Jordan and Evermann. Fishes of North America. 229 



usually 2, 5-5, 2 iu the European type ; hooked, with rather narrow grind- 

 ing surface or none. Anal basis short or more or less elongate. Dorsal fin 

 posterior, usually behind ventrals. Intestinal canal short. Size generally 

 large, some species very small. A very large group, one of the largest 

 current genera in ichthyology, represented by numerous species in the 

 rivers of Europe, Asia, and North America. Most of our species have been 

 poorly defined. As the species are extremely variable in form, the number 

 of nominal ones has been very greatly multiplied. Much larger series of 

 each form are necessary before the species can be properly discriminated. 

 Individual irregularities in dentition are common in this genus. 



The typical species of the genus, Leuciscus leuciscus, is the common Dace 

 or Vandoise of Europe, and differs greatly from any of the American 

 forms. The presence of various intermediate species, however, makes 

 it impossible for us to draw any satisfactory line between the Dace 

 (Leuciscus) on the one hand, and such extreme forms as the long-mouthed 

 minnows (Clinostomus) on the other. 



In the subgenus Leuciscus the pharyngeal teeth are 2, 5-5, 2, rarely vary- 

 ing to 3,5-6, 2, and the scales are rather large (about 50 in lateral line), 

 closely imbricated and along the sides distinctly silvery. The anal fin is 

 also long, of 11 to 12 rays, and the lateral line complete. The genus 

 Squalius,SiS understood by us, is strictly synonymous with Leuciscus. In 

 southeastern Europe and western Asia Leuciscus is replaced by the sub- 

 genus Telestes, which has the teeth 2, 5-4, 2, the scales much smaller (70 to 

 80), and not silvery, the anal fin still remaining long, and the lateral line 

 complete. The American species ca.led Tigoma and Cheonda are very close 

 to Telestes, from which they differ only in the less closely imbricated 

 scales, most of them, but not all, having the short anal fin generally char- 

 acteristic of American Cyprinidce. Tigoma can not be generically separated 

 from Telestes, though it may be a question whether either should be united 

 to Leuciscus. Cheonda differs from Tigoma in having the long anal fin of 

 Leuciscus. Eichardsonius is simply an extreme form of Cheonda. Siboma is 

 founded on a Tigoma with very deep body and the scales less loosely imbri- 

 cated than usual. Clinostomus is a peculiar group of small, fine-scaled 

 minnows, with the gape of the mouth larger than in any other Cyprinidw 

 whatever. The relationship of the species to those called Richardsonius is, 

 however, very close. The type of Phoxinus differs from Leuciscus in its 

 incomplete lateral line and very small scales. In the latter respect the 

 eubgenus Hemitremia forms a complete transition to Leuciscus, and some of 

 its species (as margarita) have the lateral line scarcely defective. Con- 

 sidering all the known species, Phoxinus can not be separated from 

 Leuciscus. It may even be necessary to merge Rutilus and its American rep- 

 resentatives, Leucus and Mylolencus, in the same great group. (Leucixcn*, 

 old name of the Dace, from Aeu/cof, white.) 



I. Lateral line complete in the adult. 

 a. Mouth moderate, terminal, or subinferior, the lower jaw included, or scarcely projecting ; 



teeth normally 2, 4-5, 2 ; scales rather small. 



b. Anal basis short, its raya 7 or 8, rarely 9" fins low; males not brilliantly colored. 

 SIBOMA, (a coined name without meaning*): 



*Liko many other of Girard's generic names; drawn ostensibly from "words tak<m from the 

 North American Indians as more euphonic than any I might have framed from the Greek. 



