166 Thirty-fifth Report on the State Museum. 



D. urceolata, Carter. 



Not common, generally typical in form. Locality, Island 

 creek. 

 D. cratera, Leidy. 



Rare ; I have seen them living, therefore I could not be mis- 

 taken. Locality, Water-supply. 

 D. acuminata, Ehrb. 



Rather common in the Albany basin . 

 D. lobostoma, Leidy . 



Not common. Localities, Water-supply, etc. 

 D. corona, Wall. 



Quite common during July and August . Locality, Water- 

 supply. 

 D. constricta, Ehrh. 



Rare. Localities, Black-rock pond and Botany pond. 

 D. spiralis. 



Rare. Locality, Normanskill. 

 D. obliqua, n.sp. Figs. 1 and 2. 



General outline of the shell elliptical, obtusely or acutely 

 pointed at the vertex, to which is often attached a few 

 granules of quartz. Shell constricted above the mouth. 

 Perostome set at an angle to the long axis of the body. 

 Color yellowish-brown. 



This species is quite 'common at certain seasons in the 

 Water-supply, but is only rarely found elsewhere. I have 

 only two localities noted. Localities, Black-rock pond, 

 Island creek. 

 Hyalosphenta, Stein. 

 H. tincta, Leidy. 



Extremely rare. Locality, Island creek. 

 Quadrula, Schulze. 



Q. symmetrica, Wall. 



Rare. Locality, Water-supply. 

 Heliopera, Leidy. 

 H. picta, Leidy. 



Seldom seen. Locality, Black-rock pond. 

 Arcella, Ehrb. 



A. discoides, Ehrb. 



Not common . Locality, Botany pond. 

 A. vulgaris, Ehrb. 



Very rare in most localities but common at Botany pond. 



PSEUDODIFFLUGIA, Schl. 



P. gracilis, Schl 



Common. Locality, Water-supply. 



