The Food of Fishes. 47 



Ambloplites rtjpestris, Raf. Rock Bass. 



This favorite and widely distributed species does not 

 diifer from the otlier fishes me7itioned in respect to the 

 food of the young. The smallest specimen examined, five- 

 eighths of an inch long, contained only a few Cladocera 

 (Pleuroxus). Another, three-fourths of an inch long, had 

 eaten Daphnids (seventy-five per cent.), Cyclops (ten j)er 

 cent.), and larvae of Ohironomus. A third, seven-eighths 

 of an inch long, contained only minute fragments of a few 

 larva^ of Neuroptera. These specimens were all taken 

 from Fox River, in July, 1879. The remaining young of 

 the year were living chiefly on Corixa (eighty-three per 

 cent.), as were also the young of the year preceding (nine- 

 ty per cent.), so far as could be judged from the food 

 of two specimens, from three to four inches in length. 

 Some land insects, ephemerids, water-beetles, and a few 

 Allorchestes were also found in the food. 



Four adult specimens, taken at Ottawa, on the 8th of 

 July, had eaten some minute fishes (fifteen per cent.), a 

 few water-beetles, including Tropisternus Ihnhatus^ over 

 forty per cent, of Neuroptera larva^, and about thirty per 

 cent, of small crawfishes. The Neuroptera included Baetis 

 and other ephemerids (twenty per cent.), Agrionida? and 

 large Libellulidfie, and fifteen per cent, of case-flies (Phry- 

 ganeidas). Pond-weed (Potamogeton) found in two stom- 

 achs, had probably been taken accidentally. 



OHyENOBRYTTUS GULOSUS, 0. & V. WiDE-MOUTHED SUNFISH. 



This fine species is among the commonest of the family 

 in the lakes and ponds of southern Illinois, where it is 

 commonly known as the "goggle-ej^e." 



The northern limit of its range, so far as known, is the 

 Illinois River valley. In number and habitat it replaces 

 in the south the Eupomotis aureus of the north; but this 

 equivalence is only apparent, as the two species differ 

 widely in food. From its size and abundance, it is no in- 

 significant food resource. 



Fo Oil of the Y o u n q . 

 My smallest specimens were from lakes in the Mississip- 



