121 
Six specimens between one and three inches long, differed espe- 
cially in the introduction of about eighteen per cent. of Corixas 
and three per cent. of small ephemerid larve. Chironomus larve 
were reduced to seven per cent. The Entomostraca were about 
equally divided between 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 exam- 
ined. Highty-three per cent. of their food was Kntomostraca, about 
three-fourths of this amount being Cyclops, and the remainder 
nearly all Simocephalus. Twelve per cent. of larve of Chironomus 
and Corethra, three per cent. Corixas and two per cent. larve of 
small ephemerids were the insect elements. Chydorus, Pleuroxus 
-and Cypris were present in small numbers. 
These fifteen young, agreeing so closely in food, irrespective of 
size, were nevertheless from a variety of situations and dates. All 
were from the Illinois River, its lakes and tributaries, from Ottawa 
to Pekin, but ranged in time from June to October in three differ- 
ent years. 
Six were P. nigromaculatus, seven. were P. annularis, and two 
were not identified specifically. 
Food of the Adults. 
An examination of the notes on the twenty-seven adults shows 
material differences of food at different parts of the year. As all 
but one were taken from the Illinois River, I have not the means 
of noting the correspondence of food with locality. 
Five specimens taken at Peoria, in March, were found feeding 
most freely upon Cladocera, which composed fifty-five per cent. of 
their food. These were chiefly of the two species Simocephalus 
vetulus and S. americanus. These little Entomostraca were taken 
at that time in such quantity as visibly to distend the stomach 
when seen from the outside, and the immense numbers of their | 
eggs gave a reddish color to the contents of the alimentary canal. 
The larvae of Neuroptera, both ‘“‘darning-needles” and May-flies 
(Palingenia), were also eaten in considerable numbers (thirty-nine 
per cent.). A small Hybopsis, a little darter (Boleosoma maculatum) 
and an unrecognizable fish were found in these stomachs, making 
about six per cent. of the food. Only trivial numbers of Ento- 
mostraca appear after this time. 
Nine specimens, taken in April, likewise at Peoria, were feeding 
chiefly upon Neuroptera larve (eighty-six per cent.), especially upon 
that almost invaluable element of fish food, the larve of Palingenia 
bilineata (sixty-six per cent.). A few larve of Gyrinide and Dytis- 
cide were noted (three per cent.’, and a few Corixas also. A Gam- 
marus fasciatus and a little Ceratophyllum, etce., were noticed; and 
also the flower of an elm and the feather of a bird. ; 
A single specimen from Pistakee lake, in McHenry county, taken 
in May, gave evidence of a similar reliance upon neuropterous 
larve (eighty-five per cent.) Here, howéver, in the absence of 
