The Food of Fishes. 53 



These specimens were all from the Illinois River, in 

 June, July, October and November. 



Food of the Adult. 



The twenty-four adults examined were from various 

 parts of the state north of the center ; and, as the food has' 

 been found to differ so widely according to the local sit- 

 uation, I have treated them in three groups, — the first 

 including those taken in the clear, inland, northern lakes; 

 the second those from Calumet River, at South Chicago, 

 and the shallow, muddy lakes of that vicinity, and the 

 third those from the Illinois River from Ottawa to Peoria. 



The specimens from the northern lakes were taken in 

 May and June. Sixty-two per cent, of the food consisted 

 of Neuroptera, — eight per cent, being a black caddis-fly 

 (Sialis mfumata) and the remainder the larvae of large 

 dragon-flies (Libellulid^v), Agrions (eleven per cent.) 

 and Baetis (two per cent.). AUorchestes dentata was the 

 next most important element (twenty-seven per cent.). 

 A number of terrestrial insects besides Sialis appeared in 

 the food. These included a Harpalid beetle, an Aphodius 

 flmetarlus, and some grasshoppers (Tettigidse, etc.). 



The second group of four, from Calumet River, and from 

 Lake George, Indiana, was peculiar in the number of 

 tetradecapod Crustacea and case-worms taken, and espe- 

 cially in the amount of vegetation eaten. 



The Crustacea were AUorchestes (thirty-two per cent.) 

 and Asellus (twenty per cent.). The vegetation was pres- 

 ent in such quantities as to make it evident that it had 

 been taken as food. It amounted to about a fourth of the 

 contents of these stomachs. The stomach of one fish was 

 packed with a piece of the stem of a plant (apparently a 

 Scirpus) a third of an inch in diameter and six inches long. 

 Three others contained smaller amounts of confervoid 

 Algae. 



The fifteen specimens remaining were taken from the 

 Illinois in May, July, August, October and November. 

 Their food was especially noticeable for the presence of 

 mollusks (sixteen per cent.), for the number and variety 

 of land insects (fifteen per cent.), and for the large amount 



