82 



LAND AND FRESH- WATER SHELLS OF N. A. [PART IL 



Phijsa obesa, DeKay, appears to me identical with this species, 

 judging only from his description and figure here copied. 



Fig. 140. 



Physa obesa, DeKay. — Shell ventricose ; when young, very thin and 



fragile. Whirls four to five, rapidly attenuated to a minute and slightly 

 elevated polished apex. Body whirl inflated, with its upper 

 surface near the suture depressed, and forming an ohtuse 

 angle with the lewer portion ; suture semicanaliculate. Sur- 

 face polished, with minute incremental lines. Aperture 

 elliptical. Color pale horn. Length 0.5, of aperture 0.4 

 inch. 



This species was communicated to me by Dr. Budd, who 

 obtained it from the Mohawk and Hoosic Rivers, Rensselaer 

 • County. I have since received from the same gentleman 



specimens eight-tenths of an inch long, and 



quite solid with a stout callus. Some ^^S* l^l* 



naturalists who have seen it are disposed 



to consider it as 'identical with P. ancil- 



laria. {DeKay.) 



Haldeman refers Physa sayii, Tap- 

 pan,, to P. ancillaria. I h'ave con- 

 sidered it as distinct. 



The lateral teeth of the lingual 

 membrane of Physa oncillaria are 

 represented in Fig. 141, as well as 

 the line formed by one transverse row 



01 the teexQ. Xlngual dentition of P. ancillarta. 



I'Biysa osciilans, TIai.pk.man. — Shell ovate or subglobose, ashy-rod, 

 tbin ; whirls five, suture impressed; aperture wide. Shell allied to /'. 



