166 FISHES OF ILLINOIS 



Males without tubercles or flushed coloration in spring. Females much 

 distended with eggs taken about first of June. 



This is one of our Illinois species whose distribution in the 

 state presents an ecological problem which we have no present 

 means of solving. Ranging from Lake Erie to the Black Warrior 

 and the Alabama southward, and to Iowa and Arkansas on the 

 west, it occurs abundantly in southeastern Illinois, but has been 

 taken by us in only two neighboring localities additional, one on 

 the upper Kankakee and the other on the Mackinaw. It is one 

 of the species, in fact, which has the appearance of spreading over 

 the state from the south and east mainly by the branches of the 

 Wabash, but reaching adjacent waters as if by overland migra- 

 tion. It is notably a species of creeks, for which its frequency 

 coefficient rises to the unusual figure of 3.97. We have found it 

 relatively about half as abundant in the smaller rivers, and of 

 only occasional occurrence in rivers of the larger class. None of 

 our 51 collections has been taken from stagnant waters of 

 any kind. 



HYBOPSIS STORERIANUS (KIRTLAND) 

 STOKER'S CHUB 



(MAP L) 



Kirtland, 1842, Proc. Bost. Soc. Nat. Hist., I, 71 (Rutilus). 



J. & G., 213 (Ceratichthys lucens); M. V., 65; J. & B., I, 321; N., 46; J., 56 

 (Alburnops); L., 19. 



A large species, known at once from our other species of Hybopsis by 

 the double-rowed dark edging of the scales above the lateral line. Length 

 5 or 6 inches; body elongate, considerably compressed; back often somewhat 

 elevated; depth 4.3 to 5.3 in length; caudal peduncle rather slender, its 

 depth 2.2 to 2.6 in head. Color translucent greenish above, with purplish 

 reflections; brilliantly silvery on sides and below; an indistinct plumbeous 

 lateral band, overlaid in life with emerald, below which is a band of silvery 

 to bluish blending with the silvery of belly; no caudal spot and no vertebral 

 streak; scales above lateral line, except a few along middle of back in front 

 of dorsal fin, each with two subparallel rows of dark dots near posterior 

 border, between which is a crescentic lighter space; cheeks and opercles 

 bright silvery; fins plain, the dorsal and caudal sometimes slightly dusky. 

 Head 4.3 to 5.3 in length, comparatively short and compressed, cheeks 

 nearly vertical; width of head 1.8 to 2; interorbital space entirely flat or 

 somewhat concave, 3.3 to 3.5; eye 2.9 to 3.4 in head; preorbital bone especially 

 prominent, large, oblong, and silvery; nose 2.8 to 3.1, a little longer than 

 eye, moderately decurved, the tip of the muzzle somewhat thickened and 

 pad-like, though not projecting much beyond mouth; mouth rather small, 



