40 The Food of Fishes. 



Koccus CHRYSOPS, Raf. White Bass. 



This species is of medium abundance throughout the 

 northern half of the state, — most common in Lake Michi- 

 gan. A curious fact of its distribution is its rarity in Fox 

 River and the lakes connected with that stream. Indeed, 

 during several days' active collecting in this region we did 

 not see a single specimen, neither could we hear of the 

 occurrence of the species in those waters, although we 

 made careful inquiry for it among experienced fishermen. 



My notes on its food relate only to eleven specimens, of 

 which three, taken at South Chicago, in August, were 

 young, but of unknown size. Two of these had eaten only 

 Chironomus larvae and the larvae of a remarkable ephem- 

 erid ? not yet determined, and the stomach of the third 

 contained only a minute fish. The remaining eight indi- 

 viduals had depended chiefly on the larvae of May-flies 

 (sixty-nine per cent.). The other important articles of 

 their food were twenty per cent, fishes (including one sun- 

 fish — Oentrarchidae) and eight per cent, isopod Crustacea 

 (Asellus). Several attempts to secure food from Lake 

 Michigan specimens were unsuccessful, as, being taken in 

 pound-nets, their stomachs were always empty. Those 

 studied were from various interior situations in the north- 

 ern third of the state. 



MORONE INTERRUPTA, Gill. StRIPED BaSS. BrASSY BaSS. 



This fish replaces the preceding in the southern half of 

 the state, the Illinois River forming a neutral zone be- 

 tween the respective territories of the two species. 



The food of six specimens of this species was studied, all 

 taken from the Illinois River from May to October. 



Four of these were young. The smallest, one and a 

 fourth inches long, taken at Peoria, in June, 1878, had 

 eaten about equally of small Dorysoma cepedia7ium and 

 Entomostraca — forty per cent. Leptodora and ten per cent. 

 Cyclops. One, an inch and a half in length, taken at the 

 same time and place, had eaten only Dorysoma, with a 

 trace of Cyclops. The next, one and five-eighths inches in 

 length, had eaten a small undetermined fish and a few Daph- 



