32 FISHES OF PENNSYLVANIA. 

Famity CYPRINIDA. Tue Mrynows. 
Genus CAMPOSTOMA Aaassiz. 
Al. Campostoma anomalum (RarFinesque). 
The Stone Roller, 
In the stone roller the body is moderately stout and not greatly compressed ; the 
caudal peduncle is long and deep. ‘he greatest depth of the body is contained four 
to four and one-half times in the total length without the caudal; the depth of the 
caudal peduncle, eight and one-half to nine times in the same length. The snout is 
obtuse, twice as long as the eye, and two-fifths as long as the head. The maxilla 
reaches to the vertical from the posterior nostril, which is more than twice as far 
from tip of snout as from eye. The dorsal origin is over the twentieth scale of the 
lateral line, and the ventral origin under the nineteenth. The dorsal base is one- 
half, and its longest ray two-thirds as long as the head. The ventral reaches nearly 
to vent. The pectoral is one-sixth of total length without caudal. The anal origin 
is under the thirty-second scale of the lateral line; the anal base is as long as the 
snout, and the longest ray equals the head, not including the snout. The caudal is 
moderately forked. D. 8; A. 7 or 8; scales, 8-52 to 53-8; teeth, 4-4. Color in spirits 
brownish above, lower parts pale. In living examples the scales are somewhat 
mottled with blackish, and there is a dusky vertical bar behind the opercle; dorsal 
and anal fins olivaceous in females and with a nearly median dusky cross-bar. 
Breeding males have the iris orange, the dorsal and anal fins crimson, and the head, 
and sometimes the body, covered with large roundish tubercles. 
The stone roller is likewise called stone toter, stone lugger and steel- 
back minnow. It is a fish of very wide distribution, ranging from west- 
ern New York to North Carolina and throughout the Ohio and Missis- 
sippi valleys west to Minnesota and southwest to Texas. It is an 
extremely variable species, and everywhere common. It is, more- 
over, one of the most singular of American fishes, in having the air 
bladder surrounded by numerous turns of the long intestine. In this 
respect it is unique among fishes. The stone roller grows to a length 
of eight inches, but has no importance as food. It feeds upon aquatic 
plants. The young are hardy in the aquarium, where they feed upon 
conferve and diatoms. The sexes are very unlike. The males in the 
breeding season have the head, and frequently the entire body 
covered with large tubercles, and the upper half of the dorsal and anal 
fins fiery orange and with a dark cross-bar about the middle of these 
fins. 
The species is rather sluggish, but when frightened its movements 
are very rapid. It is a bottom feeder. 
Genus CHROSOMUS Rarinesque. 
42. Chrosomus erythrogaster RarinesQue. 
The Red-bellied Dace. (Figure 35.) 
The red-bellied dace has a fusiform, moderately elongate and thick body, whose 
greatest height is contained from four and one-fifth to five times, and the least depth 
