200 Wisconsin Academy of Sciences, Arts, and Letters. 
THE MOLLUSCAN FAUNA OF TOMAHAWK LAKE, 
WISCONSIN. 
>With Special Beference to its Ecology. 
BY FRANK COLLINS BAKER. 
Curator, The Chicago Academy of Sciences. 
Of the states of the northern part of the Mississippi Valley, 
the Wisconsin inollnscan fauna is the least known, although 
that of Minnesota is known hut imperfectly. With this fact 
in mind, the writer planned his summer vacation of 1908 so 
that it included a three weeks’ visit to Tomahawk Lake, in 
northeastern Wisconsin. But little systematic molluscan work 
has been done in Wisconsin, that of Mr. Chadwick (’02) being 
the most complete. Such work as that which Buthven (’06), 
and Walker (’06, ’09) have accomplished in the study of the 
Mollusca of Michigan is totally lacking. 
The methods now in use for studying faunal areas are quite 
different from those in vogue a decade or more ago, the time 
honored annotated list being largely replaced by a discussion of 
the environment factors under which the organisms live. This 
ecological view point is of great value if properly interpreted, 
and when a large number of accurate papers based on studies of 
this kind have been published it will be possible to make many 
generalizations concerning the laws which govern the changes 
and formations of various habitats. The laws of succession are 
very interesting and very important and the study of these 
laws will help us not a little to understand the extinction of old 
species and the appearance of new ones in certain localities. 
