Percoidea, or Perch-like Fishes 523 
fish for the people it is, we will grant, and it is the anglers from 
among the people who have neither time nor patience for long 
trips nor complicated tackle who will prove its steadfast friends.” 
The boy values it, according to Thoreau. When he returns 
from the ‘mill-pond, he numbers his perch as ‘“‘real fishes.” 
“So many unquestionable fish he counts, and so many chubs, 
which he counts, then throws away.” 
In the perch, the oral valves, characteristic of all bony fishes, 
are well developed. These structures recently investigated by 
Fic. 409.— Yellow Perch, Perca flavescens Mitchill. Potomac River. 
Evelyn G. Mitchill, form a fold of connective tissue just behind 
the premaxillary and before the vomer. They are used in respi- 
ration, preventing the forward flow of water as the mouth closes. 
Several perch-like fishes are recorded as fossils from the 
Miocene. 
Allied to the perch, but long, slender, big-mouthed, and 
voracious, is the group of pike perches, found in eastern America 
and Europe. The wall-eye, or glass-eye (Sizzostedion vitreum), is 
the largest of this tribe, reaching a weight of ten to twenty 
pounds. It is found throughout the region east of the Mis- 
souri in the large streams and ponds, an excellent food-fish, 
with white, flaky flesh and in the north a game fish of high 
rank. The common names refer to the large glassy eye, con- 
cerning which Dr. Goode quotes from some “ardent admirer” 
these words: “Look at this beautiful fish, as symmetrical in 
form as the salmon. Not a fault in his make-up, not a scale 
