246 



THE CHICAGO ACADEMY OF SCIENCES. 



LOESS. 



IOWA: Des Moines, Polk Co. (McGee and Call; Van Hyning; Walker); 

 Turkey Creek, Johnson Co.; common in Loess with humilis (modicella) and 

 capcrata (Shimek) ; Loess of Iowa (Todd). 



GENERAL PLEISTOCENE. 



COLORADO: South Platte River, Arapahoe Co. (Henderson). 

 ILLINOIS: Tazewell shore, Illinois River, Tazewell Co. (Wolf). 

 Recently Mr. Junius Henderson sent the writer a specimen of a 

 small Lymnsea which seems to be a form of parva. It has a pointed 

 spire, well-rounded whorls, deep sutures, a well-marked umbilicus, a 

 long ovate aperture and the inner lip erect. The last whorl is much 

 contracted, but this may be a malformation. It measures as follows: 

 Length. Width. Aperture length. Width. 



5.50 3.00 2.00 1.25 mill. 



FIG. 22. 



"I am sending you for examination a specimen of a small species 

 of Limnsea of the identity of which I am not certain. I found two 

 or three, but the material when freshly exposed was very fragile and 

 this seems to be the only one which arrived home in recognizable 

 condition. This shell is interesting to me and may be to you in your 

 w r ork on the Limnccas, because it was found in what I at present con- 

 sider Pleistocene deposits containing in the same horizon the following : 



This form of Lymnsea was found in deposits supposed to be Pleis- 

 tocene, which are thus described by Mr. Henderson: 



