FISHES CYPRINIDAE LUXILUS SECO. 



281 



Numerous immature specimens of this species were collected, together with one pJbout five 

 inches in length. The &quot;body is very much compressed, deepest upon the middle of its length, 

 and tapering towards both extremities ; the greatest depth being contained four times in the 

 total length. The snout is sub-conical, the head rather small, and forming about the fifth of 

 the total length, it being slightly depressed above the eyes. The anterior margin of the dorsal 

 fin is nearer the base of the caudal than the extremity of the snout. The caudal is furcated. 

 Both the anal and dorsal are anteriorly elevated. The insertion of the ventrals is situated in 

 advance of the anterior margin of the dorsal. The pectorals and the ventrals are of medium 

 development. 



D 2, 10 + 1 ; A 2, 11 -f 1 ; 8, 1, 9, 8, 1, 9 ; V 10 ; P 15. 



The scales are of medium size, anteriorly sub-truncated, elsewhere rounded, and provided 

 with radiating furrows upon their posterior section only. The lateral line is bent downwards 

 upon the abdomen, constituting a curve, the convexity of which is nearer the ventral than to 

 the dorsal outline. 



The color of the upper region is dark greyish brown, the middle of the flanks being silvery, 

 and the belly yellowish, speckled with grey. The fins are unicolor, of a greyish olive tint. 



List of specimens. 



2. LUXILUS SECO, Grd. 



SPEC. CHAR. Body rather elongated, sub-fusiform in its outlines. Head small, contained five times and a half in the total 

 length. Snout sub-conical, rather abbreviated. Gape of the mouth slightly oblique ; posterior extremity of maxillary 

 extending to a vertical line intersecting the anterior nostril. Eye very large, sub-circular ; its diameter entering about three 

 times in the length of the side of the head. Anterior margin of dorsal fin equidistant between the extremity of the snout and 

 the fork of the caudal. Vertical fins moderately developed ; pectorals and ventrals rather small. Light reddish brown above ; 

 yellowish white beneath. Fins light olive. 



SYN. Luxilus seco, GRD. in Proc. Acad. Nat. Sc. Philad. VIII, 1856, 203. 



The body is deeper than in L. leptosomus, figured and described in the Report of the United 

 States and Mexican Boundary Commission. Its depth is equal to the fourth of the total length. 

 The head is contained five times and a half in the same dimension. The eye is very large ; 

 its diameter entering three times only in the length of the side of the head. The mouth is 

 small. The dorsal is much higher than long, superiorly sub-convex, whilst the anal is nearly 

 as long as deep and inferiorly sub-concave. The anterior margin of the latter is somewhat 

 nearer the tip of the lower lobe of the caudal fin than the isthmus. The caudal is longer than 

 the head. The origin of the ventrals is nearer the extremity of the snout than the insertion of 

 the caudal ; their external edge is sub-convex, and, when extended backwards, their tips scarcely 

 reach the vent. The pectorals are sub-ovate and far from reaching the insertion of the ventrals. 

 D 2, 8 + 1 ; A 2, 14 + 1 ; C 5, 1, 9, 8, 1, 6 ; V 9 ; P 14. 



The scales are of moderate development, and the lateral line very much deflexed upon the 

 abdomen. 



