Baker—Molluscan Fauna of Tomahawk Lake, Wisconsin . 233 
20. Pisidium suhrotundum Sterki. 
Station XXI. Fairly abundant in swampy places along 
the Wisconsin Fiver. 
21. Pisidium virginicum Gmelin. 
Station XX 2 . Common in the sandy shore of the Wis¬ 
consin Fiver, in shallow water associated with Sphwrium 
striatinum, Campeloma and Lampsilis luteola. 
Numbers 17, 18 and 19 are not in Chadwick’s list. 
Class GASTROPODA. 
Order PFOSOBFAN CHI AT A. 
Familv Vivipaeidae. 
Genus Campeloma Fafmesque. 
22. Campeloma decisum (Say). 
Stations II 1 , III, VII, VIII, XX 2 , XXII. Campeloma 
decisum is abundant in this region on sandy shores in 
rough or rapidly moving water. The Wisconsin Fiver 
habitat was the best and furnished the largest and finest 
specimens. The current here is very swift and the Campe- 
lomas bury themselves completely in the sand or rest on the 
lee side of anchored logs. Some specimens approach 
Campeloma milesi, but lack the peculiar rounded whorls so 
characteristic of the Michigan species. 
Family Amuicolidae. 
Genus Amnicola Gould and Haldeman. 
23. Amnicola cincinnatiensis (Lea). 
At Stations V, XII 2 and XIV 1 this species lives in 
abundance, its habitat being the under side of lily leaves. 
At stations III and VII the dead shells were found in shore 
debris, evidently washed from the sheltered bays. 
