CONCHOLOGIA CESTRICA. 



81 



B. Nickliniana, LEA. 



Paludina Nickliniana, Lea, Tr. Amer. Phil. Soc., VI., 

 1839. 



Shell, green, with four convex, smooth, ^-^liniana. 



[ W. (j. B.] 



whorls, turrited ; apex obtuse ; aperture Fig, 170, 



ovate. H. 3^, W. i^, mill. & 



Station, tributaries of the Susquehanna \~S\ 

 River, Chester County ; common. 



Lingual Dentition of B. Nickliniana. [Stimp.] 

 Fig, 171, 



OBS. B. attenuata, Haldeman, is the more perfect 

 specimen of this species, occurring in spring heads, and 

 still water. 



Genus POMATIOPSIS, TRYON, 1862. 



Animal of I*, lapidaria. [Stimp.] 

 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. 



