62 
The Food of Fishes. 
had eaten little else than Entomostraca and the larvae of 
minute Diptera (Chironomus Corethra). Even full- 
grown specimens were found eating Cladocera more free- 
ly than any other food. As might be inferred from the 
pharyngeals, 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 Ento- 
mostraca and insect larvae became less abundant. 
Food of the Young. 
The smallest specimen, three-fourths of an inch long, 
had eaten about equal quantities of Cyclops and Simo- 
cephalus, with only a few Pleuroxus beside. Three, an 
inch long and under, had confined their food entirely to 
Entomostraca and Chironomus larvae — the latter form- 
ing about a fourth of th& whole. A third of the Entomos- 
traca were Cyclops, the remainder chiefly Simoceplialus. 
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 
larvae. Chironomus larvae were reduced to seven per 
cent. The Entomostraca were about equally divided be- 
tween Cyclops 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 tliree-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, Pleu- 
roxus 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 situ- 
ations 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 f 
and two were not identified specifically. 
