160 College of Forestry 
(op. cit., p. 21) finds upwards of twelve species of mollusks 
in the stomachs of fourteen specimens of fish from Lake 
Michigan. These are noted below: 
Galba catascopiuin. Planorbis parvus. 
Galba species (juvenile). Valvata tricarinata. 
Physa species (juvenile). Valvata sincera. 
Amnicola limosa. Spherium striatinum. 
Amnicola porata. Sphawriam (new species). 
Amnicola lustrica. Pisidium (several species). 
In three cases out of fourteen, mollusks formed the bulk 
of the food, being present to the extent of 60, 90 and 95 
per cent. ‘One individual contained all but two of the species 
listed. Of the mollusks it was found that: 
Pisidium constituted from 0 to 60 per cent of total food, averaging 
16 per cent. 
Spherium constituted from 0 to 55 per cent of total food, averaging 
7 per cent. 
Valvata constituted from 0 to 10 per cent of total food, averaging 
2 per cent. 
The balance of the other invertebrate food consisted of 
Mysis relicta (20 per cent.), Pontoporeta hoyr (43 per 
cent.), Hurycercus lamellatus, and chironomid and hydro- 
philid larvee (about 8 per cent.). 
In Walnut Lake, Michigan, Hankinson (1908, p. 201) 
found the Whitefish to subsist almost exclusively on the larvee 
of small flies. During the spring 30 specimens were exam- 
ined, 19 of which contained insect food, and one a few mol- 
lusk shells. The insects consisted principally of midge 
larvee and pup, with a few larve of Sayomyia, Sralis, and 
other insects. In a few examples a small percentage of fish 
remains was present. In August, nine Whitefish were exam- 
ined and found to have eaten no midge larvie,; the stomach 
contents being almost all entomostracans of the genus 
Daphma, apparently taken from the water above the bottom 
as they were free from dirt. 
