164 Series Ostariophysi 



they may be hooked at tip in those which eat smaller fishes; 

 they may be serrated or not; they may have an excavated 

 "grinding surface," which is most developed in the species which 

 feed on mud and have long intestines. In the Cyprinida:, or 

 carp family, the barbels are small or wanting, the head is naked, 

 the caudal fin forked, the mouth is toothless and without suck- 

 ing lips, and the premaxillaries form its entire margin. With 

 a few exceptions the Cyprinida are small and feeble fishes. 

 They form most of the food of the predatory river fishes, and 

 their great abundance in competition with these is due to their 

 fecundity and their insignificance. They spawn profusely and 

 find everywhere an abundance of food. Often they check the 

 increase of predatory fish by the destruction of their eggs. 



In many of the genera the breeding color of the males is 

 very brilliant, rendering these little creatures for a time the 

 most beautifully colored of fishes. In spring and early summer 

 the fins, sides, and head in the males are often charged with pig- 

 ment, the prevailing color of which is rosy, though often satin- 

 white, orange, crimson, yellow, greenish, or jet black. Among 

 American genera Chrosomus, Notropis, and Rhinichthys are most 

 highly colored. RJwdens, Rutilus, and Zacco in the Old World 

 are also often very brilliant. 



In very many species, especially in America, the male in 

 the breeding season is often more or less covered with small, 



FIG. 123. Black-nosed Dace, Rhinichthys dulcis Girard. Yellowstone River. 



grayish tubercles or pearly bodies, outgrowths of the epidermis. 

 These are most numerous on the head and fall off after the 

 breeding season. They are most developed in Campostoma. 



The Cyprinidaz are little valued as food -fishes. The carp, 

 largely domesticated in small ponds for food, is coarse and 



