FISHES CYPRINIDAE GILA GRACILIS. 



287 



preceding species. The insertion of the anal takes place immediately behind the base of the 

 dorsal. The origin of the ventrals being much nearer the extremity of the snout than the 

 insertion of the caudal fin. Their formula is as follows : 



D 3, 9 ; A 3, 10 ; C 9, 1, 9, 9, 1, 10 ; V 9 ; P 16. 



The scales are much longer than deep, anteriorly sub-truncated or undulated, and deepest, 

 whilst they taper somewhat towards a posterior rounded margin, which alone exhibits radiating 

 furrows. The lateral line is deflexed upon the middle of the abdomen, so as to approximate 

 more the base of the ventrals than that of the dorsal fin ; further back it is median to the 

 insertion of the caudal. 



The color is uniform reddish brown above, and metallic yellow or white beneath ; the fins 

 being of a dull olive tint. 



List of specimens. 



3. GILA GKACILIS, B. & 0-. 



SPEC. CHAR. Body sub-fusiform, compressed. Head constituting the fourth of the total length. Eye large, sub-circular ; 

 its diameter entering nearly six times in the length of the side of the head. Posterior extremity of the maxillar bone extending 

 to a vertical line drawn somewhat in advance of the orbit. Anterior margin of dorsal fin nearer the insertion of the caudaj 

 than the extremity of the snout. Base of anal fin entering twelve times in the total length. Origin of ventrals somewhat 

 nearer the insertion of the caudal than the extremity of the snout. Yellowish brown above ; beneath silvery white. 



STN. Gila gracilis, B. & G. in Proc. Acad. Nat. Sc. Philad, VI, 1853, 369 ; and, in Sitgr. Rep. Zufii and Color. Rivers, 

 1853, 151. Fishes, PI. m, GRD. in Proc. Acad. Nat. Sc. Philad. VIII, 1856, 205. 



The body is sub-fusiform in profile, quite compressed, tapering more gradually backwards 

 than in the preceding two species. The greatest depth corresponds to the anterior margin of 

 the dorsal fin, and enters about five times and a half in the total length ; the greatest thickness, 

 at the origin of the body, is comprised eight times and a half in the length. 



The head, which is sub-pyramidal and slightly depressed above, constitutes the fourth of the 

 total length. The eyes being large and sub-circular ; their longitudinal diameter entering 

 nearly six times in the length of the side of the head. The nostrils, which are situated 

 towards the upper surface of the head, are much nearer the orbit than the extremity of the 

 snout. The upper jaw overlaps the tip of the lower one ; the posterior extremity of the 

 maxillar bone extending somewhat beyond a perpendicular line drawn through the anterior 

 rim of the orbit. Series of mucous pores may be traced from the origin of the lateral line 

 across the nape, hence to the nostrils along the parietal region ; also downwards along the 

 preopercle to the angle of the mouth, and under the orbit towards the snout. 



The dorsal fin is situated slightly in advance of the middle of the total length ; its anterior 

 margin being somewhat nearer the insertion of the caudal than the extremity of the snout. It 



