FAMILY CYPRINIDEZ — LEUCISCUS. 205 
geographical limits are not ascertained. Richardson (Vol. 3, p. 122) describes one from Lake 
Huron, under the same name, which must be a different species. 
I have ventured to construct a new genus for the reception of this species. The deep body, 
smal] head, cultrate abdomen and dorsal spine, clearly show that it can be arranged with 
no previously described genus of this family. The name alludes to its silvery lustrous 
appearance. 
GENUS LEUCISCUS. Klein. 
The dorsal and anal fins short, without strong rays at their commencement. No cirri, nor 
barbels on the head. The dorsal either above the ventrals, or between these and the anal. 
THE BLACK-NOSED DACE. 
Levciscus ATRONASUS, 
PLATE XXIII. FIG. 69. 
The Brook Minnow, Cyprinus atronasus. Mircuitt, Lit. and Phil. Soc. Vol. 1, p. 460. 
Leuciscus atronasus, The Brook Minnow. Storer, Massachusetts Report, p. 92. 
Characteristics. Small, with a broad black longitudinal band. Trail forked. Length one to 
three inches. 
Description. Body oblong, cylindrical, tapering. Head small, flattened. Scales moderate, 
orbicular, and, under the lens, exhibiting concentric and radiating strie ; towards the tail they 
become oblong. Lateral line straight, composed of a double series of tubes, and running 
along the lower margin of the dark longitudinal band. Eyes rather large, with black pupils 
and golden irides, the lower portion being darkest. Nostrils large, oval. Mouth small; the 
under jaw shortest. A few sharp incurved teeth in the pharynx. 
The dorsal fin higher than long, subquadrate, slight, emarginate above; the rays succes- 
sively shorter to the last. It arises nearly equidistant between the extremity of the caudal 
fin, and the tip of the snout; its first ray is slightly in advance of the ventrals. The pectorals 
are placed very low, fan-shaped, and with very minute rays. Ventrals feeble, and very 
closely approximated to the anal, which latter equals in length some of the longest rays of the 
dorsal fin; the third and fourth rays longest. his fin is quite remote from the caudal, which 
is deeply forked, and with numerous accessory rays. 
Color. Body above greenish ; summit of the head blackish brown. A broad dark brown 
or blackish band passes from the nose, including the lower half of the eyes, and proceeds in 
a straight line to the tail; bordering this above, is a light yellow line, which, however, com- 
mences only from the gill-covers: this is occasionally inconspicuous. Under the lens, the 
scales appear minutely punctate with brown. Abdomen silvery, with a few brownish and 
metallic blotches. Pectorals orange. Dorsal and caudal dark brown. 
