The Food of the Smaller Fresh- Water Fishes. 
89 
occurring in two of the specimens. Numerous examples of 
Gordius were found in two, and were reckoned at three per cent. 
; of the food.* The vegetable food (twenty-four per cent.) was half 
Algm, the remainder miscellaneous vegetable debris. 
Eight had eaten only insects, two having filled themselves with 
grasshoppers. Three from a prairie stream near Normal had taken 
only crawfishes, while of four specimens captured in McLean 
County in July, filamentous Algas composed ninety-four per cent, 
of the food. 
Ceratichthys biguttatus, Kirt. Horned Chub. 
This species is everywhere abundant northward, chiefly, like 
Semotilus, in the smaller streams, but preferring swifter waters. 
We have not taken it, however, south of the center of the State. 
It differs from the preceding members of the group by the 
greater length of its alimentary canal, which considerably exceeds 
the head and body, the latter being contained in the intestine 
about one and one-fourth times. The gill-rakers are not peculiar. 
Thirteen specimens from Northern and Central Illinois had 
derived less than half their food from the animal kingdom. Only 
about one-fourth of it consisted of insects, largely case-worms and 
other neuropterous larvae, another fourth being Crustaceans 
(crawfishes), eaten, however, by only two of the specimens. The 
vegetable food (fifty-four per cent.) was about equally divided 
between filamentous Algae and seeds of Setaria and other grass- 
like plants. 
Notwithstanding- the small ratio of insects figured out, it is 
worthy of note that two specimens out of four captured in a creek 
in September had eaten only insects, chiefly case-worms, while 
these composed ninety-five per cent, of the food of another. As 
the intestines of these fishes contained a considerable quantity of 
gravel, it is evident that they had fed upon the bottom in rather 
swift wat6r. On the other hand, two specimens had derived all their 
food from vegetable sources, and three others had eaten eighty 
per cent, or more of vegetation. The extraordinary amount of 
vegetation in the food of this fish is possibly related to the 
increased length of the alimentary canal. 
•These were not from the same specimens as those containing the 
grasshoppers. 
