Family V. Cyprinid^e. 55 



22. Leuciscus Cuvier. 

 Dace. 



Leuciscus (Klein) Cuvier, Regne Animal, Ed. 1, 194, 181 7. (No 

 type mentioned, Cyprinus leuciscus Linnaeus, understood.) 



Body oblong, robust, compressed or nearly terete, caudal pedun- 

 cle rather strong; mouth usually large, terminal and oblique; no 

 barbels; scales large or small, 36 to 100 in the lateral series; dorsal 

 fin usually behind the ventrals; intestinal canal short; teeth (in 

 American species) 2, 5-4, 2, to 1, 4-4, 1, hooked, with a narrow 

 grinding surface or none; lateral line decurved, complete or not; anal 

 fin composed of from 7 to 22 rays. A very large genus of very 

 variable fishes, of which only two species are known from Mexico. 



KEY TO THE SPECIES OF LEUCISCUS. 



a. Body rather slender; head <\\ in length of page 



body ; depth 4! nigrescens 5 5 



aa. Body elongate, heavy forward; head 3^; 



depth 4 [intermedius] 56 



47. Leuciscus nigrescens (Girard). Pescadito; Chub of the Rio 



Grande. 

 Tigoma nigrescens Girard, Proc. Acad. Nat. Sci. Phila., 1856, 207; 



Boca Grande and Rio Janos, Chihuahua: Girard, Mex. Bd. 



Sur., 64, pi. xxxii, figs. 1-4, 1859; Boca Grande and Rio 



Janos, Chihuahua. 

 Tigoma pulchella Girard, Proc. Acad. Nat. Sci. Phila., 1856, 206; 



Rio Mimbres, tributary of Lago de Guzman, Chihuahua: 



Girard, Mex. Bd. Sur., 62, pi. xxxiv, figs. 5-8, 1859; Rio 



Mimbres, Chihuahua. 

 Tigoma pulchra Girard, Proc. Acad. Nat. Sci. Phila., 1856, 207; 



Rio Chihuahua, Chihuahua. 

 Gila conspersa Garman, Bull. Mus. Comp. Zool., 1881, 91; Rio 



Nazas. 

 Cheonda modesta Garman, Bull. Mus. Comp. Zool., 1881, 92; Rio 



Salinas, Saltillo, Coahuila. 

 Cheonda nigrescens Garman, Bull. Mus. Comp. Zool., 1881, 92; 



Parras, Coahuila. 

 Leuciscus nigrescens Woolman, Bull. U. S. Fish Comm., 1894, 



57; Rio Chihuahua, Chihuahua: Jordan & Evermann, Bull. 



47, U. S. Nat. Mus., 1896, 233: Meek, Field Col. Mus. Pub. 



65, 1902, 80; Colonia Juarez; Santa Maria; Chihuahua; Bus- 



tillos; San Andres; Miriaca; Ahumada.. 



