440 FRANK COLLINS BAKER 



Logan County is within the late Wisconsin drift border and the 

 fauna is without question of post- Wisconsin age. 



The fauna of the Ohio deposit contains several species of unusual 

 interest. A new variety of Amnicola is related to a recent species 

 described from Maine — Amnicola winkleyi leightoni. The two 

 forms are widely separated geographically, but the relationship 

 seems unquestionable. It is probable that this variety, as well as 

 the t^-pical form, occur in other places between the two localities, 

 but have not yet been recognized. All of the large Amnicolas have 

 generally been identified as "limosa^' and many of the more recently 

 described species and races of this and other groups will be found in 

 other Pleistocene deposits when these are critically examined. 

 Physa anatina is the most easterly record for this species which is 

 abundant, living, west of the Mississippi River, and also more or 

 less common in Illinois and Michigan. This is the first record of 

 this Physa in Pleistocene deposits of the glaciated regions. The 

 recently described Planorhis altissimus, first noted in a marl deposit 

 in Illinois, occurs in abundance in the Ohio deposit. This small 

 Planorhis is beUeved to have a wide distribution in the eastern and 

 central parts of the United States in Pleistocene formations. It 

 may also occur living. The number of species and varieties of the 

 genera Valvata, Amnicola, and Planorhis in this deposit is also note- 

 worthy. 



It will be observed that in the Ohio deposit there are no land 

 shells and only one naiad species, an Anodonta, a genus character- 

 istic of quiet bodies of water hke lakes and ponds. The Sphaerium 

 is a species commonly found in lakes. The other genera present, 

 particularly Valvata and Planorhis, contain species that usually 

 have a wide distribution in lakes. The Ohio deposit may, 

 therefore, be considered as having Hved in a larger Rush Lake, 

 perhaps not long after the ice had disappeared from Ohio. 



The Indiana deposit contains many land shells and six species of 

 naiads, characteristic of rivers and streams. Sphaerium and 

 Pisidium are largely represented, as is also the family AmnicoKdae. 

 The presence of Goniobasis semicarinata also stamps this deposit 

 as fluviatile in character, as distinguished from the Ohio deposit, 



