50. LKUcisctis. 24l 



to be closely allied to the species which h ive bccu nanied Plijcho- 

 cheilus and Gila. 



39. Leuciscus robastus. 



Gila robiista, Baird i^- Girard, Froc. Ac. Nat. Sc. Philad. 18"53, 

 p. 3G8; and in Silqreaves, Hep. Zuhi and Colorado Riv. p. 148, 

 Fish. pi. 1 J or in U. S. Sf Pac. R. R. Exped. Fish. p. 285. 



D. 1/9. A. 1/9. V. 10. 



Scales very small. The upper profile of the head is concave, the 

 back being elevated and the snout produced and depressed ; the 

 free portion of the tail low and elongate, its depth being about one- 

 third of its length. Mouth large, the intermaxillary extending 

 beyond the vertical from the front margin of the orbit; iipper jaw 

 overlapping the lower. Eye small, one-eighth of the length of the 

 head, and about two-fifths of that of the snout. Intcrorbital space 

 veiy broad. The origin of the dorsal fin is nearer to the root of 

 the caudal than to the end of the snout, and opposite to the base of 

 the inner ventral rays. Caudal fin forked. Pectoral fins extending 

 beyond the insertion of the ventrals in the male, and not reaching 

 it in the female. Coloration uniform. 



Pharyngeal teeth 5 . 2 — 2 . 4, subcylindrical, hooked, without 

 grinding-surface. (Girard.) 



Zufii lliver. Specimens 13 inches long. 



This is probably the type of a distinct genus, which, however, we 

 are unable properly to characterize, being unacquainted with im- 

 portant details of structure. 



40. Leuciscus elegans. 



Gila elegans, Baird fy Girard, Proc. Ac. Nat. Sc. Philad. 1853, 

 p. 369 ; and in Sitgreaves, I. c. p. 150, pi. 2 ; or in U. S. i^- Pac. R. 

 R. Exped. Fish. p. 28Gj and in U. S. ^ 3fex. Bound. Ichthyol, 

 p. 61. 



This fish would appear to diff"er from L. rohustus in being con- 

 siderably more elongate, the depth of the free portion of the tail 

 being one-fifth of its length. Also the maxillary is said not to ex- 

 tend to the vertical from the front margin of the orbit. 



Zuni River. 



41. Leuciscus zuimensis. 



Gila gracilis, Baird Sf Girard, Proc. Ac. Nat. !Sc. Philad. 1853, 

 p. 369; and in Sitr/rcavcs, Rep. ZuTii and Colorado Riv. p. 151, 

 Fish. pi. 3 ; or in U. S. 8,- Pac. R. R. Exped. Fish. p. 287. 



D. 3/8. A. 3/8. V. 9. 

 Scales very small. The upper profile of the head is but slightly 

 concave, the back being scarcely elevated. The length of the head 

 is contained thrice and two-thirds in the total (without caudal), the 

 height of the body four times and one-fourth. Snout of moderate 

 length, not quite tmce as long as the eye, which is one-sixth of the 

 length of the head. The free portion of the tail is moderately 

 elongate, aboxxt twice as long as deep. Mouth large, oblique, the 



VOL. VII. 11 



