’ 
CONGCHOLOGIA CESTRICA. 8I 
B. Nickliniana, LEa.. 
Paludina Nickliniana, Lea, Tr. Amer. Phil. Soc., VI., 
1839. 
Shell, green, with four convex, smooth, aes 
whorls, turrited; apex obtuse; aperture Fig, 170. 
ovate. H. 3%, W. 1%, mill. 2 
Station, tributaries of the Susquehanna © 
River, Chester County ; common. 
Lingual Dentition of B. Nickliniana. — [Stimp.] 
Fig. 171. 

Oss. — 4. attenuata, Haldeman, is the more perfect 
specimen of this species, occurring in spring heads, and 
still water. 
Genus POMATIOPSIS, Tryon, 1862. 
Animal of P. lapidaria. — (Stmp.] 
Fig. 172, 


Shell, small, thin, smooth, elongated, turreted, sub- 
umbilicate ; aperture ovate; peristome reflected. 
Animal, tentacles short, subulate, pointed; rostrum 
large, longer than the tentacles, and transversely wrin- 
kled ; foot broad, with lateral sinuses ; verge very large, 
flattened, broad, spiral; gills pectinate; opercle thin, 
sub-spiral, amphibious; progression stepping. 
F 
