The Shell-Collector’s Handbook. 47 
just visible externally, transverse strive coarser.’ (=S. 
Pisidiodes, Gray. Ann and Mag. Nat. Mist. July, 1856.) 
v. compressa (Gray): Shell rather compressed, mar- 
gins meeting at an acute angle. 
v. minor (Gray): Shell smaller, and nearly globular. 
v. brunneo-fasciata (Williams): Shell paler than 
type, with the umbones shaded with brown colour, in 
which there are three just discernible bands forming 
segments of a circle, and of a darker brown. Externally 
to these, and separated by a band of ground-colour, is 
another similar band of the same tint as the others, but 
much better defined in outline. - 
SPHARIUM RIVICOLA, LEACH. 
SHEL larger than S. corneum, S. ovale, or S. lacustre, 
oval-ventricose, brownish green, or yellowish horn-colour, 
with two or three darker bands and strong concentric 
ridges; umbones central, blunt ; ligament very conspicuous 
on the outside: muscular scars distinct; teeth and hinge 
as In 8. corneum, but stronger. Length of shell 10 lines ; 
width 7 lines; thickness 5 lines. 
Habitat.—Canals and sluggish streams. 
SPHAGRIUM OVALE, FERUSSAC. 
SHELL oblong, compressed, pale drab or yellowish in 
colour, with faint concentric strize ; anterior side roundish ; 
‘posterior side truncate, and sloping towards lower margin ; 
umbones small, slightly prominent, and nearly central; 
ligament long, narrow, and visible externally; hinge-line 
straight on posterior, but incurved on anterior side; teeth 
as in S. corneum, but differing in having the cardinal 
