82 CONCHOLOGIA CESTRICA. 
P. lapidaria, Say. 
Cyclostoma lapidaria, Say, Jour. Acad. Phila., 1, 1817. 
re Shell, sub-umbilicate ; whorls 6, obsolete- 
Fig.173, ly, and transversely, wrinkled; aperture 
A 
longitudinally ovate-orbicular, more than 
b one-third the length of the shell. H. 6, 
W. 2%, mill. 
Lingual Dentition of P. lapidaria, — [Stimp.]} 
Fig, 174, 

Station, under stones, near water. New Garden, 
Chester County ; not common. 
P. lustrica, Say. 
Paludina lustrica, Say, Jour. Phila. Acad., II., 1821. 
P.lustrica, Shell, conic; whorls’ convex; aperture 
Ee can oval-orbicular ; upper margin of the lip not 
Se appressed to the last whorl ; umbilicus rather 
large, rounded. H. 5, W. 34, mill. 
Station, shores of the Delaware River. 
(Tryon.) 

Oss. — Possibly, the young of the preceding species. 
Genus SOMATOGYRUS, GILL, 1863. 
Shell, short, sub-conic, striate, thin, or moderately 
thickened; spire small; aperture large, broad-ovate, 
oblique ; operculum thin, sub-spiral. 
Animal, with the foot oblong, broadly rounded be- 
hind, and auricled in front; rostrum broad; tentacles 
long, slender, and pointed; eyes at the outer sides of 
