226 
U. S. P. K. R. EXP. AND SURVEYS—ZOOLOGY—GENERAL REPORT. 
4. CATOSTOMUS SUCKLII, Grd. 
Plate LI. 
Spec. Char.— Head constituting the fifth of the entire length. Eye small. Mouth rather small; lips moderately developed, 
covered with conspicuous papillae. Isthmus of medium width. Dorsal fin as high as long; its anterior margin somewhat nearer 
the insertion of the caudal fin than the extremity of the snout. Insertion of ventrals a little in advance of the middle of the 
dorsal, and equi distant between the extremity of the snout and the fork of the caudal. Posterior extremity of anal extending 
beyond the rudimentary rays of the caudal. Greyish olive above; yellowish olive beneath. 
Syn .—Catostomus sucklii, Grd. in Proc. Acad. Nat. Sc. Philad. VIII, 1856, 175. 
The head forms the fifth of the entire length. It is sub-quadrangular, the upper surface 
rather sloping towards the blunt snout. The eye is small and sub-elliptical ; its horizontal 
diameter being contained somewhat over five times in the length of the side of the head. The 
anterior margin of the dorsal fin is equi-distant between the tip of the snout and the insertion 
of the caudal. Its height is equal to its length, and its upper margin is slightly concave. The 
posterior margin of the caudal is deeply emarginated, crescent-shaped. The insertion of the 
ventrals is situated somewhat in advance of the middle of the dorsal fin. 
D 2, 12 ; A 2, 8 ; C 5, 1, 8, 8, 1, 4 ; Y 10 ; P 18. 
The scales are large and but a little smaller anteriorly than posteriorly ; they are sub¬ 
elliptical in shape, longer than deep, with their anterior and posterior margins irregular, 
exhibiting radiating grooves upon the anterior and posterior sections. The upper regions are 
greyish olive, and the inferior regions yellowish olive. The young being of a darker and less 
yellowish tint. 
References to the figures. —Plate LI, fig. 1, represents the adult Catostomus sucklii, size of 
life. Fig. 2 is a scale from the dorsal region. Fig. 3, a scale from the lateral line. Fig. 4, 
a scale from the abdominal region. Fig. 5 is the young of the same species. 
List of specimens. 
Catal. 
No. 
Cor. No. 
of teeth. 
No. of 
spec. 
Age. 
Locality. 
When 
collected. 
Whence obtained. 
Nature of 
specimen. 
Collected by— 
175 
2739 
2 
A. & Y. 
Milk river, Upper Missouri. 
1853 
Gov. 1.1. Stevens. 
Alcoholic. 
Dr. Geo. Suckley.. 
TKXBE OF CHONDROSTOMI. 
The characters of Chondrostomi, as derived chiefly from the American representatives, consist 
in the absence of barbels ; in the position of the mouth, which is generally overhung by the 
upper jaw, and sometimes both jaws are equal. The pharyngeal teeth are of the grinding 
type ( Dentes masticatorii) and cultriform kind ( Dentes cultriformes'), disposed upon a single 
series, with one exception only, and that occurs occasionally in Campostoma. I say occasionally, 
because in the majority of cases there is also but one single row in the latter genus. Exoylossum 
is removed from this group, of which it has none of the characters, except the absence of 
barbels. 
Syn. —Chondrostomi , Agass. in Amer. Journ. of Sc. 2d series, XIX, 1855, 94.— Grd. in Proc. Acad. Nat. Sc. Pbilad. VIII, 
1856, 175. 
