260 College of Forestry 
more or less partly protected. This is a widely distributed 
species, listed from Tomahawk Lake, Traverse Bay, Lake 
Michigan, and Georgian Bay. It is listed by Beauchamp. 
Used by the Common Whitefish (Coregonus clupeaformis). 
17. Spherium vermontanum (Prime). Fig. 45, Nos. 82, 
2 
33. 
An abundant species occurring at twelve stations. It lives 
in sand in both exposed points and in protected bays. Dr. 
V. Sterki refers this mussel to vermontanum with some 
doubt as the specimens collected are undersized or immature. 
Vermontanum appears to be comparatively unknown among 
collectors, being absent from nearly all local lists. It some- 
what resembles solidulwm. and was so identified by the writer 
many years ago (Baker 1898, p. 113; 1902, p. 394). It is 
listed by Letson (1905, p. 72) but not by Beauchamp, by 
whom it was probably identified as solidulum, which is listed. 
It is used as food by the Common Sucker and Pumpkinseed. 
Genus Muscutium Link. 
18. Musculium securis (Prime). Fig. 45, No. 29. 
Observed at two stations, but common at but one on a 
sandy bottom, partly protected from wave action. This is a 
common mullusk throughout the United States east of the 
Rocky Mountains. It is recorded from Tomahawk Lake, 
Saginaw Bay, Georgian Bay, and Isle Royale. In all of 
these localities it lives in protected bays, in pools or swamps. 
It does not live normally on exposed shores. Listed by Beau- 
champ. It is eaten by the Common Whitefish and the 
Yellow Perch. 
19. Musculium rosaceum (Prime). Fig. 45, No. 30. 
Found at one station on a bouldery exposed shore. It is 
rare. Reported from Traverse Bay. Not listed by 
Beauchamp. 
