THE IOWAN ICE INVASION 351 



Other wells vary from 12 to 22 feet, and show similar layers of peaty ma- 

 terial. 



References to Peorian vertebrates in Minnesota are exceedingly rare. 

 Winchell 23 records Ovibos (Symbos) cavifrons from a farm between Wabasha and 

 Theilman, near the railroad from Wabasha to Zumbrota. It was 10 feet below 

 the surface, in a gravel terrace of the valley. This is in the Driftless Area and 

 it may belong to post-Iowan tune. In Winona County, near Stockton, the 

 remains of Elephas primigenius were found in Iowan loess. 24 



4. ILLINOIS 



Some fossils in the loess of northern Illinois should probably be referred 

 to the Peorian interval. In this horizon should be placed the mollusks from 

 Fulton, Whiteside County, listed by McGee. 25 



Succinea avara Vallonia pulchella (=gracilicosta.) 



Pyramidula cronkhilei anthonyi Pupa species 



Oreohelix iowensis Galba humilis modicella 



The upper layers of the loess in other parts of Illinois are doubtless to be 

 classed as post-Iowan (Peorian) but no fossils have been observed. 



5. WISCONSIN 



The Peorian interval is believed to be represented in Wisconsin but no 

 fossils have been observed. The loess is believed to be post-Iowan and pre- 

 Wisconsin. 26 



6. THE DRIFTLESS AREA 



a.. Invertebrate fauna 

 if' 

 The Driftless Area of Wisconsin, Illinois, Iowa, and Minnesota is partly 



covered with loess deposits, especially along the Mississippi River, a large part 



of which is referable to the post-Iowan interval. McGee 27 lists eight species 



from Galena, Illinois, as noted below: 



Succinea avara Pupilla muscorum 



" obliqua Bifidaria contracta 



Pyramidula conkhilei anthonyi Galba humilis modicella 

 Vallonia pulchella " obrussa 



» N. H. Winchell, Bull. Minn. Acad. Sci., IV, No. 3, p. 419. 



u Op. cit., p. 416. 



a Pleistocene History of Northeastern Iowa, p. 448. 



* Weidman, Science, N. S., XXXVII, p. 457. 



* Op. cit., p. 448. 



