198 AMERICAN JOURNAL 



DESCRIPTIONS OP THREE NEW SPECIES OP SHELLS. 



BY JOHN WOLF. 



Vertigo tridentata, Wolf. Plate 17, fig. 1. 



Description. — Shell narrowly ovate, amber-colored, highly 

 polished ; whorls 5, smooth, with three teeth in the mouth, one 

 on the middle of the lower lip and one on each side, forming a 

 a regular triangle. 



Canton, Illinois. 



Abundant in shady copses on green weeds, climbing as high as 

 three feet from the ground. I collected 12,000 from standing 

 weeds and not one from the ground, although it was searched 

 well to find them. 



Pyrgula scalariformis, Wolf. Plate 17, fig. 3. 



Descriptioyi. — Shell turrited, slender ; whorls 6, chalky white ; 

 suture deeply impressed ; carinate its entire length on the lower 

 edge of the whorls ; mouth small, ovate, but slightly connected 

 with the last whorl. Length y^gths of an inch. 



Post Pliocene : abundant on the Tazewell shore of the Illinois 

 River. 



This is the first American species of the genus. 

 Limnea Tazewelliana, Wolf. Plate 17, fig. 2. 



Description. — Shell turrited, slender ; whorls 7, convex ; su- 

 ture deeply impressed, umbilicate ; mouth elliptical, small. 

 Length f of an inch. 



Post Pliocene, Tazewell side, Illinois River. 



Allied to L. caperata, Say, but more slender and turrited. 



