244 
U. S. P. R. R EXP. AND SURVEYS—ZOOLOGY—GENERAL REPORT. 
Eeferences to the figures. —Plate LTV, fig. 5, represents Argyreus dulcis, 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. 
Cor. No. 
of teeth. 
No. of 
spec. 
Age. 
Locality. 
When col¬ 
lected. 
Whence obtained. 
Nature of 
specimen. 
Collected by 
52 
2665 
9 
Adt. & 
y’g- 
Sweetwater, tributary of 
Platte river, Nebr. 
1853 
J. S. Bowman...... 
Alcoholic.. 
J. S. Bowman . 
53 
1 
Young. 
Cottonwood creek, Utah. 
1854 
Lt. E. G. Beckwith . 
-do- 
Mr. Kreuzfeld 
2. ARGYREUS NUBILUS, G r d . 
Spec. Char. —Head rather small, constituting the fifth of the entire length. Mouth small, and barbel inconspicuous ; lips 
cartilaginous. Eye moderate sized, sub-circular ; its diameter entering five times in the length of the side of the head. Anterior 
margin of dorsal fin nearer the extremity of the snout than the tip of the middle rays of the caudal. Insertion of ventral fins 
equi-distant between the angle of the mouth and the base of the caudal. Blackish brown above ; dirty or dull white beneath. 
Syn.— Argyreus nubilus , Grd. in Proc. Acad. Nat. Sc. Philad. VIII, 1856, 186. 
This is a very characteristic species. The head is very small, and the body, fusiform in shape 
and compressed, is thick and swollen upon its middle. The tail again is rather slender. The 
snout is suh-conical, though not more protruding than in the preceding species ; the mouth is a 
good deal smaller than in the latter, and its barbels less conspicuous. The head constitutes 
about the filth of the entire length. The eye is moderately developed and sub-circular in shape; 
its horizontal diameter is contained about five times in the length of the side of the head. The 
dorsal, caudal, and anal fins are of but moderate development, the pectorals and ventrals being 
rather small. 
D 2, 8 ; A 2, 7 ; C 5, 1, 9, 8, 1, 6 ; Y 8 ; P 12. 
The number of rays in the fins does not materially differ from that of the preceding species; 
in both, the anterior two rays of the dorsal and anal fins are mere rudiments. 
The scales are sub-ovoid in their outline, with radiating furrows upon their entire periphery. 
The color above is blackish brown, with a purplish hue along the middle of the flanks ; the 
inferior regions are of a soiled white or yellowish brown. The upper surface of the head and 
upper half of the sides, including the eye, is deep black; interiorly it is whitish or yellowish 
white. 
Specimens four inches in total length were observed. 
List of specimens. 
Catal. 
No. 
Cor. No. 
of teeth. 
No. of 
spec. 
Age. 
Locality. 
When 
collected. 
Whence obtained. 
Nature of 
specimen. 
Collected by— 
51 
2664 
2 
Adult 
Fort Steilacoom, Puget’s Sound,W.T. 
1853 
Gov. 1.1. Stevens. 
Alcoholic. 
Dr. Geo. Suckley 
