72 The Food of the Smaller Fresh - Water Fishes. 



to those of Fimdulus, except that the intestine is possibly a little 

 longer, being about equal to the head and body. The only strik- 

 ino- peculiarity is the depressed head, with the mouth placed at the 

 upper angle and opening obli(piely 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 

 Alo-a?, 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 Algte 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 larva? 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 larvse were about one 

 per cent., taken by only two of the specimens. 



Zygonectes inukus, 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 north 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 difier sufficiently from those 

 of Zijgo)iectes notatus to make it worth while to treat them sepa- 

 rately, and a summary for the genus will be given instead. 



