditches, Appin : Captain Carmichael. In old
peat pits about Dolgelly, North Wales ; sparingly near
Penzance : Mr. Ralfs. In a watercourse on Chiltington
Common, near Pulborough, Sussex : Mr. Jenner. Ches-
hunt : A. H. H. In Caragh Lake, Kerry : Mr. An-
drews. Bog holes, co. Meath : Mr. Moore.

The above description embraces all the essential characters
of the species which may be regarded as the type of the
genus. In consequence of the spiral twisting of the filaments
the crenatures are much more perceptible in certain cells than
in others ; they are most strongly marked as a rule at about
every tenth cell, gradually diminishing from these towards
the central cells of the series, where they are much less ap-
parent, and where the extremities of the crenatures, instead

DESMIDIUM. 343

of being pointed are truncate. This species, as well as in-
deed all the Desmidece, are most beautiful microscopic objects.
I do not see the necessity for instituting a new genus for its
reception. I have not, therefore, adopted that of Kiitzing ;
viz. Didymoprium.

** Mucous sheath not apparent.
2. DESMIDIUM BORRERI Ralfs.
Plate LXXXIII. Figs. 9, 10.

Char. Filaments slender. Cells biangular, inflated, elongated,
being about twice as long as broad. Endochrome^ue or
six rayed.

Desmidium Borreri Ralfs, in Annals of Nat. Hist., vol. xi.
p. 375. t. 8. p. 4. Didymoprium Borreri Jenner, in
Fl. Tunbridge Wells, p. 192.

Hob. Boggy ditch at Crom Bychan : Mr. Borrer. Llyn
y Cwyn : Mr. Borrer and Mr. Ralfs. In all peat bogs
near the outlet of Llanberris Lakes and near Dolgelly,
North Wales : Mr. Ralfs. , On Ashdown Forest near
Duddles Well ; in the great bog near Forest Row, and
at Chiltington Common, near Pulborough : Mr. Jenner.
Bog holes, co. Meath : Mr. Moore.

This is one of the most graceful and easily recognised spe-
cies of the genus, remarkable principally for the great length
of the cells ; the endochrome in each cell is distinctly divided
into two masses, which arrangement imparts to the plant
somewhat the appearance of a Tyndaridea.

The cells are somewhat inflated, and each resembles in
form two flower-pots juxtaposed by their mouths ; the rims
being represented by the crenatures of the cells, between
which passes circularly round each cell a superficial groove,
in the situation of which the cells at an advanced period of
their developement separate, and give issue to their granular
contents. Viewed transversely, the cells are spherical, with

slight lateral projections.

z 4

344 DI>.\II 1>K.K.

b. Filaments triangular.
* Mucous sheath not apparent.

3. DESMIDIUM SWARTZII Ag.
Plate LXXXIII. Figs. 7, 8.

Char, Filaments triangular. Cells rather shorter than broad,
bicrenate, angles of the cells well marked. Endochrome
three-rayed.

Grev. Scot. Flor. t. 292. ; Ehren. Die Infus. p. 140. t. 10.
f. 8. ; Pritch. Infus. p. 183. ; Harv. in Manual, p. 196. ;
Ag. Syst. p. 9. ; Ralfs, in Annals of Nat. Hist. vol. xi.
p. 375. plate viii. fig. 3. ; Jenner, in loc. cit. p. 192.

Hob. Scotland : Dr. Greville. Appin : Captain Car-
michael. Tunbridge Wells : Mr. Borrer. Swansea,
South Wales ; Caernarvon and Dolgelly, North Wales ;
Penzance : Mr. Ralfs. High Beech, Epping : A. H. H.
Kusthall Common, and in a pond between Ramslye
rocks and Broad water Forest ; Battle ; Chiltington Com-
mon, near Pulborougb : Mr. Jenner. Bog holes, co.
Meath: Mr. Moore.

In consequence of the filaments of this species being trian-
gular, the spiral twisting of the threads is more evident than
in any other species of the genus. When the microscope
is brought to bear upon any filament, two of the three lines
of crenatures are visible, and the third is indicated by a dark
waved line passing from one margin of the filament gradually
towards the other, the dark appearance of the line being
occasioned by the dense endochrome of the cells situated
immediately behind the crenatures.

Kiitzing limits the genus Desmidium to this one species,
which he considers to d lifer generically from the other species
usually associated with that genus, in the fact of the presence
of the third angle to the cells — a distinction not considered to
to be sufficient in the case of the genus Staurastrum for
the foundation of new genera. The German professor has

DESMIDIUM. 345

therefore been induced to institute a new genus for D.
cylindricum, under the name of Didymoprium. This genus,
in my humble opinion, ought not to be adopted ; and if it be
really a good and valid genus, then is there sufficient reason
why D. Borreri should form the type of a genus different
from both, for it differs from D. Swartzii in the cells being
biangular and not triangular, and from Desmidium cylindricum
Grev., the Didymoprium Grevillei of Kiitzing, in the absence
of a mucous sheath. There would thus be as many genera as
there were formerly considered to be species of Desmidia, a
result not altogether satisfactory.

c. Filaments with four angles.

4. DESMIDIUM QUADRANGULATUM Rolfs.

Plate LXXXIV. Fig. 3.

Char. Filaments quadrangular. J^ndochrome four-rayed.
Ralfs, in Annals, vol. xv. p. 405. pi. xii. fig. 9.

Hob. In a boggy pool at Balogas, near Penzance : Mr.
Ralfs.

Notwithstanding the strong resemblance which it bears to
Desmidium Swartzii, this plant appears to me to be very dis-
tinct. In consequence of the filaments having four angles
instead of three, and as they are spirally twisted in the
same manner as those of other Desmidia, it follows, that two
dark, and waved lines, describing two of the four angles, are
visible in the length of the thread. The observation of these
will at once serve to distinguish it from Desmidium Swartzii,
of which Mr. Berkeley, Mr. Borrer, and Mr. Ralfs consider
this plant to be a variety : the latter, however, remarks
that he has gathered it for two successive years quite unmixed
with that species.

It seems to me that this plant has not merely a right to be
considered as specifically distinct from D. Swartzii, but nearly
as much claim (a claim however which I do not allow) to be

346

regarded as generally distinct therefrom, as D. cylindricum
and D. Swartzii have to be so considered.*

52. GL^EOPKIUM Berk. MSS.

Char. Filaments cylindrical, invested in a broad elastic sheath.
Cells slightly crenate. Endochrome stellate.

From the above definition it would appear that this genus
does not differ in any marked manner from Desmidium
There is certainly more ground for its formation than for the
establishment of Kiitzing's Didymoprium ; but perhaps the
ends of science and of nomenclature would have been an-
swered to have placed the two species which it is made to
comprise and which differ as widely from each other as they
do almost from the genus Desmidium in a distinct section of
that genus.

1. Gl^EOPRIUM D1S8ILIENS Berk.

Plate LXXXIII. Figs. 3, 4.

Char. Filaments fragile. Cells slightly crenate, grooved be-
tween the crenatures, nearly as long as broad. Sheath
broad. Endochrome six or seven rayed.

Desmidium mucosum Breb. Conf. dissiliens, Eng. Bot.
t. 2464. D. mucosum Ralfs, in Annals, vol. xi. p. 374.
plate viii. fig. 2. Glaoprium dissiliens Jenner, in Fl.
Tunbridge Wells, p. 192.

Hub. - Crom Byclan : W. Borrer, Esq. Tunbridge Wells
and other places in Sussex, frequent : Mr. Jenner. Near
Bedgelert and about Dolgelly, North Wales ; Swansea,
South Wales ; plentiful near Penzance, Cornwall : Mr.
Ralfs. High Beech, Essex; Hertford Heath and

* Mr. Jenner has pointed out a character which seems to set the ques-
tion of the distinctness of this species at rest. He states that in Desmidium
quadrangvlatum the angles of the cells are rounded, while in D. Swartzii
they are acute.

GL^EOPRIUM. 347

Wormley West End, Herts : A. H. H. Bandon : Prof.
G. J. Allman. Co. Kerry : Mr. Andrews.

The filaments when viewed separately, or as regards the
line of cells are rather slender, but when taken in connec-
tion with the broad sheaths, their diameter is considerable ;
this sheath, though expanded and firm, often, unless a good
microscope be used, escapes detection. It is from the pre-
sence of this sheath that the plant owes its excessive muco-
sity, and it is by it that we account for the parallel arrange-
ment which the filaments frequently assume on the field of
the microscope, without at the same time appearing to touch
each other, although they really do so by means of the almost
invisible mucous sheath. The contrast between the coloured
cells and the transparent sheath renders this an exceedingly
beautiful microscopic object.

2. GL^OPRIUM MUCOSUM Berk.
Plate LXXXIII. Figs. 5, 6.

Char. Filaments not fragile. Cells usually nearly as long
as broad, not grooved round the centre. Angles of cells
mostly minutely bicrenate. Sheath very broad, faint.

Conf. mucosa Mertens, Dillw. Syn. t. /3; Harvey, in
Hook. Br. Fl. p. 351. ; also in Manual, p. 127. Glceo-
prium mucosum Jenner, in Flora of Tunbridge Wells.
Desmidium bimucronatum Hassall, MSS.

Hab. In stagnant water, Baiitry : Miss Hutchins. Appin :
Captain Carmichael. Cheshunt Common, High Beech
and elsewhere : A. H. H. Penzance : Mr. Ralfs. Bogs
at Fisher's Castle, very abundant, Sept. 1844 ; Chilting-
ton Common : Mr. Jenner.

This species differs very considerably from the previous one,
in having somewhat longer cells, a more highly developed
mucous sheath, in the absence of the central constriction of
the cells, and in the presence of the excessively minute bicrenate
processes placed at the angles of the cells, and which were

348 DESMIDE^E.

noticed by Mr. Ralfs and Mr. Jenner nearly simultaneously.
The processes are not present at all the angles of every cell,
but only at those angles which have been for the longest
period formed : thus, when a cell has become but recently
divided no processes are present on the newly formed angles
which result from this division. Owing to the existence of
the highly developed mucous sheath, the filaments are dis-
posed often as in the previously described species parallelly.

Mucous sheath much broader than in G. dissiliens, but less
perceptible.

53. SPHJEROZOSMA Corda.

Char. Filaments very fragile, compressed, consisting of bipar-
tite cells united by means of gland-like processes, and much
constricted between each cell.

This genus is distinguished from the previous genera by
its compressed frond, and by the glandular processes at the
junction of the cells.

1. SPH^EROZOSMA ELEGANS Corda.
Plate LXXXIV. Fig. 1.

Char. Cells smooth, rather longer than broad, deeply divided

on each side into two portions. Glands single, one in the

centre of each margin.
Spharozosma elegans Corda, Almanac de Carlsbad, 1835,

t. iv. f. 37. Odontella ? unidentata Ehr., Infus. p. 159.

Desmidium compressum, Annals of Nat. Hist. vol. ix.

p. 253. Schistochilum Ralfs, unidentatum Jenner, in Fl.

of Tunbridge Wells, p. 192. Desmidium vertebratum

Breb. et Godey.
Hab. Chyan-hal Moor, near Penzance ; and Towednack

Moor, near St. Ives : Mr. Ralfs. Rotherfield, and in

Jack's Wood spring : Mr. Jenner.

For the figures of this and the following species I am in-
debted to Mr. Jenner.

GONIOCYSTIS. 349

2. SPH^EROZOSMA EXCAVATUM.
Plate LXXXIV. Fig. 2.

Char. Cells longer than broad, excavated laterally, with two
glands or teeth at each margin.

Schistochilum excavatum Ralfs, MS. ; Jenner, in Flora of
Tunbridge Wells, p. 192.

Hob. In a boggy spot near Cross in Hand, opposite to
where the road branches to Hailsham ; bogs at Fisher's
Castle, and in a pond between Ramslye and Broadwater
Forest : Mr. Jenner.

A very distinct and interesting species.

Section ii.
Frond not forming Jilaments.

54. GONIOCYSTIS Hass.
Char. Cells angular.
Derivation. From <ycovia, an angle, and /cvans, a cell.

Section i. TRIGONOCYSTIS Hass.

Char. Cells with three angles.

Derivation. From rpvyowov, triangular, and KVCTTIS, a cell.

1. TRIGONOCYSTIS ORBICULARIS Hass.
Plate LXXXIV. Fig. 7.

Char. Frond smooth, suborbicular. End view triangular.
Angles obtuse.

Staurastrum orbiculare Meneghini, Synop. Desmid. p. 225.
Desmidium orbiculare Ehr., Infus. p. 141. tab. 10. fig. 9.
Staurastrum orbiculare Ralfs, in Annals, vol. xv. p. 152.
pi. x. fig. 4. a. b. c. ; Jenner, in loc. cit. p. 192.

350 DESMIDEJE.

Hob. Jack's Wood spring ; Cross in Hand, &c. : Mr.
Jenner. Dolgelly and Penzance : Mr. Ralfs.

The fronds are rather large, smooth, deeply constricted in
the centre ; the segments, broader than long, are in close ap-
proximation with each other, and when taken together form
an orbicular frond in their front view, in which aspect the
species might be taken for a Cosmarium, from which genus
it differs in the triangular transverse form of the segments.

T. orbicularis forms a distinct link between Cosmarium on
the one side and Desmidium on the other. It is distinguished
from the following species by its suborbicular frond and by
its blunt angles being destitute of processes.

2. TRIGONOCYSTIS MUCRONATA Hass.
Plate LXXXIV. Fig. 8.

Char. Fronds smooth, deeply constricted in the front view, seg-
ments cither transversely elliptical or lunate. End view
three-lobed. Lobes inflated, blunt, mucronate, a single
mucro terminating each lobe,
a In the front view the segments are transversely elliptic

and the mucro straight.

ft Segments, in front view, transversely lunate, outer mar-
gin straight, mucro curved outwards.

7 Segments, in front view, transversely lunate, outer margin
curved, mucro curved inwards.

Staurastrum mucronatum Ralfs, in Annals, vol. xv. p. 152.
pi. x. figs. 5, 6. ; Jenner, in loc. cit. p. 192.

Hob. On Ashdown Forest ; Piltdown Common ; Fisher's
Castle, and near Cross in Hand : Mr. Jenner. Dol-
gelly and Penzance : Mr. Ralfs.

This, although a variable species, would appear to be well
characterised by the lobed form of the segments viewed end-
ways and the presence of the spine-like teeth.

Mr. Ralfs and Mr. Jenner have observed the occurrence

QONIOCYSTIS. 351

and formation of sporangia in this species, resulting as mother
Desmidece from the union of the endochromes of two cells,
which in them is never effused from one cell into another,
but always into a distinct receptacle intermediate between
the two fronds: this is also the case in certain species of
TyndaridecB and Mesocarpi amongst the Conjugates.

The sporangia in T. mucronata are circular and smooth,
and at first enclosed in a membrane larger than itself, this
gradually disappears, and the sporangium becomes spinous,
in which state it bears some resemblance to a Xanthidium.
I have observed occasionally the sporangia of the Vesicu-
liferce to present an appearance exactly similar, a fact which
has not escaped the attention of Mr. Thwaites.

3. TRIGONOCYSTIS MUBICATA Hass.
Plate LXXXIV. Fig. 9, 10.

Char. Fronds muricated, deeply constricted, transversely el-
liptic. Segments approximate. End view triangular, with
convex sides.
/3 Fronds furnished with short spines.

Meneghini, Synops. Desmid. p. 266. Binatella muricata
Breb., Alg. Fal. p. 66. (1835). Desmidium apiculosum
Ehr., Infus. p. 142. ; Ralfs, in Annals, vol. xv. p. 154.
pi. xi. fig. 1.; Jenner, in loc. cit. p. 194. — /?. Xanthi-
dium deltoideum Corda, Observ. Microscop. sur les Aui-
malc. de Carlsbad, p. 29. pi. v. figs. 38, 39.

Hob. In small pools ; Cheshunt : A. H. H. Weston Bogs,
Hants ; Kackham Common, near Pulborough ; Pilt-
down Common, near Uckfield ; Mayfield and Heathfield.
Sussex : Mr. Jenner. Dolgelly and Penzance : Mr.
Ralfs. — /3. Sussex: Mr. Jenner. Dolgelly: Mr. Ralfs.

From Staurastrum tricorne this species may be at once dis-
tinguished by the convex sides of the segments in the end
view, and by the adult fronds being not merely muricated
but spinous. The variety is probably distinct.

352 DESMIDE^E.

4. TRIGONOCYSTIS HEXACEROS Hass.
Plate LXXXIV. Fig. 11.

Char. Fronds rough. Segments about twice as long as
broad, separated from each other by a deep notch, twisted.
End view triangular, with concave sides and blunt entire
angles.

S. tricorne Meneghini, Synopsis Desmid. p. 225. Binatella
tricornis Breb., Alg. Fal. p. 57. (1835). Desmidium
hexaceros Ehr., Abhand. der Akademie d. Wissensch.
zu Berlin (1832), p. 292. ; Ehr. Die Infus. p. 141. t. x.
fig. 10. Staurastrum tricorne Kail's, in Annals, vol. v.
p. 155. pi. xi. fig. 2. ; Jenner, in loc. cit. p. 194.
Hab. Shallow pools, Piltdown Common; Ashdown Forest;
Rusthall Common ; between May field and Hadlow
Down : Mr. Jenner. Barmouth : Rev. T. Salwey. Dol-
gelly and Penzance : Mr. Ralfs. High Beech : A. H. H.

" The conic granules arranged in transverse lines at the
angles are generally very minute, but in some Sussex spe-
cimens gathered by Mr. Jenner they are large, and on the
margin produce a dentate appearance." — Ralfs.

5. TRTGONOCYSTIS GRACILIS Hass.
Plate LXXXV. Fig. 1.

Char. Fronds muricated, deeply constricted in the centre, two
or three times longer than broad, tapering on each side into
a slender process, which is terminated by three minute teeth.
End view triradiate.

Euastrum No. 13. Bailey, in American Bacillaria, pi. i.
fig. 2 — 5. Staurastrum gracile Ralfs, in Annals, vol.
xv. pi. xi. fig. 3.

Hab. Boggy pools, Dolgelly, and Penzance : Mr. Ralfs.

Although but three processes or teeth usually present them-
selves to the observer, the real number is four ; but this is only
to be seen when one of the angles or rays is so situated that
its extremity is directly presented to the observer.

GONIOCYSTIS. 353

/

6. TRIGONOCYSTIS ? ACULEATA Hass.
Plate LXXXIV. Fig. 12.

Char. Fronds spinous. Segments in the front view, with a
process on each side terminating in three minute spines.
End view triangular, with concave sides,
ft End view quadrangular, with four distorted rays.

Staurastrum aculeatum Menegh., Synops. Desmid. p. 226.
Desmidium aculeatum Ehr., Infus. p. 142. t. 10. fig. 12. ;
Ralfs, in Annals, vol. xv. pi. xi. fig. 4. ; Jenner, in loc.
cit. p. 194.

Hob. Cross in Hand ; Sussex, and Beckley Furnace :
Mr. Jenner. Penzance : Mr. Ralfs. — /3. Woking Com-
mon, Surrey, and Piltdown Common, Sussex : Mr.
Jenner. Penzance: Mr, Ralfs.

The spines are larger and longer in this than in any other
species of the genus. The variety., which I have not seen,
would appear to be referrible to the species proper, and is
therefore very interesting.*

Section ii. STA UR ASTR UM Ehr.

Char. End view quadrangular., often four-rayed, rays of one
segment diverging from those of the other.

Derivation. From a-ravpos, a cross, and aarrpov, a star.

1. STAURASTRUM DILATATUM Ehr,
Plate LXXXV. Fig. 5.

Char. Frond rough, deeply constricted in the centre. Seg-
ments twice as broad as long, obtuse at the sides, and not
elongated into processes. End view quadrangular. An-
gles obtuse, sides excavated.
Ehr. Die Infus. p. 143. t. 10. fig. 13. ; Menegh. Synops.

* Is not the normal number of rays in this species four, and is it not
therefore a Staurastrum f

A A

354 DESMIDE.E.

Desmid. p. 227. ; Ralfs, in Annals, vol. xv. pi. xi.
fig. 5.; Jenner, in loc. cit. p. 194.

Hob. Rusthall Common, near Tunbridge Wells; and
Rackham Common, near Pulborough, Sussex: Mr.
Jenner. Dolgelly : Mr. Ealfs.

The angles in this species are not as in the others prolonged
into rays, and this will at once serve to distinguish it from
those species.

2. STAURASTRUM ? TETRACERUM Ralfs.
Plate LXXXIV. Fig. 4.

Char. Frond rough. Segments but slightly constricted, qua-
driform. Outer angles prolonged into diverging rays
which are entire at their extremities. End view com-
pressed, with a process at each extremity.

Staurastrum paradoxum Ehr., Infus. p. 143. t. 10. fig. 14.

Micrasterias tricera and tetracera K (it /.., Synops. Desmid.

in Linnaea, 1833, p. 602. figs. 83, 84, 85.; Ralfs, in

Annals, vol. xv. pi. x. fig. 1.
Hob. Dolgelly and Penzance : Mr. Ralfs.

The minute granules with which the frond is covered form
transverse lines on the rays, and give them a jointed appear-
ance. This species, in its compressed ellipsoidal form in the
end view, would appear to approach closely the genus Ar-
throdesmus.

3. STAURASTRUM PARADOXUM Meyen.
Plate LXXXV. Fig. 3.

Char. Fronds rough, constricted. Ends truncate. Front view
elongated, diverging processes minutely trifid. End view
usually quadrangular, but sometimes triangular.

Meyen, Nov. Act. Scap. Holm. voL xiv. p. 43. figs. 37. 38. ;
Menegh. Synops. Desmid. p. 227. Micrasterias Staur-
astrum Kiitz., in Linnica, p. 399. ; Ralfs, in Annals
vol. xv. p. 151. pi. x. fig. 2.

GONIOCYSTIS. 355

Hab. Dolgelly and Penzance : Mr. Ralfs.

This Staurastrum is to be distinguished from the previous
species by the trifid extremities of the rays.

4. STAURASTRUM ? BIPIDUM Ralfs.
Plate LXXXV. Fig. 2.

Char. Frond smooth, but little constricted in the centre, truncate
laterally. Rays trifid. End view triradiate.

Desmidium bifidum Ehr., Die Infus. p. 141. t. 10. f. 11.;

Ralfs, 1. c. p. 151. pi. x. fig. 3.
Hab. Dolgelly and Penzance: Mr. Ralfs,

The smoothness of the frond will always distinguish this
from the previous species. It should probably be referred to
Trigonocystis.

Section iii. PENTASTERIAS Ehr.

Char. Frond in front view without diverging processes. End
view circular, with usually Jive rays.

Derivation. From TTSVTS, Jive, and acrrepias, starred.

1. PENTASTERIAS ARACHNIS Hass.
Plate LXXXV. Fig. 8.

Char. Frond rough, deeply constricted in the centre. Seg-
ments about as long as broad, suborbicular, with elongated
slender hyaline and incurved processes. End view Jive-
rayed.

Staurastrum Arachne Ralfs, in Annals, vol. xv. p. 157.
pi. xi. fig. 6.

Hab. Boggy pool near Dolgelly, very rare : Mr. Ralfs,

" This plant is remarkable for its slender processes which
will easily distinguish it from St. margaritaceum. It cannot
be a five-rayed variety of St. gracile, for the rays are longer,
more slender, remarkably incurved, and also entire at the
extremity." — Ralfs.

A A 2

356 DESMIDEJE.

2. PENTASTERIAS MARGARITACEA Elu.
Plate LXXXV. Fig 7.

Char. Frond rough. Segments in front view subglobose, at-
tenuated at their junction, with short lateral converging
processes which are entire at their apices. End view with
Jive, rarely sip or seven, short obtuse rays.

Staurastrum margaritaceum Menegh., Synops. Desmid.
p. 227. ; Ralfs, in Annals, vx>l. xv. p. 157. pi. xi. fig. 7.
Pentasterias margaritacea Ehr., Infus. p. 144. t. 10.
fig. 15. ; Jenner, in loc. cit. p. 194.

Hob. Dolgelly : Mr. Ralfs. Ashdown Forest, Sussex :
Mr. Jenner.

The rays are much stouter and shorter in this than in the
preceding species.

3. PENTASTERIAS JENNERI Hass.
Plate LXXXV. Fig. 6.

Char. Fronds large, dentated. Segments about as broad as
long, lengthened into a toothed angle on each side. End
view with Jive, sometimes six, broad short-toothed rays.

Staurastrum Jenneri Ralfs, in Annals, vol. xv. p. 158.
pi. xi. fig. 8. ; Jenner, in loc. cit.

Hob. Mayfield, Sussex : Mr. Jenner.

A very fine species. " The transverse view has a large
central opening surrounded by a row of large granules." —
Ralfs.

55. ARTHRODESMUS Ehr.

Char. Fronds smooth, deeply constricted. End view com-
pressed, angles prolonged into a spine.

Derivation. From apffpov, a joint, and Seoy/,oy, a link.

The stout spines terminating the angles of the segments
seein to connect this genus with Xanthidium.

ARTHRODESMUS. 357

1. ARTHRODESMUS CONVERGENS Ehr.
Plate LXXXV. Fig. 9.

Char. Segments broader than long, somewhat elliptic, elon-
gated at each side into an incurved spine. End view
compressed, with a spine at each extremity.

Arthrodesmus convergens Ehr., Infus. p. 152. t. 10. fig. 18.
Staurastrum convergens Menegh., Synops. Desmid
p. 228. ; Ralfs, in Annals, vol. xv. p. 158. pi. xii. fig. 1. ;
Bailey, Amer. Baeil. pi. i. fig. 11. ; Jenner, in loc. cit.
p. 194.

Hob. Brambletye, near East Grinstead ; Rackham Com-
mon, near Pulborough, Sussex ; and Rusthall Common,
near Tunbridge Wells : Mr. Jenner. Dolgelly and
Penzance : Mr. Ralfs. Cheshunt : A. H. H.

The incurved mucrones will at once serve to distinguish
this species.

2. ARTHRODESMUS INCUS Hass.
Plate LXXXV. Fig. 10.

Char. Segments externally lunate, with a mucro at each
angle. End view elliptic, mucronated at each extremity.

Euastrum Bailey, Amer. Bacil. pi. i. fig. 12. ? Staurastrum
Incus Meneghini, Synops. Desmid. p. 228. ; Ralfs, in
Annals, vol. xv. p. 159. pi. xii. fig. 2. ; Jenner, p. 194.

Hob. Weston Bogs, near Southampton; Rackham Com-
mon, near Pulborough, Sussex : Mr. Jenner. Dolgelly
and Penzance : Mr. Ralfs.

The mucro in this species is turned outwards : in the front
view the segments resemble those of Trigonocystis mucro-
nata, but the end view is very different.

3. ARTHRODESMUS OCTOCORNIS Ehr.
Plate LXXXV. Fig. 11.

Char. Fronds compressed. Segments broader than long,

A A. 3

358 DESMIDE.S.

quadrangular, each angle produced into a spine. End
view subelliptic, with a spine at each extremity.

Arthrodesmus octocornis Ehr., Infus. p. 152. S. ? octocurne

Haifa, in Annals, vol. xv. p. 159. pi. xii. fig. 3.
Hob. Boggy ponds near Dolgelly, rare : Mr. Ralfs.

" The newly formed segments at first have only two
spines, and in this state somewhat resemble those of Staur-
astrum Incus, of which indeed this plant may eventually
prove a variety. But S. Incus has only two spines on each
segment, and its end is not concave but truncate." — Ralfs.

The Micrasterias octocornis of Meneghini would appear to
be a different plant.

