The Food of the Smaller Fresh- Water Fishe.^. Si 



NOTEMIGONUS CHRYSOLEUCUS, Mitcll. ShINEK. 



This extrenielj abundant minnow, commonly called the shiner, 

 occurs in all waters throughout the State, from the largest rivers 

 to the smallest creeks, and from Lake Michigan to small stagnant 

 ponds. 



The intestine is shorter than in any of the preceding species, 

 although still rather long, the head and body being contained one 

 and one-third times in its length. The gill-rakers are long, fine, 

 and numerous, about twenty in number on the anterior arch, and 

 fully one-third the length of the corresponding filaments, making, 

 tlierefore, an effective apparatus for the separation of the Ento- 

 mostraca fi-om the water. As this fish presents a peculiar combi- 

 nation of alimentary structures, and as its food was found unusu- 

 ally various, a larger number of specimens were studied than of 

 any of the species already discussed. 



Twenty-five fishes were dissected, from a great variety of sit- 

 uations in all parts of the State, and representing various dates 

 from May to September inclusive. As the food differed Avidely 

 according to situation, that of specimens from certain localities 

 being more widely different than the food of different species 

 has usually been found, it will be best to mention the most con- 

 spicuous differences depending upon situation. 



Specimens taken from the Pecatonica River at Freeport, an 

 extraordinarily muddy stream, noted for the abundance of its 

 mollusks, had eaten no other food than univalve MoUusca, chiefly 

 Valvata tricarinata and Plaiiorbis dejlectus. Another, from the 

 Illinois River at Pekin, had also eaten largely of mollusks, while 

 tiu-ee taken in Otter Creek in Jersey County, in almost stagnant 

 reaches of the stream, extremely muddy, and green with Algse, 

 had filled their intestines with mud, like Campostoma; and still 

 others from ponds near Normal had eaten only Entomostraca, 

 about equally Cladocera and Copepoda. Another specimen from 

 the Illinois River had taken similar food, all Daphnias. One speci- 

 men from Nippersink Lake, in the northern part of the State, was 

 full of wild rice (Zizania). Taking all these groups together, and 

 considering the species as a whole, besides the mud already men- 

 tioned, about fourteen per c(!nt. of the food consisted of mollusks, 

 and only six per cent, of insects, nearly all of which were of 



