22 The Food of Fishes. 



structure and food habits sufficiently detailed and exact 

 to make the tedious and difficult labor of examining the 

 contents of stomachs unnecessary hereafter. Some gener- 

 alizations of this sort are given in the following pages, and 

 others relate to genera not included in this report. 



The method of this paper differs from that of the pre- 

 vious one referred to by the calculation of the ratios of the 

 different kinds of food for each species or group of indi- 

 viduals. These ratios were obtained by averaging careful 

 estimates of the relative amounts of the different food 

 elements found in each stomach. 



It is proposed to follow a similar method hereafter down 

 through the remaining orders of the class. Most of the 

 material has been collected for this purpose, and much of 

 it has been already studied. 



Order TELEOCEPHALI. 

 Suborder AOANTHOPTERI. 



This suborder includes all Illinois fishes which have the 

 anterior dorsal fin (where there are two) or the first rays 

 of the dorsal (where there is but one) stiff, spinous, and 

 sharp, and united by an evident membrane ; excepting 

 only the remarkable "brook silversides," which is placed 

 by Drs. Gill and Jordan in another group. It embraces 

 all our game fishes except those belonging to the x)ickerel 

 family {Esocidce) and the salmon family {Salmonidae). 

 Its principal members are the darters, the various species 

 of perch and bass, the sunfishes, and the sheepshead. For- 

 ty-six species of the order have been collected in the state, 

 but only thirty-four of these are common enough to form 

 features of any importance in our fish fauna. 



The most numerous family of the group is the Centrarchi- 

 d(B (sunfishes) ; the most important species are the two 

 kinds of black bass, the pike-perch or "wall-eyed pike," * 



*It is generally to be desired that the absurd names of "Salmon" and 

 "Jack Salmon" for these species should be suppressed. They might as 

 well be called suckers orcatfislies or minnows, as far as accuracy is con- 

 cerned. Common names are many times harder to kill than the cat of 

 the proverb, however; and it is probable that unnumbered generations 

 will continue to call the pike-perch "salmon"; the sunfishes, "perch" ; 

 and the black bass, "trout." 



