452 Illinois State Lahoratori/ of Natural Ilistori/. 



This species seems to differ in food from the preceding, 

 especially in the inferior amount of mollusks and the larger 

 ratio of vegetation. The animal food of seventeen specimens 

 collected in seven lots from the Illinois and Mississippi Rivers 

 and the northern lakes in various months from April to Octo- 

 ber of five different years, was about two thirds the whole, the 

 remaining third consisting largely of Algae, unicellular and 

 filamentous, and otherwise chiefly of distillery slops (taken by 

 Illinois River specimens) and miscellaneous vegetation of ter- 

 restrial origin. This last was occasionally found in quantities 

 sufficient to show that it had been intentionally swallowed, 

 making in one instance the greater part of the food. The 

 molluscaa food of these specimens amounted to only three per 

 cent., nearly all Spheerium ; the insect food to thirty-three per 

 cent., practically all aquatic, and very largely larvse of Chi- 

 ronomus (twenty per cent.). The Neuroptera were chiefly 

 Hexagenia larvae (nine per cent.). Except a single Crangonyx, 

 the Crustacea were all Entomostraca. These occurred in 

 much greater variety than in cyprinellns, among them being 

 representatives of Daphnella,Simocephalus, Bosmina, Chydorus, 

 Pleuroxus, Alona, Cypris, Cyclops, and Canthocamptus. Frag- 

 ments of Plumatella were noticed in a single specimen, Dif- 

 flugia in two. 



IcTioBUS URUS, Ag. Black Buffalo ; Mongrel Buffalo; 

 Big-mouthed Buffalo; Chuckle-head. 



This species occurs commonly with the preceding, but less 

 abundantly. Said by fishermen to frequent shallower water. 



With respect to food, it closely resembles cyprinellus, our 

 seventeen specimens, well distributed as to date and place, 

 having taken almost identical ratios of animal and vegetable 

 food — sixty-seven per cent, and thirty-three per cent, respec- 

 tively. Twelve per cent, were mollusks, — nearly all Sphaerium, 

 as before. The large ratio of insect food (about forty-two 

 per cent.) was more than half Chironomus larvae, most of the 

 remainder being Hexagenia larvae, taken, however, by only one 

 of the specimens. The Crustacea (thirteen per cent.) were 

 practically all Entomostraca, fragments of a young crayfish 

 appearing in only a single specimen. 



