50 The Food of Fishes. 



of the country schoolboy and the picnic party. It is the 

 constant companion of the "bull-head" (Amiurus) and 

 "shiner" (Notemigonus) in the small stagnant ponds of 

 the prairie regions, and of the "chub minnow" (Semotilus) 

 in muddy creeks. It was found abundant with Centrar- 

 chus, Aphredoderus and Atniicrus catus, in the rapidly dry- 

 ing mud-holes,* only a few feet across, left by the retreat- 

 ing overflow of the Mississippi bottoms, in Union county. 



Fo d of the Y o ung . 



The smallest of nineteen specimens studied, was one 

 inch in length — taken in July, in a prairie pond near Nor- 

 mal. Ninety-five per cent, of its food was Cyclops and 

 three per cent. Daphnids. The trifling remainder con- 

 sisted of a Oorixa just hatched, and a Ohironomus larva. 



Nine specimens, ranging from one to two and a fourth 

 inches in length, vary so little in food that it is not worth 

 while to treat them separately. These were taken from 

 various ponds, streams and lakes in central Illinois. Their 

 food was distributed quite generally through the various 

 orders of insects and crustaceans accessible to them, show- 

 ing the indifl^erent appetite of this fish and the general 

 effectiveness of its collecting apparatus. 



Larva3 of Ohironomus, Dytiscidse, Staphylinidae, Corixas, 

 Ephemerid larvse, Decapoda, Isopoda, Cladocera, Oyprids 

 and Copepoda were all found in considerable quantities in 

 the food of these specimens. As usual, the most important 

 insects were Corixas and May-flies, — sixteen per cent, of 

 the former and twenty-nine per cent, of the latter. About 

 eight per cent, of the food was Cladocera (Daphnia, Simo- 

 cephalus, Pleuroxus, Chydorus), 



Food of the Adult. 



The eight adults, from northern and southern Illinois, 

 differed from the young in the disappearance of En- 



*All the specimens taken from these holes, so muddy that the water 

 was almost opaque, were of a peculiarly bleached appearance, — manyof 

 them almost colorless, — a fact of interest relative to the laws of coloration 

 among fishes. 



