216 
U. S. P. R. R. EXP. AND SURVEYS-ZOOLOGY-GENERAL REPORT. 
1. MYLOPHARODON CONOCEPHALUS, Grd. 
Plate XLYI, Figs. 5 — 8. 
Spec. Char.— Head sub-conical. Posterior extremity of maxillar bone not extending as far as the anterior rim of the orbit. 
Eye well developed. Pectoral and ventral fins of moderate size. Vertical fins well developed. Anal and dorsal much deeper 
than long. Base of anal entering twelve times and a half in the total length. Brown above ; whitish beneath. 
Syn. — Gila ccnocephala, B. & G. in Proc. Acad. Nat. Sc., Philad. VII, 1854, 134. 
Mylopharodon conocepliulus, Grd. in Proc. Acad. Nat. Sc., Philad. VIII, 1856, 169. 
There was but one specimen of this species collected, about seven inches and a half in length. 
Its general shape is sub-fusiform, compressed ; the back slightly convex from the nape to the 
posterior margin of the dorsal fin. The head is sub-conical and contained exactly four times in 
the length, the caudal fin excluded. The mouth is comparatively large, although the posterior 
extremity cf the maxillar bone does not quite extend to the anterior rim of the eye ; the snout 
being prolonged, and the cleft of the mouth nearly horizontal. The eye is sub-circular and its 
diameter contained five times and a half in the length of side of head. The anterior margin of 
the dorsal is nearer the end of snout than to the tip of the central rays of the caudal. The 
furcated caudal participates of the slender appearance of the body. The origin of anal is 
situated behind the base of the dorsal. The insertion of the ventrals is situated in advance of 
the anterior margin of dorsal; their tip reaching the anus. 
D 2, 9 ; A 2, 9 ; C 8, 1, 9, 8, 1, 9 ; Y 1, 9 ; P 16. 
The scales are sub-circular and of medium size ; the lateral line forms an open curve along 
the sides, the convexity of which is downwards. 
The upper regions of body and head are brown ; the sides yellowish ; and the abdomen 
whitish. 
Btferences to the figures .—Plate XLVI, fig. 5, represents Mylopharodon conocephalus, size of 
life. Fig. 6 is a scale from the dorsal region. Fig. 7, a scale from the lateral line. Fig. 8, 
a scale from the abdominal region. 
List of specimens. 
Catal. 
No. 
Correspond’g 
No. of teeth. 
No. of 
spec. 
Age. 
Locality. 
When col¬ 
lected. 
Whence obtained. 
Nature of 
specimen. 
Collected by— 
243 
2795 
i 
Young. 
Rio San Joaquin, 
Cal. 
1853 
Lt. R. S. Williamson 
Alcoholic. 
Dr. A. L. Heermann. 
2 MYLOPHARODON ROBUSTUS, Ayres. 
Plate XLYII. 
Spec. Char. —Upper surface of head very declivous ; snout tapering, almost wedge-shaped. Posterior extremity of max- 
il ary extending to a vertical line drawn across the anterior rim of the orbit. Eye of medium size. Pectoral and ventral fin s 
broad and stout. Anal nearly as large as the dorsal. Ground color olivaceous, darker above than below. 
Syn. —Mylopharodon robustus, Ayres, in Proc. Cal. Acad. Nat. Sc., I, 1855, 33.—Grd. in Proc. Acad. Nat. Sc. Philad. 
VIII, 1856, 169. 
This species is closely allied to the preceding one. The head is contained four times and a 
half in the total length. The diameter of the eye entering nearly eight times in the length 
