154 CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY IV. 
minutely tiiberculate and the fins are briglit yelloY". Head 4; depth 4. 
D. 7; A. 8; scales lG-8u-10j teeth usually 5-5. L. 2-3 inches. Penn- 
sylvania to Dakota and Tennessee; abundant in small streams; one of 
the most beautiful of our fishes. 
{Luxilus or Chrosomus eri/throgaster Raf. Ichth. Oh. 1820, 47: LuxUus erijthrogastcr 
Kirt. Bost. Journ. Nat. Hist, iv, 23, fig. 1844; Cope, Cypr. Penu. 391: Leiidscus ery- 
throyaster Giiuther, vii, 247 ; Jordan, 302.) 
** Sides of body ■with the upper hand beginning oiiposite the vent and extending 
backward to the middle of the caudal, terminating in a black spot; lower 
band extending from snout through eye, downward and backward, ceasing 
at base of anal ; back with dark spots and cross-bars. 
l'S'8, C. oreas Cope. 
Form of the preceding, the snout rather more obtuse. Coloration 
similar to that of the preceding, except for the diflerence in pattern. 
The back clear olive-green, with dark cross-bars; belly, interspace be- 
tween the lateral bands, and bases of vertical fins bright crimson ; fins 
otherwise yellow. Head 4; depth 4^. D. 8; A. 8; Lat. 1. C7; teeth 
5-5. L. 2^ inches. Tennessee and Eoauoke Ei vers ; even more brill- 
iant than the preceding. 
(Cope, Journ. Acad. Nat. Sci. Phila. 1808,233.) 
*** Body with two black lateral bauds on the side, which unite on the caudal i)edun- 
cle, the lower broader, decurved, the iqjjjer narrow and straight. 
C. eos Cope. 
Slenderer than the preceding; tlie lateral line less distinct, often en- 
tirely wanting. Variations in color as in the other species. Head 4; 
depth 5. D. 8; A. 8; Lat. 1. 77 ; teeth 5-5. L. 24 inches. Susquehanna 
Eiver. Perhaps a variety of G. erythrogasier, 
(Co^je, Proc. Acad. Nat. Sci. Phila. 1801, 523; Cope, Cypr. Penn. 391.) 
76.— SOPEiaE'^iDUM Jordan. 
(Jordan, Bull. Hayden’s Geol. Surv. Terr, iv, 780, 1878: type Hyhorhynchus sidcrius 
Cope.) 
This genus is very closely related to Ilyhognafhus, differing only in 
the small size of the scales, there being 55-90 in the course of the 
lateral line. The physiognomy is somewhat diflerent, and the dorsal 
fin is inserted more posteriorly than usual in Ilyhognatlius. As in Hyho- 
gnafhtiSj the teeth are 4-4, scarcely hooked, tvith narrow grinding surfiice, 
and the intestinal canal is elongate, the .peritoneum black. Eocky 
Mountain region; one species in Western Mexico.* darkness; 
evflov, within ; in allusion to the black iieritoneum.) 
* Scales very small, 85-90 in the course of the lateral line. 
*Z. australe Jordan. Body rather elongate, formed much as in Campostoma anoma- 
him, somewhat compressed, the back somewhat elevated and rounded anteriorly. 
Head rather large, slightly depressed above. Mouth moderate, low ; the lower jaw 
