132 LOWER VERTEBRATES. 



of the genera are restricted to the region cast of the Rocky Mountains, although 

 species of Catostonius, Vhasmistes, and Pantosteiis are equally abundant in indivi- 

 duals in the Great Basin and the Pacitic slope. 



In size the suckers range from six inches in length to about three feet. As food- 

 fishes they are held in low esteem, the flesh of all being flavorless and excessively full 

 of small bones. Most of them are sluggish fishes ; they inhabit all sorts of streams, 

 lakes, and ponds, but even when in mountain brooks, they gather in the eddies and 

 places of greatest depth and least current. They feed on insects and small aquatic 

 animals, and also on mud, taking in their food by suction. They are not very tena- 

 cious of life. Most of the species swarm in the spring in shallow waters. In the 

 sjjawning season they migrate up smaller streams than those otherwise inhabited by 

 them. The large species move from the large rivers into smaller ones; the small 

 brook species go into smaller brooks. In some cases the males in spring develop black 

 or red pigment on the body or fins, and in many cases tubercles similar to those found 

 in the Cyprinida; appear on the head, body, and anal and caudal fins. 



The buffalo-fishes and carp-suckers, constituting the genus Ictiobus (including 

 Carjnodes and Sderognathus), are the largest of the Catostomidfe, and bear a con- 

 siderable resemblance to the carp. They have the dorsal fin many-rayed, and the scales 

 large and coarse. They abound in the large rivers and lakes between the Rocky 

 Mountains and the Alleghanies, one species being found in Central America, and a 

 species of a closely related genus {JIi/.i:oci/2}nims asiaticus) in eastern Asia. They 

 rarely ascend the smaller rivers except for the purpose of spawning. Although so 

 abundant in the Mississipjii Valley as to be important commercially, they ai-e very 

 inferior as food-fishes, being coarse and bony. The genus Cydeptus contains the 

 black-horse or 5[issouri sucker, a peculiar species with small head, elongate body, and 

 jet black coloration, which comes up the smaller rivers tributary to the Mississippi 

 and Ohio in large numbers in the spring. Most of the other suckers belong to 

 the genera Catostonius and Ifoxostomu, the latter being known, from the red 

 color of the fins, as red horse, the former as sucker. Some of the species are 

 very widely distributed, two of them (C'atostomus teres, Erimyzon sucetta) being 

 found in almost every stream east of the Rocky Mountains. The most peculiar 

 of the suckers in appearance is the hare-lip sucker (Quassilabia lacera) of the 

 western rivers. 



The large family of CHAEACiNiDiE. seems to be naturally associated with the 

 Cyjarinidae, although in many respects resembling the Salmonidse. It inhabits the 

 fresh waters of those regions which ha\e neither Cyprinoids nor Salmonoids, thus in 

 a way representing both in the streams of South America and Africa. About three 

 hundred species are known. 



The Characinidas have the anterior vertebrte 'coalesced and modified, and the air- 

 bladder communicating by auditory ossicles with the organ of hearing, as in the 

 Cyprinidse and other Plectospondylous families. They differ from the latter in 

 several respects as regards the skeleton. More obvious distinctions are in the form of 

 the lower pharyngeal bones, which is more like that seen in ordinary fishes, and with- 

 out the peculiar and specialized teeth seen in the Cyprinidaj, Catostomidse, and Cobi- 

 tidte. The mouth is in most cases provided with teeth, which are of various forms, 

 sometimes ))i'oad incisors, sometimes sharp canines, sometimes small or even entirely 

 wanting. An adipose fin is usually but not always present. The pseudobranchia? are 

 wanting, and there is much \arietv in tlu' attachment of the gill membranes. The 



