OBSERVATIONS. 
Inhabits with the preceding species. It was given 
me by Professor Witt1aM B. Rogers, to whom [have 
dedicated the species. 
PLANORBIS ENGONATUS. 
Piate 1X.—Fig. 8. 
DESCRIPTION. 
Shell yellowish; biangulated above; spire not pro- 
foundly impressed; side of the body whirl flattened 
and both margins carinated; aperture longitudinally 
subovate, slightly campanulate. 
OBSERVATIONS. 
This species was found at Albany, N. Y., by Mr. 
Atva Mason. It differs from all other species of the 
United States in the flattened form of its lateral or 
outer margin, &c. 

“Kf 

