146 THE CHICAGO ACADEMY OF SCIENCES. 
a portion of the Arctic, the Hudsonian, Canadian, Transition and the 
extreme northern portion of the Upper Austral life zones. 
GEOLOGICAL RANGE (Figure 10): Pleistocene. The records of 
fossil stagnalis show that the species extended from eastern Ontario 
west to Nevada. The records are few in number and, being mostly 
post-glacial, no generalizations are nossihle. Stagnalis doubtless lived 
in Pliocene or earlier times, and Lymnea stearnsi, a Middle Miocene 
fossil found in the Mascall beds of Grant County, John Day Valley, 
Oregon, is probably an ancestor of appressa. The specimens thus far 
obtained, however, are too imperfect to afford a basis for comparison 
with the recent species. 


ye? Geological 
Distribution 
@ Loess 
| 
| 

a: 9 
LYMNAA STAGNALIS APPRESSA 4, 



RECORDS. 
LOESS. 
Ittinois: Base of Loess in bluff of Mill Creek, about five miles north of 
Milan, Rock Island Co. (Leverett; Shimek; Udden). 
NEBRASKA: Washington Co. (Aughey). 
SoutH Dakota: Otis Mill, Union Co. (Darton coll., Smith. Inst.). 
MARL BEDS. 
Itt1no1s: Clay and marl, Cook Co., various localities (Baker); marl 
beds, Clyde Ave. near Austin Ave., Chicago (Scharf). 
MicuiGAN: Crooked Lake, Oden, Emmet Co. (Slocum). 
Utan: White marl, Lake Bonneville (Gilbert). 
Ontario, CANADA: Hemlock Lake, near Edinburgh, east of Ottawa, in 
soft white calcareo-argillaceous matrix (Ami. Ottawa Nat., XI, p. 20, 1897). 
SAND AND GRAVEL PITS, CLAY, ETC. 
Itt1NoIs: Bowmanville, Cook Co. (Baker). 
MicuicAn: Found with mastodon remains in Niles, Berrien Co., from 
muck beneath the mastodon (Walker, Nautilus, XI, p. 121, 1898). 
