PLECTOSPONDYLICYPRIN1DAE ALBURNELLUS SIMUS. 649 



and length of muzzle. Length of head four, and depth of body four and three- 

 quarters times in length without caudal fin. Radii: D. I. 8 ; A. I. 7; the first 

 dorsal ray intermediate between the base of the caudal fin and the posterior 

 border of the orbit, and a little behind the line of the basis of the ventral fins. 

 Pectorals reaching three-fifths the distance to the ventrals; the latter not quite 

 reaching the anal. Caudal peduncle stout. The barbels are small, and in 

 some specimens appear to be wanting on one side or both. Scales very 



18 



small, >. Isthmus wide. Color dusky olive above, white below. A dark 



15 



band along the side of the head through the orbit. A similar black band 

 occupies the middle of the sides on the posterior two-thirds of the length, 

 which is well defined above and below, and is sometimes irregularly shaded. 



Length of a specimen to base of caudal, O m .061; length to base of anal, 

 O m .043 ; to base of ventral, O m .033 ; to base of dorsal, O m .035 ; length of 

 head, O m .0162 ; width of head between orbits, O ra .0045 ; at middle of ptero- 

 tics, O m .0073. 



A red spot in the axils of the ventral and pectoral fins, one at the 

 superior canthus of the branchial fissure, and one on the side of the muzzle. 

 Length three inches. 



Specimens from Arizona and New Mexico. 



ALBURNELLUS, Gir. 



This genus was established by Girard in Proc. Acad. Nat. Sci. Phila., 

 1856, 193, and represents and nearly resembles the Alburnus of the Old. 

 World. The dental formula is 2.4-4.2 ; the teeth without masticatory sur- 

 faces. The dorsal fin rises behind a point opposite to the basis of the ven- 

 trals. 



ALBURNELLUS SIMUS, Cope, sp. nov. 



PLATE XXXI, FIGS. 2, 2a. 



Represented by many individuals from the Rio Grande. It is of rather 

 stout form for the genus, and resembles especially the typical forms of 

 Hybopsis in its decurved, obtuse muzzle. It is, however, a true Alburnellus 

 as indicated by the dentition and position of the ventral fins. The first dor- 

 sal ray stands above the last ray of the ventrals, and the latter fins, appressed, 

 reach the line of the last ray of the dorsal. The teeth are 4.1-1.4 of the 



