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 gen- 
eralizations 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 
individuals. 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 ACANTHOPTEBI. 
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 1 1 brook silversides,” which is placed 
by Drs. Gill and Jordan in another group. It embraces 
all our game fishes except those belonging to the pickerel 
family (Esocidce) and the salmon family (Salmonidce ) . 
Its principal members are the darters, the various spe- 
cies of perch and bass, the sunfishes, and the sheepshead. 
Forty-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 Centrar- 
chidce (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 or catfishes 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.” 
