MOLLUSCA FROM INDIANA AND OHIO 453 



Amnicola lustrica (Pilsbry). Apparently typical examples of 

 this common Amnicola occur more or less abundantly in the Indiana 

 deposit. These are different from the Amnicola which occurs so 

 abundantly in the Ohio deposit, and also commonly in the deposits 

 in and about the Chicago region, which has a larger shell with more 

 elongated spire and thickened lip margin. Many of the Indiana 

 shells are immature. 



Pyrgulopsis sheldoni (Pilsbry). The presence of this tiny 

 species in these deposits is surprising, the species having been 

 originally described from material collected in Lake Michigan, off 

 Racine, Wisconsin, and dredged from a depth of thirty fathoms 

 (Pilsbry, 1890, Vol. IV, p. 53). Its occurrence in an interglacial 

 deposit far removed from the original locality and in an entirely 

 different ecological environment, a river, is very interesting. These 

 fossils are possibly the ancestors of the species that later restocked 

 the waters of Lake Michigan after the recession of the Wisconsin ice. 

 It should be looked for in other Pleistocene deposits. Sheldoni is 

 not uncommon in the Indiana deposit, but the shell is smaller on 

 the average than that of recent specimens. The identification of 

 this tiny species has been confirmed by Dr. Bryant Walker. 



Somatogyrus depressus Tryon. The half-dozen specimens of 

 this species are typical. 



Pomatiopsis lapidaria (Say). The single specimen occurring 

 in the material is normal in size and general shape, but the whorls 

 are rounder and the sutures more deeply impressed than is usually 

 the case among recent shells of this species. 



Pomatiopsis cincinnatiensis (Lea). Four specimens of this 

 smaller species of the genus occurred. They do not differ from 

 recent shells. 



Pleuroceridae 



Goniobasis semicarinata (Say). A Goniohasis abundant in the 

 deposit is referred to Say's semicarinata by Mr. Calvin Goodrich, 

 to whom specimens were sent for examination. It is a long-spired, 

 graceful shell which seems very characteristic. In the lot from 

 Bartholomew County there is Httle variation except in the com- 

 parative width of the last whorl. 