56. XANTHIDIUM Ehr.

Cliar. Frond composed of two slightly compressed segments
constricted in the centre, neither lobed, sinuated, nor emar-
ginate. Surface clothed with simple or branched elon-
gated spines, either scattered or confined to the margin,
where they are apparently placed in two rows, one on each
side the marginal lines. Segments anteriorly perforated
in the centre (?).

Derivation. From %av6os, yellow ?

This genus bears a close resemblance to Cosmarium, from
which there is no satisfactory character to distinguish it,
unless indeed the projection or aperture noticed to occur by
Mr. Dalrymple in Xanthidium furcatum, and by Mr. Ralfs
in X. aculeatum be constant in all the true species of the
genus Xanthidium. Meneghini even goes so far in the union
of the genera Xanthidium and Cosmarium, as to retain in the
former genus only those species whose spines are scattered
over the surface, while he refers to the latter genus those in
which the spines are confined to the margin. This arrange-
ment seems arbitrary ; and that it is so, is proved by the fact
that in a species of Xanthidium figured by Dr. Bailey in the
" American Bacillaria," and which has six pairs of marginal

XANTHIDIUM. 359

spines, the central apertures exist ; that is, in the species re-
ferred by Meneghini to Cosmarium these openings are met
with — the only character which is even supposed to belong
exclusively to Xanthidium.

" I have little doubt that there are more British species of
Xanthidium than I shall here describe, and indeed believe
that I have more than once gathered X. hirsutum ; but as
my attention was not directed to the Desmidecs at the time,
I neglected to examine it with sufficient care to be able to
state my observations with any confidence in this paper."-—
Ralfs.

1. XANTHIDIUM FURCATUM Ehr.
Plate LXXXIX. Fig. 1.

Char. Segments reniform. Spines at first marginal, sub"
sequently scattered, dividing at their terminations into
three or four acute divergent points.

Xanthidium furcatum Ehr., Infus. p. 148. tab. x. f. xxv. ;
Menegh. Synops. Desmid. p. 224. Xanthidium No. 2.,
Bailey's American Bacillaria, p. 291. pi. i. fig. 15. ;
Ralfs, in Annals, vol. xiv. p. 466. pi. xii. fig. 1.

Hab. Several places in Sussex : Mr. Jenner. Dolgelly,
and near Carmarthen : Mr. Ralfs. High Beech and
Cheshunt Common : A. H. H. Aberdeen : Dr. Dickie.
Ireland : Mr. Moore.

This is the finest as well as commonest species of the genus.
There is no other with which it can be confounded.

In the figure of this species, given by Ehrenberg, the een-
tral aperture seems to be indicated.

2. XANTHIDIUM FASCICULATUM Ehr.
Plate LXXXIX. Fig. 2.

Char. Segments small, reniform. Spines in pairs, and
usually six pairs to each segment.

Xanthidium aculeatum, Abhandl. d. Akademie d. Wissensch.

A A 4

360 DESMIDE-aJ.

zu Berlin, 1833, p. 318. X. fasciculatum Ehr., Infus.
p. 147. tab. x. fig. xxiv. b. Xanthidium fasciculatum
Ralfs, in Annals, vol. xiv. p. 166. fig. 3. c. d. e. Cos-
marium aculeatum Menegh., 1. c. p. 218. Euastrum
No. 10., Bailey's Amer. Bacil. p. 296. pL i. fig. 10. ;
Jenner, in loc. cit. p. 194.

This species is smaller than the following, the segments of
a different form, and the spines more numerous.

3. XANTHIDIUM POLYGONUM Hass.

Plate LXXXIX. Fig. 4.

Char. Frond polygonal. Segments four-angled. Spines
eight to each segment, in pairs, situated at the angles.

Xanthidium fasciculatum (Bpolygonum Ehr., Infus. p. 148.
t. 10. fig. 24. a. Xanthidium fasciculatum ft poly-
gonum Kail's in Annals, vol. xiv. p. 467. pi. xii.
fig. 3. a. b.

Hob. Near Dolgelly : Mr. Ralfs. Near Tunbridge Wells :
Mr. Jenner.

This doubtless ought not to be regarded as a variety, but
as a distinct species, differing from Xanthidium fasciculatum,
of which it has hitherto been regarded as a variety, in being
altogether a much larger plant, in the polygonal form of the
segments, and in the number of the spines to each segment,
which are eight in X. poly gonum, arranged in four pairs, while
in X. fasciculatum they are twelve, disposed in six pairs.

4. XANTHIDIUM ACULEATUM Ehr.

Plate LXXXIX Fig. 3.

Char. Segments reniform, almost globose. Spines single,

marginal, and scattered.

Xanthidium aculeatum Ehr., Infus. p. 147. tab. 10. fig. 23.;
Menegh. 1. c. p. 224. ; Ralfs, in Annals, vol. xiv. p. 467.
pi. xii. fig. 2. a. b. c. d.

COSMARIUM. 361

Hob. Ashdown Forest, and near Cross in Hand : Mr.
Jenner. Penzance : Mr. Ralfs.

This species differs from X. fasciculatum principally in the
spines being single and not in pairs as in that species.

" In the centre of each segment, on both surfaces, is a pro-
jection similar to that described under X. furcatum, but less
evidently dentated." — Rolfs.

57. CYLINDROCYSTIS Menegh.

Char. Frond mucous, indefinite. Corpuscles cylindrical, Jilted
with sporidia, copulating, at length bearing two spores
transversely divided into halves.

Derivation. From /cvhivSpos, a cylinder, and KVGTLS, a cell.

1. CYLINDROCYSTIS BEEBISSONI Menegh.
Plate XCII. Fig. 17.

Char. Cells cylindrical, two or three times longer than broad,
with rounded extremities.

C. Brebissoni Menegh., Monog. Nostoc. Italic.

Hob. Sussex : Mr. Jenner. High Beech : A. H. H.
Aberdeen: Dr. Dickie. Gal way : M'Colla.

This is a particularly interesting production, as it seems to
form a direct link between the Protococcoidece and the Des-
midece, and by Meneghini himself is placed in the family
NostochinecB. The conjunction of the cells, as well as their
great size and regular form, have induced me to refer it to the
Desmidecs, in which the phenomenon of union of the cells is
of such frequent occurrence. The frond does not appear to
be divided in the centre as in most true Desmidece.

58. COSMARIUM Corda.

Char. Frond constricted in the middle. Segments fre-
quently as broad and sometimes broader than long, neither

362 DESMIDE^l.

notched nor lobed, but mostly either denticulated or dotted,
almost touching each other.

Derivation. From tcoa/juipiov, a small ornament.

The form of the frond in this genus is much more simple
than that of most of the other genera of Desmidece, being
neither notched nor lobed. The genus to which it is most
closely allied is Xanthidium, from which it chiefly differs in the
minuteness of the spines or teeth, which are placed on the
outer surface of the frond in most species, as well as in the
absence of the lateral apertures noticed in Xanthidium fur-
catum and X. aculeatum. Through Closterium cylindricum,
it exhibits some relation to the genus Closterium, in which
the form of the frond is also very simple ; but the two genera
are abundantly distinct. In Cosmarium the fronds are never
elongated nor curved as in Closterium, and they are always
constricted in the centre ; neither are they notched as in
Tetmemorus and Euastrum, nor lobed as in the latter genus,
nor compressed as in Micrasterias.

The denticulations observed on the surface of the fronds
of most species of the genus vary according to the age of the
specimens, being most strongly marked on the more fully de-
veloped examples.

a. Fronds denticulated.

\. COSMARIUM JIARGARITIFERUM Menegh.

Plate LXXXVI. Fig. 1.

Char. Fronds denticulated. Segments broader than long,
somewhat hemispherical or reniform, compressed. End
view elliptic.
/S Fronds dotted, but not denticulated.

Menegh. Synop. Desmid. in Linnaea, 1840, p. 219. Cos-
marium dentiferum Corda, Observ. Microscop. sur les
Animalc. de Carlsbad, p. 30. pi. vi. f. 41. Euastrum
margaritiferum Ehr., Infus. p. 163. tab. 12. f. 7.; Pritch.

COSMARIUM. 363

Infus. p. 196. f. 126. ; Bailey, Amer. Bacil. in Am.
Journ. of Sciences and Arts, vol. xli. No. 2. p. 295. fig. 8.
UrsinellamargaritiferaTurp., Diet, des Sc. Nat. (1820).
Heterocarpella Ursinella Kiitz., Syn. Diatom, p. 598.
Cymbella reniformis Ag., Consp. Diatom, p. 10. ; Grev.
in Hook. Br. Flor. vol. ii. p. 415. ; Harv. Brit. Alg.
p. 215. Cosmarium margaritiferum Ralfs, in Annals of
Nat. Hist. vol. xiv. p. 393. pi. xi. fig. 4. ; Jenner, in
loc. cit. p. 194.

Hab. In bogs and pools, &c. common ; Weston bogs,
near Southampton, and numerous habitats in Sussex
and Kent : Mr. Jenner. Farnham, Surrey : Mr. Reeves.
Cheshunt, Herts : A. H. H. Near Bristol : Mr. Thwaites.
Barmouth : Rev. T. Salwey. Dolgelly, Carnarvon, and
Penzance : Mr. Ralfs.

This species varies considerably in size, form, and in the
number and degree of developement of the spines, which
cover the frond. Each segment may be compared in form
to a kidney. It is the most abundant species of the genus.
Ehrenberg figures the denticles as placed in regular series
or rows, which in some specimens I have seen to be the
case.

2. COSMARIUM BOTRYTIS Menegh.
Plate LXXXVI. Fig. 2.

Char. Frond denticulated, compressed. Segments truncate-
triangular. End view elliptic.

C. Botrytis Meneg., Synop. Desmid. p. 220. Euastrum Bo-
try tis Ehr., Infus. p. 163. tab. xii. fig. 8. C. Botrytis
Ralfs, in Annals of Nat. Hist., vol. xiv. pi. xi. fig. 5.
Heterocarpella Botrytis Bory, in Diet. Classique, 1825.
Euastrum angulosum Ehr., Infus. tab. xii. fig. 8. Cos-
marium deltoides, in part, Corda, Almanac, de Carlsbad,
1835, p. 205.

Hab. Near Bristol : Mr. Thwaites. Sussex : Mr. Jenner.

364 DESMIDE2E.

Near Manchester: Mr. Sidebotham. Dolgelly: Mr.
Ralfs. High Beech: A.H.H.

A very distinct species. The frond is usually about a
third less than that of Cosmarium margaritiferum.

3. COSMARIDM ORNATUM Ralfs.

Plate LXXXVI. Fig. 3.

Char. Frond denticulated. Segments broader than long.
Front view curved at the sides, but truncate at the extremi-
ties. End view, four-lobed.

Cosmarium ornatum Ralfs, in Annals, vol. xiv. p. 392. pi. xi.
fig. 3. ; Jenner, in Fl. of Tunbridge Wells, p. 194.

Hob. In boggy pools about Dolgelly and Barmouth:
Mr. Ralfs. Ashdown Forest, Sussex : Mr. Jenner.
Cheshunt Common : A. H. II.

This species is likewise very distinct, and there can be no
danger of confounding it with any other hitherto described.
The fronds are about as large as those of C. margaritiferum,
the four-lobed form of the segment when viewed endways is
peculiar to the species ; this form is occasioned by the central
inflation of each segment.

4. COSMARIUM ORBICULATUM Ralfs.
Plate LXXXVI. Fig. 5.

Char. Segments minute, nearly spherical, both in front and

end views.
Cosmarium orbiculatum Ralfs, in Annals, vol. xiv. p. 392.

pL xi. fig. 2.

Hob. Boggy pools, near Dolgelly: Mr. Ralfs. Near
Manchester : Mr. Sidebotham.

A distinct little species, and the smallest of the genus.

COSMARIUM. 365

5. COSMARIUM CYLINDRICUM Ralfs.
Plate LXXXVI. Fig. 4.

Char. Fronds small, finely denticulate. Segments longer
than broad, in the front view, subquadrate, broadest at the
extremity, narrower at their junction. End view cir-
cular.

Cosmarium cylindricum Ralfs, in Annals, vol. xiv. pi. xi.
f. 1.

Hob. Mixed with other Alace on the wet sides of a cave
at Laurarna Cove near Penzance : Mr. Ralfs.

The fronds are minute, and about twice as long as broad.
Segments united along their entire breadth, so that no
notches are formed at the sides.

b. Fronds mostly punctated or smooth.

6. COSMARIUM CRENATUM Ralfs.

Pkte LXXXVI. Fig. 6.

Char. Fronds punctated. Segments broader than long, com-
pressed, somewhat triangular, with the margins deeply cre-
nated. End view elliptic.

C. crenatum Ralfs, in Annals, vol. xiv. pi. xi. fig. 6. ; Jen-
ner, loc. cit. p. 1^96.

Hab. Weston bogs, near Southampton, and several stations
in Sussex : Mr. Jenner. Near Bristol : Mr. Thwaites.
Near Manchester : Mr. Sidebotham. Dolgelly and Pen-
zance : Mr. Ralfs.

"This plant very much resembles a young specimen of
C. margaritiferum ; but as the margin is always strongly
crenated, even in the earliest stage, and the surface is punc-
tated and not granulated, I am induced to describe it as dis-
tinct."— Ralfs.

366 DESMIDEJE.

7. CO8MAKIUM OVALE Rttljs.

Plate LXXXVI. Figs. 8. and 9.

Char. Fronds large, compressed, punctated. Segments tri-
angular, slightly truncate at the extremity. End view
broadly elliptic.
@ Segments dentated.

Cosmarium ovale Ralfs, in Annals, vol. xiv. pi. xi. fig. 7. —
/9. Euastrum No. 6. Bailey, 1. c. p. 295. fig. 28. ; Jen-
ner, in loc. cit. p. 196.

Hob. Dolgelly : Mr. Ralfs. Barmouth : Rev. T. Salwey.
Near Tunbridge Wells, in a pond between Ramlye and
Broadwater Forest ; Beckley Furnace : Mr. Jenner. —
/3. Weston bogs, near Southampton : Mr. Jenner.

The characters of the different species of Desmidece may
generally be so accurately embodied in the definition as to
preclude the necessity of any lengthened remarks attached to
each species ; this conciseness it is to be hoped as our know-
ledge of the works of creation becomes more extensive, will
be found applicable to the description of all organised pro-
ductions.

8. COSMARIUM CUCUMIS Corda.
Plate LXXXVI. Fig. 10.

Char. Fronds orbicular, much compressed. Segments hemi-
spherical, quite smooth, being neither denticulated nor dotted.
End view elliptico- lanceolate.

Meneghini, Synops. Desmid. p. 220. Euastrum integerri-
mum Ehr., Infus. p. 163. tab. 12. fig. 9. Cosmarium
Cucumis Corda, Almanac de Carlsbad, 1835, p. 206.
tab. 11. figs. 27, 28. C. Cucumis Kalfs, 1. c, p. 395. pi. xi.
fig. 8.; Jenner, in loc. cit. p. 196.

Hab. Sussex : Mr. Jenner. Dolgelly : Mr. Ralfs.

The frond is more orbicular and not punctated as in Cos-
marium ovale.

CLOSTERIUM. 367

9. COSMARIUM QUADRATUM Ralfs.

Plate LXXXVI. Figs. 11. and 12.

Char. Fronds about twice as long as broad. Segments qua-
drate, in front view slightly compressed, smooth.

Ralf&, 1. c. vol. xiv. t. 11. f. 8. ; Jenner, 1. c. p. 196.

Hob. Rusthall Common, near Tunbridge Wells : Mr.
Jenner. Dolgelly : Mr. Ealfs.

The front view of the segments is somewhat quadrangular,
the distal or free angles being slightly rounded, and the
proximate, protuberant.

10. COSMARIUM CUCURBITA Breb.
Plate LXXXVI. Fig. 7.

Char. Fronds small, about twice as long as broad, cylindrical,
with a slight constriction in the centre, minutely punctated.
End view circular.

Ralfs, in Annals, vol. xiv. ; Jenner, in Flora of Tunbridge
Wells, p. 196. Cosmarium Cucurbita Desm., No. 1103.

Hob. Dolgelly : Mr. Ralfs. Ashdown Forest and
Greatham bogs, near Pulborough : Mr. Jenner.

This species approaches rather closely to Cosmarium cylin-
drum Ralfs, but the frond in that species is distinctly den-
tated, whereas in C. Cucurbita Breb. it is merely dotted :
it also has a great resemblance to Closterium cylindrus, but in
that plant the puncta are described as arranged in longitudinal
lines, whereas in Cosmarium Cucurbita they are scattered.

59. CLOSTERIUM Nitzsch.

Char. Fronds elongated, mostly crescentic, sometimes con-
jugating; each formed of two similar segments, which
unite without constriction, and the free extremity of each

368 DESMIDE^E.

of which is occupied by a vesicle filled with active mole-
cules.

Derivation. From /cXoxm;/), a fine thread ; in allusion to
the attenuated form of the frond.

The two peculiarities which distinguish the genus Clos-
terium from all other Desmidea are the crescentic form of
the fronds and the presence in the free extremity of each
of the segments, of the vesicle filled with revolving particles.
These particles occasionally escape from the vesicle, and cir-
culate vaguely and irregularly round the circumference of
the frond. The use of these particles is not determined : it
may be conjectured that they are in some way or other con-
nected with reproduction.

The existence of motive papillae or processes issuing from
the open extremities of the segments has been denied by
most recent observers.

Conjugation has been noticed to occur by Ehrenberg in
Closterium Diana, Cl. lineatum, Cl. striolatum, and Cl.
incequale.

Ehrenberg, by whom the genus Closterium is placed
amongst the polygastric animalcula, thus defines it : —

" Animalia polygastrica anentera (tubo intestinali desti-
tuta) gymnica (non appendiculata), et corpore uniformi in-
volucrato seu loricato, cryptomonadibus simillima, cum lorica
sponte et imperfecte dividua, hinc in polyparium bacilliforme
(aut fusiforme) abeuntia, papillis denique in loricae apertura
discretis. "

Independently of the irregular motion of the particles
escaped from the cells, a circulation has been noticed, con-
sisting of two opposite currents, the one along the side of the
shell, and the other along the periphery of the internal gela-
tinous matter, which is invested with an elastic envelope.

By some systematists the Closteria are placed next to the
Conjugates, with which in the occasional conjugation of the
fronds of two Closteria and formation of sporangia they do
indeed exhibit a certain degree of relationship.

Through Closterium cylindrus Ehr., Infus. pi. v. fig. 6.
this genus would appear to be united to the genus Cosma-

CLOSTEKIUM. 369

rium : it is most probable, however, that that species ought
to be referred to the latter genus.

a. Closteria curved, smooth, not appendaged.

1. CLOSTERIUM EHRENBERGII Menegh.
Plate LXXXVIL Fig. 1.

Char. Frond semilunar, thinned, and rounded at the ex-
tremities. Granules scattered. Endochrome fasciated.
Bands two or three in each segment.

Der halbe Mond, Eichorn, Kleinste Wassenthiere, p. 48.
taf. 5. fig. c. 1775, 1781, 1784. Vibrio Lunula Miiller,
Naturforscher, 20. p. 142. 1784. ; Herman (after Miil-
ler) ebenda, p. 169. taf. 3. fig. 59. V. Lunula Miiller,
Animalc. Infus. p. 55. taf. vii. figs. 1 3. and 15.1717? Mul-
leria? Lunula Leclerc, 1802 ? Conferve inedite, No. 77.
(Zygnemadeciminum) Gerod Chantrans, Recherche sur les
Conferves, t.33. 1802. Mulleria Lunula Schrank, Fauna
boica, iii. 2. p. 47. 1803. Closterium Lunula Nitzsch,
Beitrage, £ Infusarienkunde, 60. and 67. 1817? Vibrio
Lunula Gruithuisen, Acta Nat. Curios, x. 2. p. 449.
1821. cfr. Cl. moniliferum. Bacillaria Lunula, Acta Nat.
Curios, xi. 2. p. 533. 1823. Lunulina vulgaris Bory,
Encyc. Method. 1824, and in Diet. Class. d'Hist. Nat.
1826. Lunulina vulgaris Turpin, Diet. d'Hist. Nat.
Planches Yegetaux, i. p. 3. 1828. Closterium Lunula
Hemprich et Ehrenberg, Symbolae Physica?, Ever-
tebrat. i. Phytozoa, tab. ii. iv. fig. 6. 1828. Closterium
Lunula, Isis, 1830, p. 168. Closterium Lunula, Abhandl.
der Academic d. Wissensch. zu Berlin, 1829, p. 7. 15.
1830, p. 40. 56. 62., 1831, p. 67. Closterium Lunula,
Symbol® Physicae, text 1830 (1831), fol. b. a. 2. Clos-
terium Lunula Kiitz., Algas Aquat. siccatae, dec. iii.
No. 22. 1833, and Synopsis Diatomearum, Linnasa,
1833, p. 596. Closterium Lunula and acuminatum Corda,
Almanac de Carlsbad, 1835, p. 190. tafel 5. f. 56—60.

B B

370

Closterium Lunula, Annales des Sciences Naturelles,
1836, torn. v. Botanique, p. 263. tafel ix. x. a, xi. ; Jen-
ner, in Flora Tonbridgensis, p. 196. Cl- Ehrenbergii
Menegh., Synops. Desmid. Cl. Lunula Ehr., Die Infus.
t. v. f. 2.

Hab. Several places in Sussex : Mr. Jenner. Cheshunt :
A. H. H.

This species might readily be confounded with the next,
Cl. moniliferum, in which the reproductive granules are in a
single series, and not scattered as in Cl. Ehrenbergii.

The synonyms given require revision, on account of Ehren-
berg having confounded two species.

2. CLOSTERIUM MONILIFERUM Ehr.
Plate LXXXVIL Fig. 2.

Char. Frond much curved. Apices thinned and rounded.
Granules disposed down the middle in a single series. En-
dochrome/ascz'afec?. Bands two or three.

Vibrio Lunula var. Mtiller, Animalc. Infus. p. 55. taf. 7.
fig. 8. 11. 1786. P. planzenthier Gruithuisen, Beitr.
% Physiognosie a Eautognosie, p. 322. t. ii. fig. 40. Clos-
terium Lunula Nitzsch, after Kiitzing, 1817. Lunulina
monilifera Bory, Encyclope'd. Method. 1824 ; Diet.
Classique d'Hist. Nat. 1826. Lunulina vulgaris Tur-
pin, Diet, des Sciences Naturelles, Planches Ve'ge'taux,
i. F. 3. a. rechts, 1828. Closterium Lunula var., Abhandl.
der Akademie d. Wissensch. zu Berlin, 1831, p. 68.
Closterium lunula Kiitzing, Synopsis Diatomearum, Bot.
Zeitsch. Linnaea, v. Schlechtendal, p. 596. t.xviii. fig. 80.
1833. Closterium Lunula var. JMorren ? Annales des
Sc. Nat. Botanique, torn. v. p. 337. planche xi. fig. 42. ;
Jenner, in Flora of Tunbridge Wells, p. 196. Cl. Lei-
blinii Menegh., loc. cit.

Hab. Framfield, Hillingly, Reigate, &c. : Mr. Jenner.
Cheshunt Common : A. H. H.

CL08TERIUM. 371

This species comes near to Closterium Diana Ehr., which,
however, is a more elongated and more slender plant.

3. CLOSTERIUM DIAN^ Ehr.
Plate LXXXIV. Fig. 5.

Char. Frond slender, much attenuated towards each end.
Granules in a single series down the centre. Endochrome
fasciated. Fasciae obscure.

Cl. ruficeps, Abhandl. der Akademie d. Wissench. zu Ber-
lin, 1831, p. 67. Cl. Diana Ehr., Die Infus. p. 92. t. v.
f. 17.

Hob. Chiltington Common, near Pulborough : Mr. Jenner.

A distinct and elegant species.

b. Closteria curved, not appendaged, striated.

4. CLOSTERIUM TURGIDUM Ehr.
Plate LXXXVII. Fig. 3.

Char. Frond large, slightly curved, subcylindrical, but little
attenuated, very finely striated. Apices roundish and
rubescent.

Closterium turgidum Ehr., Infus. tafel vi. fig. 7. ; Jenner,
in Flora of Tunbridge Wells, p. 196.

Hab. Several places in Sussex : Mr. Jenner.

The striae in this species are finer, and the frond larger
than in Closterium striolatum.

5. CLOSTERIUM STRIOLATUM Ehr.
Plate LXXXVII. Fig. 4.

Char. Frond fusiform, gradually attenuated towards each
end, evidently striated, ten or twelve times as long as broad.
Extremities rounded.

B B 2

372 DESMIDE^E.

Closterium striolatum, Abhandl. der Akademie d. Wissensch.
zu Berlin, 1831, p. 68. ; 1833, p. 238. Closterium cos-
tatum ! and Cl. spirals Corda, Almanac de Carlsbad,
1835, p. 191. taf. v. f. 61—63. and fig. 67.?; Ehr. In-
fus. p. 96. taf. 6. fig. 12. ; Jenner, 1. c. p. 196.

Hob. Several places in Sussex and Kent : Mr. Jenner.
Hertford Heath : A. H. H. Aberdeen : Dr. Dickie.
Galway: M'Colla.

This is a smaller species, more attenuated at the extre-
mities, and with striae more evident than in Closterium tur-
gidum. Each segment is occasionally divided by a transverse
line, as is well represented in one of the figures given by
Ehrenberg.

6. CLOSTERIUM LINEATUM Ehr.
Plate LXXXVIII. Fig. 1.

Char. Frond very long, slender, slightly curved, in the centre
cylindrical and filiform, much attenuated at each extre-
mity, distinctly striated, often twenty times as long as
broad.

Closterium lineatum, Abhandl. der Akademie d. Wissensch.
zu Berlin, 1833 (1832), p. 238. ; Ehr. Infus. p. 96. t. 6.
fig. 8. ; Jenner, in Flora of Tunbridge Wells, p. 196.
Hob. Ashdown Forest : Mr. Jenner.

This is one of the most striking species of the genus ; the
granules are often arranged in single series, but sometimes
they are scattered.

7. CLOSTERIUM CORNU Ehr.
Plate LXXXVIII. Fig. 2.

Char. Frond small, very slender, subcylindrical, slightly

curved. Endochrome undulated.

Vibrio Lunula Mtiller, Animalc. Infus. tab. vii. fig. 8. ?
Closterium Cornu, Abhandl. der Akademie d. Wissensch.

CLOSTERIUM. 373

zu Berlin, 1830, p. 62. ; 1831, p. 67. Closterium tenue
Kiitzing, Synopsis Diatom, in v. Schlechtendal's Lin-
naea, p. 595. tafel xviii. f. 78. ; Ehr. Infus. p. 94. taf. vi.
fig. 5. ; Jenner, in Flora of Tunbridge Wells, p. 196.

Hab. Piltdown Common: Mr. Jenner.
Apparently a very distinct little species.

c. Closteria appendaged, curved, striated.

8. CLOSTERIUM ROSTRATUM Ehr.
Plate LXXXVII. Fig. 6.

Char. Closterium fusiform, slender, slightly curved, striated,
much attenuated, appendaged, each horn scarcely equalling
the body in length, often much shorter.

Closterium rostratum, Abhandl. der Akademie d. Wis-
sensch. zu Berlin, 1831, p. 67. ; 1833, p. 240. Frustulia
subtilis and subulata Kiitzing? Synops. Desmid. p. 538.
taf. xiii. fig. 3., 1833. Closterium caudatum Corda, Al-
manac de Carlsbad, p. 190. 209. tafel v. fig. 66., 1835 ;
Jenner, 1. c. p. 196.

