50 The Shell-Collector’s Handbook. 
Habitat—Canals, ponds, ditches, and slow-running 
streams. 
v. Henslowana (Shepp): The valves with a plate-like 
appendage near the umbones. (= Tellina Henslowana. 
Sheppard, Zinn Trans, xiv.) 
v. pulchella (Jenyns): Shell more glossy, strongly 
grooved ; umbones less acute. (=P. pulchellum. Jenyns, 
p. 18, tab. xxi., f. 1—5.) ; 
v. pallida (Gasstes): Shell more tumid and _ paler, 
with a few darker rays diverging from the umbonal region 
to the inferior margin, irregularly striate. 
v. cinerea (Alder): Shell larger and flattter; stri 
fainter. (=P. cinmerewm, Alder, Suppl. Cat. Moll. 
Northumb., p. iv.) 
PISIDIUM PUSILLUM, GMELIN. 
SHELL oval, thin, compressed but swollen, finely but 
irregularly striated, yellowish-white or greyish-horn 
colour; anterior side very rounded; posterior side very 
convex and sloping gradually downwards ; lower border 
arched; umbones obtuse, short and nearly central; liga- 
ment short, narrow, and not visible from the exterior ; 
hinge, teeth, and scars the same as P. fontinale. Animal 
whitish or reddish ; siphon short, subconic or cylindrical, 
truncated. 
Habitat.—Marshes, and ditches. 
v. obtusalis. (Lam): Shell smaller and much more 
tumid ; umbones sharp, pronounced. 
v. grandis (Adams): Shell much larger. 
v. ventrosa (Moq.): Shell slightly more trigon-shaped, 
more ventricose. 
v. cireularis (7. D. A. Cockerell) : Shell greyish, 
rather shiny, almost circular in outline, subtruncate 
anteriorly ; umbones almost central; diam. 3 mill. 
