290 THE CHICAGO ACADEMY OF SCIENCES. 
RANGE (Figure 31): Maine west to Wisconsin, northern Michi- 
gan south to northern Illinois. 
This variety occupies a large part of the Alleghanian division of 
the Transition life zone; it enters the Carolinian division of the Upper 
Austral life zone on the south and the Boreal (Canadian) life zone 
on the north. This area of distribution will probably be greatly ex- 
tended when the variety becomes known. It has been confounded with 
obrussa heretofore. The geological range is at present much wider 
than the present range (the race has not been observed living outside 
of Illinois and Michigan), probably showing that the variety is ap- 
NL 
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proaching extinction. As a marl fossil it is one of the most abundant 
of the Lymmezeas, and a characteristic mollusk of the Canadian and 
Nova Scotian regions. 
RECORDS. 
UNITED STATES. 
Intinois: Fox Lake, Lake Co. (Baker); Silver Lake and Algonquin, Mc- 
Henry Co. (Nason); Cedar Lake and Long Lake, Lake Co. (State Laboratory). 
MicuicaAn: Brook’s Lake, Newaygo Co. (Streng; Walker); Charlevoix, 
Hillsdale, Jackson, Lake, Marquette, Muskegon, Newaygo, Shiawassee and Tus- 
cola Counties ( Walker’). 
GEOLOGICAL DistRiBUTION: Pleistocene. 
1A number of these records refer to fossil or subfossil specimens. 