Hab. Heathfield ; "Warbleton ; Waterdown Forest, &c. :
Mr. Jenner. High Beech : A. H. H.

A singular but not uncommon species.

9. CLOSTERIUM SETACEUM Ehr.
Plate LXXXVII. Fig. 7.

Char. Frond fusiform, setaceous, straight, or very slightly
curved, faintly striated, appendaged, appendages longer
than the frond itself.

Closterium setaceum, Abhandl. der Akad. d. Wissensch.
zu Berlin, 1833, p. 239. ; Jenner, in loc. cit. p. 196.

Hab. Waterdown Forest, and near Cross in Hand : Mr.
Jenner. Cheshunt Common : A. H. H.

BBS

374 DESMIDE^E.

This species differs from the previous one in being much
smaller, more finely striated, and having longer setaceous
appendages.

d. Closteria smooth, not appendaged, straight.

10. CLOSTEBIUM LUNULA Ehr.
Plate LXXXIV. Fig. 4.

Char. Frond fusiform, ventricose, with rounded extremities.
Granules numerous, scattered. Endochrome fasdated,
bands usually three.

Cl. Lunula Ehr., Die Infus. t. v. figs. 1. and 3. C. Lunula
Menegh., Synops. Desmid.

Hob. Beckley Furnace: Mr.Jenner. High Beech: A.H.H.

This species I noticed when examining some Pediastra
kindly sent me by Mr. Jenner. It is figured by Ehrenberg
as a state of Closterium Lunula, and indeed Meneghini regards
it as that species, conferring the name of Ehrenberg upon
what better agrees with the name of Lunula, and with
Ehrenberg's description, although this last is evidently so
contrived as to embrace both species. The frond, in Mr.
Jenner's specimens, was not of the gigantic size figured by
Ehrenberg.

11. CLOSTERIUM ACEROSUM Ehr.
Plate LXXXVII. Fig. 5.

Char. Closterium fusiform, gradually attenuated towards
each extremity. Granules in a single series down the
centre of the frond. Endochrome banded.

Corpicetti a baccillo Corti? Observaz. Micros, p. 111. t. 11.
fig. 17. i. g. and r. s., 1774. Vibrio Lunula Miiller, Ani-
malc. Infus. taf. 7. f. 12., 1786. Vibrio acerosus Schrank,
Fauna boica, 111.2. p. 47., 1803. Baccillaria multistriata
Hempritch et Ehrenberg, Symbol* Physicae, Phytozoa,

CLOSTERIUM. 375

pi. ii. Sanaitica, f. 9. 1828. Closterium multistriatum,
Abhandl. der Akademie d. Wissensch. zu Berlin, 1829,
p. 15 — 20. Closterium acerosum, Symbolae Physicae,
Evertebrata, text 1830 (1831); Polygastrica, fol. b.
a. 2. Closterium acerosum, Abhandl. der Akademie d.
Wissensch. zu Berlin, 1831, p. 68. Closterium Lunula
Morren, fig. 43. ; Ehr. Infus. p. 93. pi. vi. fig. 1. Cym-
bella Hopkirkii Moore, in Ord. Survey; Harv., in
Manual, p. 215. Cl. acerosum Jenner, in Flora of
Tunbridge Wells, p. 196. Conf. ovata, Flora Glottiana.

Hob. Near Glasgow : Mr. Hopkirk. About Lisburn and
in one of the caves, Cave Hill, Belfast: Mr. Moore.
Warbleton, &c. : Mr. Jenner. Galway: M'Colla.

There is no species hitherto described with which it is
necessary that this should be compared, the straight and
fusiform frond rendering it clearly distinct from all other re-
corded species. This species was named by Mr. Moore Cym.
Hopkirkii, in memory of Mr. Hopkirk, author of " Flora
Glottiana."

e. Closteria straight, not lunar.

12. CLOSTERIUM TRABECULA Ehr.
Plate LXXXVIII. Fig. 3.

Char. Frond broad, longitudinally symmetrical, somewhat
quadrangular. Granules scattered or disposed in several
series, ^ndochrome fasciated. Bands several.

Closterium Trabecula, Abhandl. der Akademie d. Wis-
sensch. zu Berlin, 1830, p. 62. 70. ; 1831, p. 68. ; Ehr.
Infus. 93. pi. v. fig. 2. ; Jenner, in Flora of Tunbridge
Wells, p. 196.

Hob. Rusthall Common ; Piltdown Common ; Scrubbs,
Colebrooke Park ; Waterdown Forest : Mr. Jenner.

This Closterium bears some resemblance in form at least to
Cl. margaritaceum, but differs from that species in being
altogether much larger, in its entire margins and in the posi-

B B 4

376 DESMIDE^E.

tion of the vesicles containing the active molecules, which in
Closterium Trabecula as in all other Closteria hitherto de-
scribed are placed near to each extremity of the frond.

13. CLOSTERIUM MARGAEITACEUM Ehr.
Plate LXXXVIII. Fig. 5.

Char. Frond cylindrical., narrow, two to eight times as long as
broad, somewhat quadrangular, often slightly constricted,
striated. Striae denticulated. Cells containing the revolving
particles distant from each extremity.

Ehr. Infus. p. 93. pi. v. fig. 13. ; Jenner, inloc. cit. p. 196.
Hob. Piltdown Common ; Warbleton ; and in the pond
between Ramslye and Broadwater Forest : Mr. Jenner.

A distinct and very interesting little species : it is some
eight or ten times smaller than Cl. Trabecula.

14. CLOSTERIUM DIGITUS Ehr
Plate LXXXVIII. Fig. 4.

Char. Frond broad, ovate, cylindrical, four or Jive times
as long as broad; transverse lines of division sometimes
triplex. Endochrome/asczafcrf. Bands Jive or six, often
waved.

Closterium digitus, AbhandL der Akademie d. Wissensch.
zu Berlin, 1831, p. 68. Pleurosicyos Myrio(po)dus
Corda, Almanac de Carlsbad, 1835, p. 182. t. 5. f. 68,
69. Cl. Digitus ? Menegh., 1. c. p. 236.

Hob. Bogs at Fisher's Castle, Ashdown Forest ; Scrubbs,
Colebrook Park, and between Heathfield and Warble-
ton : Mr. Jenner. Aberdeen : Dr. Dickie.

This is one of the finest and most distinct of the nume-
rous species described by Ehrenberg, whose figures of Clos-
teria are most beautiful and accurate, and whose descriptions
are not less so. The species of this genus being for the most

TETMEMORUS. 377

part of considerable size do not require for their satisfactory
examination the high and delicate powers with which most of
the DesmidecB need to be examined.

60. TETMEMOKUS Ralfs.

Char. Frond elongated, straight, subcylindrical, slightly con-
stricted in the centre. Segments emarginate at their ex-
tremities but otherwise entire, being neither lobed nor
sinuated.
Derivation. From T£fj,va>, to cut.

The two species for the reception of which this genus has
been created are placed by Meneghini in the genus Closterium
with the other species of which they do not well accord.

From Closterium it differs in the emarginate extremities of
the segments, and in the absence of the cells containing the
revolving particles : from Cosmarium it is separated by the
divided segments, as well as by its elongated fronds.

From Euastrum, with which it agrees in the terminal
division of the segments, it differs in being neither lobed nor
sinuated.

1. TETMEMORUS BREBISSONI Ralfs.
Plate LXXXIX. Fig. 5.

Char. Frond about Jive times as long as broad, considerably
constricted in the centre. Segments in the front view
somewhat quadriform, but in the lateral view attenuated,
longitudinally striated. Granules in a row down the
centre of the frond.

Closterium Brebissoni Menegh., Syn. Desmid. in Linnsea,
1840, p. 236. Closterium (sp. 9.) Bailey, American
Bacillaria, in Amer. Jour, of Science and Arts, vol. xli.
No. 2. pi. i. fig. 38. Tetmemorus Brebissoni Ralfs,
Ann. vol. xiv. p. 258. pi. viii. fig. 1. ; Jenner, in Flora
of Tunbridge Wells, p. 198.

378 DESMIDE^:.

Hob. Bogs at Fisher's Castle ; Waterdown Forest ; Pilt-
down Common ; Cross in Hand, &c. : Mr. Jenner.
Dolgelly, Caermarthen, and Penzance: Mr. Ralfs.
High Beech : A. H. H. Aberdeen : Dr. Dickie,

The fronds when empty are found to be minutely punc-
tate, the puncta being arranged in longitudinal rows. It
differs from Tetmcmorus granulatus in its form altogether
and in its puncta arranged in longitudinal lines.

2. TETMEMORUS GRANULATUS Ralfs.
Plate LXXXIX. Fig. 6.

Char. Frond six or seven times as long as broad, tapering
both in front and lateral views, but slightly constricted
in the centre. Segments rounded at the extremities
and terminating in a colourless, projecting, lip-like pro-
cess, punctated. Puncta arranged in diagonal lines.
Granules in a row down the centre of the frond.

Closterium granulatum Breb., in Menegh. Synop. Desmid.
p. 236. Tetmemorus granulatus Ralfs, in Annals of
Nat. Hist., vol. xiv. p. 257. pi. viii. fig. 2. T. granu-
latus Jenner, in Flora of Tunbridge Wells, p. 198.

Hob. Bogs at Fisher's Castle ; Scrubbs, Colebrook Park,
Waterdown Forest; Ashdown Forest, and Cross in
Hand : Mr. Jenner. Dolgelly and Penzance : Mr. Ralfs.
High Beech : A. H. H. Aberdeen : Dr. Dickie.

Tetmemorus granulatus differs from the preceding species
in several respects. In the form of the frond, which is alto-
gether different, being quadriform in T. Brebissoni, and fusi-
form in the present species, in the remarkable lip-like pro-
jection of the extremities of the segments, and in the arrange-
ment of the puncta in diagonal and not longitudinal lines.
Near the junction of the segments the puncta are observed
to be arranged in three or four transverse lines.

This species has been found by Mr. Ralfs in a state of
conjugation, and with the sporangium formed similar to that

EUASTRUM. 379

of numerous Closteria, and not differing from that of Stau-
rocarpus amongst the Conjugates. The steps of the form-
ation of this in Closterium and Tetmemorus are as follow.
Two fronds coalesce, a cell is gradually formed between
them into which the endochrome passes from each frond
and which finally becomes moulded into a distinct organ or
sporangium invested with its membrane.

61. EUASTRUM Ehr.

Char. Frond compressed, deeply divided into two segments.
Segments longer than broad, usually pyramidal, emar-
ginate at their extremities, and lobed and tuberculated or
sinuated.

Derivation. From sv, beautiful, and aarpov, a star.

" In this genus Ehrenberg includes Micrasterias Ag. (not
Micrasterias Ehr.} and Cosmarium; Meneghini separates the
former from it, but includes it in the latter genus. Euastrum
appears to me to be distinct from both, and especially from
Cosmarium. It agrees with Micrasterias in having lobes and
emarginate ends ; but the fronds are not incised, nor do the
lobes radiate from the centre. From Cosmarium it differs in
the lobed and emarginate segments, and also in the inflated
projections on the surface. These characters will also dis-
tinguish it from the other genera of this family." — Ralfs.*

a. Segments of the frond deeply lobed, tuberculated. Terminal
lobes cuneate.

1. EUASTRUM VERRUCOSUM Ehr.
Plate XCI. Fig. 7.

Char. Frond denticulated. Segments three-lobed. Lobes
broad, subcuneate, with a broad shallow notch between each
lobe.

Euastrum verrucosum, Abhand. der Akademie d. Wissensch.
* Annals, vol. xiv. p. 188.

380 DESMIDE^.

zu Berlin, 1833 (1832), p. 247.; Ehr. Infus. p. 162.
pi. xii. fig. 5.; Haifa, in Annals, vol. xiv. pi. vi. fig. 3.;
Jenner, in Fl. Tunb. Wells, p. 198. ; Pritch. Infus.
p. 196. fig. 125. Cosmarium verrucosum Menegh.,
Synops. Desmid. in Linnaea, 1840, p. 222.

Hob. Cheshunt : A. H. H. Rusthall Common, and Ash-
down Forest : Mr. Jenner. Penzance : Mr. Ralfs.

This is a very distinct species and the only British one of
the genus which has a dentated frond.

2. EUASTKUM OBLONGUM Ralfs.

Plate XCI. Fig. 1.

Char. Frond large, smooth, oblong, oval, dotted, three or four
times longer than broad. Segments in front view five-
lobed, semi-oval ; lobes broad, subcuneate, emarginate : in
lateral view pyramidal, furnished with six tubercles each.

Euastrum pecten, Abhandl. der Akademie d. Wissensch. zu
Berlin, 1831, p. 82. Euastrum pecten Ehr., Infus. p.162.
pi. xii. fig. 4. ; Pritch. Infus. p. 196. Echinella oblonga
Grev., in Hook. Br. Fl. vol. ii. p. 398. (1830). Cos-
marium oblongum Menegh., 1. c. p. 221. Eutomia oblonga
Harv., Man. Br. Al. p. 188. ; Ralfs, in Annals, vol. xiv.
p. 189. pi. v. fig. 4. ; Jenner, in Fl. Tunbridge Wells,
p. 198.

Hob. Bogs at Fisher's Castle ; Rusthall Common ; War-
bleton, &c., Beckley : Mr. Jenner. Penzance, Dolgelly,
and Caernarvon : Mr. Ralfs. Aberdeen : Dr. Dickie.
High Beech : A. H. H.

This is the finest species of the genus, and a beautiful
microscopic object, as are most of the species of this genus.

3. EUASTRUM PELTA Ralfs.

Plate XCI. Fig. 3.
Char. Frond three times as long as broad, subquadrilateral,

EUA8TRUM. 381

compressed, dotted. Segments in front view three-lobed ;
lateral lobes each twice slightly emarginate : in lateral view
much compressed.

Cosmarium Pelta Corda, Almanac de Carlsbad, p. 121. (7.
Pelta Menegh., Synops. Desmid. p. 222. Euastrum
Pelta Ralfs, in Annals, vol. xiv. pi. vii. f. 1. ; Jenner,
loc. cit. p. 198.

Hob. Bogs at Fisher's Castle and on Ashdown Forest ;
Piltdown Common : Mr. Jenner. Dolgelly ; Penzance :
Mr. Ralfs. High Beech : A. H. H.

There is no other species with which this need be con-
trasted.

4. EUASTRUM DIDELTA Ralfs.
Plate XC. Fig. 8., and Plate XCI. Fig. 11.

Char. Frond about three times as long as broad, dotted.
Segments in front view pyramidal, and laterally usually
twice emarginate; in transverse somewhat four-lobed, and
in end view oval.

Heterocarpetta Didelta Turp.,Mem. p. 295. (1828). Hetero-
carpellapolymorpha}L\Mz., Synops. Diatom, in Linnaea,
1833, p. 70. fig. 82. Euastrum ansatum, Abhandl. d.
Akademie Wissensch. zu Berlin, 1831, p. 82. ; Ehr.
Infus. p. 162. t. 12. fig. 6. Cosmarium lagenarium, Al-
manac de Carlsbad, 1835, p. 206. pi. ii. fig. 26. Cos-
marium Didelta Menegh., 1. c. p. 2 1 9. Euastrum Didelta
Ralfs, in Annals, vol. xiv. pi. vii. fig. 2. ; Jenner, in Flora
of Tunbridge Wells, p. 198,

Hob. Frequent in Sussex : Mr. Jenner. Henfield : Mr.
Borrer. Cheshunt : A. H. H. Barmouth Road : Rev.
T. Salwey. Caernarvon ; Dolgelly, near Carmarthen ;
and Penzance : Mr. Ralfs. Aberdeen : Dr. Dickie.

A very distinct species.

382 DESMIDE^.

5. EUASTRUM AFFINE Ralfs.

Plate XC. Fig. 9.

Char. Frond about three times as long as broad. Segments
pyramidal in front view, and thrice emarginate ; in lateral
view twice emarginate.

ft Frond about once and a half as long as broad, twice
emarginate.

Euastrum affine Ralfs, in Annals, vol. xiv. pi. vii. fig. 3.

Hab. In peat pools near Dolgelly : Mr. Ralfs. High
Beech : A. H. H. Aberdeen ; Dr. Dickie.

Fronds about as large as those of Euastrum Didelta ; the
segments somewhat resemble a decanter in form ; the base
is broad and inflated, and contracted upwards into a wide neck ;
the terminal notch is deep but not gaping ; the body of the
segment is broadly emarginate on each side ; all the lobes or
projections are rounded and the sinuses shallow.

The var. J3 is probably distinct.

6. EUASTRUM GEMMATUM Ralfs.
Plate XCI. Fig. 6.

Char. Frond rather more than twice as long as broad. • Seg-
ments in front view scarcely emarginate at their extremi-
ties, laterally twice so; in transverse view eiaht-lobed,
longer than broad ; and in end view four-lobed.
/9 Terminal lobe emarginate at each side.
Cosmarium gemmatum Breb., Menegh. 1. c. p. 221. Euas-
trum gemmatum Ralfs, Ann. vol. xiv. p. 191. pi. vii.
fig. 4. ; Jenner, in Flor. Tunbridge Wells, p. 198.

Hab. Near Dolgelly : Mr. Ralfs. Scrubbs, Colebrook
Park, and on Ashdown Forest, in the great bog near
Forest Row : Mr. Jenner.

"Fronds rather smaller than those of E. Didelta, nearly
three tunes as long as broad. Each segment consists of a broad
basal portion which is somewhat quadrilateral and emarginate

EUASTRUM. 383

at each side, and suddenly contracted to form the very short
neck ; the terminal lobe has each side elongated and rounded
entire in a and slightly emarginated in /S; the terminal
notch is very obscure. The transverse view is twice as long
as broad, with two rounded projections at each end, and three
on each side, and a small central opening at the original
junction-point of the segments." — Ralfs.

7. EUASTRUM CIRCULARS Hass.

Plate XC. Fig. 5.

Char. Frond about twice as long as broad, small, smooth ;
each segment anteriorly occupied with seven tubercles, Jive
at the basal, and two at the distal extremity, four of the
five basal tubercles disposed in a half circle around the fifth.

Hal. High Beech : A. II. H.
A very distinct little species.

b. Segments with acute angles, sometimes prolonged into spinous
processes not generally tuberculated.

8. EUASTRUM ROSTRATUM Ralfs.

Plate XCI. Fig. 8.

Char. Basal lobes of the segments broad and emarginate.
Terminal lobe with a curved acute spine-like process on
each side.

Euastrum rostratum Ralfs, in Annals, vol. xiv. pi. vii. f. 5.
Hab. In freshwater pools near Dolgelly : Mr. Ralfs.

" Frond very minute, about twice as long as broad ; seg-
ments obscurely three-lobed, or rather with a broad base,
which is emarginate on each side, and then contracted into a
broad short neck, connecting it with the terminal lobe. The
terminal portion has on each side a curved subacute tubercle
or process, somewhat like a beak; the end of the lobe is
prominent, generally angular, with a deep rounded terminal
notch."

384 DESMIDE^E.

9. EUASTRUM SPINOSUM Ralfs.

Plate XCI. Fig. 9.

Char. Frond minute, somewhat oval, compressed, rather better
than twice as long as broad. Segments twice emarginate
at the side. Angles often spinous, especially the distal
ones.

Euastrum spinosum Ralfs, in Annals, vol. xiv. p. 192. pi.
vii. fig. 6. ; Jenner, Flor. Tunbridge "Wells, p. 198.

Hob. Cheshunt : A. H. H. Barmouth : Rev. T. Salwey.
Mayfield; Rusthall Common; Piltdown Common;
Chiltington Common ; and Rackham, near Pulborough ;
Dolgelly ; Penzance : Mr. Ralfs.

A distinct though variable little species, and one by no
means uncommon.

10. EUASTRUM BINALE Ralfs.
Plate XCI. Figs. 4, 5.

Char. Frond about twice as long as broad. Segments con-
cave or truncate, at the end not projecting beyond the acute
angles,
a " Segments inflated at the base, the notch broad, forming

a concavity between the angles."

/9 truncatum. — " Fronds quadrilateral ; the end truncate,
acute at the angles, icith a small triangular notch in
the middle ; " segments laterally twice crenate.

Heterocarpella binalis Turp., Kiitzing, Synops. Diatom, p.

70. Cosmarium binale Menegh., Syn. Desmid. p. 221.;

Ralfs, in loc. cit. ; Jenner, in loc. cit., p. 198.
Hob. Mayfield ; Piltdown Common, and bog near Cross

in Hand : Mr. Jenner. Dolgelly ; Penzance : Mr.

Ralfs.

The variety /S may prove to be distinct.

MICBASTERIAS. 385

62. MICRASTERIAS Ag.

Char. Frond compressed, deeply divided into two segments.
Segments lobed, radiant, and incised.

Derivation. From fit/epos, small, and aa-rsptas, starred.

The flat and orbicular fronds, and the radiant and incised
lobes, will distinguish this at once from all other genera of
Desmidece.

The genus Micrasterias of Agardh differs entirely from the
Micrasterias of Ehrenberg, which has been referred to the
Pediastrum of Meyen.

1. MICRASTERIAS ROT ATA Ag.
Plate XC. Fig. 1.

Char. Fronds smooth, orbicular, ten-lobed. Lobes cuneate,
approximate, the end lobe emarginate, the others bifid, the
divisions being notched.

Micrasterias rota Menegh., Synops. Desmid. in Linnaea,
1840, p, 215. Echinella rotata Grev., in Hook. Br.
Flora, vol. ii. p. 398. (1830). Eutomia rotata Harv., Br.
Alg. p. 187. Euastrum rota Ehr., Infus. p. 167. tab. 12.
fig. 1.; Pritch. Infus. p. 195. figs. 121—123.; Bailey,
American Bacillaria, pi. i. fig. 22. and fig. 24. Micra-
sterias Ag., Bot. Zeit. 1827. ? Cosmarium stellinum et
C. truncatum Corda, Almanac de Carlsbad, 1835, p. 206.
pi. ii. pp. 22, 23. ; Ralfs, in Annals, vol. xiv. ; Jenner, in
loc. cit. p. 198.

Hob. Frequent in Sussex : Mr. Jenner. Henfield : Mr.
Borrer, About Barmouth : Rev. T. Salwey. Aber-
deen : Dr. Dickie. Stevenston, Ayrshire : Rev. D.
Landsborough. Penzance ; Dolgelly ; &c. : Mr. Ralfs.
Cheshunt Common : A. H. H.

The frond of this species in its young condition differs so
much from the adult form that it might be easily regarded as
a distinct production, the lobes being neither bifid nor den-
tated.

c c

386 DE8MLDE^.

2. MICRASTERIAS RADIATA HttSS.

Plate XC. Fig. 2.

Char. Frond orbicular, smooth. Segments hemispherical
each Jive-lobed. Lobes approximate, deeply bifid. Divi-
sions divergent, linear, and slightly bidentate.

Micrasterias melitensis Ralfs, in Annals, vol. xiv. p. 260.
pi. vi. f. 2.

Hob. Amongst Diatoma fenestratum in a small pool a
little below the outlet of Llyn Genernon, near Dolgelly,
very rare : Mr. Ralfs.

This species is described by Mr. Ralfs under the name of
Micrasterias melitensis, and as the Euastrum crux melitensis
of Ehrenberg, which species it seems to me that it as-
suredly is not. In the true Micrasterias crux melitensis the
frond is oval, rather than circular, and each segment is three-
lobed instead of five-lobed, and the lobes themselves are not
approximate but divergent ; see PI. xc. fig. 7. The plant
which Ehrenberg figures as the young of his species seems
to be referrible to the following genus.

63. HOLOCYSTIS Hass.

Char. Fronds much compressed, formed of two deeply divided
segments not incised. Segments not divergent. Lobes
angular, not radiant. Angles often spinous.

Derivation. From 6\os, entire, and KVtms, a cell ; in allu-
sion to the fact of the segments being entire at their
extremities, and not emarginate as in Micrasterias.

This genus bears considerable resemblance to Micrasterias
Ag., from which it differs mainly and essentially in the absence
of the radiant disposition of the lobes, which is the chief
character of that genus. To it should be referred perhaps
the Euastrum crux melitensis, pi. xii. fig. 3 c. of Ehrenberg ;
Arthrodesmus conoergens Ehr. approaches likewise rather
closely to the genus Holocystis.

PEDIASTRUM. 387

1. HOLOCYSTIS OSCITAN8 Hass.

Plate XC. Fig. 4.

Char. Frond large, smooth. Segments dilated below, con-
tracted above, and again dilated into a large triangular
lobe, which is somewhat rounded on its distal side. Angles
spinous.

Micrasterias ? oscitans Ralfs, MSS. ; Jenner, in Flora of
Tunbridge Wells.

Hob. On Ashdown Forest, near Duddleswell: Mr.
Jenner.

Of this species I noticed several fine specimens mixed up
with other Desmidea sent me by Mr. Sidebotham.

64. PEDIASTKTJM Meyen.

Char. Fronds compressed, circular, or star-like, each com-
posed of several cells, arranged in one or more united con-
centric circles. Marginal cells bipartite.

Micrasterias Ehrenberg.

Derivation. From TrsSiov, a bond or fetter, andaarpov, a star.

The DesmidecB are a beautiful tribe of productions ; and
none of them more so than the subjects of the present genus,
which cannot be confounded with any other. Distinct, how-
ever, as the genus Pediastrum is, considerable difficulty is ex-
perienced in the determination of the species, owing to there
being no one character which can be depended upon ab-
solutely in their definition ; the size of the fronds, number
of cells in each, and the degree of incision of the marginal
cells varying considerably in each : there is, however, a cer-
tain mean in these particulars which enables the observer to
determine in most cases the species or variety to which each
frond which presents itself to him really belongs.

Meneghini has noticed the occurrrence of transparent
vesicles in the cells of the frond, the number of these varying
according to the species : he has therefore availed himself of
these vesicles in their determination.

c c 2

388 DESMIDEJE.

1. PEDIASTRUM TETRAS Rolfs.
Plate LXXXVI. Fig. 17.

Char. Fronds small, cruciform. Cells four, deeply bipartite.
Divisions, truncate, emarginate.

Micrasterias tetras Ehr., Infus. p. 155. t. xi. f. 1. Hete-
rocarpella tetracarpa Bory de St. Vincent, Diet.
Classique d'Hist. Nat. 1825. Heterocarpella poly-
morpha Kiitzing, in part, Linnaea, 1833, t. xix. fig. 82.
Stauridium bicuspidatum, Stauridium crux melitensis
Corda, Almanac de Carlsbad, 1835, pi. iii. figs. 33, 34.
Pediastrum tetras Ralfs, in Annals, vol. xiv. p. 469.
pi. xii. fig. 4.

Hab. Barmouth and Penzance : Mr. Ralfs. Beckley
Furnace, near Battle, Sussex : Mr. Jenner.

A very rare and elegant species, and one of the least va-
riable of the genus*

2. PEDIASTRUM SIMPLEX Hass.
Plate LXXXVI. Fig. 18.

Char. Frond constituted of seven cells disposed in a circle, con-
taining in the centre one or two other cells which are emar-
ginate. Divisions of the marginal cells slightly dentate.

Pediastrum heptactis Ralfs, in loc. cit.

Hab. Barmouth : Mr. Ralfs. Beckley Furnace : Mr.
Jenner.

Distorted fronds of this species frequently occur, in which
the central cell is altered in form and displaced in situation.
See PI. LXXXVI. fig. 18. a. Meneghini describes a single
hyaline vesicle in each cell.

Under the name of Micrasterias heptactis, Ehrenberg seems
to me to have figured two species, fig. 4. a. t. xi., being dif-
ferent from b, c, d, which certainly represent the present
plant.

