85. PERCID^. 
487 
are explained in a word by the hyi)othesis of the progressive adapta- 
tion of the young of certain Percidce to a peculiar place of refuge and a 
peculiarly situated food supply. Perhaps we may without violence call 
these the mountaineers among fishes. Forced from the populous and 
fertile valleys of the river beds and lake bottoms, they have taken 
refuge from their enemies in the rocky highhmds, where the free waters 
l^lay in ceaseless torrents, and there they have wrested from stubborn 
nature a meager living. Although diminished in size by their constant 
struggle with the elements, they have developed an activity and hardi- 
hood, a vigor of life and a glow of high color almost unknown among 
the easier livers of the lower lands. * * * Notwithstanding their 
trivial size, they do not seem to be dwarfed so much as concentrated 
fishes.” (Am. Nat. 1880, October, pp. 697-702.) 
The colors of the Etheostomatince are usually very brilliant, species of 
Pcecilichthys, NotJio)iotiis, and DipJesium being among the most brilliantly 
colored fishes known ; the sexual diftereuces are often great, the females 
being as a rule dull in color and more speckled or barred than the males. 
jMost of them prefer clear running water, where they lie on the bottom 
concealed under stones, darting, when frightened or hungry, with great 
velocity, for a short distance, by a powerful movement of the fan-shaped 
pectorals, then stopping as suddenly. They rarely use the caudal fin 
in swimming, and they are seldom seen moving or floating freely in the 
water like most fishes. When at rest, they sa])port themselves on their 
expanded veutrals and anal fin. x\ll of them can turn the head from 
side to side, and they frequently lie with the head in a curved position 
or partly on one side of the body. The species of Ammoa'iipUi and 
perhaps some of the others prefer a sandy bottom, where, by a sudden 
plunge, the fish buries itself in the sand and remains quiescent for 
hours at a time, with only its ej'es and snout visible. The others lurk 
in stony places, under rocks and weeds. Although more than usually 
tenacious of vitality, the Darters, from their bottom life, are the first 
to be disturbed by impurities in the water. All the Darters are car- 
nivorous, feeding chiefly on the larvm of Biptera, and in their way vora- 
cious. All are of small size; the largest {Fercina) reaches a length of 8 
inches, while the smallest (Micyoperca) is probably the smallest spiny- 
rayed fish known, barely attaining the length of an inch and a half. 
They are of too small size to be used for food, although, according to 
Eafinesque, “they are good to eat, fried.” 
The Percuice <\ve represented in America by two genera, and in Eurojre 
by the same two and three others^Acerina, Perccwina, and Aspro — the 
