i82 College of Forestry 



The increase in Sphseriidse from 14 to 32 species is note- 

 worthy. New species are recorded in the LJnionid?e and Amni- 

 coHdse. The latter family is increased from 8 to 11 species. 

 Mollusks were collected from all varieties of bottom, boulder, 

 gravel, sand, clay, and mud, but were most abundant on a 

 mud bottom (50 species) and least abundant on a sandy clay 

 bottom (25 species). Mollusks were also found at all depths 

 being most abundant in three feet of water (46 species) and 

 least abundant in 16-18 feet (11 species) and in very shallow 

 water, six inches deep (6 species). A deeper water fauna 

 was discovered in Lower South Bay and vicinity (15-18 feet 

 deep) including such species as Anmicola einarginafa and 

 Valvata sincera, which have not been previously reported from 

 the lake. Variation of the habitat was observed in relation 

 to age and season, many young living in algse in comparatively 

 deep water in summer and in the fall migrating to shallow 

 water near the shore. .Icella, Galha, Physa, and Lymncca 

 were noted to exhibit this habitat migration. A striking fea- 

 ture of the July field work -was the observation that quite the 

 majority of the individuals were young or immature at this 

 time of the year. It was also noted that many species were 

 below the normal in size. This was also true of many of the 

 associated animals. The majority of mollusks live in the fila- 

 mentous algae which covers, to a large extent, the bottom of 

 the bay. 



