40 
The Food of Fishes. 
Roccus chrysops, Raf. White Bass. 
This species is of medium abundance throughout the 
northern half of the State — most common in Lake Mich- 
igan. A curious fact of its distribution is its rarity in 
Fox River and the lakes connected with that stream. In- 
deed, 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 fisher- 
men. 
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 x 
(sixty-nine per cent.). The other important articles of 
their food were twenty per cent, fishes (including one 
sunfish — Centrarchidae) and eight per cent, isopod Crus- 
tacea (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 northern 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 cepedianum 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 