PEDIASTRUM. 389

3. PEDIASTRUM ELEGANS Hass.
Plate LXXXVI. Fig. 19.

Char. Frond circular, star-like, composed of six marginal
crescentic cells, and two central cells of an angular form.

Pediastrum Napoleonis Ralfs, in Annals, vol. xiv. p. 470.

pi. xii. fig. 6.
Hal. Dolgelly : Mr. Ralfs.

The above species, described and figured by Mr. Ralfs
under the name of Pediastrum Napoleonis, and as the Micra-
sterias Napoleonis of Ehrenberg bears no resemblance what-
ever to the figures given of that species, nor indeed to any
of Ehrenberg's figures, save a distant one to fig. 5 e. of pi. xi.,
which is regarded by the author as a state of Micrasterias
Boryanum, which it certainly cannot be, as the frond in the
figure alluded to is made of ten marginal crescentic cells, and
five internal angular cells.

4. PEDIASTRUM BORYANUM Menegh.
Plate LXXXVI. Fig. 13.

Char. Frond composed usually of two circles of cells, en-
closing a central cell, but sometimes there are three and
even four concentric circles, inner circle formed of Jive
cells, and second circle of ten. Marginal cells deeply bifid.

Helierella Boryana Turpin, Mem. du Mus. vol. xvi. p. 319.
pi. xiii. fig. 22. 1828. Pediastrum simplex, P. duplex,
P. biscidiatum Meyen, Nov. Act. Nat. Cur. xiv. 1829, p,
772, 773. t. 3. figs. 7. 13, 14. 16, 17, 18. ; Isis, 1830,
p. 163. Opharium speciosum, O.formosissimum, et O. ver-
ticillatum Losano, Mem. de Zarino, xxxiii. 1829 ; Isis,
1832, p. 768. t. xiv. figs. 17, 18. 21. Micrasterias sim-
plex, M. Boryi, M. duplex, et M. Selancea Kiitzing, Lin-
naea, 1833, p. 601. 3. t. xix. fig. 92 b. Euastrum
pentangulare et Pediastrum quadrangum Corda, Almanac
de Carlsbad, 1835, p. 206. 7. t. iii. figs. 32. 35. Mi-
ce 3

390 DESMIDEJE.

crasterias Boryana Ehr., Infus. p. 157. pi. f. 5. a. c. x.
k, h, 1, f, g, but not b, c, d, e. Micrasterias tricyclia
Ehr., Infus. p. 158. pi. xi. f. 8. b, c, d, f, g, e, i, but
not a. Pediastrum Boryanum Menegh., Synops. Desmid.
p. 210.; Bailey, American Bacil. fig. 20. Pediastrum
Boryanum Ralfs, in Annals, vol. xiv. p. 470. pi. xii.
fig. 7. in part 1.

Hob. Cheshunt, Herts : A. H. H. Brambletye, near
Forest Row ; Tunbridge Wells, &c. : Mr. Jenner. Dol-
gelley ; Barmouth ; and Penzance : Mr. Ralfs.

It appears to me that more than one species has been con-
founded together by different observers, and regarded as the
present plant. Ehrenberg has figured four species under
the name of Micrasterias Boryana., one of these being re-
ferrible to the Micrasterias tricyclia of Ehrenberg, pi. xi.
fig. 7. a, a plant which is British, and Mr. Ralfs, pro-
bably three species, the one of these being doubtless identical
with Ehrenberg's Micrasterias angulosa. The Pediastrum
Boryanum is the commonest species of the genus.

" Sometimes plants are met with having more than three
circles : these are probably the Micrasterias elliptica Ehr.,
Infus. p. 158. tab. xi. fig. 9., which Meneghini refers to
the present species. I am not, however, satisfied that it is
not distinct : the external cells agree with the description
given above, but the inner ones are variable in number, and
not arranged in regular circles. Whether it possesses any
other distinctive character I have not yet clearly ascertained.
This form is fig. 21. of the American * Bacillaria.' " — Ralfs.

5. PEDIASTRUM TRICYCLIUM Hass.
Plate XCII. Fig. 1.

Char. Fronds usually constituted of three circles, the inner
circle formed of four or Jive cells placed round a central
cell, the second circle of eight or ten cells, and the third
circle of fifteen cells. Cells somewhat quadriform, those of
the centre as well as the marginal ones usually incised.

PEDIASTRUM. 391

M. Boryana Ehrenberg, Infus. p. 157. pi. xi. fig. 5. i, b.
Micrasterias tricyclia, pi. XL fig. 8. a, but not b, c, d,
e, f, g, h, i, k.

Ha b. In a pond in a brick-field Netting Hill : A. H. H.

This appears to me to be a very distinct species. The
central cells are not always placed in exact apposition with
each other, frequently intervals or triangular interstices are
left between them. Ehrenberg has strangely confounded
the Pediastrum Boryanum with this species, and on the other
hand this species with P. Boryanum.

6. PEDIASTRUM AMGULOSUM Hass.
Plate LXXXVI. Fig. 14.

Char. Fronds constituted of two concentric circles of cells
surrounding a single central cell, the first circle being
formed usually of Jive cells and the second of ten. Mar-
ginal cells alone incised.

Micrasterias angulosa Ehr., Infus. p. 158. pi. xi. fig. 6. Pe-
diastrum Boryanum Ralfs, loc. cit. p. 470. pi. xii. fig. 7.
in part 1.

Hab. England.

There can be scarcely a doubt of the distinctness of this
species. It is figured by Mr. Ralfs as the Micrasterias Bory-
ana Ehr., with which species it has no affinity. Mr. Ralfs'
figure accords closely with Ehrenberg's of Pediastrum an-
gulosum,

7. PEDIASTRUM CONSTRICTUM Hass.
Plate LXXXVI. Figs. 15, 16.

Char. Frond large, composed of two or three concentric circles
of cells surrounding a single central cell, Jive cells in the
inner circle, ten in second, and fifteen in the outer circle.
Marginal cells toothed, teeth constricted.

Pediastrum Boryanum var. Ralfs, in Annals, pi. xii. fig. 8.

c c 4

392 DESMIDE^E.

This species differs so considerably in the form of the
marginal cells, that it is difficult to conceive it to be merely
a variety of that species. None of Ehrenberg's figures
come near to it. PL xi. fig. 5. d. E. represent distinct species
of Pediastrum, which have not been described as such, and
the first of which might be named Pediastrum cribriforme,
and the second P. lunare. See Plate xcn. figs. 3, 4. Se-
veral other species of Pediastra are represented in Ehren-
berg's figures, and confounded with other species. These I
propose to figure in an appendix to this genus, in the hope
that they may attract the attention of those who study the
beautiful tribe of Desmidece.

65. SCENEDESMUS Meyen.

Char. Frond composed of from two to ten cylindrical) fusi-
form or oblong cells disposed in one or two series, outer
ones often lunate.

Derivation. From a-Ktjvr}, a tent, and Sea-pos, a bond.
Arthrodesmus Ehrenberg, in part.

1. SCENEDESMUS QUADBICAUDATUS Breb.
Plate XCII. Fig. 12.

Char. Cells usually four, but sometimes there are eight in

each frond, rounded at the ends, disposed in a single

series, each extremity of the two external cells prolonged

into a bristle.

/9 Cells rather small, external ones with a bristle at each

extremity, and one at the outer margin.
7 ecornis Ehr. — External cells without bristles.

Breb. Alg. Falaise, p. 66. Menegh. Syn. Desmid. in Lin-
naea, 1840, p. 206. Arthrodesmus quadricaudatus Ehr.,
Infus. p. 150. t. 10. fig. 16.; Pritch. Infus. p. 189.;
Ralfs, in Annals, vol. xv. pi. xii. fig. 4. ; Jenner, in Fl.
of Tunbridge Wells, p. 200. — 7 ecornis. Scenedesmus

SCENEDESMUS. 393

Leibleini Kiitz., Synops. Desmid. in Linnaea, 1833,
p. 607. fig. 98. ; Menegh., 1. c. p. 207. Scenedesmus
bijugatus, trijugatus, and minor Kiitz., 1. c. p. 607. figs.
97. 99. ; Jenner, 1. c. p. 200.

Hob. Storrington Common and Eastbourn, Sussex ;
Shoreham, Kent : Mr. Jenner. Cheshunt : A. H. H.
Dolgelly: Mr. Ralfs. — $. Dolgelly : Mr. Ralfs.—
7. Weston Bogs, near Southampton : Mr. Jenner.
Bristol : Mr. Thwaites. Dolgelly, and Penzance : Mr.
Ralfs.

The cells in this species are quadrangular, about three
times as long as broad, and rounded slightly at their ex-
tremities ; the external ones are usually more turgid, and the
bristles at their extremities are directed outwards. The
variety /8 and 7 are figured by Ehrenberg.

2. SCENEDESMUS DIMOEPHUS Kutz.
Plate XCII. Fig. 13.

Char. Cells from four to eight in each frond, arranged in a
single series. Inner cells fusiform, attenuated at each
end; outer externally lunate.

Achmanthis dimorpha and bilunulata Turpin, Mem. du
Mus. xvi. p. 309. pi. xiii. f. 11, 12, 1828. Scenedesmus
pectinatus Meyen, Nov. Act. Nat. Cur. xiv. p. 375.
tab. 43. f. 34. 1829. Scenedesmus bilunulatus, dimorphus,
pectinatus Kiitz., Synops. Diat. Linnaea, 1833. 608.
t. xix. fig. 93. ; Ehr. Die Infus. p. 150. tab. x. fig. 17. ;
Kalfs, in Annals, p. 403. pi. xii. fig. 5.

Hob. Dolgelly : Mr. Ralfs. Near Bristol : Mr. Thwaites.
This is a very distinct and pretty species.

3. SCENEDESMUS ACUTUS Meyen.

Plate XCII.. Fig. 14.
Char. " Cells two to six, fusiform, acute at both ends, un-

394 DE8M1DEJE.

equally ventricose, arranged in a double, irregularly alter-
nating series."

Arthrodesmus acutus Ehr., Infus. p. 150. tab. 10. fig. 19.
c, d ; Meneg. 1. c. p. 207. ; Ktitz. 1. c. p. 609. fig. 96. ;
Ralfs, in Annals, vol. xv. p. 403. pi. xii. fig. 6.

" I notice this species because the Rev. M. J. Berkeley
has gathered it near King's Cliff, and I have occasionally
met with specimens which agree with Ehrenberg'e figures ;
but as I omitted to draw up a description at the time, I have
borrowed the specific character from Meneghini." — Ralfs.

4. SCENEDESMUS OBTUSUS Menegh.
Plate XCII. Fig. 15.

Char. Cells three to eight, ovate or oblong, with rounded ends,
and arranged alternately in two rows.

Menegh. 1. c. p. 208. Scenedesmus quadraltcrnus Kiitz.,
L c. p. 608. fig. 94. Scenedesmus octalternus Kiitz.,
L c. p. 609. fig. 95. Arthrodesmus acutus Bailey,
Amer. Bacil. fig. 18?; Ralfs, in Annals, vol. xv. p. 404.
fig. 8.

Hob. In boggy pools, Dolgelly : Ralfs.

" The specimens I have examined did not agree in every
respect with the description and figures of this species, but
they probably belonged to it. The cells were ovate, the
broad ends of the rows placed alternately, the smaller ends
being in different directions ; sometimes the cells seemed only
held together by the hyaline matrix, in which state they
appear to connect the Desmidece, through Gonidium Ehr.
and Trochiscia Kiitz., with the Ulvacece. The cells of one
row are separated by the interposition of the broader ends of
the other."— Ralfs.

Note. Several of the figures of this family, especially certain of those
of the genera Euastrum and Cosmarium, are taken from those of Jenner
and Ralfs, illustrating the series of papers on the Desmidea inserted in
the " Annals."

395

ALGM SILICATE.

FAM. XX. DIATOMACE^E.

Char. Algae silicious.

THE Diatomacecs form a group of natural productions not
less distinct and remarkable than the previous one of Desmi-
decB, with which it may be contrasted.

The Desmidece are Alga of figured and peculiar forms,
binary composition, vivid green colour, destitute of silex in
their constitution, and therefore subject to considerable change
of form in drying.

The Diatomacea are productions possessing also, to a cer-
tain extent, figured forms, but are not binary, of excessive
fragility, of a dark brown colour, which changes somewhat to
green on drying, of a metallic lustre and silicious composi-
tion, and therefore unalterable in drying, and indestructible
by fire.

The silex which enters so abundantly into the composition
of these plants is disposed throughout the interior of the
frustules in plates, which are often arranged in series, which
when the frustules are examined microscopically, are seen to
impart certain lines or markings to them, which contribute
much to their beauty, and which are of importance in the
discrimination of genera and species.

It is thus seen how very little connection this group and
family of productions has with the undoubted Alga which
have hitherto been described ; indeed, the claims which they
possess to be regarded as subjects of the vegetable kingdom
are by no means so conclusive as those which have been
advanced in favour of the vegetability of the Desmidece.

396 DIATOMACECE.

But the evidence of which we are in possession would appear
greatly to preponderate in proof of the vegetable character
of the Diatomacece ; thus, putting aside their silicious consti-
tution, and the partitions in the cells : the filaments of the
Meloseirce do not differ in the least in their modes of develope-
ment and growth from those of the Vesiculiferce, nor indeed
do those of Fragilaria differ very essentially from the fila-
ments of the true Alga ; in their reproduction, likewise, so
far as this has been ascertained, the Diatomacea correspond
with the Desmidea, and perhaps with all the lower Algce.

In support of their animal nature may be urged their
colour, which is different from that of all other undoubted
vegetable productions, and the silex of which they are prin-
cipally constituted. These arguments, however, are not con-
clusive, nor are they of as much weight as those adduced in
proof of their vegetability. It is probable that in this matter,
as in many other disputed points, the truth lies in the mean,
and that the Diatomacece are neither exclusively animal, nor
exclusively vegetable, but of a nature intermediate.

Owing to the presence of silex, the most indestructible
of substances, the species of this family are frequently found
beautifully preserved in a fossil state, and often in amazing
quantities all over the world. In the arts, the powder which
they form has been employed for polishing. Many of the
fossil species are identical with those now found in a recent
etate.

Section i.
Frond filamentous.

A. Filaments cylindrical.

66. MELOSEIRA Ag.

Char. Filaments cylindrical, subulate. Cells divided in the
centre or bilocular, sometimes vesicular. Junction sur-
faces of the cells either rounded or truncate, plain or
striated.

MELOSEIRA, 397

Derivation. From pe\os, a member, and trsipa, a chain.

The species of the genus Meloseira admit of division into
two subgenera. The first of these, the species of which are
chiefly marine, and to designate which the word Sphcerophora *
might be employed, are characterized by a peculiar form and
structure of the cells. The extremities of these are rounded,
and each contains, at first, one, and afterwards two spherical
vesicles or globules, divided by strongly marked double lines.
In consequence of there being no distinct articulating sur-
faces, the filaments are excessively fragile, so that it is rare
to find one of any length.

In the second subgenus, with which we have chiefly to do,
and the species composing which are, for the most part, in-
habitants of freshwater, the cells are truncate at their ex-
tremities, so that their articulating surfaces are directly applied
to each other, and simply bilocular, and not globuliferous.
This subgenus admits also of further division, according as
the articulating surfaces of the cells are either plain or ser-
rated, and striated.

The genus Meloseira, amongst the Diatomacea, seems to
have been constituted with a view of making apparent the
affinity which undoubtedly exists between the Diatomaceoz
and the Algce proper, not merely in form and developement
approximating so closely to the genus Vesiculifera amongst
the true Conferva, but also in a measure in its reproduction.
As in Vesiculifera, at a certain period, particular cells lose
their cylindrical form, and become globular or vesicular, and
contain endochrome : here, however, the analogy would ap-
pear to cease ; for this endochrome, so far as my observation
goes, never becomes condensed into a distinct organ or spo-
rangium similar to that with which we are familiar in the
families Conjugates and Desmidece. Notwithstanding this
striking resemblance to a genus of the Conferva, the Melo-
seircB are true members of the family of Diatomacece, as is
clearly indicated by their silicious nature, and consequent
striated structure.

* Derivation. From fffaipov, a globule, and 0op?w, to bear.

398 DIATOM ACE^:.

The species are all included by Ehrenberg in his genus
Gallionella.

a. Filaments not globuliferous.

* Extremities of the cells serrated at the edges.

1. MELOSEIBA ARENOSA Moore, MS.

Plate XCIII. Figs. 2, 3.

Char. Filaments large, dark brown. Frustules * twice or even
three times broader than long, divided in the centre by a
double line.

Gallionella variant Ehr., Die Infus. p. 167. t. 21. fig. 2.
Meloseira arenosa Moore, MS. M. arenaria Kails,
in Annals, vol. xii. p. 349. pi. ix. fig. 4.
Hal). On a wet bank near Larne, co. Antrim : Mr. Moore.
Inner extremity of the Giant's Causeway: Mr. W.
Thompson. Very sparingly in a stream near Shoreham,
Kent : Mr. Jenner.

This is by far the finest species of the genus, and is evi-
dently the plant which Elirenberg had in view as the Melo-
seira varians of Agardh, his description of that plant being as
follows : —

" Corpusculis utrinque planis, cylindricis aut nummifor-
mibus, a dorso glabris, a latere radiatim striolatis, ovariis
flavis aut flavo-viridibus."

It is probable, as Ehrenberg has correctly figured both
species, that he regarded the true Meloseira varians of Agardh
as the young state of his species.

The end surfaces of the frustules are closely applied to each
other, faintly marked with radiating striae with their margins
serrated, the teeth of one frustule locking into those of the
other with which it is in contact, in the same manner as the
teeth of certain wheels arc made to fit each other.

The name should be arenosa, and not arenaria.

* The term frustule, applied to the Diatomacece, has the same meaning
as the word cell used to describe the Conferva.

MELOSEIRA. 399

2. MELOSEIRA ORICHALCEA Kutz.
Plate XCIII. Figs. 6, 7.

Char. Filaments rather slender, when recent of a fawn colour.

Frustules two or three times longer than broad, twice

divided near the centre.
Kiitzing, in Linnasa, 1833, p. 71. fig. 68. Gallionella auri-

chalcea Ehr., Die Infus. p. 168. t. 10. fig. 6. ; Amer.

Bacil. part 2. p. 5. pi. xi. fig. 4 b.
Hob. In ditches and slow streams, Cheshunt : A. H. H.

Stevenston, Ayrshire : Rev. D. Landsborough. Dol-

gelly : Mr. Rolfs.

This species differs from Meloseira varians, with which it
might be confounded, in its smaller filaments, different colour,
longer frustules, in the double division of these, and especially
in the dentated margins, by which M. orichalcea is related to
Meloseira arenosa, and which is the only character in common
between the two species. The Gallionella distans of Ehr.
comes close to this species, if it be not identical with it.

** Margins of the cells smooth.

3. MELOSEIRA VARIANS Ag.

Plate XCIII. Figs. 4, 5.

Char. Filaments rather thick, dark brown, becoming greenish
in drying. Frustules once or once and a half as long as
broad, once divided in the centre.

Ag. Conspect. Diatom, p. 64. ? Kutz. in Linnsea, p. 71.
fig. 69. ; Harv. Br. Alg. p. 195. M. lineata Ag., Syst.
p. 8.; Harv. in Manual, p. 195. Gallionella varians
Ehr., Die Infus. t. 10. fig. 4. G. aurichalcea Bailey,
Amer. Bacil. part 2. pi. 2. fig. 4 c. Conf. lineata Dillw.,
p. 44. t. ft Jurg, Dec. 5. No. 18. Conf. hyemalis Jurg,
Dec. No. 17. No. 6. Vesiculifera composita Hassall, in
Annals of Nat. Hist. vol. x. p. 394. ; Kalfs, in Annals,
vol. xii. p. 350. pi. ix. fig. 5.

400 DIATOMACE2E.

Hab. Everywhere common in ditches and rivulets.

" In a stream below Penmaen Pool, near Dolgelly ; and
within the influence of the tides, I have gathered a tufted
state of this species of a bluish colour, not unlike the iridescent
tints of Cystoseira ericoides. It was growing with Ectocarpus
littoralis. I have also for several years observed it in the
same state in a cave by the sea side at Penzance ; in both
instances it afterwards became brownish, and finally green."
— Ralfs.

It is on this species that the inflated vesicles usually occur,
and which formerly induced me to refer it to a section of the
genus Vesiculifera,

4. MELOSEIRA OCHRACEA Ralfs.

Char. " Frustules very slender, convex at each end, ovate, not
striated, ferruginous. Filaments often connected together
in a subramose manner."

Gallionella ferruginea Ehr., Die Infus. p. 169. t. 10. fig. 8.,
and t. 21. fig. 3. Conf. ochracea Dillw., t. 62. Oscil-
latoria ochracea Grev., Flor. Edin. p. 304. ; Harv. Br.
Alg. p. 167. M. ochracea Kalfs, in Annals, vol. xii.
p. 35.

Hab. Pools and slow streams in boggy soils.

" This plant occurs in delicate ochraceous or ferruginous
masses, falling into powder on the slightest touch. The fila-
ments are so slender, and the joints so obscure, that I have
been unable to determine the form of the frustules, and have
therefore taken the specific character from Ehrenberg : I am
also unable to ascertain whether the joints are marked by any
central line. Having received from Mr. Dillwyn a specimen
of his Conf. ochracea, which I am able confidently to refer to
this species, I have restored the original specific name.
Ehrenberg is no doubt correct in placing the plant in this
genus, as the filaments are cylindrical and silicious.

" When submitted to a red heat it acquires a reddish tinge,

ACHNANTHES. 401

which circumstance, together with the colour and slender fila-
ments, will distinguish it from all other species." — Rolfs.

67. ACHNANTHES Bory.

Char. Frond stipitate, standard-shaped, composed of few
frustules, which are longer than broad., curved, and have a
punctum at the centre of the inferior margin.

Derivation. From a%vr), the froth of the ocean, and avOos,
a flower.

The stipes is attached not to the centre of the lower frus-
tule but to one of its angles, and this position of it gives rise
to the resemblance of each entire frond to a standard.

1. ACHNANTHES MINUTISSIMA Kutz.
Plate C. Fig. 4.

Char. Frustules small, slender ; in lateral view obtuse, and
apparently without striae. Stipes very short.

Kutz. Syn. Diatom, p. 578. f. 54. ; Ehr. Infus. p. 228.
pi. xx. f. 5. ; Ralfs, in Annals, vol. xiii. p. 492. pi. xiv.
fig. 2. ; Jenner, in Flor. of Tunbridge Wells, p. 200.

Hab. Parasitic on other Algce, Newtimber, Sussex : Mr.
Borrer. Several places in Sussex, &c. : Mr. Jenner.
Cheshunt : A. H. H. Oswestry : Rev. T. Salwey. Pen-
zance : Mr. Ralfs. Bristol : Mr. Thwaites.

The fronds are very minute, and rarely consist of more than
two frustules.

" Before I had the opportunity through Mr. Borrer's kind-
ness of comparing our plant with the specimen in Kiitzing's
' Alg. Aq. Dulc.' I considered it a variety of the following
species; and I am still uncertain whether they should be
separated, although the plant above described is undoubtedly
Kiitzing's Achnanthes minutissima." — Ralfs.

D D

402 DIATOMACE^I.

2. ACHNANTHES EXILIS? KutZ.

Plate C. Fig. 5.

Char. Frustules slender, from one to nine in each Jrond.
Lateral surfaces subacute. Striae indistinct or wanting.
Stipes longer than thefrustule.

Kutz. Syn. Diatom, p. 578. f. 53. ; Ehr. Infus. p. 228.
pi. xx f. 5. ; Ralfs, in Annals, vol. xiii. pi. xiv. fig. 12.

Hob. Parasitic on Gomphonema geminatum in several
streams, near Dolgelly : Mr. Ralfs.

From Achnanthes minutissima this species differs in its
elongated stipes, greater number of frustules in each frond,
and in its more acute lateral surfaces.

Although I have compared our plant with Kutzing's
Achnanthes exilis I am not certain that it is the same species.
It agrees with Kutzing's specimen in its crowded habit and
elongated stipes, but its frustules are much smaller, and
its lateral surfaces less acute, in both which respects it is inter-
mediate between Ach. minutissima and Kutzing'a specimen of
Ach. exilis.

B. Filaments compressed.
A. Frustules in front view quadrangular.

68. TETRACYCLUS Ralfs.

Char. Frustules cohering so as to form a fragile, attenuated
filament, never united by their angles, striated strongly
laterally ; four-sided, each side rounded, and forming the
segment of a distinct circle.

Derivation. From rerpas, four, and KVK\OS, a circle.

This genus differs only from Tessella and Striatella in the
frustules uot cohering by the angles.

TETRACYCLUS. 403

1. TETRACYCLUS LACUSTRIS JRalfs.
Plate XCIII. Figs. 8, 9.

Char. Frustules about twice as long as broad. Lateral sur-
faces with from seven to nine distinct transverse strict ; in
end \iewfour-lobed.

Hob. Llyn Prefeddyr, near Barmouth : Rev. T. Salwey.
Pools near Dolgelly : Mr. Ralfs.

In consequence of the four-lobed form of the frustules
composing a filament, and which arises from the inflation of
the central part of each frustule, it happens that when ex-
amined by the microscope that the centre of one side or lobe
is seen together with a portion of two other lobes, one on each
side, the boundaries of the lobe in view being indicated by two
lines running down the length of the filament. But as the
lobes are not all of equal size, those only being so which are
opposite to each other in the filament, it follows that the
quantity of the other two lobes seen varies according to the
side of the filament which is uppermost. Now, the longer sides
or lobes are those which form the margins of the filaments, and
those which form the centre the shorter, the filament rests of
course usually upon one of the shorter lobes : from this it re-
sults that in the filaments in their usual position, that a con-
siderable portion of the lateral lobes is seen, but in the cases in
which they rest upon their longer or marginal lobes a very
small portion only of the lateral lobes is in view. The smaller
and shorter lobes correspond to the back and front of the fila-
ment, and the larger and longer to the margins, which may be
distinguished in addition to their breadth by the presence of
stria?, more strongly marked than they are in the centre of
the filament : the terminations of the frustules in this view
are also punctated, although not contracted. In the marginal
view, that is with the margin of the filament uppermost, but
a very slight portion of the back and front lobes is seen, the
striae are most strongly marked in the centre, and describe
quadrangular spaces, the frustules are contracted also at their
points of junction where they present no puncta.

DD 2

404 DIATOMACE.E.

In the end view the frustules have been aptly compared to
the quatrefoil of a gothic window : in the smaller filaments in
this aspect, they are about as long as broad, in the larger one
and a half times as broad as long ; and each has about seven
well-marked striae, a central straight stria which extends from
one marginal lobe to the other, and three curved striae be-
longing to each of the front and back lobes.

69. TABELLARIA Shut.

Char. Frustules quadrangular, fusiform, cohering by their
angles, traversed in the centre by a longitudinal canal,
marked with transverse * stria, interrupted in the centre by
the canal. End view destitute of markings.

Derivation. From tabella, a letter ; which the frustules re-
semble in form.

The term Bacillaria is applied by Ehrenberg to the spe-
cies of this and the following genus, as well as to a curious
production wholly different from either genus, the Bacillaria
paradoxa, and to which species I propose that the genus
Bacillaria should now be confined. By Agardh, the ap-
pellation of Diatoma is given to them. Mr. Shuttleworth
has proposed the division of the genus Diatoma into two
genera, in the propriety of which I fully concur ; for one of
these Mr. Shuttleworth reserves the name of Diatoma, that
of the other is derived from a species named by Ehrenberg
Bacillaria tabellaris, and which species is typical of the genus.

