THE FOOD OF THE SMALLER FRESH-WATER FISHES. 
By S. A. FORBES. 
In a paper on the food of fishes, published in 1880,* I charac- 
terized the food of all the Illinois Acanthopteri, with the excep- 
tion of the Aphredoderidag ; and in the present article, which is 
to be regarded as a continuation of that just mentioned, I propose 
to summarize mj observations on all the smaller fishes occurring 
in the waters of the State, with the exception of the darters 
(Etheostomatinag), 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, Cottidag, Gasterostei- 
dag, Atherinidag, Cyprinodontidag, Umbridag, and Cyprinidag. 
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 structure to food-habits than 1 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 by a de- 
tailed statement of the observations made upon its food, and 
closing 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. 
