53 



the catfishes. The delicate pond snails fSuccinea, Lemna, and 

 Physa) were taken chiefly by the smaller mollusk-eating fishes — 

 a few of them also by the catfishes and the suckers. 



It is from the class of insects that adult fishes derive the most 

 important portion of their food ; and, taken as a whole, this 

 class furnishes thirty-eight per cent, of the food of all which I 

 examined. The principal insectivorous fishes are the smaller 

 species, whose size and food structures, when adult, unfit them 

 for the capture of Entomostraca and yet do not bring them 

 within reach of fishes or Mollusca. Some of these fishes have 

 peculiar habits which render them especially dependent upon 

 insect life — the little minnow, Phenacobius, for example, which, 

 according to my studies, makes nearly all its food (ninety-eight 

 per cent.) from insects found under stones in running water. 

 Next are the pirate perch, Aphredoderus (ninety-one per 

 cent), then the darters (eighty-seven per cent.), the croppies 

 (seventy-three per cent.), half-grown sheepshead (seventy- 

 one per cent), the shovel fish (fifty-nine per cent.), the 

 chub minnow, Semotilus (fifty-six per cent), the black war- 

 rior sunfish (Chaenobryttus) and the brook silversides (each 

 fifty-four per cent.), and the rock bass and the cyprinoid genus 

 Notropis (each fifty-two per cent). 



Those which take few insects or none are mostly the mud 

 feeders and the ichthyophagous species, Amia (the dog-fish) 

 being the only exception to this general statement. Thus we 

 find insects wholly or nearly absent from the adult dietary of 

 the burbot, the pike, the gar, the black bass, the wall-eyed 

 pike, and the great river catfish, and from that of the hickory 

 shad and the mud-eating minnows (the shiner, the fat head, 

 etc.). It is to be remembered, however, that the larger fishes 

 all go through an insectivorous stage, whether their food when 

 adult be almost wholly other fishes, as with the gar and the 

 pike, or mollusks, as with the sheepshead. The mud-feeders, 

 however, seem not to pass through this stage, but to adopt 

 the limophagous habit as soon as they cease to depend upon 

 Entomostraca. 



Terrestrial insects, dropping into the water accidentally or 

 swept in by rains, are evidently diligently sought and largely 



