YELLOW BASS. 957 
among the most singular and interesting of our fishes. They differ from the typical 
Percine in their small size, bright colors, and large fins, and more technically in the 
rudimentary condition of the pseudobranchia and the air-bladder, both of which organs 
are usually inappreciable. The preopercle is unarmed, and the number of branchiostegals 
is six. An anal papilla is likewise developed, as in the Gobiide, to which group the 
Darters bear a considerable superficial resemblance, a resemblance, however, which in- 
dicates no real affinity. 
The colors of the Etheostomatine are usually very brilliant, species of Pecilichthys, 
Northonotus, and Diplesium being among the most brilliantly colored fishes known; the 
sexual differences are often great, the females being as a rule dull in color and more 
speckled or barred than the males. Most 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 
support themselves on their extended ventrals and anal fin. All 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. 
Ammocrypta, and perhaps some of the others, prefer a sandy bottom, where, by a sud” 
den plunge, the fish buries itself in the sand and remains quiescent for hours at a time, 
with only its eyes and snout visible. The others lurk in stony places, under rocks and 
weeds. Although more than usually tenacious of vitality from their bottom life, the 
Darters are the first to be disturbed by impurities in the water. All the Darters are 
carnivorous, feeding chiefiy on the larvae of gnats, and, in their way, voracious. All are 
of small size; the largest, Percina, reaches a length of eight inches, while the smallest, 
Microperca, 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, accord- 
ing to Rafinesque, ‘‘ they are good to eat, fried.” 
The Percine are represented in America by two genera, and in Europe by the same 
two and three others—Acerina, Percarina, and Aspro—the latter bearing a strong external 
resemblance to the Htheostomatine, and serving as a connecting link between them and 
the more typical forms. 
ANALYSIS OF GENERA OF PERCIDZ. 
a. Pseudobranchie well developed; preopercle serrate; branchiostegals 7. 
(Percine.) 
b. Canine teeth none; body oblong. . 3 ; : : 6 PERCA. 
bb. Canine teeth in jaws and palatines; body Boieate . . » STIZOSTEDIUM. 
aa. Pseudobranchize imperfect or wanting; preopercle entire; branchiostegals 6. 
| ( Hiheostomatine:. ) 
c. Premaxillaries protractile. 
d. Body extremely elongate, subcylindrical, translucent, the belly at least 
naked ; lateral line complete; gill-membranes broadly united. 
e. Anal spine single; anal fin nearly as large as second dorsal. 
: AMMOCRYPTA. 
dd. Body less elongate, opaque, chiefly scaled. 
f. Anal spine obscure, normally single; lateral line complete. 
BOLEOSOMA. 
ee, Anal spines two, the first commonly the longer. 
