214 
U. S. P. R. R. EXP. AND SURVEYS-ZOOLOGY-GENERAL REPORT. 
limb is also more slender. The head is more elongated, more conical than in M. lateralis , and 
larger than in M. fraterculus. The mouth is larger than in either of the two species just alluded 
to. The fins are well developed ; the dorsal and anal both are deeper than long; their formula 
reads: 
D 2, 8 + 1; A 2, 8 + 1; C 8, 1, 9, 8, 1, 7; V 1, 9 ; P 17. 
The scales are suh-elliptical, somewhat smaller on the abdominal region than on the dorsal 
region. 
References to the figures. —Plate XLVI, fig. 1, represents Mylocheilus caurinus, size of life. 
Pig. 2, a scale from the dorsal region. Fig. 3, a scale from the lateral line. Fig. 4, a scale 
from the abdominal region. 
List of specimens. 
Catal. 
No. 
Correspond’g 
No. of teeth. 
No. of 
spec. 
Age. 
Locality. 
When 
collected. 
Whence obtained. 
Nature of 
specimens. 
Collected by— 
213 
2770 
12 
Adult 
Astoria, 0. T- 
1855 
Lt. W. P. Trowbridge. 
Alcoholic. 
Lieut. Trowbridge ... 
2. MYLOCHEILUS LATERALIS, Agass. & Pick. 
Plate XLV, Figs. 5—8. 
Spec. Char. —Head constituting the fifth of the total length. Snout sub-conical. Posterior extremity of the maxillary 
extending to a vertical line drawn across the hind nostril. Diameter of the eye entering five times and a half in the length of 
the side of the head. Anterior margin of dorsal fin equi-distant between the extremity of the snout and the insertion of the 
caudal, Base of anal fin contained fourteen times in the total length. 
Syn. — Mylocheilus lateralis, Agass. & Pick, in Amer. Journ. of Sc. 2d ser. XIX, 1855, 231.— Grd. in Proc. Acad. Nat. Sc. 
Philad. VIII, 1856, 169. 
Although the dorsal and anal are both deeper than long, the length of the latter is propor¬ 
tionally less, than in the preceding and the following species. The fins present the general 
aspect, with a few differences in the number of the rays: 
D 1, 8 + 1; A 1, 9 ; C 8, 1, 9, 8, 1, 9 ; V 1, 10; P 19. 
The scales exhibit, also, the same general characters; their anterior margin, however, ap¬ 
pears to be more irregular ; hence their outline assumes a somewhat less elliptical form. 
Referenced to the figures. —Plate XLY, fig. 5, represents Mylocheilus lateralis, size of life. Fig. 
6, 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 
collected. 
Whence obtained. 
Nature of 
specimens. 
Collected by— 
212 
2769 
3 
Adult 
Fort Steilacoom, 
Puget’s Sound, 
Wash. Ter_ 
1853 
Gov. 1.1. Stevens.... 
Alcoholic. 
Dr. Geo. Suckley_ 