1. TABELLARIA FLOCCULOSA.
Plate XC1V. Figs. 9, 10.; Plate XCVI. Fig. 11.

Char. Frustules in young spscimens as long as broad, in older
specimens their breadth exceeds their length by two or three
times. Striae from one to seven on each side. In end

* The word transverse has here a meaning different to that generally
assigned to it ; it here has Reference to the width of the cell or filament,
and not to its depth.

TABELLARIA. 405

view frustules dilated in the centre by the canal, with
rounded extremities.

Diatoma flocculosum Ag., Syst. p. 4. ; Kiitz. in Linnaea,
1833, p. 584. 1. 17. f. 67. ; Hook. Br. Fl. vol. vii. p. 406. ;
Harv. Br. Alg. p. 202. Conf. flocculosa Dillw., Conf.
t. 28. ; Eng. Bot. t. 1761. Bacillaria tabellaris Ehr.,
Infus. p. 199. pi. xv. f. 7. Diatoma flocculosum Ralfs,
in Annals, vol. ix. pi. ix. fig. 3. Bacillaria flocculosa
Ehr., Infus. t. xv. f. 9. B. seriata Ehr., Infus. t. xv.
fig. 8.

Hob, Common in pools, &c.

This is a very variable species, and it is not to be wondered
at that a difference of opinion should have existed as to
whether the conditions of it represented in " Eng. Bot." and
in Dillwyn's " Confervas " were not in reality distinct species.
That they are not so, however, is certain, as well as that both
are different stages of the growth of the same production.
In the young state, the cells are as long and even longer than
broad, each side of the frustule being marked with often as
many as seven well-marked striae ; and the central canal is
large and circular. From this state intermediate specimens
are often met with, some having the frustules once and a half,
others twice, and others thrice, and even many times as broad
as long. Corresponding with this gradual lateral enlargement
of the frustules, we find the number of the striae to diminish
gradually, until at last but one or two exist on each frustule,
and at the same time, a gradual diminution in the size of the
central canal occurs, until at length this is nearly obliterated.
Thus the ultimate stage of the species bears some resemblance
to Tabellaria fenestrata, and is the Bacillaria seriata of
Ehrenberg. For these changes see the figures.

2. TABELLARIA FENESTRATA.
Plate XCVI. Fig. 10.

Char. Frustules four or Jive times longer than broad; in end
view subinftated in the centre with incrassated ends.
D D 3

406 DIATOMACE^E.

Diatoma fenestratum Lyngb., Hydr. Dan. t. 61. E. 3. ;
Ag. Consp. Diatom, p. 53. ; Hook. Br. Fl. vol. vii.
p. 406. ; Harv. Br. Alg. p. 202. ; Kalfs, in Annals,
vol. xi. p. 453. pi. ix. fig. 4. ; Jenner, in Flora of Tun-
bridge Wells, p. 200.

Hab. Pools, &c. ; Sussex, &c. : Mr. Jenner. Cheshunt :
A. H. H. Barmouth, North Wales : Rev. T. Salwey.
Dolgelly, and near Pont-Aberghas lyn, North Wales,
and Penzance : Mr. Ralfs. Stevenston, Ayrshire : Rev.
D. Landsborough. Aberdeen : Dr. Dickie.

This is one of the least variable of the species of this and
the following genus ; it may however be confounded with
Tabellaria flocculosa in the last stage of its developement ;
but with a little care it may be readily distinguished there-
from. In T. fenestrata the frustules are connected by a per-
ceptible hinge, and on each fully developed frustule there are
at each extremity two striae. In T. flocculosa the mucous
hinge is not visible connecting the frustules, which are usually
much longer, and on the narrowest, which approach nearest to
T. fenestrata, there is frequently but a single stria at one
side, and two at the other. The end views of the frustules
in the two also differ. In T. flocculosa the frustule is more
slender, the ends less incrassated, and the canal more pro-
longed.

The frustules in this species and in D. elongatum are often
curiously thrown back so as to form two lengthened series.

70. DIATOMA Ag.

Char. Frustules not having a central canal or lateral stria,
punctated at the sides, the puncta being produced by the
presence of grooves, which pass round the frustules. Junc-
tion surfaces often striated.

Derivation. From Simoon, incision ; the plant looking like
a band cut into portions, which cohere only at the
angles.

DIATOMA. 407

1. DIATOMA VULGARE Bory.
Plate XCIV. Figs. 1, 2.

Char. Frustules two or three times broader than long, some-
times attached by a stipes. Lateral puncta very evident.
End view inflated, incrassated at the terminations, and
striated.

Diatoma vulgare Kiitzing, in Linneea, 1833, p. 582. f. 66.
D. tenue Grev., Crypt. Fl. t. 354. ; Berk. Brit. Alg.
t. 6. ? Hook. Br. Fl. vii. p. 406. ; Harv. Manual of Br.
Algse, p. 202. D. tenue a moniliforme (Young) Kiitz.,
in Linnaea, 1833, p. 580. f. 60.? D. tenue ft interme-
dium Kiitz., 1. c. p. 580. f. 61. ? D. flocculosum Ag.,
Consp. Crit. Diatom, p. 53. excl. syn. Dillw. Bacil-
laria vulgaris Ehr., Die Infus. p. 197. pi. 15. f. 2.
Diatoma vulgare Ralfs, in Annals, vol. xi. p. 450. pi. viii.
fig. 8. ; Jenner, in Fl. of Tunbridge Wells, p. 202.

Hab. Pools, streams, &c. King's Cliff, Northampton-
shire : Rev. M. J. Berkeley. Henfield, Sussex : Mr.
Borrer. Shoreham, Kent, and several stations about
Lewes and Tunbridge Wells : Mr. Jenner. Shrewsbury :
Mr. Leighton. Oswestry, Shropshire : Rev. T. Salwey.
Cheshunt, Herts : A. H. H. Ireland : Mr. D. Moore.

This species, like most of the Diatomacecs, varies very con-
siderably in the length and breadth of the frustule, as well as
in the degree of its convexity. Usually each frustule is about
two and a half times as broad as long ; in this state the frus-
tules are seen to be very convex in the end view, but some-
times older specimens are met with, in which the breadth of
the frustules exceeds some five or six times their length, and
in this they are scarcely at all convex when viewed endways.
This condition of the species might almost mislead one to re-
gard it as a distinct species. See the figures.

From Diatoma tenue, or rather D. elongatum, of which
D. tenue is but a state, with which, however, there is but
little danger of confounding it, D. vulgare may be distin-
guished by the greater breadth of the frustules, their con-

D D 4

408 DIATOMACE^:.

vexity in the end view, and the different character of the
marginal striae. Owing to the frustules being convex, not
merely in thickness, but having rounded extremities, the
striae are evident on a portion of the front surface.

The species grows most luxuriantly in gently running
water, frequently investing Cladophora glomerata, and causing
it to appear of a deep brown or chocolate colour. It is at-
tached to this plant by means of a stipes, first detected by
Mr. Jenner, the existence of which from its locality in flow-
ing water might have been predicted.

In drying it changes to a greenish hue.

2. DlATOMA ELONGATUM Aff.

Plate XCIV. Figs. 3, 4, 5, 6.

Char. Frustules many times as broad as long, at first with
straight margins, subsequently, when fully developed, the
sides are dilated on the front surface. End view linear,
with slightly incrassated ends. — /9 cuneatum. Frustules
wedge-shaped.

Diatoma tenue Ag., Consp. Diatom, p. 52. D. tenue 8
normale Kiitz., in Linnaea, 1838, p. 580. t. 17. f. 63. D.
elongatum Berk., Glean, t. 6. ; Hook. Br. Fl. 406. ; Harv.
Manual, p. 202. D. sulphurascens Ag., Consp. Diatom,
p. 53. Conf. fiocculosa Dillw., Br. Conf. t. 28. f. c. ?
Bacillaria pectinalis Ehr., Infus. p. 198. pi. xv. fig. 4. in
part only. D. elongatum Ag., Syst. p. 4. ; Kiitz. in Lin-
naea, p. 582. t. 17. f. 65. Bacillaria elongata Ehr., In-
fus. p. 218. f. 169. D. tenue and D. elongatum Ralfs,
in Annals, vol. xi. p. 451, 452. pi. ix. fig. 1. ; D. tenue
Jenner, loc. cit. p. 202. Bacillaria cuneata Ehr., Infus.
t. xv. fig. 6. Diatoma tenue 7 cuneatum Kiitz., in Lin-
naea, 1833, p. 580. t. 17. fig. 62.

Hob. Pools and streams. Near Tunbridge Wells : Mr.
Jenner. Shrewsbury : Mr. Leighton. Cheshunt: A. H. H.
Bangor, and Dolgelly, North Wales; Penzance: Mr.

DIATOMA. 409

Ralfs. Aberdeen : Dr. Dickie. Stevenston, Ayrshire :
Rev. D. Landsborough.

This is a very variable species. .In the young state the
frustules are plain, but in their fully developed condition
they are dilated laterally, or as most writers would say, at
each extremity. These two states have been separately de-
scribed as distinct species, but I have no hesitation in uniting
them. I have preserved the specific appellation of elonga-
tum in preference to that of tenue, because the latter term was
applied by Ehrenberg to the condition of the species with
dilated frustules, in fact to the species in its fully developed
or perfect state.

The younger frustules in the end view are slightly dilated
in the centre with incrassated ends ; in this state they bear a
slight resemblance to the older ones of Diatoma vulgare, but
are much smaller. The fully developed frustules in the end
view are linear and very slightly incrassated.

Remarkable as the variety with cuneate frustules is, it is
I suspect but an anomalous condition of the species.

Light brown or yellow when recent, assuming a faint
green tinge in drying.

3. DIATOMA VIRESCENS Hass.
Plate XCV. Figs. 7, 8.

Char. Frustules usually two or three times broader than long,
frequently cohering together in the manner of a Fragi-
laria. In end view oval, with slightly constricted extre-
mities. Strise inconspicuous.

Fragilaria pectinalis Ehr., Die Infus. p. 206. t. 16. f. 1.
excel, a; Pritch. Infus. p. 222. fig. 176. Fragilaria
virescens Ralfs, in 1. c. p. 110. pi. 11. fig. 6. ; Jenner,
1. c. p. 202.

Hob. Cold bath spring, Broadwater Forest ; Lower
Green ; Rotherfield and Piltdown Common : Mr. Jen-
ner. Madron and Chyanhal Moor, near Penzance :

410 DIATOMACEJE.

Mr. Ralfs. Pond near Wormley, West End, Herts :
A. H. H.

The greatest peculiarity of this species is, that frequently
the frustules cohere together in considerable numbers, so as
to form filaments apparently similar to those of Fragilaria,
but in all probability really distinct. If, however, the speci-
mens be dried or kept in water, these filaments will generally
be found broken up in the manner of a Diatoma.

The only species with which it needs to be contrasted is
Diatoma vulgaris, from which it may be distinguished by the
absence, or at all events the exceeding fineness of the strias,
on the end surfaces of the frustule, as well as by the fila-
ments, which it usually forms.

The colour is stated to be green, not altering much in dry-
ing. In my specimens it has been dark brown, changing to
a greenish hue in the herbarium.

The removal of this species from Fragilaria to Diatoma
will render that genus a natural and not an anomalous one.

71. BACILLARIA Gmelin.

Char. Frustules sliding one upon the other.
Derivation. From bacillum, a small stick.

In the genus Bacillaria Ehrenberg includes not merely
the species of the two preceding genera, but likewise the sin-
gular production which forms the type of the limited genus
Bacillaria.

1. BACILLAKIA PARADOXA Gmelin.
Plate XCII1. Fig. 10.

Char. Frustules very many times broader than long, cohering
together in considerable numbers upon the same plane,
motive upon each other. In end view striated.
F. sonderbares Stabgenthier Miiller, Muller's Kleine

BACILLARIA. 411

Schriften v. Goze, p. 1. fab. 1. 8., 1782; Pinddyr Nye
Samling af Dansk Vidensk. Sallsk. Skrift. 11. p. 277.
Vibrio paxillifer Miiller, Animalc. Infus. p. 54. t. 7.
f. 3. 7., 1786. Bacillaria paradoxa Gmelin, Linnaei
Syst. Nat. ed. xiii. vol. vi. 1788. Vibrio paxillifer La-
mark, Systeme des Anim. sans Vert. 1815. Bacillaria
palea Nitzsch, in part, Beitrage zur Infusorienkunde,
1817; Encyclopadie v. Ersch u. Gruber, 1821. Bacil-
laria paradoxa Bory de Saint Vincent, Diet. Classique,
1822. B. Mulleri Bory, Encyc. Meth. 1824. Oscil-
laria paxillifera Schrank, Nov. Act. Nat. Cur. xi. 2.
p. 534. 539. Bacillaria Mulleri Turpin, Diet, des Sc.
Natur. Vegetaux Acotyledones, 1828. Bacillaria para-
doxa, Abhandl. der Akademie d. Wissensch. zu Berlin,
1831, p. 83. ; 1833, p. 319. ; Ehr. Infus. p. 196. t. xv.
f. 1.

This is the most singular of all the Diatomacece, and the
most protean in the forms which it assumes ; the variety of
which results from the power which the frustules undoubt-
edly possess of gliding one upon the other. Sometimes
the margins of the frustules correspond in position with
each other, and then an elongated lamina is formed similar
to that of the Fragilarice. At others the frustules are drawn
out from each other by two and three together, and the
margins are rendered uneven ; and again at others, each frus-
tule composing a frond is drawn out, so that it adheres but
by a very small portion of its length to the frustule or frus-
tules, one on each side, with which it is connected. Now
this disposition of the frustules could only be effected by the
possession of a power of motion the one upon the other.

Ehrenberg in his definition of this species makes use of
the following phrase, " baccillis singulis alacriter mobilibus ; "
and, again, in the definition given in French, " les baguettes
vivement mobiles." Now it ought not, I apprehend, to be
imagined, as the words quoted would lead us to suppose, that
the frustules possess each and individually a power of loco-
motion centered in themselves, but merely that they are BO

412 DIATOM ACE^E.

loosely aggregated together as that a slight force should
occasion a lateral displacement of them. Still it must be
allowed to be very singular, that the frustules should not
rather separate altogether from each other, than allow so
great a displacement as is frequently seen to occur, and yet
should retain their adherence.

A separate frustule bears much resemblance to the un-
dilated form of the frustule of Diatoma elongatum. Colour
yellowish brown.

I am in some doubt as to the precise locality of this pro-
duction. It was either gathered by the Rev. D. Lands-
borough at Stevenston, in Ayrshire, and then probably found
near the sea, or (what is less likely) by myself, somewhere in
the neighbourhood of Cheshunt

72. FRAGILARIA Lyngb.

Char. Filaments compressed, attenuated, fragile, rarely an-
gular, with., in most cases, two canals or grooves passing
round the centre of each frustule, indicated by the presence
of puncta on the lateral margins.

Derivation. From frango, to break ; in allusion to the
brittleness of the filaments.

The genus Fragilaria approaches very closely to that of
Diatoma as restricted in this work ; indeed the two genera
merge into each other, through Fragilaria virescens or rather
Diatoma virescens. The compressed character of the frond
is sufficient to distinguish it and all other Diatomacea from
the genus Meloseira.

1. FRAGILARIA PECTINALIS Lyngb.
Plate XCV. Figs. 1. 4.

Char. Filaments large, dark brown. Frustules in front view
quadrangular, two or three times broader than long, longi-
tudinally striated with two evident puncta on the lateral

FBAGILARIA. 413

margins ; in end view curved with slight constrictions at
each extremity, striated.

ft undulata Ralfs. — Convex margin of end view of the
frustule with two indentations; centre of concave margin
prominent.

Ag. Syst. p. 7. ; Consp. Diat. p. 62. ; Grev. in Br. Fl.
vol. ii. p. 403. ; Harv. Br. Alg. p. 197. Conf. pectinalis
Dillw., t. 4. ; Eng. Bot. 1. 1611. ; Jurg, Dec. 18. No. 12.
Fragilaria grandis Ehr., Die Infus. p. 203. 1. 15. fig. 11.;
Pritch. Infus. p. 220. — ft undulata, fig. 171. ; Ralfs, in
Annals, vol. xii. pi. 2. fig. 3. F. pectinalis Ehr., pi. xvi.
fig. 1 a ; Jenner, loc. cit. p. 202.

Hob. Everywhere common in pools, ditches, &c. — ft un-
dulata. Drws Ardudwy, near Barmouth : Rev. T. Sal-
wey. Scr ubbs, Colebrook Park : Mr. Jenner.

The filaments of this species and others of the genus vary
exceedingly in size, or rather in diameter, on account of the
cells of the species of the genus developing themselves in
breadth as well as length, and this developement occasions
the greatest variations in the width of the cells, compared to
their length : thus sometimes the cells are longer * than broad
in the very slender filaments ; at others, as in the longest
threads, they are six or seven times broader than long, but
• usually their breadth exceeds their length only by three or
four times.

On the anterior surfaces of the frustules at either extremity,
but not extending entirely across them, a delicate row of striae
may be detected : these add greatly to the beauty and interest
of the plant, and do not appear hitherto to have been described :
they are doubtless formed by the continuation of the striae
observed in the end view of the frustule. Mr. Jenner has

* The terms length and breadth, when employed in this work in the
description of the Diatomacece, are used in the same sense in which they
are employed in the definitions of the Conferva, the breadth of the frustule
corresponding to the diameter of the filament, and the length to its longi-
tude. In the DiatomacecB the breadth of the frustule usually exceeds the
length.

414 DIATOM ACE^J.

verified my observation on these minute striae : when first I
observed them, I thought that they were found only in the
undulated variety of the plant, and that this therefore might
form a distinct species. I am now satisfied, however, that the
striae are to be found in every well-developed specimen ; and
the difference observed in the end view of the frustules in
certain species is indicative of merely a condition of the
plant.

A remarkable state of this species has been met with by
Mr. Ralfs and Mr. Jenner. In this, within each frustule is
enclosed apparently a second frustule of a more or less oval
form, and striated laterally in the same way as the extremities
of the cells.

Occasionally it happens in this and in other species and
genera of Diatomacece that the cells in their front aspect
are not in the form of a parallelogram, but somewhat cuneate :
this occurs in consequence of the frustule being divided ob-
liquely, and not by a straight line.

The frustules, Mr. Ralfs observes, have sometimes a central
pellucid spot, which does not appear to be connected with the
endochrome.

When recent, Fragilaria pectinalis is of a dark brown, but
in drying it turns to a greyish green, with a metallic lustre.

2. FBAGILAEIA HYEMALIS Lyngb.
Plate XCV. Fig. 5.

Char. Filaments very fragile. Frustules long. Sides slightly
emarginate, puncta very small. End view elliptico-lanceo-
late, with from two to seven or eight well-marked stria,
which terminate in distinct puncta along the anterior ter-
minal margins of the frustules.

Lyngb. t. 63. ; Ag. Syst. p. 7. ; Consp. Diatom, p. 63. ;
Kiitz. in Linnaea, 1833, p. 72. Fragilaria confervoides
Grev., in Br. Flor. vol. ii. p. 403. ? Harv. Br. Algje,
p. 197. ; Ralfs, in Annals, vol. xii. pi. ii. f. 3.

Fragilaria turgida Ehr., Infus. pi. xv. f. 13.

FRAGILARIA. 415

Hob. In freshwater pools and rivulets, Sussex : Mr. Bor-
rer. Llyn Prefeddyr, near Barmouth : Rev. T. Salwey.
Aberdeen : Dr. Dickie. Stevenston : Rev. D. Lands-
borough. Ballantrae, Ayrshire : Mr. W. Thompson. Dol-
gelly, Tavistock, and Trenteshoe, Devonshire ; Pen-
zance, Cornwall : Mr. Ralfs.

This is a smaller species than Fragilaria pectinalis, differ-
ing from it also in the slightly emarginate sides of the frustules,
the elliptico-lanceolate form of their end view, and the paucity
and decided character of the striae seen on the end surface.

The filaments are so fragile, that the frustules separate on
the slightest touch, so that it is rare to meet with a filament
of any length. In most specimens the frustules are as long
as broad, and some even longer ; but in others, again, they are
two or three times broader than long. The filaments not so
unequal as in the other British species of the genus. When
recent, it is of a dark brownish colour, becoming whitish
brown in drying.

There can be no doubt of the correctness of the reference
to Ehrenberg.

3. FRAGILARIA RHABDOSOMA Ehr.
Plate XCV. Fig. 6.

Char. Filaments much compressed. Frustules usually many
times broader than long ; in the end view lanceolate, and
without strice.

Ehr. Die Infus. p. 204. t. 15. f. 12. Frag, pectinalis
Kiitz., in Linnaea, 1833, p. 73. ? Frag, tenuis Ag., Con-
spect. Diatom, p. 63. ? Ralfs, in 1. c. p. 108. pi. xi. fig. 4.
F. bipunctata, F. angusta, F. scalaris, and F. diopthalma
Ehr., t. xv. F. rhabdosoma Jenner, in Flora of Tun-
bridge Wells, p. 202.

Hob. Common in pools and ditches.

The exceedingly narrow frustules, and the lanceolate form

416 DIATOMACE.fi.

of the end view of these, will distinguish this plant from all
other freshwater species.

It is of a pale brown when recent, becoming in drying of a
greyish hue with a silvery lustre.

73. EUNOTIA Ehr.

Char. Frustules free, striated laterally, with two superficial
grooves running round each, and indicated by lateral
puncta.

This genus differs only from Fragilaria in that the frus-
tules never form filaments, as in that genus.

1. EUNOTIA ARCUS Ehr.
Plate XCVII. Fig. 5.

Char. Frustules elongated, striated. In front view qua-
drangular, with straight sides. In lateral aspect narrow,
curved, constricted towards either extremity.

Eunotia Arcus, Bericht. der Akademie d. Wissensch. zu
Berlin, 1837, p. 45. ; Ehr. Die Infus. t. 21. fig. 22. ;
Eunotia monodon? Ehr. ; Ralfs, in Annals, vol. xv. p. 459.
pi. xiv. fig. 1 ? ; Jenner, in loc. cit. p. 202.

Hab. Cheshunt : A. H. H. Piltdown Common : Mr.
Jenner. Penzance : Mr. Ralfs.

A distinct and not uncommon species.

2. EUNOTIA DIODON Ehr.
Plate XCVII. Fig. 6.

Char. Frustules elongated. In front view quadrangular,
with straight sides. Convex margin of lateral aspect
Indent ate.

Eunotia Diodon, Bericht. der Akad. d. Wissensch. zu Ber-
lin, 1837, p. 45. ; Die Infus. p. 192. t. xxi. fig. 13. ;

MERIDION. 417

Jenner, loc. cit. p. 292. ; Kalfs, in Annals, vol. xv.
p. 460. pi. xiv. fig. 2. ; Bailey Amer. Bacil. pi. ii. f. 29.
Hob. Piltdown Common : Mr. Jenner.
The teeth or processes in this species are obtuse and but
little elevated.

3. EUNOTIA TRIODON Ehr.

Plate XCVII. Fig. 7.
Char. Frustules in lateral view semi-lunar, having three

obtuse teeth on the convex margin.

Eunotia Triodon Bericht. der Akademie d. Wissensch. zu
Berlin, 1837, p. 45.; Die Infus. t. xxi. fig. 24.; Jen-
ner, in Fl. of Tunbridge Wells, p. 202. ; Ralfs, in
Annals, vol. xv. p. 461. pi. xiv. fig. 23 ? ; Bailey, Amer.
Bacil. pi. ii. f. 30.
Hob. Cold bath spring : Mr. Jenner.

A distinct species, noticed hitherto, I believe, only by Mr.
Jenner.

4. EUNOTIA TETRAODON Ehr.
Plate XCVII. Fig. 8.

Char. Frustules in lateral view semilunar, with four obtuse
teeth on the convex margin.

Eunotia Tetraodon Mittheilungen der Berl. Naturforsch.
Freunde (Berl. Staatszeitung, April 1837); Die Infus.
p. 192. t. xxi. fig. 25. ; Ralfs, in Annals, vol. xv. p. 461.
pi. xiv. fig. 4. ; Bailey, 1. c., pi. ii. f. 31.

Hab. Piltdown Common, Sussex, and Weston Bogs near
Southampton : Mr. Jenner.

B. Frustules wedge-shaped.
74. MEEIDION Leiblein.

Char. Frustules cuneate, united so as to form segments of
circles or spirals.

E E

418 DIATOMACE^.

Derivation. From pepis, a portion or particle.

This is a very natural genus, differing from Fragilaria in
the cuneate form of the frustules in the front view, and atte-
nuated outline in the end or lateral aspect, and from Stylaria
in the number of frnstules, which cohere, and which form
more or less considerable portions of circles.

1. MERIDION CIRCULARS Ag.
Plate XCVI. Figs. 1—6.

Char. Frustules very variable in size, broad margin, punc-
tated. Articulating surfaces clavate, strongly striated;
the ends of the strife appearing as puncta along the edges
in the front view.

Meridian circulare Ag., Consp. Diatom, p. 40. ; Kiitz. Sy-
nop. Diatom, in Linntea, 1833, p. 558. f. 37. ; Harv.
Manual, p. 205. Meridian vernale, p. 207. t. 16. f. 2.
Bailey's American Bacillaria, in Amer. Jour. Sci. Jan.
1842, pi. ii. f. 42. Echinella circularis Grev., in Wer-
nerian Society, vol. iv. p. 213. pi. viii. fig. 2., 1822; Scot.
Crypt. Fl. vol. i. t. 35. M. circulare Ralfs, in Annals,
vol. xii. p. 458. pi. xviii. f. 1. ; Jenner, in Flora of Tun-
bridge Wells, p. 206.

Hob. Common throughout Great Britain, in pools, &c.

The frustules of this very beautiful production exhibit all
the variety of sizes which characterise the different threads
of the Fragilarice, and this resulting from the same cause, viz.
the lateral growth of the frustules. In the smaller and nar-
rower frustules the end view is broadly clavate ; in the larger
and deeper frustules it is but slightly so, indeed almost linear.
I have occasionally met with frustules which have been very
perceptibly curved ; this form possibly arising from the
spiral disposition of the lamina in the more perfect spe-
cimens.

Colour yellowish brown, assuming a green tinge in drying.

MERIDION. 419

2. MERIDION CONSTRICTUM Ralfs.
Plate XCVI. Figs. 7, 8, 9.

Char. Articulating surfaces constricted at the broader end,
striated ; the striae forming puncta in the front view.

Meridian constrictum Ralfs, in Annals, vol. xiii. p. 458.
pi. xiii. fig. 2. ; Jenner, in Flora of Tunbridge Wells,
p. 206.

" This is one of the additions to our Flora, for which I
am indebted to Mr. Jenner, whose discoveries have added so
largely to the Sussex Cryptogamia, and who is as indefatigable
in his researches as he is accurate in his observations. Mr.
Jenner finds it rather plentifully in the Cold Bath Spring,
Tunbridge Wells, growing on Fragilaria virescens. I have
received from him both dried and recent specimens. In the
latter I find the frustules solitary or binate, the circles being
entirely broken up before the specimens reached me ; but
Mr. Jenner informs me, that when gathered, they are united
together so as nearly to form a circle. As, however, they
are not arranged on a plane as in Meridian circulare, but
stand nearly erect, somewhat like the staves of a tub which
is broader above than below, when they are dry and fall
down they necessarily separate, and gaps are produced in the
circular outline. In the dried specimens I find some of the
frustules arranged in a circle, which, however, exhibits the
gaps already noticed, whilst others seem to be fasciculated.

