222 
U.. S. P. R. R. EXP. AND SURVEYS-ZOOLOGY-GENERAL REPORT. 
scales are larger than in A. griseus, especially those on the anterior portion of the body. The 
lateral line runs nearly straight along the middle of the flanks to the base of the caudal. 
The color of the dorsal region and sides of the body is olivaceous, obscurely dark blotched ; 
the inferior regions being unicolor, yellowish olive. All the fins assume the latter tint. 
List of specimens. 
Catal. 
No. 
No. of! 
spec. 
Locality. 
When col¬ 
lected. 
Whence obtained. 
Nature of 
specimen. 
Collected by— 
256 
3 
Cottou-wood creek, Utah.. 
1854 
Lieut. E. G. Beckwith .. 
Alcoholic ... 
Lieut. E. G. Beckwith .. 
2. ACOMUS GRISEUS, Grd. 
Plate XLIX, Figs. 5—9. 
Spec. Char. —Head constituting the fifth of the entire length. Mouth moderate sized. Granules of lower lip largest close 
to the mouth. Eye small, sub-elliptical; its longitudinal diameter entering about seven times in the length of the side of the 
head. Anterior margin of dorsal fin equi-distant between the extremity of the snout than the insertion of the caudal. 
Extremities of ventrals not reaching the vent; their origin taking place under the posterior third of the dorsal. Greyish brown 
above; whitish or yellowish beneath. 
Syr. —Catostomus ( Acomm ) griseus, Grd. in Proc. Acad. Nat. Sc. Philad. VIII, 1856, 174. 
The body is slender, gracefully fusiform in its outline, the head forming the fifth of the 
entire length. The longitudinal diameter of the eye is contained seven times in the length of 
the side of the head in the adult, and five times in the young. The anterior margin of the 
dorsal is equi-distant between the tip of the snout and the insertion of the caudal fin. The 
ventrals are inserted opposite the posterior third of the dorsal. The anal is slender. 
D 13 ; A 10 ; 0 6, 1, 8, 8, 1, 5 ; V 10 ; P 16. 
The scales are elliptical in their outline, exhibiting radiating furrows upon their entire 
periphery. In the lateral line they assume various sizes and shapes. 
The color of the upper regions is greyish brown ; the inferior regions being whitish or 
yellowish. The dorsal and caudal are olivaceous ; the anal and ventrals yellowish, whilst the 
pectorals are greyish above and yellowish beneath. 
References to the figures .—Plate XLIX, fig. 5, represents Acomus griseus , size of life. Fig. 6 
is a scale from the dorsal region. Figs. 7 and 8, scales from the lateral line. Fig. 9, a scale 
from the abdominal region. 
List of specimens. 
Catal. 
No. 
Cor. No. 
of teeth. 
No. of 
spec. 
Locality. 
When col¬ 
lected. 
Whence obtained. 
Nature of 
specimen. 
Collected by— 
259 
2805 
2 
Sweetwater Fork of Platte 
river, Nebraska. 
1853 
J. S. Bowman. 
Alcoholic.... 
J. S. Bowman. 
