250 
U. S. P. R. R. EXP. AND SURVEYS—ZOOLOGY-GENERAL REPORT 
The color is uniform yellowish brown, with a silvery streak along the middle of the flanks. 
The opercular apparatus and cheek are highly silvery. 
List of specimens. 
Catal. 
No. 
Cor. No. 
of teeth. 
No. of 
spec. 
Age. 
Locality. 
When 
collected. 
Whence obtained. 
Nature of 
specimen. 
Collected by— 
78 
2683 
10 
Adult 
Arkansas river, near Ft. 
Smith. 
1853 
Lt. A. W. Whipple- 
Alcoholic. 
Dr. G. G. Shumard. 
LEUCOSOMUS, Heck. 
Gen. Char.— The tody is elongated, sub-fusiform, compressed. The head is stout, conical, either abruptly truncated or 
tapering off. In either case, the mouth is large, subterminal, and the upper jaw slightly protruding beyond the lower A 
small barbel upon the maxillary, near the angle of the mouth. Eyes of medium size. Insertion of ventrals a little in advance 
of the anterior margin of the dorsal. Caudal furcated. Scales large, somewhat longer than high ; lateral line following the 
middle of the flanks. Pharyngeal bones stoutish, sickle-shaped ; the inferior branch rather slender, the convexity having a slight 
expansion tapering off towards the tip of the upper branch. The teeth are sub-conical, compressed and strongly hooked, of 
the raptatoiial kind, of the hooked type, without grinding surface. They are disposed upon a double row of four and two in 
the following manner : 2 | 4 —4 | 2 ; sometimes 2 | 5— 4 | 3, and even 1 | 4 — 4 | 2. 
Syn. — Lewcosomus, Heck, in Russeg. Reisen, I, ii, 1842, 1042.— Grd. in Proc. Acad. Nat. Sc. Philad. VIII, 1856, 189. 
Clieilonemus, Bd.— Grd. in Storer, Hist. Fishes, Mass, in Mem. Amer. Acad. New S. V. 1855, 288. 
The genus Cheilonemus, Bd., is strictly synonymous with Leucosomus; the latter differs from 
Semotilus by the presence of maxillar birbels. 
On a former occasion the genus Leucosomus was altogether misunderstood by me, and from 
an advice of mine it thus en’ered into the “ History of the Fishes of Massachusetts, by Dr. D. 
H. Storer.” On framing the genus Leucosomus , Heckel, by inadvertence, applies the name of 
Cyprinus chrysoleucus, Mitch., to Leuciscus pulchellus, Storer, as shown by the figures given of 
its teeth, and the wording of its generical diagnosis. Leucosomus , therefore, is identical with 
Cheilonemus , and accordingly is the name to be adopted. Cheilonemus was proposed for Leuciscus 
pulchellus , and allied species, when it was supposed that Cyprinus chrysoleucus would constitute 
the type ol the genus Leucosomus. But it is now well ascertained that Cyprinus chrysoleucus 
of Mitchell belongs to Rafinesque’s genus Luxilus; and Luxilus has the priority over Leucosomus. 
1. LEUCOSOMUS DISSIMILIS, Grd. 
Spec. Char _Head rather small, sub-conical, constituting the fifth of the total length. Eye large; its diameter entering 
four times in the length of the side of the head. Gape of mouth somewhat oblique; posterior extremity of maxillar bone 
reaching a vertical line drawn in front of the orbit. Anterior margin of dorsal fin nearer the insertion of the caudal than the 
extremity of the snout. Insertion of ventrals situated in advance of the anterior edge of the dorsal. Greyish brown above, 
yellowish beneath; flank silvery. Fins greyish olive. 
Syn. — Leucosomus dissimilis, Grd. in Proc. Acad. Nat. Sc. Philad. VIII, 1856, 189. 
This species may be easily recognized by the small size of the scales of the back compared to 
those of the flanks. In that respect it approximates certain species of the genus Semotilus. Its 
bead is sub-conical, contained about five times in the total length. The eye is large; its diame¬ 
ter being contained four times in the length of the side of the head. The dorsal fin is higher, 
and the anal deeper, than long. The tips of the ventrals approximate the vent. 
D 1, 8 + 1 ; A 2, 8 + 1 ; C 4, 1, 8, 8, 1, 5 ; V 1, 8 ; P 17. 
