88 The Food of the Smaller Fresh - Water Fishes. 
Phenacobius scopiferus, Cope. 
This species occurs not very abundantly throughout the State, 
from Galena to extreme Southern Illinois. It has been taken by us 
almost invariably in swift and shallow streams. 
The mouth is small and inferior, provided with fleshy lips 
somewhat resembling a sucker’s in form. The gill-rakers and 
pharyngeal teeth are as usual in this group and the intestine is 
contained once and a half in the length of the head and body. 
The nine specimens studied were from five localities, distributed 
from Galena to Union county. The food was almost purely insects, 
only two per cent, being unrecognized vegetation. Seventy-six per 
cent, consisted solely of Chironomus larvae, and six per cent, of 
case-worms. Adult chironomids, taken by two of the specimens, 
amounted to two per cent. A few Cyclops found in a single 
specimen were the only Crustacea eaten by these fishes. 
The peculiar character of this food, almost precisely that of a 
darter, is evidently related to the habitat of the fish.* 
Semotilus corporalis, Mitch. Chub. 
This is a widely distributed and very abundant fish, perhaps the 
commonest species in the small creeks; but is less abundant in 
lakes and ponds. 
The head and mouth are unusually large for a minnow; the 
intestine is six-sevenths the length of the head and body; and the 
gill-rakers are of the usual form. 
Twenty-two specimens, from widely separated localities, give a 
ratio of seventy-six per cent, of animal food, four per cent, being 
fishes (partly Cyprinidge), thirteen per cent, vegetation, and three 
per cent, worms. Insects make a little over half the whole, about 
one-half of them terrestrial. No Chironomus larva? were found 
in the food of these fishes. Of neuropterous larvge only a trace 
occurred, aquatic Coleoptera were noted in two, and Corixain one. 
Grasshoppers (Acrididge) made ten per cent, of the whole and were 
eaten by three of the specimens. Five had taken crawfishes, 
which made twelve per cent, of the entire food. No Entomostraca 
were noted, with the exception of one per cent, of Cyclops 
*For a discussion of this matter, see Bulletin 3 of this scries, p. 25. 
