THE KANSAS UNIVERSITY 

 SCIENCE BULLETIN. 



Vol. XIIL] MAY, 1920. [No. 2. 



Pleistocene Mollusks from Wallace County, Kansas.* 



BY G. DALLAS HANNA. 



Curator of Invertebrate Paleontology, California Academy of Sciences. 



ONE of Mr. H. T. Martin's numerous fossil hunting expedi- 

 tions for the Universitj^ of Kansas took him to the Mio- 

 cene mammal beds of Wallace county of that state. Here, in 

 one locality he found some ant hills about which were numerous 

 shells the indefatigable insects had collected. A small quan- 

 tity of the general debris about the nests was preserved and 

 the mollusks have come to me for study. 



The collection, although small, is valuable because it throws 

 more definite light upon the size and duration of the Pleistocene 

 Kansas lake which Prof. J. E. Todd has aptly named "Kaw 

 Lake." Some of the species of mollusks found inhabit lakes 

 solely and since there are none of these bodies of water within 

 a long distance of the locality at the present time, practically 

 conclusive proof is offered of the existence of Kaw Lake before 

 the present epoch. And since many of the species now live in 

 northern cold waters it seems justifiable to conclude that this 

 body of water was coexistent with the great glaciers. Probably 

 its inhabitants lived during the deposition of the Aftonian 

 giavels; that is, prior to the descent of the Kansan ice sheet. 

 It seems likely that the lake was formed by the pre-Kansan ice 

 sheets, continued through the Aftonian period and that its dam 

 was broken by the Kansan sheet. 



Kaw Lake probably existed for several hundred years. This 

 is indicated by the presence in it of a large molluscan popula- 

 tion which would require a very considerable number of years 



* Received for publication on February 2, 1920. 



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2 — Sci. Bui. — 860 



