FISHES—CYPRINIDAE—GILA GRACILIS. 
287 
preceding species. Tlie 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 ; Y9; 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 hack 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. 
Catal. 
No. 
Cor. No. 
of teeth. 
No. of 
spec. 
Age. 
Locality. 
When 
collected. 
Whence obtained. 
Nature of 
specimen. 
Collected by— 
248 
3 
Adult. 
Gila river. 
1853 
Lieut. J. G. Parke.... 
Alcoholic. 
Dr. A. L. Heermann.. 
249 
2799 
1 
> 
1854 
Lieut. E. G. Beckwith. 
....do. •.. 
Mr. Kreuzfeld.. 
250 
Colorado river. ••••••• 
1854 
Major F-mory .. 
Arthur Schott. .. 
^ 25J 
2800 
1 
..do.. 
Zuni river .. 
4852^ 
Capt. L. Sitgreaves... 
....do. •.. 
Dr. S. W. Woodhouse. 
935 
3 
Fort Yuma, California. 
1855 x 
jYIajor S. H. Thomas. 
....do.... 
Major Thomas. 
- 
3. GILA GRACILIS, B. & G. 
Spec. Chau. —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. Zuni and Color. Rivers, 
1853, 151. Fishes, PI. hi.—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 
