490 Illinois State Laboratory of Natural History. 



in a single gizzard shad, in a stone cat, and in a top minnow. 

 The commonest forms, as would be supposed, were those pro- 

 tected by permanent shells; viz., Difflugia, Centropyxis, Arcella, 

 and the like; but occasionally specimens of Actinosphserium, 

 Euglena, and Dinobryon were present and recognized. 



SCAVENGERS. 



The only scavenger fishes of our collection were three 

 species of the common catfishes; the spotted cat, the yellow 

 cat, and the marbled cat, — all of which had eaten dead animal 

 matter, including pieces of fish, ham, mice, kittens, and the 

 like. A single large-mouthed black bass had likewise eaten 

 food of this description. 



VEGETABLE FEEDERS. 



Considering the wealth of vegetation accessible to aquatic 

 animals, and the fact that few other strictly aquatic kinds 

 have the vegetarian habit, it is indeed remarkable that the 

 plant food of fishes is an unimportant part of their diet. Taking 

 our nine hundred specimens together, the vegetation eaten by 

 them certainly would have amounted to less than ten per cent, 

 of their entire food, and excluding vegetable objects apparently 

 taken by chance, it probably would not reach five per cent. 



The greatest vegetarians are among the minnow family, 

 largely in the genera Hybopsis, Notemigonus, and Semotilus, 

 thirteen specimens of the first and twenty-five of the second 

 having taken about half their food from vegetable objects. 

 One hundred and twelve Notropis, twenty-two Semotilus, 

 eighteen Hybognathus, and nine Campostoma, had found in 

 the vegetable kingdom a fourth or fifth of their food. Count- 

 ing each genus as a unit, I find that the family as a whole 

 obtained from plants about twenty-three per cent, of its food. 

 The little Phenacobius, already reported as strictly insectiv- 

 orous, was the only one studied in which vegetation can scarcely 

 be said to occur. 



The mud minnows (Umbridifi) are also largely vegetarian 

 (forty-one per cent.) ; and likewise the cyprinodonts, the vegeta- 



