The Pradiiclk'Uy of Fish Food in Oneida Lake 157 



one and a half feet (Wilson and Clark, '14, p. 24). At various 

 other localities in the river, mussels were found on a gravel and 

 clay bottom in from 5 to 20 feet of water. The current was 

 usually from two to four miles an hour. 



The lakes and streams of central and northern Minnesota 

 have been examined to some extent by the United States 

 Bureau of Fisheries for their mussel fauna (Wilson and 

 Danglade, '14). In Lake Minnewaska c^uantities of mussels 

 (including Laiupsilis luteola which is common in Oneida 

 Lake.) were found on a bottom of sand and rather fine gravel 

 in water from 12 to 15 feet deep (1. c, p. 23). In Lake 

 Benidji mussels were collected on a sand bottom, buried two 

 and three feet deep and they were placed as thick as they could 

 lie (p .15). In Shell River, at Twin Lakes, near Menahga, the 

 fishermen are obliged to rake off the algae and weeds which 

 cover the bottom before they are able to dig the mussels, which 

 are buried in the underlying gravel and sand to the depth of a 

 foot or more (p. 15). These examples of buried, living mus- 

 sels are interesting. Similar conditions have not been .met with 

 in Oneida Lake. For these observations a bottom sampler 

 similar to that used by Petersen but somewhat larger is neces- 

 sary to bring up the sample with the bottom layers intact. A 

 dredge a foot square would be admirable for the purpose. 



4. Relation of Age and Season to Migrations. It has been 

 observed that there is a relation between the range in depth, 

 age and season in some of the mollusks of Oneida Lake. 

 Certain species inhabit the deeper water of the lake when 

 young, which is usually in the spring or summer, and later in 

 the year migrate to the shore or surface of the water. The 

 slender pond- snail Acella haldemani occurs on vegetation, 

 usually Potamogeton, at depths of one and a half to four feet 

 when young (in July) and when adult, which is in August or 

 September, it seeks the larger vegetation of the surface, or near 

 the shore, lily-pads, rushes, pond-weeds, etc., when these plants 

 are used for food and support. It is not definitely known 

 whether Acella completes its growth in one or more years, but 

 no adult shells could be found anywhere during July. Only 

 young were seen and these were rare. 