" The front view cannot be distinguished from a frustule
of Meridian circulare, with which it agrees in size and form,
and also in having two conspicuous terminal puncta, and a
series along the lateral margins. As in Meridian circulare,
the lateral surfaces have a few distinct, strongly marked
transverse striae ; but they differ from it most remarkably in
the constriction below the apex." — Ralfs.

In the very deep frustules the constriction is almost lost.

E K 2

420 DIATOMACE.E.

Section ii.
Frond stipitate.

A. Frustules wedge-shaped.

75. GOMPHONEMA^.

Char. Frustules cuneate, solitary or geminate, supported on
a simple or branched and attached filiform stipes.

Derivation. From <yop<pos, a wedge, and vrjfta, a thread.

The extremities of the frustules in the front view are
punctated and truncated, but in the lateral aspect rounded
or pointed ; the frustules are for the most part striated late-
rally, the stria; being interrupted by a longitudinal pellucid
line, in the centre of which is a depression often assuming
the appearance of a foramen. The genus bears a close re-
lation to the genera Styllaria and Lichmophora, the former
genus differing only from Gomphonema in the frustules being
invariably sessile, and the latter in having several frustules
associated together at the end of each branch of the stipes,
and forming a fan-like expansion.

The species of the genus Gomphonema are usually found
in freshwater.

a. Frustules in lateral view constricted below the apex, so as
to appear urn-shaped.

1. GOMPHONEMA GEMINATUM Ag.
Plate XCVIII. Fig. 1.

Char. Stipes much branched, tufted. Frustules large, cu-
neate, often geminate, puncta at the end obsolete. Lateral
surfaces urn-shaped, striated. Stria? radiating.

Ag. Syst. p. 12. ; Conspect. Diatom, p. 35.; Grev. Crypt.
Fl. t. 244. f. 2.; Kiitz. Synop. Diatom, in Linnaea, 1833,
p. 569.; Harv. British Algae, p. 207. Gomph. ampul-
laceum Grev., in Hook. Br. Fl. p. 410. G. geminatum
Ralfs, in Annals, vol. xii. p. 460. pi. xviii. fig. 3.

GOMPHONEMA. 421

Hab. On rocks in subalpine streams, Scotland : Dr. Gre-
ville. North of Ireland : Mr. D. Moore. Near Bandon,
co. Cork : Prof. G. J. Allman. On dripping rocks,
near a waterfall at Carnlough, co. Antrim : Mr. W.
Thompson. Rapid streams at base of Cader Idris ;
and in the river above Dolgelly, North Wales: Mr.
Ralfs.

" This plant forms large cushion-like tufts on the rocks in
rapid streams. It is not in the least mucous, but is of a
spongy texture, being composed of densely interwoven
filaments. In a young state its colour is brownish, from the
frustules covering the surface ; but as these fall off it becomes
whitish, and indeed not unlike a tuft of wool. Filaments
repeatedly dichotomous ; frustules much larger than in any of
the following species, simple or binate, linear cuneate, with-
out puncta at the upper end ; portions of the lateral surfaces
are frequently visible along the sides. Lateral surfaces urn-
shaped, broader than the front, with numerous transverse
dotted stria?. There is a central longitudinal pellucid line,
slightly dilated at each end with a larger dilatation in the
centre ; the,latter at first sight may be taken for a perforation,
which it undoubtedly is not : from the central punctum the
stria? are somewhat radiant : the pellucid line does not quite
extend to the upper end."-— Ralfs.

2. GOMPHONEMA TEUNCATUM Ehr.
Plate XCVIII. Fig. 2.

Char. Frustules in front view cuneate, with two evident puncta
at the upper end. Lateral surfaces urn-shaped, striated.

G. truncatum and G. paradoxum Ehr., Abhandl. der
Akademie d. Wissensch. zu Berlin, 1831, p. 88. 1833,
p. 319. G. pohliaforme Kiitzing, in Linna3a, 1833,
p. 569, 570. t. xvi. fig. 50. G. truncatum Ehr., Die
Infus. p. 216. pi. xviii. fig. 1. G. subramosum Kiitz.,
Synops. Diatom, p. 570. fig. 44. G. poliliceforme Ralfs,
in Annals, vol. xii. p. 461. pi. xviii. f. 4. G. capitatum

E E 3

422 DIATOMACEJE.

Ehr., Die Infus. ; Jenner, in Flora of Tunbridge Wells,
p. 206.

Hal. On aquatic plants in pools and ditches, near Hen-
field : Mr. Borrer. Frequent in Sussex : Mr. Jenner.
Cheshunt and neighbourhood : A. H. H. Oswestry :
Rev. T. Salwey. Ilfracombe; Swansea; Dolgelly and
Bangor, North Wales : Mr. Ralfs.

A very distinct little species. The degree of constriction
of the neck varies considerably in different specimens ; and
this circumstance doubtless led to the institution on the part
of Ehrenberg of the Gomphonema capitatum, which is as-
suredly but a state of G. truncatum.

3. GOMPHONEMA ACUMINATUM Ehr.
Plate XCIX. Fig. 1.

Char. Frustules in front view cuneate and truncate. Lateral
surfaces constricted, acuminate, striated.

G. minutum Ag., Conspect. Diatom. 1832, p. 34. ; Grev.
in Hook. Br. Flor. vol. ii. p. 410. Gomph. acuminatum,
Abhandl. der Akademie d. Wissensch. zu Berlin, 1831,
p. 86. ; Bericht. der Akademie d. Wissensch. zu Berlin,
1836, p. 53., 1837, p. 44.; Die Infusor. p. 217. t. xviii.
fig. 4. G. minutum Ralfs, in Annals, vol. xii. p. 462.
pi. xviii. f. 5. ; Jenner, in Flora of Tunbridge Wells,
p. 206.

Hob. Sussex : Mr. Jenner. Cheshunt, &c. : A. H. H.
Barmouth : Rev. T. Salwey. Trengwainton ponds,
near Penzance, and pond on Towednack Moor, near St.
Ives ; Dolgelly : Mr. Ralfs.

The degree of constriction and acumination of the frus-
tules would appear to be subject to very considerable variation.
As the species was published at nearly the same period, by
both Agardh and Ehrenberg, and apparently first by Ehren-
berg, I have retained the name of the latter which is infi-
nitely the more appropriate.

GOMPHONEMA. 423

b. Lateral surfaces not constricted below the apex.

4. GOMPHONEMA CRISTATUM Rolfs.

Plate C. Fig. 1.

Char. Frustules crested, not constricted below the apex, striated

laterally.

Gomphonema cristatum Ralfs, in Annals, vol. xii. p. 463.
pi. xviii. fig. 6. ; Jenner, in loc. cit. p. 206.

Hob. On Conferva glomerata in a stream near Shoreham,
Kent, Dec. 1842. Farnham, Surrey : Mr. Jenner.

The only species with which this beautiful Gomphonema
could be confounded is G. acuminatum, from which it differs
in being altogether a smaller plant, and in the absence of the
constriction below the apex.

For its discovery naturalists are indebted to Mr. Jenner.

5. GOMPHONEMA DICHOTOMUM Kutz.

Plate XCIX. Fig. 2.

Char. Frustules linear, cuneate in front view, with very minute .
terminal puncta. Lateral surfaces lanceolate, faintly
striated.

Kiitz. Synops. Diatom, p. 569. fig. 48. ; Ralfs, in Annals,
vol. xii. p. 463. pi. xviii. fig. 7. Gomph. gracile Ehr.,
Die Infus. p. 217. t. 18. fig. 3.; Pritch. Infus. p. 227.
G. angustum ? Ag., 1831.

Hab. Trengwainton ponds, near Penzance: Mr. Ralfs.

The frustules of this species somewhat resemble those of
Gomphonema Berkeleyi, but they are more elongated, nar-
rower, often nearly linear, and their lateral surface lanceolate,
and not clavate.

6. GOMPHONEMA BERKELEYI Grev.

Plate C. Fig. 2.

Char. Frond forming large mucous masses. Stipes branched,

E E 4

424 DIATOMACE-ffi.

entangled. Frustules short, triangular, with two con-
spicuous puncta at the end. Lateral surfaces obovate or
sub-clavate.

ft Frustules scattered, more firmly attached to the stipes,
which is more evident.

Grev. in Hook. Br. Fl. vol. ii. p. 409. ; Harv. Br. Alg.
p. 207. Gomph.? olivacea Ehr., Die Infus. 218. t. 18.
f. 9. ; Pritch. Infus. p. 228. Exilaria minutissima
Berk., Br. Alg. p. 22. t. 7. f. 1. Miridion vernale Ag.,
Consp. Diatom, p. 556. f. 31. Gomph. geminatum
Kiitz., Alg. Aq. clulc. No. 13. Gomph. Leiblini Ktitz.,
Synop. Diatom, p. 568. fig. 46.

Hab. On stones, &c., in freshwater spring, King's Cliff,
Northamptonshire : Rev. M. J. Berkeley. Henfield, Sus-
sex : Mr. Borrer. Mayfield, Sussex : Mr. Jenner. Yar-
mouth : Mr. Daioson Turner. River Severn, near
Shrewsbury : Mr. Leighton. Cheshunt, Herts, and River
Lea : A. H. H. At the base of Bandon Mountains :
Mr. Andrews. — ft. Duddingston Loch : Dr. Greville.

The stipes in the species in its ordinary state, owing to its
being imbedded in a mucous matrix, is often with difficulty
discernible. The frustules approach rather closely to those
of Gomph. dichotomum; than which, however, they are shorter,
broader, and more decidedly cuneate.

7. GOMPHONEMA MINUTISSIMUM Ag.

Plate C. Fig. 3.

Char. Frustules curved, striated; terminal puncta well
marked. Lateral surfaces clavate, striated.

Kiitz. Syn. Diatom, p. 567. fig. 43. ; Ehr. Die Infus.
p. 219. t. 18. fig. 5.; Pritch. Infus. p. 228. Gomph.
curvatum Kutz., Syn. Diatom, p. 567. f. 51. ; Kiitz.
Aq. dulc. No. 76.

llab. Shrewsbury : Mr. Leighton. Shoreham, Kent :

COCCONEMA. 425

Mr. Jenner. Cheshunt : A. H. H. Near Dublin : Prof.
G. J. Allman. Swansea : Mr. Rolfs.

" This species differs from all the foregoing in its curved
frustules, in having a notch on one only of the lateral margins
and two striae passing down the frustule and connecting the
upper and lower puncta." — Ralfs.

76. PODOSPHENIA.

Char. Frustules wedge-shaped, never constricted. Stipes none,
or very short.

Derivation. From TTOVS, afoot, and a^rjv, a ivedge.

This genus differs from Gomphonema in the absence of a
regular and branched stipes. In their young condition the
frustules are attached in the same manner as those of the
Exilarice.

1. PODOSPHENIA? OCULATUM.
Plate C. Fig. 9.

Char. Frustules large, in front view wedge-shaped ; laterally
ovoid, striated. Stria3 short.

Gomphonema oculatum Kiitzing, in Linnasa, p. 568. f. 45.
G. rotundatum Ehr., xviii. f. 7.

Hab. By the side of a rapid stream, parasitic on Lyngbya
zonata, at Corham, near Bristol: Mr. Thwaites.

A very beautiful species, for an examination of which in a
recent state I am indebted to Mr. Thwaites, its first and
only discoverer in this country.

B. Frustules semi-elliptical.
77. COCCONEMA.

Char. Frustules stipitate, semi-elliptical, tvith a longitudinal
furrow, striated.

426 DIATOMACE-ffl.

Derivation. From KOKKOS, a grain, and vrj^ia, a thread.

The frustules in this genus may be compared to a grain of
wheat in form.

1. COCCONEMA LANCEOLATUM Ehr.

Plate CI. Fig. 1.
Char. Frustules large, semi-lanceolate, straight, obtuse.

Gomphonema lanceolatum Agardh, Conspect. Crit. Diatom.
1831, p. 34. Gomphonema (Paltonophora) lanceolatum
Ktitz., in Linnaea, 1833, p. 38. ; Jenner, in Flora of
Tunbridge Wells. Cocconema lanceolatum Ehr., Die
Infus. p. 224. pi. xix. fig. 6.

Hab. Waterfall at Hill Park, Westerham, and at Shore-
ham, Kent ; Parham, near Pulborough, &c. : Mr. Jenner.
Cheshunt: A. H. H.

This is a very fine and distinct species.

2. COCCONEMA CYMBIFOKME Ehr.
Plate CI. Fig. 2.

Char. Frustules slightly curved, narrow, attenuated, sub-
acute.

Frustulia cymbiformis Kiitz., in Linnaea, 1833, p. 540. t. 15.
fig. 9. Cocconema cymbiforme Ehr., Die Infus. p. 225.
pi. xix. f. 8. ; Jenner, in Fl. of Tunbridge Wells.

Hab. New River reservoir, Cheshunt : A. H. H.

This species might readily be confounded with the previous
one, from which it is to be distinguished by its smaller, nar-
rower, more attenuated and somewhat curved frustules.

3. COCCONEMA CISTULA Ehr.

Plate CI. Fig. 3.
Char. Frustules crescentic, ventricose, obtuse, often in pairs.

CYMBELLA. 427

Cocconema cistula Ehr., Die Infus. p. 224. pi. xix. f. 7. ;
Jenner, in Fl. of Tunbridge Wells. Cymbella copulata
Breb. and Godey. N. geminata ? Turp. (1828).

Hob. Frequent in Sussex : Mr. Jenner. Cheshunt: A.H.H.

The frustules in this species are shorter than in those pre-
viously described, more ventricose and obtuse. In C. lanceo-
latum the frustules are straight, in C. cymbiforme but slightly
curved, while in C. cistula they are considerably so.

4. COCCONEMA VENTRICOSA? Hass.
Plate CI. Fig. 4.

Char. Frustules small, straight, ventricose, obtuse.

Cocconema? gibbum Ehr., Die Infus. p. 225. pi. xix. f. 9.;
Jenner, in Flora of Tunbridge Wells. Cymbella ven-
tricosa Ag. ? Flor. Bot. Zeit. ; Breb. and Godey.

Hob. Cheshunt : A. H. H. Waterfall at Harrison rocks :
Mr. Jenner.

This is the smallest species of the genus which has hitherto
been described. From Cocconema phcenicenteron, with which
it might be confounded, it differs in size and in the frustules
not being curved.

78. CYMBELLA Hass.

Char. Frustules cymbiform, striated, sulcated, not stipitate.

Derivation. The diminutive of cymba, a boat ; in allusion
to the form of the frustules.

This genus differs from Cocconema only in the frustules
not being stipitate as they are in that genus. Although not
stipitate, the frustules frequently are attached in the entire
length of their flat surface to other Algce, often to Clodo-
phora crispata. The Cymbella of Agardh embraces species
belonging to several distinct genera, and not one of those here
described under the name of Cymbella. The following are

428 DIATOMACEJS.

species of the genus Cymbella : JV. amphora Ehr., N. lineolata
Ehr., and N. JVestermanni.

1. CYMBELLA ZEBRA Hass.
Plate C. Fig. 8.

Char. Frustules in side view semi-lanceolate, truncate ; in
front aspect elongated, quadrangular, with straight sides.
Striae distant, strongly marked, double.

Navicula zebra, Abhandl. der Akademie d. Wissensch. zu
Berlin, p. 262. ; Bericht. der Akademie d. Wissensch.
zu Berlin, 1837, p. 53. Eunotia zebra Ehr., Die
Infus. p. 191. pi. xiv. fig. 7. pi. xxi. f. 19.

Hab. Cheshunt : A. H. H. On the moist conglomerate
sandstone cones near Cushendall, co. Antrim : Mr.
Moore.

This fine species approaches rather closely to the following,
from which it differs however in two respects ; in the stria;,
which in Eunotia zebra are less numerous than in E. turgida,
and in the form of the frustule, which in the front view is
not attenuated at the extremities as it is in that species.

2. CYMBELLA TURGIDA Hass.
Plate C. Fig. 7.

Char. Frustules semi-lanceolate , truncate at either extremity
in side view ; in lateral aspect narrower towards either
end than in the centre.

Navicula turgida, Abhandl. der Akademie d. Wissensch.
zu Berlin, 1830. Eunotia turgida, Bericht. der Aka-
demie d. Wissensch. zu Berlin, 1837, p. 45. ; Die Infus.
p. 190. t. xiv. fig. 5.

Hab. Storrington Common : Mr. Jenner.

This species needs only to be contrasted with Cymbella
zebra, from which it differs in the two particulars indicated
in the description of that species, viz. in its finer and closer

NAVICULA. 429

striaB, and in the frustules being attenuated in the front view
towards either extremity.

3. CYMBELLA ? AECUS Hass.
Plate C. Fig. 6.

Char. Frustules smooth. In front view contracted towards
either end; in lateral aspect curved, attenuated, with a
projection in the centre of the concave margin.

Navicula arcus, in Wiegmann's Archiv. fur Naturg. 1836,
p. 243, 244. ; Die Infus. p. 182. t. xxi. fig. 10.

Through this species the genera Cymbella and Navicula
would appear to be united, it agreeing with the first in the
semilunar and curved form of the frustule in its lateral view,
and with the latter in its attenuation in its anterior aspect.

C. Form of frustules various.
79. NAVICULA Bory.

Char. Frustules straight. In front view usually somewhat
attenuated towards either end, extremities generally trun-
cate ; in lateral aspect boat-shaped, extremities often
acute.

Derivation. From navicula, a little boat.

This genus, as limited to those species, which the above
definition is intended to include, would appear to be an ex-
ceedingly natural one.

a. Frustules without transverse strice.

1. NAVICULA PHCENICENTERON Ehr.
Plate CII. Fig. 9.

Char. Frustules elongated, smooth, large. In front view
attenuated towards either end; in lateral aspect extre-
mities lanceolate.

430 DIATOMACE^.

Navicula phcenicenteron Ehr., Die Infus. p. 175. t. xiii.
fig. 1. ft.

Hab. Cheshunt : A. H. H. — Var. 8. Gardener Street :
Mr. Jenncr.

It is possible that the variety ft of Ehrenberg, which is that
here described under the name of N. phcenicenteron, is really
distinct. The frustule is not transversely striated, but several
longitudinal lines may frequently be noticed running along
the centre of each.

2. NAVICULA PALEA Hass.
Plate CII. Fig. 10.

Char. Frustules small, smooth. In front view attenuated,
with truncate extremities ; in side aspect lanceolate.

Navicula gracilis Ehr., Die Infus. p. 176. t. xiii. fig. 2.
Frustulia gracilis Jenner, in Flora of Tunbridge Wells,
p. 204. Cymbella avenacea Breb. et Godey.

Hab. Cheshunt : A. H. H. In the great bog near Forest
Row ; bogs at Fisher's Castle, &c. : Mr. Jenner.

This species resembles N. phoznicenteron in miniature.

3. NAVICULA AMPHISB^NA Bory.
Plate CII. Fig. 5.

Char. Frustules elongated. In front view quadrangular,
with straight sides ; in lateral aspect oval, prolonged at
each end into a blunt process.

Navicula amphisbana Bory, Encycl. Meth. 1824. Navi-
cula amphisbcena Turpin, Diction, des Sc. Nat. 1828.
N. ventricosa, Abhandl. der Akademie d. Wissensch. zu
Berlin, 1830, p. 67. N. amphisbcena, Abhandl. &c.
1833 (1832), p. 254. Frustulia cuspidata Kiitz., Lin-
nrca, 1833, p. 549. t, xiv. fig. 26. N. amphisbana, Die
Infus. p. 178. t. xiii. f. 7. Cymbella appendiculata
Godey et Breb.

NAVICULA. 431

Hob. Cheshunt : A. H. H. Aberdeen : Dr. Dickie.
A very well marked species.

4. NAVICULA PLATYSTOMA Ehr.
Plate CII. Fig. 6.

Char. Frustules elongated, quadrangular, with straight sides,

rostrated at each end.
Hob. Cheshunt: A.H.H.
Die Infus. p. 178. t. xiii. fig. 8.

A distinct and not uncommon species.

b. Frustules striated.

5. NAVICULA NODOSA Ehr.

Plate CII. Fig. 7.

Char. Frustules small, in side view thrice undulated, ros-
trated at each extremity.

Die Infus. t. xiii. fig. 9. Frustulia nodosa ? Jenner, in
Fl. of Tunbridge Wells, p. 204.

Hab. On Ashdown Forest, near Forest Row, between
Gardener Street and Hailsham, &c. : Mr. Jenner.

Mr. Jenner remarks that his specimens agree with Ehren-
berg's description and figures in every respect save that the
frustules were striated. It is probable that Ehrenberg
overlooked the striae, and that these are always present.

6. NAVICULA IK&QUALIS Ehr.
Plate CII. Fig. 13.

Char. Frustules in front view attenuated, towards each end
truncate ; in side aspect unequal.

Navicula incequalis, Bericht. der Akademie d. Wissensch.
zu Berlin, 1836, p. 53. ; Die Infus. p. 184. t. xiii. f. 18.

432 DIATOMACE^E.

Hab. Gardener Street : Mr. Jenner.

Through this and the following species the genus Navicula
seems to pass into that of Cymbella, in which genus indeed
the striated Navicula would not be very improperly placed.

7.. NAVICULA GIBBA Ehr.
Plate CII. Fig. 4.

Char. Frustules in lateral view straight, narrow, inflated; near
the centre gibbous.

Navicula gibba, N. unciata, Abhandl. der Akademie d.

Wissensch. zu Berlin, 1830, p. 64, 65. 68. 1831, p. 80.

Frustulia incrassata Kiitzing, Linnaea, 1833, p. 545.

t. xiii. fig. 17. Navicula gibba, Die Infus. p. 184. t. xiii.

f. 19. ; Jenner, in Fl. of Tunbridge Wells, p. 204.
Hab. Cheshunt : A. H. H. Ashdown Forest : Jack's

Wood Spring ; Chiltington Common, near Pulborough,

&C. : Mr. Jenner.

8. NAVICULA LANCEOLATA Ehr.

Plate CII. Fig. 14.
Char. Frustules lanceolate, extremities subacute.

Frustulia lanceolata Kiitz., in Linnaea, 1833, p. 14. t. xiii.

f. 13. Navicula lanceolata Ehr., Die Infus. p. 185.

t. xiii. fig. 21.
Hab. Sussex : Mr. Jenner.

A well-marked little species.

80. EXILARIA Grev.

Char. Frustules elongated, at first attached by a sessile and
undivided stipes, subsequently free, radiated, single, or bi-
nate. Junction surfaces frequently striated.
Derivation. From exilio, to issue forth ; in allusion to the
radiate disposition of the frustules.

EXILARIA. 433

This genus bears a slight resemblance to Gomphonema, the
frustules being attached in the young state of the species;
they are not, however, triangular, as in the genus Gom-
phonema.

1. EXILARIA CAPITATA.
Plate XCVII. Fig. 1.

Char. Frustules large. In front view truncate at the ends ;
in side view dilated at both extremities into an obtusely
pointed head; striated.

Ehr. Die Infus. p. 211. pi. xxi. fig. 28.

This fine and beautiful species I found growing in im-
mense quantity in some ditches running parallel to the Barge
river near Cheshunt marshes. A few frustules of it have
also, I believe, been found by Mr. Ralfs. The frustules in
the front view are not to be distinguished from those of
Exilaria ulna; the side view of E. capitata is, however, so
distinct, that it would be impossible to confound it with that
species.

2. EXILAEIA ULNA.

Plate XCVII. Fig. 2.

Char. Frustules large in the fully developed state. In front
view slightly dilated at the extremities, and truncate ; in
lateral aspect striated, extremities pointed.

Leuwenhoek's Philosophical Transactions, 1703 (1702),
fig. 8. L. K. Bacillaria ulna Nitzsch, Beitrage zur
Infusorienkunde, 1817, p. 99. t. 5. Bacillaria commu-
nis Bory, in Diet. Class. 1822. Frustulia obtusa and
F. ulna Agardh, Consp. Crit. Diatom. Echinella fasci-
culata ft truncata Greville, 1823 ; Scot. Crypt. Fl. 1.
t. xvi. Exilaria fasciculata Greville, 1827 ; Scot.
Crypt. Fl. v. f. 291 b. E. truncata Ktitz., in Linnasa,
1833, p. 560. Frustulia Ulna Harv., in Manual, p. 204.
r F

434 DIATOMACE^J.

Synedra Ulna Ehr., Infus. p. 211. pi. xvii. fig. 1. ;
E. Ulna Jenner, in Flora of Tunbridge Wells, p. 204.
Hob. Common in ponds and ditches throughout Britain.

An exceedingly distinct species, not likely to be con-
founded with any other. The extremities of the frustules
would appear to undergo the same change as has been ob-
served in those of Diatoma elongatum, and to become
somewhat dilated.

3. EXILARIA FASCICULATA Kutz.

Plate XCVII. Fig. 3.

Char. Frustules small. In front view alternated at either
end ; in side view extremities acute.

Exilaria Vaucheri<B, E. fasciculata, in part, Kiitz., in
Linnaea, 1833, p. 560, 561. t. xv. p. 38. 40. Synedra
fasciculata Ehr., Infus. p. 212. t. xvii. fig. 2. Exilaria
truncata Harv., in Manual, p. 204 . Diatoma truncatum
Grev., in Hook. Br. Fl. p. 407.

Hab. Common in ditches, &c.

This is a very distinct little species: the frustules are often
in pairs, and owing to these being frequently but imperfectly
separated from each other, a curved or fan-shaped lamina is
produced.

4. EXILARIA LUNARIS.
Plate XCVII. Fig. 4.

Char. Frustules curved, small, slender, converging at the
extremities.

Synedra lunaris Ehr., Die Infus. p. 212. pi. xvii. fig. 4.
Exilaria lunaria Jenner, in Flora of Tunbridge Wells,

A very distinct and pretty little species.

NITZSCIIIA. 435

81. GYROSIGMA Hass.

Char. Frustules straight in front view ; curved in the form of
the letter S in lateral aspect ; longitudinally striated, with
a central depression.

Derivation. From yvpos, a curve, and (rvy/j,a, the letter S ;
in allusion to the form of the frustules.

1. GYROSIGMA HIPPOCAMPA Hass.
Plate GIL Fig. 11.

Char. Frustules in front view attenuated towards each extre-
mity ; in side aspect lanceolate, curved, longitudinally
striated.

Nav. hippocampus Ehr., Die Infus. p. 180. t. xiii. f. 11.;
Frustulia hippocampus Jenner, in Fl. of Tunbridge
Wells, p 204.

Hob. Cheshunt : A. H. H. Olford and Shoreham, Kent :
Mr. Jenner.

In the same genus with this species should be placed the
Navicula sigma, N. scalprum, and N. curvula of Ehrenberg.*

82. NITZSCHIA Hass.

Char. Frustules curved in front view in the form of the letter
S; in lateral aspect straight, transversely striated, and with-
out a longitudinal furrow and central depression.
Derivation. Named in memory of M. Nitzsch.

The single species upon which this genus is founded
accords with Exilaria in all its characters, save in the seg-
moidal curvatures of the frustules.

1. NITZSCHIA ELONGATA Hass.

Plate CII. Fig. 12.
Char. Frustules linear, lengthened, with truncate extremities in

* The Sigmatella of Kutzing, the construction of which term is some-
what objectionable, is synonymous with Gyrosigma.

F F 2

436

front view ; straight, attenuated at either end in lateral
aspect.

Bacillaria sigmoidea Nitzsch, Beitrage z. Infusorienkunde,
1817 (1816), p. 104. Cymbella sigmoidea Agardh,
Consp. Crit. Diatom. 1830, p. 11. Frustulia Nitzschii
Kiitz., Linruea, 1833, p. 554. t. xiv. fig. 33. Navicula
sigmoidea Ehr., Die Infus. p. 182. t. xiii. f. 15. t. xxi.
f. 11.

