236 
U. S. P R. R EXP. AND SURVEYS-ZOOLOGY-GENERAL REPORT. 
List of specimens. 
Catal. 
No. 
Cor. No. 
of teeth. 
No. of 
spec. 
Locality. 
When col¬ 
lected. 
Whence obtained. 
Nature of 
specimen. 
Collected by— 
87 
2688 
7 
Milk river, Missouri .... 
Arkansas river, near 
Fort Smith. 
1853 
Alcoholic . 
-do- 
86 
2687 
35 
1853 
Lt. A. W. Whipple- 
Dr. Geo. G. Skumard.. 
2. HYBOGNATHUS EVANSI, Grd. 
Spec. Char. —Body sub-fusiform in profile. Head sub-conical, thickisk, contained about five times in tke total length. Eye 
moderate sized, sub-circular. Anterior margin of dorsal fin equidistant between the extremity of the snout and the base of 
the caudal. Insertion of ventrals being situated posteriorly to the anterior margin of the dorsal; is therefore nearer the base 
of the caudal than the extremity of the snout Caudal fin constituting the fifth of the total length. Scales anteriorly truncated. 
Reddish brown above; silvery on the flanks and beneath. 
Syn. —llybognalhus evarisi, Grd. in Proc. Acad. Nat. Sc. Philad. VIII, 1856, 182. 
In its general aspect this species is shorter than any of its known congeners. It may easily 
he distinguished from the preceding one by a much stouter head, more protruding snout, 
shelving inwards and downwards, small mouth, smaller eye; the diameter of the latter entering 
almost four times and a half in the length of the side of the head. The opercle is as long as 
deep, sub-quadrangular, slightly emarginated behind, as in the rest of the species. 
List of specimens. 
Catal. 
No. 
Cor. No. 
of teeth. 
No. of 
spec. 
Locality. 
When col¬ 
lected. 
Whence obtained. 
Nature of 
specimen. 
Collected by-—- 
88 
90 
2689 
4 
4 
Ft Pierre, Nebraska.. 
Sweet Water, Platte river. 
1853 
1852 
Dr. John Evans. 
J. S. Bowman ... 
Alcoholic _ 
-do_ 
Dr. Evans. 
J. S. Bowman ... 
3. HYBOGNATHUS PLACITUS, Grd. 
Spec. Char —Body sub-fusiform in profile. Head sub-conical, contained about five times and a half in the total length. 
Eye moderate sized, sub-circular. Anterior margin of dorsal fin nearer the extremity of the snout than the base of the caudal, 
whilst the insertion of the ventrals is nearly equidistant between the same points. Scales anteriorly rounded. Greyish brown 
above, silvery on the flanks, and dull metallic white beneath. 
Syn. —Ilybognathus placitus, Grd. in Proc. Acad. Nat. Sc. Philad. VIII, 1856, 182. 
The general form of the body is intermediate between H. argyritis and H. evansi. The snout 
is thickish, hut less so than in H. evansi; the mouth is also smaller. The eye is circular ; its 
diameter being contained over four times in the length of the side of the head. The scales are 
also larger than in H. evansi , rounded upon their anterior margin and, as usual, exhibiting 
radiating furrows upon their posterior section only. 
The color is greyish brown above; the middle of the flanks being greyish silver, whilst the 
inferior region is dull metallic whitish or yellowish. 
