The Relation of Mollusks to Fish in Oneida Lake 211 
from the adult gill-marsupia they quickly fall to the bottom, 
to await the passing of some bottom inhabiting fish. Their 
occurrence in the plankton is probably quite accidental. The 
plankton of Oneida Lake has not been examined. During 
September, 1915, the alga Rwularia was so abundant as to 
cloud the water and form a dense surface layer making obser- 
vations quite out of the question even with a water telescope, 
the plankton extending to the bottom in shallow water. The 
wind shifted it from shore to shore and studies had to be con- 
ducted on the shore from which the wind was blowing. 
E. SUMMARY. 
In the foregoing pages 54 species of fish have been reviewed 
as to their food habits; 46 are more or less mollusk-eaters. 
In Table No, 11 all of our fresh-water mollusk-eating fishes 
are listed together with all of the mollusks eaten. At the 
foot of the table the percentages together with the number of 
mollusean species eaten by one species of fish are given. The 
variation in percentages is noteworthy, being from one per 
cent (Brook Trout) to 100 per cent. (Sheepshead). In 11 
species (noted in column by a ¢) the percentages of molluscan 
food eaten is not given, and these might affect the total 
average a trifle. These are estimated at one per cent. The 
average for the 35 ratios ts 23.97 per cent. Among these 
may be noted Sheepshead, 100 per cent., Lake Sturgeon and 
Spotted Sucker, upwards of 90 per cent., Common Red-Horse, 
62 per cent., Pumpkinseed, 51 per cent., Short-headed Red- 
Horse, 50 per cent., Common Sucker, 30 per cent., Whitefish, 
26 per cent., Common Bullhead, 20 per cent., and Golden 
Shiner, 19 per cent. In five species the molluscan ratio falls 
to one per cent. It is to be noted that the majority of the 
species listed in Table No. 11 are bottom feeders, which 
accounts in a measure, for the large ratio of mollusks in their 
food. As has been stated elsewhere in this report, many 
of the species of fish have especially modified mouths pro- 
vided with crushing apparatus of greater or less complexity 
which indicates a mollusean diet. 
