VA 



THE FOOD OF THE SMALLER FRESH- WATEK FISHES. 



By S. a. Forbes. 



In a paper on the food of fishes, published in 188'j,* I charac- 

 terized the food of all the Illinois Acanthopteri, with the exception 

 of the Aphredoderidse ; 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 (Etheos- 

 tomatin^t"), 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, belong- 

 ing to twenty-five species, representing twenty-two genera, and seven 

 families ; namely, Aphredoderidte, Cottid<^, (lasterosteidfe, Atherinidae, 

 Cyprinodontidse, Umbridae, and Cyprinida". 



An additional feature is the description of the structures sub- 

 sidary 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 I attempted formerly. Under this 

 head I have included the length and complication of the alimentary 

 canal, the character of the pbaryngeal 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 tliroughout the State. I shall add for each genus a de- 

 scription of these alimentary structures, following this by a detailed 

 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 under the genus 

 and sometimes under the special group to which the .genus is 

 assigned. 



Family AFHREDODEKID.E. 



This family is represented by a single peculiar species {Aphre- 

 dodcrus sai/aniis), resembling the sun-fishes in most of its characters, 

 but remarkably distinguished by the fact that the vent, although 

 occupying the normal position in the young, opens in the adult far 



*Bullctin No. :!, 111. State Lab. Nat. Hist., pp. lS-<ir.. 



