The Food of Fishes. 
29 
taken refuge from their enemies in the rocky highlands 
where the free waters play in ceaseless torrents, and 
there they have wrested from stubborn nature a meager 
living. Although diminished in size by their continual 
struggle with the elements, they have developed an activ- 
ity and hardihood, a vigor of life and glow of high color 
almost unknown among the easier livers of the lower 
lands. 
The following table (see page 30) will facilitate a com- 
parison of the records of the different genera. The per- 
centages were obtained by estimating carefully the ratios 
of each element of the food of each individual, and aver- 
aging these ratios for all the individuals of a species. 
Family PERCID/E. The Perches. 
This family consists, in this State, of three species — the 
common yellow perch and the two species of pike-perch 
or “wall-eyed pike.” I have examined the food of seven- 
ty-five specimens of this family, so distributed in time 
and space as to give a satisfactory idea of the usual food. 
Perca americana, Schrank. The Common Perch. Ringed 
Perch. 
This exceedingly well-known species is most abundant 
along the shores of Lake Michigan and in the small 
streams and lakes of the northeastern part of the State, 
becoming less common to the south and west. In the Illi- 
nois River at Peoria and Henry it occurs in limited num- 
bers, but in southern Illinois disappears so completely 
that even its name (there generally pronounced 
“pearch”) is transferred to a different family, the sun- 
fishes (Centrarchidae). 
My knowledge of the food of this species is derived 
from the study of the contents of forty-nine stomachs, of 
which thirty were from adults and the remaining nine- 
teen from fishes ranging from 13/16 inch to four inches 
in length. Ten localities and as many dates are repre- 
sented by these specimens. Some were taken in the Illi- 
nois River, others in Lake Michigan and its southern 
tributaries, and still others in Fox R. at McHenry, and 
in the lakes connected with that stream. One lot included 
