200 Fortieth Annual Meeting 



fishes of the zone. None were found in stomachs, and 

 often they were seen in company with black bass forming 

 apparently peaceful associations. Three whitefish were 

 caught in some 15 feet of water in the pondweed zone in 

 April. Their food was more heterogeneous than in those 

 caught in deep water. It contained besides many midge 

 larvae, small mollusk shells and Sialis larvae. 



3. THE RUSH ZONE 



From the shore line out to the growth of pondweeds was 

 a shoal area with water not much exceeding four feet in 

 depth and varying in width from a few to some five hun- 

 dred feet. Lake bulrushes {Scirpus lacustris) were the 

 conspicuous plants here ; but they formed thick growths only 

 in a few places. There was, however, evidence of their 

 greater abundance in former times on the shoals now barren 

 of them, by the presence of old rush roots and rootstocks 

 in the bottom material, and from testimony of people who 

 have lived in the region of Walnut Lake for many years. 

 Two factors in the destruction of bulrushes in the lake were 

 apparent, and these were ice and the ravages of muskrats. 

 Small stone worts {Char a) formed a scant, even, but in- 

 conspicuous growth in shallow water everywhere except in 

 places with much sand in the bottom material or where 

 stones were numerous. 



The shoal region of the lake was much frequented by 

 fishes small and large, but these latter were seen upon it 

 only during the spring and early summer months, which 

 was probably because their food, chiefly in the nature of 

 crayfish and insect larvae, was most abundant in shallow 

 water at that time of year (this was apparent from our 

 observations and collections), or perhaps in some cases they 

 were looking for nesting places, for, as mentioned later, a 

 number of them use the shoals for nesting. In late summer 

 the shallow water was deserted by all but minnows and 

 other small fishes ; and these were rarely seen except where 

 the bottom was stony or where there was much vegetation. 



