-toy 



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 

 Jakes and ponds. 



The head and mouth are unusjLially large for a minnow ; the in- 

 testine 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 Cyprinidae), 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 larvse were found in 

 the food of these fishes. Of neuropterous larva- only a trace oc- 

 curred, aquatic Coleoptera were noted in two, and Corixa in one. 

 Grasshoppers (Acrididse) 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 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 Alga?, the rem linder 

 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 Algse composed ninety-four per cent, of the 

 food. 



Cbratich.hys biguttatus, Kirt. Horned Chub. 



This species is everywhere abundant northward, chiefly, like Semot- 

 ilus, 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 larvfe, 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 

 Algee and seeds of Setaria and other grass-like plants. 



Notwithstanding the small ratio of insects figured out, it is 

 worthy of note that two specnnens 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, 



*Thesi' woro not from tlie saino spooimciis as those containing tlie jirasshopiHrs. 



