278 
TT. S P. R. R EXP. AND SURVEYS-ZOOLOGY-GENERAL REPORT 
of greatest depth of the body, five above and five below the lateral line, which is nearly median, 
and at equal distance between the base of the dorsal fin and the insertion of the ventrals. 
The color is dark reddish brown, somewhat lighter beneath than above. A slender blackish 
streak may be observed along the middle of the flanks. The fins are of a uniform greyish 
olive tint. 
List of specimens. 
Catal. 
No. 
Cor. No. 
of teeth. 
No. of 
spec. 
Age. 
Locality. 
When 
collected. 
Whence obtained. 
Nature of 
specimen. 
Collected by— 
93 
2693 
5 
Adt. & y’g. 
1854 
Lt. E. G. Beckwith. 
Alcoholic. 
Mr. Kreuzfeld. 
RICHARDSONIUS, Girard. 
Gen. Char. —The body is very much compressed, sub-fusiform in its outline and deep upon its middle. The head is 
proportionally small ; the mouth terminal, slightly oblique, constructed upon the same pattern as in Luxilus, though somewhat 
larger, and unprovided with cirrhi or barbels. The eye is large. Isthmus very narrow. Caudal fin furcated. Insertion of 
ventrals situated in advance of the anterior margin of the dorsal. Anal fin longer than the dorsal; its anterior margin situated 
in advance to the posterior margin of the dorsal, in which respect it differs from Luxilus. Scales deeper than long, posteriorly 
furrowed. The pharyngeal bones are narrow, with a slight expansion upon their convexity ; the teeth being of the raptatorial 
kind of the hooked type, strongly hooked, without grinding surface, instead of which a sharp but not crenated ridge. They 
are disposed upon a double row of four or five and two or three, as follows : 2 | 4—4 | 3, or 2 | 5—5 | 2. 
Syn. — Richardsonius, Grd. in Proc. Acad. Nat. Sc. Philad. VIII, 1856, 201. 
The present genus hears some resemblance to Squolius, from which it may he distinguished 
by the smooth edge of the dental ridge and the long anal, together with the peculiar position of 
the latter in reference to the dorsal. The scales are also smaller and much deeper than long, 
which is not the case in Squalius. 
1. RICHARDSONIUS BALTEATUS, Grd. 
Plate LX, Figs. 1—4. 
Spec. Char. —Head forming less than the fifth of the total length. Snout sub-conical ; jaws even ; posterior extremity of 
maxillar bone extending to a vertical line drawn in front of the orbit. Eye large and circular ; its diameter entering three times 
and a half in the length of the side of the head. Anterior margin of dorsal fin equidistant between the extremity of the snout 
and the fork of the caudal. Anal fin longer than deep and about as long as the head. Caudal fin constituting about the fourth 
of the total length. Greyish black above ; silvery white beneath. Fins unicolor. 
Syn. — Cyprinus (Mramis) balteatus, Richards. Faun. Bor. Amer. Ill, 1836, 301.— Storer, Synops. 1846, 160. 
Richardsonius balteatus, Grd. in Proc. Acad. Nat. Sc. Philad. VIII, 1856, 202. 
The greatest depth enters about four times and a half in the total length, the thickness being 
less than the half of the depth. The head is contained five times and one-third in the total 
length, of which the caudal fin constitutes about the fourth part. The dorsal fin is higher than 
long, sub-trapezoid in its outline, the upper margin being nearly linear. The caudal is deeply 
furcated. The anal is longer than deep and longer than the head itself, and diminishing 
rapidly in depth posteriorly, its inferior edge being slightly concave, and its anterior margin 
nearer the isthmus than the tip of the inferior lobe of the caudal. The ventrals are well 
developed, posteriorly suh-truncated, their tips reaching the vent, which is situated close to the 
anterior margin of the anal fin. Their origin is nearer the extremity of the snout than the 
insertion of the caudal. The pectorals are large, elongated, posteriorly rounded, and, when 
