FAMILY V. CYPRINID.E. 63 



inches in length, seldom do any of them exceed 5 inches; in color and 

 form most of the species are very variable. 



This genus contains a large number of species of small fishes in- 

 habiting the streams of the United States east of the Rocky Moun- 

 tains, ranging south into Mexico to the Rio Panuco and west to the 

 headwaters of the Rio Yaqui, and south on the Pacific side to the Rio 

 Balsas. They are among the most feeble of our fresh-water fishes. 

 None of them are of any value as food for man, but are of great impor- 

 tance as food for larger fishes. Very few of the species inhabit river 

 channels, nearly all being confined to the smaller streams and ponds, 

 from which they probably migrate only very short distances. So far 

 as known, the species all spawn in the spring, at which time the males 

 are more or less highly colored, some being red, or with red fins, while 

 others are white or entirely black, and the head and often the entire 

 body is covered with tubercles, an outgrowth of the epidermis. 



All of the species of this group are quite variable, many being 

 difficult to determine. Their food consists largely of small crus- 

 taceans and insect larvae. 



KEY TO THE SPECIES OF NOTOTROPIS. 



a. Body subterete, not much compressed; snout PAGE 



bluntish. 



b. Scales large, less than 40 in the lateral series. 



c. Sides of body without dark vertical bars; 



depth of body $% to 4 ; least depth of caudal 



peduncle 2 to 2^ in head. 



d. Lateral line incomplete, usually on from 3 



to 10 scales, not extending beyond base of 



ventrals calientis 65 



dd. Lateral line complete or very nearly so. 

 e. Head large, 3^ to $% in body; about 14 

 or 1 5 scales before dorsal fin. 



f. Eye large, 3 in head; dorsal rays 8; anal 

 rays 7; origin of dorsal fin midway be- 

 tween tip of snout and base of caudal fin braytoni 65 



ff. Eye smaller, 3^2 in head; dorsal rays 9; 

 anal rays 8; origin of dorsal fin midway 



between base of caudal and nostril robustus 66 



ee. Head shorter, 4 in body; about 16 scales 

 before dorsal fin. 



g. Caudal peduncle slender, its least depth 

 2 1 in head; a narrow dark lateral band; 

 upper half of body with many spots, 



each about the size of pupil chihuahua 67 



