408 ILLINOIS STATE ACADEMY OF SCIENCE 



PLEISTOCENE MOLLUSCA FROM THE VICINITY 

 OF JOLIET, ILLINOIS.* 



Feaxk Collins Baker, Curator, Museum of Natural 

 History, UisriTERSiTY of Illinois 



Several collections of Pleistocene fossil molhisks from 

 the vicinity of Joliet have recently been submitted for 

 study, which are of unusual interest from the standpoint 

 of geological and geographical distribution. All of the 

 deposits are Post-Glacial in age and represent several 

 stages in the history of Glacial Lake Chicago. It is, of 

 course, difficult or impossible to exactly correlate these 

 deposits with the lake stages, but the contained life in- 

 dicates that the lake was populated from the Desplaines 

 and Illinois valleys. 



MATERIAL FROM THE FAIR GROUND QUARRY, JOLIET 



This material was collected by Mr. James H. Ferriss, 

 of the Joliet Daily News, a veteran collector of mollusks, 

 both recent and fossil, and represents several years work. 

 It is thus as complete a collection as could well be made 

 and probably includes about all of the species possible 

 to be found in these strata. Fifty-six species are in- 

 cluded, of which eight are bivalves, six water breathing 

 gastropods, 19 pulmonate aquatic gastropods, and 23 

 land gastropods, altogether foraiing one of the largest 

 aggregations of Pleistocene Mollusca from one place. 

 One variety is recorded as new, a species listed from 

 Pleistocene deposits for the first time, and the distribu- 

 tion of several recently described species and varieties 

 is enlarged. 



Mr. Ferriss thus describes the stratigraphy of the de- 

 posits at this locality: 



^' Above the limestone on the east side, about the cen- 

 ter of the prehistoric pond, the marl is nearly pure and 

 of a thickness of from six to ten feet. Then is found a 

 bed of peat with stumps and cones of Arbor Vitae and 

 White Cedar, which do not grow within many miles of 



* Contribution from Museum of Natural History, University of Illi- 

 nois, No. 26. 