A well-marked species, which I conceive to be generically
estranged from Gyrosigma hippocampa by the difference in
the curvature of the frustule, the arrangement of the stria?,
and the absence of the longitudinal furrow and central de-
pression.

83. SPHINCTOCYSTIS Hass.

Char. Frustules contracted in the centre; longitudinal furrow

and central depression absent ?
Derivation. From afyisyicros, constricted, and KV<TTIS, a cell.

1. SPHINCTOCYSTIS LIBKILIS Hass.
Plate CII. Fig. 3.

Char. Frustules transversely striated, elongated. In front view
quadrangular, with straight sides and truncate extremities ;
in lateral aspect constricted in the centre with obtuse ends.

Navicula librilis Abhandl. d. Akadcmie d. Wissensch. zu
Berlin, 1831, p. 81. 1833, p. 267. note. Frustulia
quinquepunctata Kiitzing, Linnaea, 1833, p. 554. t. xiv.
f. 28. ; Die Infus. p. 185. t. xiii. f. 21. Frustulia li-
brilis Jenner, in Fl. of Tunbridge Wells, p. 204.

Hab. Cheshunt : A. H. H. Aberdeen : Dr. Dickie. War-
burton, Lewes, &c. : Mr. Jenner.

A very curious species, which, on account of the central
constriction and absence of the longitudinal furrow and cen-
tral depression, I have ventured to make the type of a dis-
tinct genus.

FRUSTULIA. 437

84. AULACOCYSTIS Hass.
Char. Frustules produced, longitudinally sulcated.
Derivation. From avkag, a groove, and Kvarts, a cell.

1. AULACOCYSTIS PELLUCIDA Hass.
Plate GIL Fig. 8.

Char. Frustules elongated, narrow, attenuated at each extre-
mity.

Navicula? pellucida, Die Infus. p. 176. t. xiii. fig. 3.
Frustulia pellucida Kutz., in Linnaea, 1833, p. 543.
t. xiii. fig. 11.; Jenner, in Fl. of Tunbridge Wells,
p. 204.

Hob. Ashdown Forest, and at Shoreham, Kent ; between
Tunbridge Wells and the High Rocks : Mr. Jenner.

There can be no doubt of the propriety of separating this
species from the genus Navicula of Ehrenberg.

85. FRUSTULIA Kutz.

Char. Frustules elongated, quadrangular, with two longitudinal
grooves and two central depressions.

Derivation. J?rom frustufam, a small fragment.

I must confess that I do not exactly understand the struc-
ture of the single species which I propose to retain in the
genus Frustulia. It is possible that to this genus should be
referred those species of Navicula which have striated frus-
tules ; and, if not to this genus, possibly those species should
be regarded as Cymbellce.

1. FRUSTULIA ? VIRIDIS Kutz.
Plate CII. Fig. 2.

Char. Frustules large, elongated. In front view quadrangu-
lar, with straight sides and truncate extremities ; laterally
slightly inflated in the centre, with rounded ends.
F F 3

438 DIATOMACEJS.

Frustulia viridis Kiitzing, Linnaea, 1833, p. 551. Navicula
viridis Ehr., Die Infus. p. 182. t. xiii. f. 16. t. xxi.
fig. 12. Frustulia viridis Jenner, in Fl. of Tunbridge
Wells, p. 203. Nav. biceps ? Bory, Encyc. Meth. 1 1824.

Hob. Frequent in Sussex : Mr. Jenner. Cheshunt :
A. H. H. Aberdeen : Dr. Dickie. Ireland : Mr. Moore.

This is one of the finest and most beautiful of all the
DiatomacecB. In young specimens the frustules are not at all
or scarcely inflated in the centre.

86. SURIRELLA Turp.

Char. Frustules large, solitary, quadrangular; angles pro-
duced, striated.

Derivation. Named in honour of Dr. Suriray.

This seems to be a well-marked genus. To it should be
referred, in addition to the two species described below,
Navicula? splendida, N. ? undulata, N. ? constricta, which would
stand thus : Surirella splendida, S. constricta, and S. undulata.
The two latter species differ from all the others in the trans-
verse striaj being in single and not double series, that is, they
pass entirely across the frustule. This genus seems to have
been indicated by Ehrenberg.

1. SURIRELLA BISERIATA Breb.
Plate CIL Fig. 1.

Cliar. Frustules in front view quadrangular, about three
times as long as broad, with straight sides and truncate ex-
tremities ; in lateral aspect oval, with pointed ends.

Navicula? bifrons Ehr., Die Infus. p. 186. t. xiv. fig. 2.
Surirella biseriata Jenner, in Fl. of Tunbridge Wells.

Hob. Ashdown Forest, Piltdown Common, Broadwater
Forest, and Warbleton : Mr. Jenner.

ENCYONEMA. 439

2. SURIRELLA JENNERI Hass.
Plate CII. Fig. 15.

Char. Frustules in front view obtuse at each extremity, and
with strice in double series ; end view quadrangular, each
angle being prolonged into a thin plate.

Surirella bifrons Jenner, loc. cit. p. 204.
Hob. Warbleton : Mr. Jenner.

A very distinct and beautiful production, having no re-
lation with the N. bifrons of Ehrenberg.

87. ENCYONEMA Kiitz.

Char. Frustules cymbiform, enclosed within a membrane.
Derivation. From sryicvos, full, and vrjfta, a thread.

1. ENCYONEMA PROSTRATUM Kiitz.
Plate C. Fig. 10.

Char. Frustules striated, straight, gibbous, small, enclosed
within a transparent membranous tube.

Encyonema prostratum Kiitz., Die Kreselschaligen, &c.
p. 82. t. 25. f. 7. Encyonema paradoxum Kiitz., Synops.
Diatom. Monema prostratum Berk., Glean, of Br.
Algae. Schizonema ? prostratum Grev., in Hook. Br. FL,
p. 414. ; Harv. in Manual, p. 214. Encyonema pros-
tratum Jenner, in Fl. of Tunbridge Wells, p. 206.

Hab. On the boards of a sluice forming a thin, brown
mucous stratum : Rev. J. M. Berkeley. On the boards
of a sluice on Cheshunt Marshes : A. H. H. Bramble-
tye, near Forest Row, and in the stream which parts
Sussex and Kent, between Bodiam and Sandhurst.

A very singular and beautiful production, coming near to
Schizonema.

T F 4

440

SUPPLEMENT.

ZYGNEMA INSIGNE Hass.
Plate GUI. Figs. 1, 2.

Char. Filaments of considerable size. Cells four or Jive
times as long as broad, inverted. Spires three, lax, in-
distinct. Sporangia oval, acute, producing considerable
inflation of the cells in which they are placed.

Hab. Ponds at Wadhurst, near Tunbridge Wells, and
Iden, near Rye : Mr. Jenner.

This fine species is rendered particularly interesting from
the circumstance of its being the only Zygnema with three
spires having inverted cells, all other species thus constructed
which have hitherto been discovered possessing, with but one
exception, in which there are two threads, only a single
spire.

The filaments are about equal in size to those of Zygnema
rivulare, from which it is at once distinguished by its inverted
cells.

The credit of the discovery of this species is entirely due to
Mr. Jenner.

LYNGBYA FUSCO-PURPUREA Hass.
Plate VIII. Figs. 1, 2.

Char. Filaments of considerable size, forming a brownish
green or purple stratum, glossy. Endochrome at first
homogeneous, subsequently granular. Granules./??^ about
Jive in each cell.

COCCOCHLORIS. 441

^

Grev. Alg. Brit. p. 177. ; Hook. Br. Fl. vol. ii. p. 316. ;
Wyatt, Alg. Danm. No. 167. Conf. fusco-purpurea
Dillw. t, 92. ; E. Bot. t. 255. Conf. atro-purpurea
Dillw. t. 103. ; E. Bot. t. 2085. Bangia atro-purpurea
Harv. p. 172.

Hob. Grand Canal, near Dublin : W. H. Harvey.

Between this production and Lyngbya zonata there is a
great structural resemblance, and assuredly the two species
do not differ generically from each other.

The interesting discovery of this being a freshwater pro-
duction was made by Mr. Harvey, who states that the locality
in which he gathered it had no communication with the sea.

COCCOCHLOEIS CYSTIFERA HttSS.

Plate CIII. Fig. 3.

Cliar. Granules rather large, mostly oval, contained in mucous
cysts, each cyst being occupied with either one or two, but
sometimes, four granules.

Hob. Near Bristol : Mr. Thwaites.

This and the two following species are particularly inter-
esting, from the fact of their exhibiting a cysted structure,
whereby a close relation is manifested in these species to
Hcematococcus, and which structure moreover it is probable
does in reality belong to all the species of the genus Coccochloris,
but which escapes detection from the exceeding delicacy of
the organisation of many of the species.

COCCOCHLORIS VARIABILIS Hass.
Plate CIII. Fig. 4.

Char. Granules in the dried condition not having any regular
form, rather small. Cysts somewhat large, containing
one, two, or four granules, mostly spherical.

Hab. On thatch, Northiam : Mr. Jenner.

442 SUPPLEMENT.

It is only in the exterior and more consistent portions of
the frond that the cysts are clearly visible ; they are usually
spherical, but occasionally elongated and pointed at each end,
the contained granules being likewise elongated, and small,
almost abortive.

COCCOCHLOBIS OBSCURA HdSS.

Plate CIII. Fig. 5.

Char. Granules small and circular. Cysts also small.
Hal. Limestone rocks, co. Antrim : Mr. Moore.

The granules and cysts in this species are much smaller
than in Coccochloris cystifera, and not unfrequently a little
difficulty is perceived in detecting them.

" The Observations which have been made in these latter Times by the
help of the Microscope since we had the Use and Improvement of it,
discover a vast Difference between Natural and Artificial Things. What-
ever is Natural, beheld through that, appears exquisitely form'd and
adorn'd with all imaginable Elegancy and Beauty. There are such in-
imitable Glidings in the smallest Seeds of Plants, but especially in the
Parts of Animals, in the Head or Eye, of a small Fly ; such Accuracy,
Order, and Symmetry in the Frame of the utmost minute Creatures, a
Louse, for Example, or a Mite, as no Man were able to conceive without
seeing of them. Whereas the most curious Works of Art, the sharpest
and finest Needle, doth appear as a blunt rough Bar of Iron, coming from
the Furnace, or the Forge. The most accurate Engravings, or Emboss-
ments, seem such rude, bungling, and deformed Work, as if they had
been done with a Mattock, or Trowel ; so vast a difference is there be-
twixt the Skill of Nature, and the Rudeness and Imperfection of Art.
I might add, that the Works of Nature, the better Lights and Glasses
you use, the more clearer and exactly forin'd they appear, whereas the
Effects of humane Art, the more curiously they are view'd and exarnin'd,
the more of Deformity they discover." — Ray.

443

CONCLUSION.

I HAVE at length brought to a conclusion a work which
for a considerable period has occupied much of my time and
many of my thoughts. The feelings which have attended its
progress have been various : frequently, as on the discovery
of new species or facts, or the elucidation of some difficult
point, those of pleasure and satisfaction have prevailed ; occa-
sionally the opposite ones of doubt, and even despair, have
been predominant, as when I could not satisfactorily see my
way through difficulties ; these feelings, however, poignant as
they were while they lasted, were, I am happy to say, but of
short duration. Next day the task was usually resumed, and
all the doubt and perplexities vanished before renewed ex-
amination.

Those who follow after me in the investigation of this
department of natural science, still so rich in the discoveries
which it yields to deserving perseverance, while they will to
an extent scarcely inferior participate in the feelings of satis-
faction and delight which I have expressed, will, it is hoped,
share less those of an opposite character, now that the way
is opened out, and that a clearer view of the subject may be
obtained.

It was my intention to have made this History of the
British Freshwater Algce answer more closely to the title of
a history than in its present form it does, and that it should
have contained a chapter devoted to a historical consideration
of the subject; this, although a difficult undertaking, would
have been a most grateful one, for it would have afforded an
opportunity of mentioning in the terms of eulogy which they

444 CONCLUSION.

deserve the names of all those who have made the Freshwater
Alga the object of their study. I had intended also to have
entered upon the consideration of the subject of classification,
and to have remarked on those which have hitherto been pro-
posed. I have been prevented from fulfilling these intentions
by the fact that this work has already greatly exceeded the
limits originally proposed for it. Should it be destined, how-
ever, to reach a second edition, chapters devoted to the con-
sideration of these two questions might, by the adoption of a
smaller type, be inserted with advantage. So much for the
omissions from the work. I would now refer to a super-
fluity, and beg the Reader's indulgence for what I fear,
without explanation, might be deemed an unnecessary in-
trusion on his notice, the attachment of the writer's name
either to each new species or to those which for the first time
have been referred to other genera. This was done under the
impression that the practice was usual and customary.

That much still remains to be effected ere our knowledge
of the Freshwater A lya shall be in any thing like a complete
state is evident from the number of species which for the
first time are introduced in this work. So numerous are these,
and so closely do many of them approach each other, that
there are some, I fear, and especially such as have not made
the Algce their study, and who therefore are scarcely in a
position to declare what amount of difference is of specific
value, who will be ready to assert, that the species have been
multiplied on insufficient grounds. Let such pause ere they
advance such an injurious assertion, which, like all asser-
tions, it is an easy matter to make, but more difficult to sub-
stantiate ; let them first bestow upon those species the care,
labour, and anxiety of their founder, and then their opinion
will be rendered valuable, and injustice be inflicted on no
party.

That superficial observers should arrive at the conclusion
that nearly allied species are states of one and the same pro-
duction is not so surprising, when we consider that the cha-
racters which distinguish species amongst the Alga are fre-
quently not very obvious or prominent, and since even men

CONCLUSION. 445

of acknowledged skill and powers of observation have even
fallen into the error of asserting that a number of distinct
species are conditions of one and the same plant. Thus
M. G. Thuret, whose papers on the locomotive organs of the
spores of the Algce are the most interesting and important of
any which have ever appeared on the Algce, has committed
this mistake in reference to the Vaucherice, declaring that all
the species are states of one and the same production, and
comprising them all under the name of Vaucheria Ungeri: for
a refutation of this position, see the figures of the species of
this genus contained in the present work. Other observers,
again, even go further than this, not allowing the Vaucherice
to rank as species at all, but stating that they are merely
stages in the growth of mosses. Statements of this trans-
formation of Algce into mosses, &c., are wholly without found-
ation, and wholly undeserving of credit.

The end is drawing near. How strongly are we mortals the
creatures of habit and association ! with what reluctance do
we quit a place, a companion, or a pursuit with which we
have been long connected, and it may be not altogether
agreeably so ! The prisoner of Chillon felt regret at quitting
the prison of which for so many years he had been the soli-
tary inhabitant : each of us can call to mind the pain which
we have experienced in leaving a companion with whom we
have been long associated, even though that companion may
not have been really esteemed by us; and I must confess that
I cannot banish some feeling of regret at the conclusion of
this undertaking, which has for so long a time interwoven
itself with my thoughts, notwithstanding that there are several
considerations which render the completion of the task a sub-
ject of congratulation.

Although in a few days I shall cease to be occupied with
this work, the interest with which the subject of which it
treats has inspired me will not have ceased. In the fact
that I have devoted so much time to its consideration there
is no regret : I am still willing to devote more to it ; and I
shall gladly at all times avail myself of the correspondence of
all or any who may take an interest in the Algce, and will

446 CONCLUSION.

favour me with their communications, and assist them in the
determination of the productions of the localities in which
they reside.

Apart from the interest attached to the examination of the
individual species, there is a source 6f pleasure in the addi-
tional interest which is imparted to our rambles : each spot
that we pass is rendered doubly interesting — is almost hal-
lowed — by the recollection of its being the place in which we
first became acquainted with some rare or new production,
which at the time awakened our curiosity, stimulated inquiry,
and elicited admiration.

I cannot do better than conclude these few remarks in the
appropriate language of the eloquent Vaucher : —

" I fear not to propose similar occupations to all men who
have a taste for observation, and who love the beauties of
nature. If their position and their fortune permits them
some leisure, they cannot employ it more happily. When-
ever natural history has a fixed purpose, and that some
object of study is made choice of, the labours to which we
submit ourselves become more agreeable, and at the same
time more useful. Those botanists who shall make dis-
coveries in this science, which presents so vast a field, not
only will experience a real pleasure, but moreover they will
preserve the remembrance of it. Each time that they ap-
proach the place which has been the theatre of them, it will
recal to them the objects with which it is associated. For
myself I avow that I see not without interest the place
where I perceived for the first time the floating seeds of my
ectospermes, nor that where I obtained the network of the
hydrodictyon in its first development. The species of Con-
ferva even which I have long visited, and the fructification
of which I have ascertained but with difficulty, inspire in me
a kind of attachment which I feel more than I am able to
express. I love to see spring up and develope themselves
near me those species with which I am, so to speak, in ac-
quaintance. I experience some pain if I know that any
one of them come to*e destroyed. This acquaintance
which I have acquired seems to me a kind of empire which

CONCLUSION. 447

1 desire still to extend : I say to myself sometimes, when
shall I quit the environs of Geneva ? When shall I behold
the borders of the sea ? the Mediterranean, the Ocean ?
that wandering Conferva of which Linnaeus speaks, which
floats upon the sea as our Conjugate float upon the waters ?
I do not believe that elsewhere a happier kind of life is to
be found, nor that Society furnishes to men more real pleasures
than Nature affords to those who love her."

INDEX.

A.

ACHNANTHBS Bory

exilis ? Kiitz.

minutissima Kiitz.
Agardhia Gray
ANABAINA Bory

constricta Hass.

jftos-aquee Bory

impalpebralis ? Bory

licheniformis ? Bory

? spiralis Thomp. -
ANACYSTIS Menegh.

furfuracea Menegh.
Anhaltia SchwaM
AFIIANIZOMENON Morren

incurvum Morren
APLONEMA Hass.
Apona Adans -
ARTHRODESMUS Ehr. -

acutus Ehr.

convergent Ehr.

Incus Hass.

octocornis Ehr.

quadricaudatus Ehr.
ARTHRONEMA Hass.

cirrhosum Hass. -
AUJ>ACOCYSTIS Hass. -

pellucida Hass.

B.

BACILLARIA Ehr.
communis Bory

Page

Page

cuneata Ehr.

- 408

- 401

clongata Ehr.

- ih.

- 402

floccosa Ehr.

- 405

- 401

paradoxa Graelin -

- 410

- 160

seriata Ehr. -

- 405

- 281

sigmoidea Nitzsch

- 436

- 283

tabellaris Ehr.

- 405

- 282

ulna Nitzsch

- 433

- 283

vulgaris Ehr.

- 407

- 282

BANGIA Lyngb.

- 298

• 278

calophylla Carm. -

- ib.

- 319

fusco purpurea Lyng.

- 440

- ft.

manaillosa Lyng.

- 228

- 124

BATRACHOSPERMEJE

- 101

- 279

BATRACHOSPERMUM Roth.

- ib.

- 280.

alpestre Shut.

- Ill

- 213

atrum Harv.

- 114

- 68

bombusinum Bory

- 103

- 256

confusum Hass.

- 105

- 394

fasciculatum Vauch.

- 125

- 357

glomeratum D. C.

- 120

- ib.

helmintosHm Bory -

- 105

- ib.

hispidum

- 65

- 392

intricatum Vauch.

- 127

- 238

ludibundum

- 106

- ib.

moniliforme Ag. -

- 108

- 437

myosurus Ducluz.

- 302

- ib.

plumosum Vauch. -

- 121

proliferum Hass. -

- 112

pidcherrimum Hass.

- 109

rubrum Hass.

- 113

stagnale Hass.

- 107

- 410

turfosum Bory

- 110

• 433

vagum Ag.

- 109

G «

450

INDEX.

Binatella Breb. Sf Godcy

muricata Breb.

tricornis Breb.
BOTRYDINA Breb.

vulgaris Breb.
BOTETDIUM Wall.

granulatum Grev.

BULBOCIUETE Ag.

setigera Ag.

C.

Cadmus

CALLITHAMNIE^:
CALLITHAMNION
Daviesii -
CALOTHRICE^E -

I A l.< > I 1 1 K I \ Ag.

atroviridis Hare. -
Berkeleyana Carm.
distorta Ag.
interrupta Carm. -
lucifuga Carm.
mirabilis Ag.
nivea Ag. -
rufescena Carm. -
Ccramium

caespitosum Roth. -

CH^ITOPHOEA Schrank -

dilatata Hass.

elegans Ag.

endivicefolia Ag. -

longcEva Carm.

pisiformis Ag.

tubercnlosa Hook. -
Chantransia D. C.

fluviatilis D. C. -

torulosa D. C.
CHARACE^J
CHABA Ag.

aspera

batrachosperma -

flexilis Ag.

gracilis Ag.

Page

Page

• 351

Hedwigii

- 97

• ib.

hispida

- 99

• 352

latifolia - - ,

- ib.

• 319

nidifica Ag.

- 95

• 320

pulcheUa -

- 97

• 305

translucens Ag.

- 94

• ib.

vulgaris

- 96

. 209

^harospermum Link

- 118

• 210

Uhlorococcum Grev. -

- 323

murorum Grev. -

- ib.

vulgare Grev.

- 333

3hoaspis Gray

- 135

3hthonoplastus Kiitz. -

- 260

- 193

CLADOPHORE-EJ -

- 213

- 75

DLADOPHOBA Kiitz.

28. 213

- ib.

ceruginosa -

- 224

- ib.

albida

- ib.

- 239

arcta

- ib.

- ib.

crispata -

- 216

- 243

diffusa

- 224

- 241

Jlexuosa

- ib.

- 240

glaucescens

- ib.

- 230

glomerata

- 213

- 259

gracilis

- 224

- 243

Hutchinsia

- ib.

- 241

Icetcvirens -

- ib.

- 242

lanosa

- ib.

- 57

nuda

- ib.

- ib.

pellucida -

- ib.

- 116

rectangularis

- tJ.

. 124

refracta -

- ib.

- 125

riparia

• ib.

- 127

ruptstris -

- ib.

- 125

nni-infix

- ib.

- 128

CLOSTBEIUM Nitzsch. 32.

338. 367

- ib.

acerosum Ehr.

- 374

- 126

Brebissoni Menegh.

- 377

- 71

caudatum Corda -

- 373

- 72

Cornu Ehr.

- 372

- 71

costatum Corda

- ib.

- 77

cylindrus Ehr.

- 368

- 96

Diana Ehr.

- 371

- 98

Digitus Ehr.

- 376

- 107

Ehrenbergii Menegh.

- 369

- 95

granulatum Breb.

- 378

- 96

lineatum Ehr.

- 372

INDEX.

451

^

Lunida Ehr.

margaritaceum Ehr.

moniliferum

multistriatum Ehr.

rostratuin Ehr.

ruficeps Ehr.

setaceum Ehr.

spirale Corda

striolatum Ehr.

tenue Kiitz.

Trabecula Ehr.

turgidum Ehr.
COCCOCHLORIS Spreng.

cystifera Hass.

depressa Menegh. -

Grevillei Hass.

hyalina Menegh.

Mooreana Hass.

muscicola Menegh.

obscura Hass.
protuberant Menegh.

rivularis Hass.

variabilis Hass.
COCCONEMA Ehr.

cistula Ehr.

cymbiforme Ehr. -

gibbum Ehr.

lanceolatum Ehr. -

ventricosum Hass. -
Codium
CoLEOCH-ETE Breb.

scutata Breb.
Conferva Ag.

aegagropila Linn. -
alpina Ag.
amphibia -

atrovirens Dillw. -
bicolor E. B.
bombycina Ag.
Brownii Ag.
cterulescens E.B.
chalybea Roth.
corvmbifera E. B.
crispata E.B.
dichotoma

Page

Page

• 374

dissiliens Dillw. -

- 32

• 376

dissiliens Ag.

- 202

• 370

dissiliens E. B.

- 346

• 375

distorta Dillw.

- 240

• 373

ericetorum Roth. -

- 216

371

flavescens Harv. -

- ib.

373

flexuosa -

- 65

372

flocculosa Dillw. -

- 405

371

fluviatilis Roth.

- 73

373

fracta Roth.

- 216

375

frigida

- 52

371

fugacissima Dillw.

- 223

311

furcata

- 57

441

fusco purpurea Dillw.

- 440

316

gelatinosa -

- 106

318

genuflexa Dillw. -

- 173

315

glomerata- - 31.

35. 213

316

hispida Thore

- '65

314

jugalis Mutter

- 141

442

lineata Dillw.

- 399

312

lubrica

- 121

317

lucens Dillw.

- 221

441

mirabilis Dillw.

- 237

425

mucosa Mert.

- 347

426

multicapsularis Dillw.

- 305

ib.

muralis Dillw.

- 221

427

inutabilis Roth.

- 120

426

myochrous Dillw. -

- 237

427

nana Dillw.

- 124

47

nigricans Roth,

- 216

217

nitida Dillw.

- 141

ib.

nivea Dittw.

- 241

nodosa var. Lam. -

- 71

213

ocellata Dillw.

- 231

174

ochracea Dillw.

- 400

57

ovata Hophirk

- 427

114

pectinalis Dillw. -

- 413

228

pisum Flor. Dan. -

- 290

221

porticalis Miiller -

- 145

208

protensa Dillw. -

- 123

213

pulvinata Brownii MSS.

- 213

177

punctalis Dillw. -

- 223

75

purpurascens Carm.

- 175

ib.

reticulata -

- 225

216

rivularis -

- 39

51

stritica

- 143

G G 2

452

INDEX.

toru\os&E.B. -
torulosa var. Roth
tumidula -

vaginata E. B, -
verrucosa Drap. •
vesicata Dillw, •

CONJUGATED

Conjugata Vauck,

inflata Vouch. -
longata Vouch. -
porticalis Vouch. -
princeps Vouch. -

COSMARIUM Corda -
aculcatura Menegh.
angulosum Ehr. •
binalc Menegh. -
Botrytis Menegh. -
crenatum Ralfs -
Cucumis Corda -
CucurUta Breb. -
cylindricum Kali's -
deltoides Corda -
dentiferura Corda -
Didelta Corda -
gemmatum Breb. -
lugenarium Corda-
margaritiferum -
orbiculatum Ralfs -
oblongum Menegh.
ornatum Ralfs -
ovale Haifa -

Pelta Menegh. -
quadratum Kail's -
stellinum Corda -
truncatum Corda -
verrucosum Menegh.

Cruciagenia - -

CTIJNDROCYSTIS Breb.
Brebissoni Menegh.

CYMBEIXA Hats. -

appendiculata Breb.
avenacea Breb, $• Godey
? Arcus Haas. -
copulata Breb. ~
Ilopkirkii Moore -
reniformis Ag. -

Page

Page

71

sigmoidea Ag. - »

436

ib.

turgida Hass. • •

428

207

ventricosa Ag ? ./^,\

427

260

zebra I I:ws.

428

74

CYSTOSPERME^J .

180

54

129

D.

151

ib.

Dcmatium Link

232

145

turfaceum

ib.

141

DESMIDE^E - - 30.

338

361

DESMIDIUM Ag. - - 34.

341

360

aculeatum Ehr. -

353

363

apiculosum Ehr. -

351

384

Illinium Ehr.

355

363

bimucronatum Hass.

347

365

Borreri Ralfs

343

366

compressum Ralfs

348

367

cylindricum Grev. -

342

365

hcxaceros Ehr.

354

363

mucosum Breb.

346

362

orbiculare Ehr. -

349

381

quadrangulatum Ralfs

345

382

Swartzii Ag.

344

381

vertebratum Breb. Sf Go-

362

dey - 348.

