AMNICOLIDA. 45 
margin in one plane, slightly perforate. At- 
lantic coast of United States, SomaToGyRus.* 
Shell subglobular, thick, smooth, imperforate ; 
aperture ovate, outer lip diffuse and project- 
ing anteriorly, so that the peristome is not 
continuously in the same plane. Pacific 
slope of United States, . . FLUMINICOLA. 
B. Shell sculptured. 
Shell elongated, carinated or plicated, perfo- 
rated; aperture small, effuse and sinuated 
at the base, ; ' 5 . TRYONIA. 
*T do not think that Dr. Stimpson’s genus Giza can be 
separated from Somatogyrus. The lingual dentition does 
not in my opinion afford a sufficiently reliable distinctive 
character, and I am not even entirely satisfied that the type 
of the latter—S. depressus, nob.—is specifically distinct 
from Melania integra, Say, which Dr. Stimpson supposes to 
belong to his genus Gullia. 
; (26) 
