68 



■finds these sunicicnt to crush the shells of Splian-iuni. and our nineteen 

 specimens had obtained about one-foni'lh of their food fntm this genus, 

 besides the al)ove families, smaller quantities of the bivalve mollusks oc- 

 curred in the food of one of the sunflshes [Lepomis palUdus) and — doubtless 

 by accident only — in the gizzard shad. 



The gasteropod mollusks (snails of various descriptions) were more abund- 

 ant than bivalve forms in the sheepshead and the sunflshes and all the 

 smaller tlshes which feed upon MoUusca, but less abundant in the suckers 

 and the catflshes. In the sheepshead. they made one-fifth of the food of 

 the twenty-flve sjjecimens examined, but the greater part of these had not 

 yet ])assed the insectivorous stage, this being much longer continued in 

 the sheepshead than in many other tlshes. \ few of these univalve Mol- 

 lusca occurred in the food of the common perch and in certain species of 

 suntishes, especially in the super-abundant bream or pumpkin-seed. They 

 made fifteen per cent, of the food of the minute top minnows, and oc- 

 curred in smaller q\iantities among the darters, the grass pickerel, the 

 mud minnows, and the cyprinoids. The heavier river snails. Yivipara and 

 Melantho. were eaten especially by the cylindrical suckers, and the cat- 

 flshes. The delicate pond snails (Succinea. Limna^a, and Physa) were 

 taken chiefly by the smaller mollnsk-eating flshes, — a few of them also b}' 

 the catflshes and the suckers. 



Further particulars concerning the molluscan food may be obtained by 

 the interested reader from the list of food elements at the end of this 

 article. 



INSECTIVOROUS SPECIKS. 



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

 ant portion of their food, this class furnishing, for example, forty per cent, 

 of the food of all the adults which I examined. 



The principal insectivt)rous flshes 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 flshes or Mollusca. Some of 

 these flshes have peculiar habits which render them especially dependent 

 upon insect life, — the little minnow Phanacobius, for example, which, ac- 

 cording to my studies, makes nearly all its food from insects (ninety-eight 

 per cent.) found under stones in running water. Next ai'e the pirate 

 perch. .V])hre(loderus (ninet.v-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 flsh (fifty-nine percent.), the chub min- 

 now (fifty-six per cent.), the black warrior sunfish, Chtenobryttus and the 

 brook silversides (each fifty-four per cent.), and the rock bass and the 

 cyprinoid genus Xotropis, (each flfty-two per cent.) 



Those whicli take few insects or none are mostly the mud-feeders and 

 the ichthyophagous species, Amia (the dog-flsh) being the only exception 

 noted 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 tlie 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 noted, however, that the larger fishes all go tlirough an in- 

 sectivorous stage, whether their food when adult be almost wholly other 

 tlshes. as with the gar and the pike, or mollusks. as with the sheepshead. 

 The mud-feeders, however, seem not to ])ass through this stage, but to 

 adopt the limophagous habit as soon as they cease to dejicnd iijion Ento- 

 mostraca. 



Terrestrial insects, dropping into the water accidentally or swept in by 

 rains, are evidently diligently sought and largely depended upon by several 

 species, such as the pirate perch, the brook minnow, the top minnows or 

 killitishes (cyprinodonts), the toothed herring and several cyprinoids (Semo- 

 tilus, Pimephales, and IS'otropis). 



' Dorosoma. - Pimei>hales. 