345

364

DIATOMACE^B ,»

395

380

DlATOMA Ag. -..

406

364

/3 en in <• him

408

366

elongatum Ag.

ib.

381

fenestratum Lyngb.

406

367

flocculosum Ralfs

405

385

flocculosura Ag. •

407

ib.

sulphurascens Ag.

408

380

tenue Ag.

ib.

31

norraale Kiitz.

ib.

361

ft cuneatum

ib.

ib.

virescens Hass. - -

409

427

vulgare Bory •

407

430

Didymopriura Kiitz. •

342

ib.

Borreri Jen. • «•

343

429

Grevillei Kiitz.

342

ib.

DBAPARNALDIA Bory -

118

427

condensata Hass. -

122

362

elongata Hass.

123

INDEX.

453

Page

Pago

glomerate.

117. 120

Rota Ehr.

- 385

hypnosa Dory

- 121

spinosum Ralfs

- 384

mutabilis Bory

• 120

verrucosum Ehr. -

- 379

nana Hass.

- 124

EUNOTIA Ehr.

- 416

plumosa Ag.

- 121

Arcus Ehr.

- ib.

repetita Hass.

- 122

Diodon Ehr.

- ib.

sparsa Hass.

- 124

Monodon Rolfs

- ib.

tennis Ag.

• 123

Tetraodon Ehr.

- ib.

Triodon Ehr.

- 428

turgidum Ehr.

- ib.

E.

zebra Ehr.

- ib.

Eutomia Harv.

- 380

Echinella Grev.

- 418

oblonga Harv.

- ib.

circularis Grev. -

- ib.

rotata Harv.

- 385

fascicula Grev.

- 433

Exilaria Grev.

- 432

£ truncata

- ib.

capitata

- 433

oblongata Grev. -

- 380

circularis Grev. -

- 418

rotata Grev.

- 385

fasciculata Grev. -

- 433

ECTOSPBRMA Vauch. -

- 47

fasciculata Kiitz.

- 434

clavata Vauch.

35.60

lunaris

- ib.

geminata Vauch. -

- 55

minutissima Grev.

- 244

hamata Vauch.

- 53

truncata Kiitz.

- 433

ovoidea Vauch.

- 57

Ulna

- ib.

racemosa Vauch. -

- 56

sessilis Vauch.

- 55

F.

terrestris Vauch. -

- 53

ENCYONEMA Kiitz.

- 439

FRAGILARIA -

33. 412

prostratum KiitZ. -

- ib.

angusta Ehr.

- 415

paradoxum Kiitz.

- ib.

bipunctata Ehr. -

- ib.

ENTEROMORPHA Link. -

- 303

cbnfervoides Grev.

- 4M

intestinalis Link. -

- ib.

diopthalma Ehr. -

- 415

lacustris Hass.

- ib.

grandis Ehr. -

- 413

EUASTRTJM Ehr.

- 379

hyemalis Lyngb. -

- 414

affine Ralfs

- 382

pectinalis Lyngb. -

- 412

ansatum Ehr.

- 381

pectinalis Ehr.

- 409

binale Ralfs

- 384

rhabdosoma Ehr. -

- 415

circulare Hass.

- 383

scalaris Ehr.

- 415

Didelta Ralfs

- 381

turgida Ehr.

- 414

gemmatum Ralfs -

- 382

/3 undulata

- 413

integerrimum Ehr.

- 366

virescens Ralfs

- 409

margaritiferum Ehr.

- 362

Frustulia Kiitz.

- 437

oblongum Ralfs

- 380

cymbiformis Kiitz.

- 426

pecten Ehr.

- ib.

gibba Ehr.

- 432

Pelta Ralfs

- ib.

gracilis Jenner

- 430

pentangulare Corda

- 389

Hippocampus Jenner

- 435

rostratum Ralfs

- 383

lanceolata Kiitz. -

- 432

G G 3

454

INDEX.

librilis Jenner

Page
- 436

H.

nodosa Jenner

- 431

Page

Nitzschii Kiitz.

- 436

H.EMATOCOCCU8 Ag. -

- 321

pellucida Kutz.

- 437

ceruginosus Hass. •

- 333

sigmoidea Jenner -

- 436

Allmani Hass.

- 322

Ulna Ag.

- 433

alpestris Hass.

- 328

? viridis Ehr.

- 437

arenarius Hass.

- 330

binalis Hass.

- 331

cryptophilus Hass.

- 324

G.

frustulosus Harv. -

- 330

furfuraceus Hass. -

- 331

Gallionella Ehr.

granosus Harv.

- 327

aurichalcea Ehr. -

- 399

Hookerianus Berk, and Hass. 325

ferruginea Ehr. -

- 400

insignis Hass.

• 324

varians Ehr.

- 399

lividus Hass.

- 332

GL.SOPRUM Berk.

- 346

microsporus Hass.

- 334

dissiliens Berk.

- ib.

minutissimus Hass.

- ib.

mucosum Berk.

- 347

murorum Hass.

- 323

Globulina Link.

- 160

rupestris Hass.

- 326

GOMPHONEMA Ag.

- 420

sanguineus Ag.

- 329

acuminatum Ehr.

. 422

theriacus Hass.

- 333

ampullaceum Grev.

- 420

vulgaris Hass.

- ib.

angustum Ag.

- 423

HASSALLIA Berk.

- 231

Berkeleyi Grev. -

- ib.

? byssoidea Hass.

- 233

capitatum Ehr.

- 421

compacta Hass.

- 232

cristatum Unit's

- 423

limbata Hass.

- 234

curvatum Kiitz. -

• 424

ocellata Berk.

- 231

dichotomum Kiitz. -

- 423

turfosa I lass.

- 232

gemination Ag.

- 420

Helierella Turp.

- 389

gracile Ehr.

- 423

Boryana Turp.

- ib.

lanceolatum Ag. -

- 426

Herapelia Meyen

- 187

Leiblini Kutz.

- 424

mirabilis Meyen -

- 188

minutum Ag.

- 422

polymorpha Meyen

- 190

minutissimum Ag.

- 424

Heterocarpella Bory •

- 363

oculatum Kiitz.

• 425

binalis Turp.

- 384

pohliseforme Kutz.

- 421

Botrytis Bory

- 363

subramosum Kiitz.

- ib.

didelta Turp.

- 381

truncatum Ehr.

- ib.

polymorpha Kiitz.

- ib.

Gongoseira Kiitz.

- 305

tetracarpa Bory -

- 388

clavata Kiitz.

- ib.

ursinella Kiitz.

- 363

Gongycladon Link

- 68

HYDRODICTYONE^E

- 225

GONIOCYSTIS Hass.

- 349

HYDRODICTYON Roth. -

- ib.

GTROSIGMA Hass.

- 435

pentagonum Vouch.

- ib.

Hippocampa Hass.

- ib.

utriculatum Roth. -

- ib.

Gonium Ehr.

HOLOCTSTIS Hass.

- 386

tranquillum

- 300

oscitans Hass.

- 387

INDEX.

455

HYDRURUS Ag.
Ducluzelii Ag.

Isogonium Kiitz.
capillare Kiitz.

L.

Leda Bory

capucina Bory
LEMANE^J -
LEMANIA Bory

corallina Bory

fluviatilis Ag.

incurvata Bory

torvlosa Ag.
Lichen

pubescens E. B. -

LlTHONEMA HaSS.

calcareum Hass. -

crustaceum Hass. -
Lucernaria Rouss.
Lunulina Turp.

vulgaris Turp.

monilifera Bory -
LYNGBYA Ag.

copulata Hass.

floccosa Hass.

fusco-purpurea Hass.

muralis Ag.

prolifica Grev.

punctalis Hass.

Thompsoni Hass. -

vermicuLaris Hass.

virescens Hass.

zonata Hass.

M.

MELOSEIBA Ag.

arenosa Moore

Page

Page

- 302

uurichalcea Kiitz. -

- 399

- ib.

lineata Ag.

- ib.

ochracea Ralfs

- 340

Thompsoni Harv.

- 222

varians Ag.

- 399

MERIDION Leiblein

- 417

- 195

circulare Ag.

- 418

- ib.

constrictum Ralfs -

- 419

vernale Ag.

- 424

MEBISMOPEDIA Meyen

- 299

punctata Meyen

- ib.

MESOCARPUS Hass.

22. 166

- 178

angustus Hass.

- 170

- ib.

depressus Hass.

- 168

- 68

intricatus Hass.

- 167

35. 68

notabilis Hass.

132. 170

- 72

nummuloides Hass.

- 169

- ib.

ovalis Hass.

- ib.

- 71

parvulus Hass.

- ib.

- ib.

recurvus Hass.

- 168

- 228

scalaris Hass.

- 166

- ib.

MlCRASTERIAS Ehr.

- 385

- 265

angulosa Ehr.

- 391

- ib.

Boryana Ehr.

- 389

- 266

Boryi Kiitz.

- ib.

- 160

duplex Kiitz.

- ib.

- 370

elliptica Ehr. See

Plate

- ib.

XCII. Fig. 2.

- ib.

heptactis Ehr. See

Plate

33. 219

XCII. Fig. 9.

- 222

hexactis Ehr. See

Plate

- 223

XCII. Fig. 5.

- 440

melitensis Ralfs -

- 386

- 221

? oscitans Ralfs -

- 387

- 224

radiata Hass.

- 386

- 223

rota Menegh.

- 385

- 222

rotata Ag.

- ib.

- 224

Selanaea Kiitz.

- 389

- 222

simplex Kiitz.

- ib.

- 220

Staurastrum Kiitz.

- 354

tetracera Kiitz.

- ib.

tetras Ehr.

- 388

tricera Kiitz.

- 354

tricyclia Ehr.

- 391

33. 396

MICBOCOLEUS Desmar.

- 260

- 398

anguiformis Harv.

- 261

G G 4

456

JNDEX.

gracilis Hass.

repens Harv.
Microcystis Menegh.

granosa Menegh.

livida Menegh.

mellea? Menegh.

rupestris Menegh.
Microhaloa Kiitz.

rupestris
Microspora Hass.

crispata Hass.

glomerata Hass.
Monema Berk.

prostratum
MONOCYSTE^J

MOUGEOTIA Ag.

genuflexa Ag.

glutinosa Hass.

major Hass.

parvula Hass.

stritica
MONORMIA Berk.

intricata Berk.
Myriodactylon Desv.
Miilleria Schrank

Lunula Schrank

N.

NlTELLA Ag. -

flexilis Ag.
gracilis Ag.
nidifica Ag.
translucens Ag.
NAVICULA Bory

amphisbcena Ehr. -
arcus Ehr.
biceps ? Bory
? bifrons Ehr.
geminata? Turp. -
f gibba Ehr.
gracilis Ehr.
Hippocampus Ehr.
incequalis Ehr.
lanceolata Ehr.

Page

Page

- 261

librilis Ehr.

- 436

- 260

nodosa Ehr.

- 431

- 321

Palea Hass.

- 430

- 328

? pellucida Ehr. -

- 437

- 332

phcenicenteron Ehr.

- 429

- 323

platystoma Ehr.

- 431

- 326

iigmoidea Ehr.

- 436

- ib.

turgida Ehr.

- 428

•» ib.

viridis Ehr.

- 437

- 213

zebra Ehr.

- 428

- 216

NITZSCHIA Hass.

- 435

- 213

elongata Hass.

- ib.

- 439

Nodularia /.////••.

- 68

- ib.

NOSTOC Vouch.

- 286

- 212

cceruleum Lyngb. -

• 293

22. 171

commune Vauch. -

- 288

- 178

crassisporum Menegh.

- 294

- 177

foliaceum Ag.

- 289

- 172

intricatum Menegh.

- 286

- 169

macrosporum f Menegh.

- 293

- 148

microscopicum Carm.

- 292

- 285

muscorum Ag.

- ib.

- 286

pruiniforme Ag. -

- 291

- 124

spharicum Vauch.

- 289

- 369

variegatum -Moore

- 287

- ib.

verrncosum Vauch.

- 291

vesicarium D. C. -

- 290

NOSTOCHINE^J -

- 267

- 94

0.

- 95

- 96

Odontella Ehr.

- 95

undentata

- 348

- 94

(Edogonium Link.

- 193

- 429

Opharium Losano

- 389

- 430

OSCILLATOR!^

- 224

- 429

OSCILLATOEIA Vauch. - 34.

39. 245

- 437

cerugescens Drum.

- 249

- 438

? alata Carm.

- 238

- 427

amphibia Ag.

- 251

- 432

autumnalis Ag.

- ib.

- 430

Bangii

- 259

- 435

Carmichaeli Hass.

- 256

- 431

chthoplastes /3 Harv.

- 260

- 432

cinerea Hass.

- 247

INDEX.

457

Page

Page

contexta Carm.

- 256

botryoides Lyngb. - - 318

corium Ag.

- 252

botryoides Grev. - - ib.

corticola Carm. MS.

- 257

cruenta Ag. - - 308

cyanea Ag.

- 248

cryptophylla Carm. • 324

decorticans

- 257

depressa Berk. - - 316

decorticans ft

- ib.

frustulosa Carm. - - 330

Dickiei Hass.

- 258

furfuracea Berk. - -331

elegans Ag.

- 251

granosa Berk. - - 328

Friesii Ag.

- 258

Grevillei Berk. - - 318

limbata Grev.

- 234

Grevillei ay - - ib.

limosa Ag.

- 246

grumosa Carm. - - 311

limosa Hook.

- 248

hyalina Lyngb. - - 315

limosa Grev.

- 255

hyalina ft musicola Harv. « 314

lucifuga Harv.

- 259

livida Carm. - - 332

membranacea Ag.

- 250

montana.4g-. - - 309

mucosa Hass.

- 247

Mooreana Harv. - - 316

muscorum

- 252

muscicola var. Harv. - 314

nigra Vauch.

- 255

myosurus Lyngb. - - 403

nigra Carm.

- 257

nivalis Hook. - - 335

ochracea Grev.

- 40

protuberans Ag. - - 312

pulchclla Hass.

- 250

Ralfsii Harv. - - 310

repens Ag.

- 260

rivularis Carm. - -317

rubiginosa Carm. -

- 254

rupestris Lyngb. - - 326

rupestris Ag.

- ib.

? sanguinea Ag. - - 329

spadicea Carm.

- 255

Palmogloea Kiitz. - - 312

spiralis Carm.

- 277

protuberans Kiitz. - ib.

splendida Grev.

- 251

PEDIASTRUM Meyen - - 387

subfusca Vauch. -

- 253

angulosum Hass. - - 391

tenax Carm. MS. -

- 254

biscidiatum Meyen - 389

tennis Ag.

- 248

Boryanum Meneg. - ib.

tenuissima Ag.

- 259

constrictum Hass. - - 391

terebriformis Ag. -

- 257

crebriforme Hass. - - 392

thermalis Hass.

- 250

duplex Meyen - - 389

turfosa Carm.

- 253

elegans Hass. - - ib.

violacea Johnst. -

- 254

ellipticum Hass. See Plate

virescens Hass.

- 250

XCII. Fig. 2.

viridis Johnst.

- 248

keptactis Hass. See Plate

OURACOCCUS .Ha**.

- 322

XCH. Fig. 9.

hexactis Hass. See Plate

XCII. Fig. 5.

P.

lunare Hass. See Plate

XCII. Fig. 3.

PALMELLE.E

- 306

Napoleonis Ralfs - - 389

PALMEI-LA Lyngb.

- ib.

Napoleonis Hass. See Plate

seruginosa Carm. -

- 333

XCII Figs. 10, 11.

alpicola Lyngb.

- 309

quadrangum Corda - 389

458

INDEX.

llutulu Hass. See Plate

XCn. Fig. 7.

simplex Hass. - -

simplex Meyen - -

tetras Ralfs -

tricyclium Hass. - -

PBNTASTERIAS Ehr. - -

arachnis Hass. - -

Jenneri Hass. - -

margaritaceum Ehr. -

PETALONEMA Berk. - -

Phorinidium Kutz. -

Pleurococcus Menegh.

glomeratus ? Menegh.
murorum Menegh.
theruialis Menegh.
vulgaris Menegh. -

PODOSPHENIA Ehr. -
? oculatum Hass. -

Polycoma Pa/*. -

Polysperma Vouch.

fluviatilis Vauch. -

Prasiola Xitfz.

Prolifera Vauch.

Borissii Le Clerc -
Boscii Le Clerc -
Candollii Le Clerc
composita Le Clerc
Cuvieri Le Clerc -
rivularis Le Clerc
Rothii Le Clerc -
Vaucherii Le Clerc

PROTOCOCCUS Ag. -
iiiriilia Ag. -

R.

RAPHIDIA Carm.

ungulosa Hass. -

viridis Hass. -

natans Carm. -

RIVULARIA Roth.

angulosa Roth. -

botryoides Ag. -
crustaceum Carm.

Page

388
389
388
390
355

ib.
356

ib.
237
238
246
328

ib.
323
331
333
425

ti.

64

73
295
191
202
207
208
196
198
197
208
200
335

- 264

- ib.

- 265

- 264

- 262

- 264

- 263

- 266

15.

Page

- 265

- 263

- 262

- 126

- 262

calcareum E. B. •
granulifera Carm.
pisum Ag.
tuberculosa E. B.
RIVULAREJE «

S.

Salinacis Bory - - 135

SCENEDESMUS Meyen - - 392

acutus Meyen - - 393

bijugatus Kutz. - - ib.

bilunatus Kutz. - - ib.

dimorphus Kiitz. - - ib.

•y ecornis - - 392

Leibleini Kiitz. - - 393

minor Kiitz. - - ib.

octalternus Kiitz. - - 394

obtusus Menegh. - - ib.

pectinatus Meyen - - 393

quadralternus Kiitz. - 394

trijugatus Kiitz. - - 393
triseriatus. See Plate

XCII. Fig. 15.

quadricaudatus Breb. - 392

Schistocbilum Rolfs - - 348

excavatum - - 349

unidentatum - - 348

Schizomena Ag. - - 439

? prostratum Harv. - ib.

SCYTONEME^E - - 227

SCYTONEMA Ag. - - 235

aerugineo-cincreum Kiitz. - 234

Bangii - - 259

byssoideum Ag. - - 233

cirrhosum Carm. - - 238

compactuin Ag. - - 232

contextum Carm. - - 237
Dillwynii Harv. Sf Ralfs 242

Hibernicum Hass. - - 236

minutum Ag. • - 230

myochrous Ag. - - 237

ocellatum Lyngb. - - 231

panniforme Carm. - 229

turfosum E. B. - - 232

INDEX.

459

SIPHONED
Sirogonium Kiitz.

striticum -
Sirosyphon Kiitz,
SOROSPORA Hass.

montcna Hass.

Ralfsii Hass.

virescens Hass.

.* grumosa Hass. -
Sphserocarpus Hass.
Sphaeroplea Berk. .. -

crispa Berk.

punctalis Berk.
SPH^ROPHORA Hass. -
SPH-SEROZYGA Ag.

Jacobi Ag.
SPH.2ER07.OSMA Corda

elegans Corda

excavatum -
SPIRILLUM Ehr.

Jenneri Hass.

minutissimum Hass.

rupestre Hass.

Thompsoni Hass. -
SPHYNCTOCYSTIS Hass.

librilis Hass.
Spirogyra Link
SURIRELLA Turp.

bifrons Ehr.

biseriata Turp.

Jenneri Hass.
STAURASTRUM

arachne Rolfs

aculeatum Menegh.

? bifidum Ralfs

convergens Menegh.

dilatatum Ehr

gracile Ralfs

Incus Menegh.

Jenneri Rolfs

margaritaceum

muricatum Menegh.

mucronatum Ralfs

? octocornis Ralfs •

orbiculare Menegh.
• paradoxum Meyen

Page

Page

47

paradoxum Ehr. -

- 354

143

? tetracerum Ralfs

- ib.

ib.

tricorne Menegh. -

- 352

231

Stauridium Corda

- 388

309

bicuspidatum Corda

- ib.

ib.

crux melitensis

- ib.

310

STAUROCARPUS

- 22. 176

ib.

ccerulescens Hass. -

- 177

ib.

capucinus Hass. -

- ib.

166

glutinosus Hass.

- ib.

219

gracilis Hass.

• 179

221

gracillimus Hass. -

- ib.

223

quadratus Hass.

- 178

396

virescens Hass.

- ib.

283

Staurospermum Kiitz. -

- 176

284

Stellulina Link

- 160

348

Sigmatella Kiitz.

- 435

ib.

STIGONEMEJE

- 227

349

STIGONEMA Ag.

- ib.

277

atrovirens Ag.

- ib.

ib.

interruption Hass.

- 229

278

mamillosum Ag.

- 228

277

minutum Hass.

- 230

278

panniforme Harv.

- 229

436

Stygeoclonium Kiitz. -

- 119

ib.

Stylaria

- 420

135

Symphosyphon Kiitz. -

- 234

438

Symploea Kiitz.

- 258

ib.

Synedra Ehr. -

- 433

ib.

capitata Ehr.

- ib.

439

Ulna Ehr.

- ib.

353

lunaris Ehr.

- 434

355

353

355

T.

357

353

TABELLARIA Shut

- 404

352

fenestrata -

- 405

357

flocculosa -

- 404

356

TETMEMORUS Ralfs

- 377

ib.

Brebissoni Ralfs -

- ib.

351

granulatus Ralfs -

- 378

350

TETRACYCLUS Ralfs

- 402

358

lacustris Ralfs

- 403

349

TETRASPORA Link

- 300

354

flava Hass.

- 301

460

INDEX.

gelatinosa Desv. -

Page

- 301

insignia Hass.

Page

- 163

lubrica Ag.

- 300

Rdlfsii Hass.

- 165

THORE^E -

- 64

stugnalis Hass.

- 163

THOBEA Bory -

- ib.

Lehmanni

- 65

ramosissima

• ib.

Tircsias Bory -

- 193

U.

TOLYPOTHBIX Kiitz.

• 240

Berkeleyana

- 241

ULOTHRICE-S!

- 119.219

Dillwynii Hass.

- 242

UIX>THBIX Kiitz.

- 219

distorta Kiitz.

- 240

zonata

- ib.

nivea Hass.

• 241

ULVACE^E

- 30. 225

punctata Hass.

• 240

ULVA Linn.

- 296

rufescens Hass.

- 242

hi mil is Hass.

- 299

Trcmella

- 288

bullosa Roth.

- 297

cruenta E. B.

- 308

calophylla Spreng.

- 298

fluviatilis Dillw. -

- 291

crispa Light.

- 297

granulata E. B. -

- 305

furfuracea Home.

- ib.

nostoc E. B.

- 288

incrassata E. B. -

- 125

tcrrestris E. B. -

- ib.

montana -

- 309

TBENTQPOHLIA Ag.

- 75

protuberans Smith

- 312

pulchella Ag.

- ib.

pisiformis Hudson

- 20

TBICHODESMIUM Montague

- 271

pruiniformis

- 291

Ehrenbergii Mtgne.

- ib.

Uredo

Hindsii Mtgne.

- 275

nivalis Bauer

- 335

Trichogonus -

- 68

Ursinella Turp.

- 363

TBICHOBMUS Allm.

- 284

margaritifera Turp.

- ib.

incurvus Allm.

- 285

TBIGONOCYSTIS Hass.

- 349

? aculeata Hass.

- 353

bifidus Hass.

- 355

V.

gracilis Hass.

- 352

hexaceros Hass.

- ib.

Vaginaria Gray

- 260

mucronata Hass.

- 350

vulgaris -

- ib.

muricata Hass.

- 351

VAUCHEBIA D. C. - 15.

26. 33. 47

var. rugosa

- ib.

aversa Hass.

- 54

orbicularis Hass. -

- 349

clavata -

- 16. 59

TYNDABIDEA Bory -

22. 160

dichotoma Ag.

- 51

anomala Halls

- 161

Dillwynii Ag.

- 52

bicornis Hass.

- 162

geminata Vauch. -

- 55

conspicua Hass.

- 164

hamata Hass.

- 53

cruciata Hass.

- 160

ornithocephala Ag.

- 54

decussata -

- 165

ovoidea Vauch.

- 57

lutescens Hass.

- 162

polysperma Hnss. -

- 59

immersa Hass.

- 164

racemosa Vauch. -

- 56

INDEX.

461

Page

repens Hass. '»

- 52

X.

aessilis Vauch. »

- 55

Page

terrestris Vauch. •

- 53

XANTHIDHJM Ehr.

- 358

Ungeri Thuret -

- CO

aculeatum Ehr.

- 360

Vertebraria Rouss.

• 68

/3 deltoideum Corda

- 351

VESICULIFERA - 22. 25.

28 195

fasciculatum Ehr. -

- 359

cequalis Hass.

- 205

furcatum Ehr.

- ib.

affinis Hass.

• 206

/3 polygonum Ehr.

- 360

ttlatii Hass. »

. 208

polygonwm Hass. -

- ib.

aurea Hass.

- 202

bombycina Hass. -

- 208

Borissii Hass.

- 201

Z.

Boscii Hass.

- 207

Candollii Hass.

- 208

Zoocarpa Nees of Esenb.

- 103

capillaris Hass.

- 195

Zoospores

- 11

cardiaca -

- 203

ZYGNEMA Ag. - 5. to

10. 22. 28.

ciliata Hass.

- 202

130. 135

compressa Hass. -

- 204

cestivum Hass.

- 146

concatenata Hass. -

- 201

abbreviation Hass.

- 154

condensata Hass. -

- 196

affine Hass.

- 155

crassa Hass.

- ib.

alternatum Hass. -

- 139

crispa Hass.

- 203

angidare Hass.

- ib.

Cuvieri Hass.

- 198

belle Hass.

- 142

dissiliens Hass.

- 202

catenaforme Hass.

- 147

dubia Hass.

- 206

commune Hass.

- 148

elegans Hass.

- 207

curvatum Ag.

- 143

faciata Hass.

- 204

deciminum ^.g.

- 144

jftavescens Hass. -

- 206

diductum Hass.

- 158

hexagona Hass.

- ib.

dubium Hass.

- 159

incequalis Hass.

- 205

flavescens Hass.

- 149

lacustris Hass.

- 198

gracile Hass.

- 148

Landsboroughi Hass.

- 197

Grevilleanum Hass.

- 149

Miilleri Hass.

- 207

Hassallii Jenner -

- 156

• ii-iifn Hass.

- 201

incequale Hass.

- 150

paludosa Hass.

- 199

inflatum Hass.

- 151

princeps Hass.

- 195

insigne Hass.

- 440

prolongata Hass. -

- 198

intermedium Hass.

- 157

pulchella Hass.

- 199

interruptum Hass.

- 140

Ralfsii Hass.

- ib.

Jenneri Hass.

- 158

Rothii Hass.

- 208

longatum Hass.

- 151

sphcerica Hass.

- 204

malformatum Hass.

- 147

Vaucherii Hass. -

- 200

malleolum Hass.

- 155

ventricosa Hass. -

- ib.

maximum Hass. -

- 139

virescens Hass.

- ib.

minimum Hass.

- 159

mirabile Hass.

- 132. 156

462

INDEX.

neglectum Hass.
nitidum Hass. -
orbiculare Hass.
parvum Hass.
pellucidum Hass.
quadratum Hass.
1 1 a in in a in Ag.
reversion Hass.
rivulare Hass.

Page

- 142
29. 141

- 138

- 149

- 143

- 157

- 145

- 154

- 144

Page

rostratum Hass. - - 152

serratum Hass. - - 140

subventricosum Hass. - 150

tenuissimum Hass. - - 152

various Hass. - - 145

vesicatum Hass. - - 158

Woodsii Hass. - - 153

ZYGOGONIUM Kiitz. - - 173

ericetorum KUtz. - - 174

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