62 The Food of Fishes. 



nute Diptera (Ohironomus and Corethra) . Even full-grown 

 specimens were found eating Oladocera more freely than 

 any other food. As might be inferred from the pharyn- 

 geals, not a trace of molluscan food was found in the forty- 

 two specimens examined, while fishes formed nine per cent, 

 of the food of the twenty- seven adults. Most of these were 

 eaten late in the season, when Entomostraca and insect 

 larvfe became less abundant. 



Food f the Yo u n g . 



The smallest specimen, three-fourths of an inch long, 

 had eaten about equal quantities of Cyclops and Simoceph- 

 alus, with only a few Pleuroxus beside. Three, an inch 

 long and under, had confined their food entirely to Ento- 

 mostraca and Ohironomus larvae, — the latter forming about 

 a fourth of the whole. A third of the Entomostraca were 

 Cyclops, the remainder chiefly Simocephalus. 



Six specimens between one and three inches long, dif- 

 fered especially in the introduction of about eighteen per 

 cent, of Corixas and three per cent, of small Ephemerid 

 larvoe. Chironomus larvae were reduced to seven per cent. 

 The Entomostraca were about equally divided between Cy- 

 clops and Cladocera. One specimen taken in July, 1879, 

 from the canal near Ottawa, had taken a large number of 

 Daphnella. 



Six specimens between three and four inches long were 

 examined. Eighty-three per cent, of their food was En- 

 tomostraca, about three-fourths of this amount being Cy- 

 clops, and the remainder nearly all Simocephalus. Twelve 

 per cent, of larvae of Chironomus and Corethra, three per 

 cent. Corixas and two per cent, larvae of small Ephemerids 

 were the insect elements. Chydorus, Pleuroxus and Cypris 

 were present in small numbers. 



These fifteen young, agreeing so closely in food, irre- 

 spective of size, were nevertheless from a variety of situa- 

 tions and dates. All were from the Illinois River, its lakes 

 and tributaries, from Ottawa to Pekin, but ranged in time 

 from June to October of three different years. 



Six were P. nigromaculatus^ seven were P, annularis.^ 

 and two were not identified specifically. 



