48 The Food of Fishes. 



pi bottom, near Bird's Point, Missouri. Two of these, one 

 inch long and under , taken in September, 1879, had eaten 

 only Bosmina longirostris and Cyclops. Insect food first 

 appears in siDecimens one and a half inches long. Eight 

 specimens, between one and three inches long, six of which 

 were taken from a lake in the Illinois bottoms, near Pekin, 

 in October, 1879, and two from a lake in Kentucky, near 

 Cairo, Illinois, had eaten about forty percent. Entomostra- 

 ca, thirty per cent. Neuroptera larvae, and thirty per cent. 

 Corixas and Diptera larvas. Dajphnia pulex^ Simocepha- 

 lusaniericamts, Bosmina long irosti'is^ Chydorus, Pleuroxus 

 and Cyclops, were among the Entomostraca. Corixa al- 

 ternata was found among the Hemiptera. Most of the 

 Diptera (i. e., fifteen per cent.) were larval Ohironomus. 



Fo 0(1 of the Adult . 



Six adults from nvers, streams and lakes in central and 

 southern Illinois, show the usual change in food, carried 

 farther than in the preceding species. Entomostraca dis- 

 appear — except a few Chydorus in a single specimen — and 

 fishes become the principal reliance, amounting to forty- 

 seven per cent, of the food. Corixas, larvae of Palingenia 

 hilineata^ and some terrestrial Coleoptera — Anomala hino- 

 tata — which made half the food of one specimen, are the 

 remaining items. 



The especially piscivorous habit of this species is proba- 

 bly related to the size of its mouth, which is much the 

 largest among the sunfishes proper. A similar relation has 

 already been noticed between the two black bass. 



