I have only once met with this,
must’bc of the ¡jrcceding species.
I f a condition of any, it
b. Sporangia formed in every cell.
34. Zygnema mirabile Hass.
P late X X X V . Figs. 1, 2, 3.
Char. Filaments equal to those o f Z. commune in diameter.
Cells about six times as long as broad. Sporangia oval, at
f r s t much elongated, and fn a ll y producing a slight infa
tio n o f the cells.
Z. mirabile Hassall, MSS.
Ilab. Cheshunt and its vic inity: A. II. IT. 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 ho is convinced
th a t the cells are united, but th a t 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
th a t in this species all the cells contain sporangia.
** Extremities o f cells inverted.
a. Spires two.
35. Zygnema H assallii Jenner.
Plate X X X V I . Figs. 4, 5. *
Char. Filaments o f nearly the same diameter as those o f
Zygnema Grevilleanum. Cells f v e or six times as long
as broad. Spires two, laxly disposed, and crossing each
other. Sporangia oval, large, and producing a considerable
infation o f the cells in which they are lodyed.
Zygnema Hassallii Jenner, in Flora of Tunbridge Wells,
p. 182.
Hah. Cheshunt and Netting H ill: A . H. II. S andhurst;
near the rock at Washington ; and at Hcllingly : Mr.
Jenner.
Mr. Jen n er 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 conjugated
cells is so different.
b. Spire .nngle.
36. Zygnema quadratum' / / ass.
Plate X X X V I I . Figs. 1, 2.
Char. Filaments o f rather less diameter than those o f T^yg-
nema Hassallii. Cells usually seven or eight times as long
as broad. Sporangia oval, large, and much elongated,
contained within quadrangular enlargements o f the cells.
Tubes o f communication prominent.
Zygnema quadratum Hassall, in Annals o f Nat. Hist,
v o l . X. p . 4 1 .
Hah. High Beech; Fpping F o re s t; Cheshunt; and other
places: A. II. II. Pond at Ramslye : Mr. Jenner.
This is one of the most distinct as well as curious of the
non-conjugating Zygnemata. I t is by no means uncommon.
37. Zygnema in t e rm ed ium Hass.
Plate X X X V I I . Fig. 3.
Char. Filaments o f rather less diameter than those o f Z. qua