oval, lying in cells which are considerably inflated fo r
their accommodation.
Zygnema Grevilleanum, Annals and Mag. of Nat. Hist,
vol. X. p. 38.
Ilab. Cheshunt and its vic inity: A. II. H. Framfield:
Mr. Jenner. Dolgelley: Mr. Ralfs. T u rf Dyke, near
Ardrossan: Major Martin.
“ To this fine species I have assigned the name of Dr.
Greville, author of the excellent ‘ Algaj Britannicse,’ as a
slight mark of personal respect, as well as an acknowledgement
of the eminent services rendered by tha t gentleman
to natural history.”
22. Zygnema intequale Hass.
Plate X X X IT . Figs. 1, 2.
Char. Filaments o f smaller diameter than those o f Z. Grevilleanum.
Cells about f v e times as long as hroad, and
enlarged on the side from which the tubes o f communication
arise. Sporangia oval.
Hab. Cheshunt: A . H. H.
This is not a common species. I have no doubt but that it
is distinct.
23. Zygnema sebtenteicosum Hass.
Plate X X X I I . Figs. 3, 4, and 5.
Char. Diameter o f the filaments about equal to these o f
Z. commune. Cells usually f v e 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.
Hab. Cheshunt and its vicinity : A. H. H. Heathfield;
in a pond near Boar’s Head, Ramslye Rocks; and
Rackham, near Pulborough : Mr. Jenner. Dolgelley :
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,
Fssex, In which the filaments are somewhat finer, the cells
considerably longer, and the sporangia smaller. This may
be distinct.
24. Zygnema longatum Hass.
Plate X X X I . Figs. 3, 4.
Char. Filaments about equal in diameter to those o f Z. sub-
ventricosum. Cells usually eight times as long as broad.
Sporangia not producing any inflation o f the cells, in
lohich they are formed.
Conferva pmictalis Müller, Flor. Dan. pi. 1. no. 1. Conjugata
longata Vaucher, Hist, des Conf. pp. 71, 72.
plate 6. fig. 1.; Dillw. t. 3. upper figure in part? Z.
oequale 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 an microscope que cette jolie
conjuguée.”— Vaucher.
25. Zygnema inflatum Hass.
Plate X X X I I . Pigs. 6, 7, and 8.
Char. Filaments o f much less diameter than those o f Z. suh-
ventricosum. Cells usually four, f v e , or six times as lonq
as broad. Sporangia elongated, and lodged in cells which
become considerably inflated fo r 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.
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