dratum. Cells abotit five times as long as broad. Sporangia
oval, and producing a slight inflation o f the cells.
Zygnema intermedium Hassall, in Annals of Nat. Hist,
vol. X. p. 41.
llah. High B eech; Cheshunt: A. II. II. Pond at Ramslye;
Avater-course by the road side at Wadhurst; and in
a Avet place in Tunbridge Wells Common: Mr. Jenner.
This very distinct species mig h t he readily mistaken for
Zygnema angulatum, from Avhich, hoAvever, it is a t once distinguished
by th e in v erted c e lls; Avhich cells also are longer.
38. Zygnema diductum Hass.
Plate X X X V I I . Fig. 4.
Char. Filaments about equal in diameter to those o f Z . intermedium.
Cells eight or ten times as long as hroad. Sporangia
oval, producing very considerable infation o f 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 X X X V I I . Fig. 5.
Char. Filaments about equal in diameter to those o f the preceding
species, Z . diductum. Cells usually three times as
long as broad. Sporangia oval, producing a very considerable
infation o f the cells in which they are lodged.
The chief difference betAveen th is and th e folloAving species
consists in th e more considerable size of th e filaments.
40. Zygnema J en neri Hass.
Plate X X X T I I . Figs. 6. and 9.
Char. Filaments o f less diameter than those o f Z . vesicatum.
Cells usually three or fo u r times as long as broad. Sporangia
oval, lodged in cells, which are considerably inflated.
Hab. In a Avet spot by the road side betAveen 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. II.
To this species, which is certainly a distinct one, I have
assigned the name of Mr. J enner, Avhose zeal and acuteness
in the cultivation of a knoAvledge of the freshwater Algæ, as
well as in the pursuit of other departments of Natural History,
are so eminent. I could have wished that it had been more
Avorthy to have borne his name; it has one advantage, hoAV-
ever, over some others, Avhich is this, that it is an abundant
species.
41. Zygnema dubium Hass.
Plate X X X V I I . Fig. 7.
Char. Filaments rather more slender than those o f Z. Jenneri.
Cells fiv e or six times as long as broad. Sporangia
oval, long, placed in cells, which are inflated fo r their
reception.
Hah. BetAveen SIdley Green and NInfield, near Battle :
Mr. Jenner. Near Wormly West End, Hertfordshire :
A . IL IL
This may be but a variety of Zygnema Jenneri.
42. Zatgnema minimum Hass.
P late X X X V I I . Fig. 8.
Char. as slender as those o f Z . tenuissimum. Cells
many times as long as broad. Sporangia oval, lodged in
much inflated cells.
Hab. Che shunt: A . II. H.
This possibly may not be distinct, but prove eventually to
be the unconjugated state of Z. tenuissimum.