116 FISHES OF ILLINOIS 



HYBOGNATHUS NUBILA (Forbes) 



Forbes, 1878, Bull. 111. State Lab. Nat. Hist., I. 2, 56 (Alburnops). 

 J. & G., 167 (Cllola); M. V., 53; J. & E., I, 215; F„ 79; L., 14. 



Length 2 to 2\ inches; form much as in the last, the body subfusi- 

 form, moderately compressed, and evenly tapered in both directions 

 from the rather deep middle-body region; depth 4 to 4.S in length; 

 caudal peduncle as long as head or a little longer; readily distinguished 

 from H. nuchalis by the smaller size, absence of a symphysial pro- 

 tuberance, and by the prominent dark lateral band, which passes around 

 snout. Color usually rather dusky; sides dull silvery, belly yellow; a 

 dark band along the lateral line and the row of scales above, extending 

 "from a faint caudal spot forward through the eye and around the snout, 

 tipping the chin; black vertebral line before the dorsal; dorsal scales 

 thickly specked with black, those of belly plain; none of the scales 

 distinctly dark-edged; fins plain. Head 3.5 to 4.8 in length, slender, 

 conic, depressed above, being nearly quadrate in transverse section 

 behind orbits ; interorbital space nearly flat, 2.8 to 3.5; eye large, high, 

 nearly circular, 2 . 8 to 3 . 1 in head; nose scarcely longer than eye, 3 . S to 

 4.S; mouth larger than in the last species, terminal, oblique, the maxil- 

 lary 3.5 to 4 in head, extending back of posterior nostril, and almost in 

 front of orbit; jaws about equal, the lower lacking the hard sharp edge 

 and the symphysial protuberance found in the last species; isthmus 

 less than pupil. Teeth 4-4, only slightly hooked, with long though 

 narrow grinding surfaces; intestine 2.8 to 3.5 times the length of head 

 and body; peritoneum black. Dorsal fin with 8 rays, over vcntrals 

 and farther from muzzle than base of caudal; anal rays 8; pectorals 

 reaching § to ventrals; ventrals short of vent in females, exceeding it in 

 males. Scales 5 or 6, 36-38, 3 or 4, of uniform size and distribution on 

 all parts of body; lateral line complete, very slightly decurved ante- 

 riorly; scales before dorsal 13 or 14. 



Males in breeding dress with head somewhat sparsely studded with 

 small but hard and sharp tubercles; smaller tubercles sprinkled over 

 scales of predorsal region. Tuberculate males and females distended 

 with eggs taken from the Kishwaukee at Belvidere on May 12. 



This species, which was described by the senior author from 

 specimens collected from Rock River, at Oregon, 111., has since been 

 taken only rarely in this state, principally in the extreme north- 

 western part. Our later collections number 2 from Jo Daviess and 

 Stephenson counties, 2 from the Kishwaukee at Belvidere, 1 from 

 Sand creek, "Warsaw, and 1 from the Ohio at Cairo. It seems to be 

 essentially a western species, occurring abundantly in the tributaries 

 of the Missouri River in Missouri, and in the streams of the Ozark 

 region in northern Arkansas. It is also reported from the North- 

 west as far as Wyoming. 



