360 



LIFE OF THE PLEISTOCENE 



Leporidae 

 Sylvilagus floridanus (Allen). 



Leptictedae 

 Anomodon snyderi LeConte 



Procyonidae 

 Procyon priscus LeConte 



Canidae 

 Canis mississippiensis Allen Canis indianensis Leidy 



Canis latrans Say " occidentalis Richardson 



Urocyon cinereoargentatus (Schreber) 



VI. Summary 



A difference of opinion prevails among geologists relative to the extent 

 (and even the existence) of the Iowan ice sheet. The exposed portions of 

 this drift sheet are found only in Iowa and a small portion of Minnesota and 

 Wisconsin. The deposits containing evidences of life, however, indicate that 

 there was an interglacial interval following the Kansan and Illinoian, and 

 previous to the Wisconsin, that is easily recognized stratigraphically. Two 

 loesses have been observed in many places, an early and a later. The loesses 

 above the Illinoian till are post-Illinoian (Sangamon) and post-Iowan (Peorian). 

 In Iowa the upper loess is considered post-Iowan, and there should be below this 

 a post-Illinoian overlying a post-Kansan. Deposits referred with confidence 

 to the Peorian interval have been observed in Iowa, Nebraska, Illinois, Minne- 

 sota, Wisconsin and Missouri. 



Little is known concerning the climate of the Peorian interval, tho it is 

 believed, in Iowa at least, to have been somewhat drier than that of the present 

 time. The flora is very poorly represented (only the presence of wood being 

 recorded) "but the fauna is well represented. The biota is tabulated below : 





Living 



Extinct 



Total 



Mollusks 



64 

 10 



74 



2 

 14 



16 



66 



Mammals 



24 



Total 



90 







Land mollusks predominate as would be expected in loess deposits, 53 species 

 being represented. With few exceptions all are living in Iowan territory at 

 the present time. Of the mammals recorded, 59 per cent are extinct. 



SPECIAL CHARACTERISTICS OF LOESS FOSSILS 



The fauna of the various loess deposits is but little understood by many 

 geologists, as well as by most zoologists. A paper by Prof. B. Shimek 44 of the 



44 Science, N. S., XXXVII, No. 953, pp. 501-509, 1913. 



