72 
The Food of the Smaller Fresh - Water Fishes. 
to those of Fundulus, except that the intestine is possibly a little 
longer, being about equal to the head and body. The only strik- 
ing peculiarity is the depressed head, with the mouth placed at the 
upper angle and opening obliquely upward. This, with the surface- 
swimming habit of the fish, has given rise to the supposition that 
it feeds largely upon surface insects; but I did not find this to be 
the case, as the seventeen specimens studied contain no example 
of an insect of this character. 
These specimens were taken from a considerable variety of situ- 
ations throughout Central and Southern Illinois, and at various 
times of the year. The animal food amounted to about ninety 
per cent, of the whole. Vegetation, almost wholly filamentous 
Algae, was taken by ten of the specimens, but in such quantities 
by various individuals as to make it certain that its presence was 
not accidental. In one, for example, the intestine was packed 
with these Algae to the exclusion of all other food, and in three 
others this made more than half the whole. One specimen had 
also eaten Wolffia. Mollusks (Physa) had been eaten by three, 
and insects amounted to seventy-three per cent. Spiders and 
various terrestrial insects made fully a fourth of the food. Philhy- 
drus, taken by three of the specimens, was reckoned at eight per 
cent. Corixa and other aquatic Hemiptera amounted to eleven 
per cent., and larvae of Agrion to three. Crustacea were esti- 
mated at only six per cent. They included Grangonyx gracilis , and 
various Cladocera, Ostracoda and Copepoda. Among the Ento- 
mostraca recognized were Daphnia, Chydorus, Pleuroxus, Acro- 
perus, Cypris, and Cyclops. Chironomus larvae were about one 
per cent., taken by only two of the specimens. 
Zygonectes inurus, Jor. and Gilb. Black-eyed Top Minnow. 
Zygonectes dispar, Ag. Striped Top Minnow. 
The first of these species is peculiar in this State, as far as 
known, to Southern Illinois, not having been taken by us nortli of 
White County. The second ranges throughout. 
Six specimens of the first and two of the second were studied. 
The food characters presented do not differ sufficiently from those 
of Zygonectes notatus to make it worth while to treat them sepa- 
rately, and a summary for the genus will be given instead. 
