The Food of Fishes. 43 



of the preceding group, diifered 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 Corlxa tunilda. 



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 insects, — 

 almost wholly Corixas and the larva^ of Maj^-flies (Ephe- 

 meridie). The Corixas were C. alternata^ Say, and G. tu- 

 mida^ Uhl. 



Food of the Adult . 



Turning to the food of the fourteen adults, we note the 

 total disappearance of Entomostraca, the merely accidental 

 occurrence of insects, the appearance of crawfishes {Cmn- 

 ba7'us immunis), which amount to seven percent, 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 recogni- 

 zable. 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 Entomostraca 

 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 the 

 hickory-shad (Dorysoma), — and feed upon crawfishes also 

 to some extent. 



