Zygnema quininum. Cells usually twice as long as hroad.
Sporangia oval, and not usually producing any inflation o f
the receiving cell.
llah. Cheshunt and its vicinity : A. H. H . A t Hawk-
h u rs t; in a pond in a cottage garden between Broom-
hill and Spcldhurst; 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 Magazine
of Natural History,’ vol. x. p. 35.) passed over hy me
as a variety of Z . quininum, from which I am now perfectly
satisfied tha t 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; bu t it frequently
happens tha t several adjoining cells of a filament for
some reason or other do not unite, ^;lthough the remaining
ones in tha t filament d o ; in which case, those which have not
yoked themselves swell up, assuming a moniliform appearance,
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 frustrated.
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.” — M S .
14. Zygnema testivum Hass.
Plate X X V I I I . Figs. 3, 4.
Char. Filaments o f less diameter than those o f Z . varians.
Cells usually about fo u r times as long as broad, but sometimes
much longer, and occasionally shorter. Sporangia
oval, not producing any inflation o f the cell in which they
are formed.
Zygnema cBstivum Hassall, in Ann. Nat. Hist. vol. xi. p. 433.
Hab. Cheshunt: A. H. H. W a d h u rs t; and Bury, near
Aru n d e l: Mr. Jenner.
^ This species is distinguished from the former by the smaller
size of the filaments, greater length o fth e cells, and peculiar
zigzag disposition of the spiral th re ad ; it is not, however, a
very strongly marked species.
15. Zygnema malfokmatum Hass.
Plate X X X . Figs. 1, 2.
Char. Filaments nearly equal in diameter to those o f Z . c b s -
tivum. Cells about twice as long as broad, in each o f
which a single spiral thread performs usually two revolutions.
Sporangia acutely oval, lying obliquely in the cells,
which are considerably distorted fo r 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.
I t is a very pretty species, and not uncommon. The form
of the cells is very distinct from that of Z . commune.
16. Zygnema catena;fo em e Hass.
Plate X X X . Figs. 3, 4.
Char, Filaments a little fine r than those o f Z . malformatum.
Cells usually rather more than twice as long as hroad.
Sporangia largely inflating the cells in which they are contained,
acutely oval,
Z . catenceforme Hassall, in Ann. of Nat. Hist. vol. x. p. 39.
Hab. Cheshunt: A. H. H. Between Yapton and Wal-
berton near A ru n d e l: Mr. Jenner.
I t is scarcely possible to distinguish the filaments of this
•h 2