The Food of Fishes. 
time as others of the preceding group, .differed from 
them in the smaller number of Entomostraca eaten, and 
the larger number of insects — differences evidently only 
to be explained as due to the different sizes of the fishes. 
The next two specimens, between two and three inches 
long, had eaten only insects, chiefly Corixci tumida. 
Four specimens, ranging from three to three and a 
half inches in length, all taken from a lake in the Illinois 
River bottom, in October, 1879, had eaten nothing but in- 
sects — almost wholly Corixas and the larvae of May-flies 
(Ephemeridae). The Corixas were C. alternate, Say, and 
C. tumida, Uhl. 
Food of the Adult. 
Turning to the food of the fourteen adults, we note the 
total disappearance of Entomostraca, the merely acci- 
dental occurence of insects, the appearance of crawfishes 
( Cambarus immunis ), which amount to seven per cent, of 
the whole food, and the great predominance of fishes 
(eighty-six per cent.). These were of sufficient variety 
to show that no group is safe from the appetite of the 
bass unless it be the gar. 
Perch, minnows, catfish and hickory-shad were recog- 
nizable. The last were much the most abundant, occurring 
in eight of the specimens, and constituting fifty-eight per 
cent, of the food of the whole number. They ranged 
from three to six in each stomach, and were from three 
to four inches long. It should be noted, however, that 
these were all eaten by fishes taken at the same place and 
time. A large mouse was found in the stomach of one 
bass from the Illinois River. 
We may generalize these data by saying that this black 
bass lives, at first, wholly on Entomostraca; that it com- 
mences to take the smallest aquatic insects when about 
an inch in length, and that minute fishes appear in its 
diet almost as early. From this forward, the Entomos- 
traca diminish in importance, and the insects and fishes 
become larger and more abundant in the food. The 
adults eat voraciously of a great variety of fishes — 
especially fhe hickory-shad (Dorysoma.) — and feed upon 
crawfishes also to some extent. 
