FISHES. 127 



very many species they are hooked at the tip, and the grinding surface is rudimentary 

 or entirely wanting. Besides these, all sorts of varying and intermediate forms are 

 found, and the differences in the numbers and forms of these teeth afford means for 

 the subdivision of the family into genera and sub-genera. In general, those sjjeeies 

 with long intestines, and eonse(iuently lierbivorous or rather limnophagous in habit, 

 have straight teeth with developed grinding surface, while the carnivorous species 

 have longer and more hooked teeth. The air-bladder in the Cyprinidse is without 

 bony capsule. The barbels, when present, are small. The head is naked, the body 

 usually scaly. The ventral fins are abdoiniiuil. The dorsal and anal are variable in 

 size and are sometimes armed anteriorly with a spine. The caudal fin is forked. 



For the most part, the Cyprinidaj are small and feeble fishes of comparatively 

 simple structure and weak organization. They form a large share of the food of the 

 predatory fishes which inhabit the same waters, and their great abundance, as com- 

 pared with that of more active species, furnishes another illustration of the (apparent) 

 survival of the untittest. They spawn profusely and find everywhere an abundance 

 of food. In many cases they cheek the increase of the predatory fishes by devouring 

 the eggs of the latter. 



In many cases the breeding dress of the males is very brilliant, rendering these 

 little creatures, for a time, among the most beautiful of fishes. In spring and early 

 summer, the fins, the sides and other parts of the body are often charged with bright 

 pifrment, the prevailing color of which is rosy, although in some cases it is satin- 

 white, orange, yellowish, or jet black. Among American genera, the brightest colored 

 s])ecies belong to Chrosotnus, Notropis, and Rhinichtliys. In very many species, 

 especially in America, the top of the head, the fins, and often the whole body, are 

 covered with small tubercles, outgrowths from the epidermis. These gradually dis- 

 appear after the breeding season. They are most highly developed in the peculiar 

 genus, Campostoma. 



In North America about two hundred and sixty species are now known. These 

 are referred to forty genera by Jordan and Gilbert, but many of these genera are 

 simply sections made for the sake of convenience. The division of this group and of 

 other large groups of recent origin into natural genera is subject to many difficulties, 

 because genera with exact definitions and clearly marked boundaries do not exist in 

 nature. 



Nearly half the American species belong to the genus Xotropis (= Minnilus). 

 This genus includes most of the smaller and weaker members of the family, ranging 

 from two to eight inches in length, the largest of the entire series being the common 

 shiner, or red-fin, of our streams {Xotropis meffaloj^s). The species of Notrojns are 

 characterized by the absence of any special peculiarities in mouth, intestines, or fins, 

 and by the presence of but four teeth in the main row on each side. Few, if any of 

 the European or Asiatic species h.ave the teeth so small in nund)er. None of the 

 species of JVotropis are found in the waters cf America west of the Rocky Mountains. 

 In general, the minnows of America have fewer teeth than those of Europe. In but one 

 of our s]iecies, Orthodon microlepklotus, are there more than five teeth in the main row, 

 and in none are there three rows, or more than two teeth in the lesser row. In the old 

 world, those with more than five teeth in the main row are numerous, as well as those 

 with three rows of teeth or with three teeth in the lesser row. The barbels, in the 

 few American species which ])Ossess them are very small, while in their Euro])ean 

 analogues these appendages are conspicuous. In the eastern United States, there are 



