294 
U. 8 P. R. R. EXP. AND SURVEYS—ZOOLOGY—GENERAL REPORT. 
This species has a short and deep body; the greatest depth being more than the fourth of the 
entire length. The peduncle of the tail is very stoutly built. The head is small and sub- 
conical, constituting nearly the fifth of the entire length of the fish. The dorsal and anal are 
both narrow fins compared to their height and depth ; their outer edge is nearly linear. The 
anterior margin of the anal is somewhat nearer the tip of the inferior lobe of the caudal than 
the isthmus. The caudal fin is almost equal to the head in length. The ventrals and pectorals 
are of but moderate development, the tips of the former reaching the anal aperture, whilst the 
extremities of the latter are far from extending to the origin of the ventrals. 
D 1, 8 ; A 1, 8 + 1 ; C 7, 1, 9, 8, 1, 8 ; V 1, 9 ; P 1, 19. 
The scales are well developed, longer than deep, anteriorly sub-truncated, tapering and 
rounded off posteriorly with radiating furrows upon their posterior section only. The upper 
region of the head and body is deep bluish or purplish black, of a somewhat lighter shade on 
the middle of the flanks, whilst the inferior region is yellow with a metallic reflect, affecting 
also the scale of the flanks and those of the dorsal region. 
References to the figures. —Plate LXII, fig. 1, represents Tigoma crassa, size of life. Fig. 2 
is an outline of the fish seen from above. Fig. 3, a section of the body taken across the line of 
greatest depth. Fig. 4, a dorsal scale. Fig. 5, a scale from the lateral line. Fig. 6, a scale 
from the abdominal region. 
List of specimens. 
Catal. 
Cor. No. 
No. of 
Age. 
Locality. 
When col¬ 
Whence obtained. 
Nature of 
Collected by— 
IN 0. 
of teeth.- 
spec. 
lected. 
specimen. 
216 
2777 
1 
Adult. 
Sacramento river, near 
Fort Reading. 
1855 
Lt. R. S. Williamson . 
Alcoholic. 
Dr. J. S. Newberry... 
CHEONDA, Girard. 
Gen. Char. —The body is elongated, fusiform in profile, and very much compressed. The caudal fin is furcated. The head 
is rather small and sub-conical, and the snout, though rounded, is yet elongated. The eye is large and the isthmus small or 
narrow. The ventral fins are inserted in advance of the dorsal The scales being of medium size, sub-circular in shape, with 
radiating furrows upon their posterior section alone. The lateral line is deflexed upon the abdomen. The teeth are of the 
prehensile kind, of the hooked type, with a grinding surface ; they are compressed and disposed upon a double row of two and 
four and five, thus: 2 | 4—5 | 2. 
Syn. — Cheonda, Grd. inProc. Acad. Nat. Sc. Philad. VIII, 1856, 207. 
This genus has the general aspect of both Gila and Tigoma , by the position of the ventrals 
in advance of the anterior margin of the dorsal, by the absence of barbels at the angle of the 
mouth, which is of moderate size, and its gape nearly horizontal. The jaws are either sub¬ 
equal, as in Tigoma; else the snout overlaps somewhat the lower jaw, in which case the 
resemblance to Gila becomes more manifest. 
1. CHEONDA COOPERI, Grd. 
Plate LXIII, Figs. 1—5. 
Spec. Char. —Body elongated, sub-fusiform in profile. Head contained a little short of five times in the total length. 
Snout thickish, sub-conical, overlapping somewhat the lower jaw ; posterior extremity of the maxillar bone extending to a 
vertical line drawn behind the nostrils. Eye well developed ; its diameter entering four times and a half in the length of the 
side of the head. Fins well developed. Upper regions reddish-grey ; sides and belly yellowish-white with a metallic reflect. 
Syn. — Cheonda cooperi, Grd. in Proc. Acad. Nat. Sc. Philad. VIII, 1856, 207 
