FAMILY CYPRINID.E 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, 

 small 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. 



LEUCISCUS ATRONASUS. 



PLATE XXIII. FIG. 69. 



The Brook Minnow, Cyprinus alronasus. Mitchill, Lit. and Phil. Soc. Vol. 1, p. 460. 

 Leuciscus alronasus, The Brook Minnow. Storer, Massachusetts Report, p. 92. 



Characteristics. Small, with a broad black longitudinal band. Tail 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 striae ; 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. This 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. 



