The Food of Fresh-Water Fishes. 435 



moxys), eaten however by only one of the specimens. Twenty 

 of the thirty-seven pike had taken gizzard shad (Dorosoma), 

 which made forty-six per cent, of the entire food of the species. 

 Cyprinidae (chiefly Notropis hudsonius) were found in two, and 

 three had eaten buffalo fish (Ictiobus cyprinellus and /. bubalus). 



Esox VERMICULATUS, LeS. BROOK PICKEREL. 



This fish so far as its food structures are concerned a 

 miniature of the preceding is abundant throughout the State 

 in ponds and lakes and along the borders of streams, especially 

 by the weedy margins of rivers. I have studied the food of 

 eighteen examples, and found it to differ from that of the larger 

 species only as was to be expected from the smaller size of this 

 pickerel, (which rarely reaches a foot in length), and from the 

 character of its favorite haunts. 



The specimens selected for examination were from various 

 localities in northern, central, and southern Illinois; repre- 

 sented lakes, rivers, and smaller ponds; and were collected in 

 June, July, and October of different years. 



Two had eaten the tadpoles of frogs, and eight had cap- 

 tured fishes, which made about half of the food of the entire 

 group. Only three of these were recognizable ; one a cyprinoid, 

 one a sunfish, and the other (Gambusia patruelis) a common 

 top minnow of the southern part of the State. 



Aquatic insects formed the next most important element 

 of the food, reaching thirty-five per cent., and eaten by nine of 

 the specimens. The greater part of these were larvae of Agrion 

 and larger Odonata, only four per cent, being Hexagenia larvae. 

 One specimen had taken an isopod (Asellus), but no other 

 crustaceans occurred. 



The food of this group may consequently be generalized 

 as consisting of the larger aquatic insect larvae and the smal- 

 ler fishes in nearly equal ratio, with occasional larvae of 

 Batrachia.* 



*Five additional specimens of this species, too large to be reck- 

 oned examples of the young and yet too small to class as adults had 

 eaten, like the full-grown examples, chiefly fishes and neuropterous 

 larvae. A specimen only an inch and a half in length had swallowed 

 a fish ; one three and a fourth inches long had likewise t-Ken only a 



