THE FOOD OF THE SMALLER FRESH-WATER FISHES. 



By S. a. FORBES. 



Ill a paper on tlie food of fishes, published in 1880,* I cliarac- 

 teiized tlie food of all the Illinois Acanthopteri, with the excep- 

 tion of the Aphredoderid;e; and in the present article, which is 

 to be regarded as a continuation of that just mentioned, I propose 

 to summarize my observations on all the smaller fishes occurring 

 in the waters of the State, with the exception of the darters 

 (Etheostomatiniv), which were treated in the preceding paper. 



The purposes and methods of the investigation upon which the 

 following discussion is based, are so similar to those already de- 

 scribed, that they will not need any especial present explanation. 



The data for it have been obtained by a minute and careful 

 study of the contents of the alimentary canals of 319 specimens, 

 belonging to twenty-five species, representing twenty-two genera 

 and seven families, namely: Aphredoderidae, Cottidae, Gasterostei- 

 dt\?, Atherinida^, Cyprinodontid:e, Umbridic, and Cyprinid;e. 



An additional feature is the description of the structures sub- 

 sidiary to alimentation, given, in this paper, for each genus, in or- 

 der to furnish a basis for a more exact discussion of the relations 

 of structvire to food-habits than ] attempted formerly. Under 

 this head I have included the length and complication of the ali- 

 mentary canal, the character of the pharyngeal structures, the 

 number and development of the gill-rakers, and the presence of 

 any peculiar prehensile apparatus about the mouth. 



First giving for each species a brief account of its numbers and 

 distribution throughout the State, I shall add for each genus a de- 

 scription of these alimentary structures, following this l)y a de- 

 tailed statement of the observations made upon its food, and 

 closino- with a summary of such observations, and a discussion of 

 the correlations of structure to food characters, given sometimes 



'Bulletin No. 3, 111. State Lab. Nat. Hist., pp. 18-65. 



