The Shell-Collector’s Handbook. 49 
PISIDIUM AMNICUM, MULL. 
SHELL triangular, ventricose, solid, deeply grooved con- 
centrically, whitish-grey, or pale brown in colour; anterior 
side very rounded; posterior side much produced, and 
sloping towards lower margin; lower margin arched; 
ligament short, narrow, conspicuous; teeth as in Sphee- 
rium, but, in this species, and in all the other Pisidiums, 
the lateral teeth are strong and developed in a direct ratio 
to the size of the shell; umbones blunt, rather prominent. 
Animal whitish or greyish; siphon short, conical, or 
cylindrico-conical, obliquely truncated at its extremity. 
Length of shell 4 lines ; width 3 lines; thickness 13 lines. 
Hatitat.—Canals, ponds, lakes, and rivers. 
v. striolata (Moq.): Shell smaller, wrinkles more pro- 
nounced. 
v. leviuscula (Mog.): Shell larger; wrinkles demi- 
effaced. 
v. flavescens (Mog.): Shell of an unicolorous pale 
yellow. 
- PISIDIUM FONTINALE, DRAPARNAUD. 
SHELL sub-triangular, thin, swollen, greyish-white, 
finely striated concentrically ; anterior side abruptly 
truncated; posterior side rounded, and gently sloping 
towards the inferior margin; umbones prominent and 
pointed ; ligament short and scarcely visible; hinge short, 
very strong; teeth the same as in last species, but with 
the exception that the cardinal teeth are not arranged in 
the shape of an inverted V; muscular scars deepish. 
Animal whitish, or greyish; siphon sub-conical, short, 
and obliquely truncated at the extremity. 
E 
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