256 



LIFE OF THE PLEISTOCENE 



The post-Kansan loess is widely distributed in Harrison and Monona coun- 

 ties, and is highly fossiliferous in places. Shimek, who has studied this terri- 

 tory exhaustively, lists the following species: 38 



Vallonia gracilicosla 

 Polygyra monodon 



" multilineata 

 Bifidaria armifera 

 Vertigo modesta ( = oiata) 



" tridentata 

 Sphyiadium edentulum allicola 

 Vitrea hammonis 

 Euconulus fulvus 

 Zonitoides arborea 

 Eggs of small snails 



Pyramidula allernata 

 shimekii 



cronkhhei anlhonyi 

 (= striatella) 

 Helicodiscus parallelus 

 Succinea aiara 

 " oialis 

 Helicina occulta 

 Galba caperala 

 " obrussa 

 " humilis modicella 



In Pottawattamie County, Kansan drift occurs overlaid by loess, the lower 

 portion of which is referable to the post-Kansan interval. At Council Bluffs 

 the following species occur: 39 



Helicina occulta 



Valionia gracilicosla 

 " parvula 



Polygyra profunda 

 " multilineata 

 " kirsuta 

 " leai 



Slrobilops lirgo 



Bifidaria armifera 

 " holzingeri 

 " contracta 

 " cunidens 

 " pentodon 



Leucochila fallax 



Pupitta blandi 



Vertigo bollesiana 

 Cocklicopa lubrica 

 Vitrea hammonis 

 " indentata 

 Euconulus fuhus 

 Zonitoides arborea 



" minuscula 

 Pyramidula allernata 



cronkhitei anlhonyi 

 perspediva 

 shimekii 

 Helicodiscus parallelus 

 Succinea obliqua 

 " grosvenori 

 " avara 

 Eggs of land snail 



Both post-Kansan and post-Iowan losses occur in Warren, Madison, and 

 Page counties (vide Shimek). 



McGee 40 has reported Ovibos cavifrons from the Council Bluffs loess, 12 

 feet below the surface, associated with mastodon and elephant remains, the 

 bones of a small rodent, and several pulmoniferous mollusks. 



Udden 41 lists the fauna of numerous loess deposits in Pottawattamie County, 

 the majority of the species being from the lower (post-Kansan) loess. His list 



38 Geol. Iowa, XX, pp. 395-396; sections, pp. 379-385. 



36 Shimek, Proc. Iowa Acad. Sci., VI, p. Ill; Journ. Geol., VII, p. 137. Some of these 

 are probably also referable to the upper or post-Iowan loess, but no division is made in these 

 papers. 



"Amer. Journ. Sci., (iii), XXXIV, p. 217. 



"Geol. of Iowa, XI, pp. 258-267. 



