80 The Food of Young Fishes. 



Other specimens of this genus, making thirteen in all, 

 none longer than an inch and five-eighths, were obtained 

 from various places on the Illinois, and from mud-holes in 

 the Mississippi bottoms, in Union Co. These thirteen in- 

 dividuals were feeding almost wholly on Entomostraca and 

 larvas of Chironomus, the latter composing seventy-four 

 per cent, and the former eighteen per cent, of their food: 

 Twenty-two per cent, of Oladocera include Sitnocephalus 

 americanus and S. vetuliis^ Ceriodaphnia, and Macrothrix 

 laticornis,* J ur., a species not hitherto reported from this 

 country. Among the Lynceidse (ten per cent.) I recog- 

 nized Ohydorus, Pleuroxus detitatus^ Alona and Eurycercus 

 lamellatus^ and among the Ostracoda a species of Candona 

 answering precisely to the description of Caiidona hifasci- 

 ata^ Say. A few young Amphipoda and a few unknown 

 insects' eggs account for the remainder of the food. 



Six specimens of Noturus sialis^ varying in length from 

 seven-eighths of an inch to an inch and a quarter, differed 

 from the foregoing in the much larger proportion of Chi- 

 ronomus larvae (forty-one per cent.) and in the twenty-six 

 per cent, of young AUorchestes dentata^ — eaten by the 

 larger specimens. These had also taken seven per cent, 

 larvae of Ephemeridje. Those under an inch in length were 

 peculiar only in the large ratio of Chironomus larva^ (sixty- 

 five per cent.), a fact probably indicating that this species 

 seeks its food chiefly on the muddy bottoms. 



No specimens of the other genera of catfisheswere taken 

 small enough to show their earliest food, but so far as 

 can be judged from the food of four specimens of Ictalu- 

 rus, from two and a half to three and a half inches long, 

 the other genera will not be found to differ especially from 

 the foregoing. 



Amiid^. 



A single dog-fish (Amia), one and three-fourths inches 

 long, taken in June, had eaten seventy per cent, of Ento- 

 mostraca, — about equally Copepoda and Cladocera, — and 



*Possibly this is not the species cited, but a careful comparison, with 

 the description and figures in Lilljeborg's "Crustacea ex Ordinibus 

 Tribus," etc., failed to show any difference. 



