HYBOPSIS 167 



3.7 in head, barely reaching front of orbit; barbel evident, though 

 scarcely projecting; isthmus less than pupil. Teeth 1, 4-4, 1 or 0, stout 

 and little hooked, with grinding surface usually not much developed; 

 intestine about .9 of length of head and bodv; peritoneum silvery. 

 Dorsal fin with 8 rays, occasionally 9, more or less falcate, set a little in 

 advance of ventrals, and distinctly closer to muzzle than base of caudal; 

 longest dorsal ray 1 to 1 .2 in head; anal rays usually 8, sometimes 7 or 9; 

 pectorals § or less to ventrals; ventrals to vent in young only. Scales 6, 

 3 7 to 40, 4; 14 to 16 rows in front of dorsal; upper longitudinal rows with 

 appearance of running out behind dorsal fin, as in Notropis cornutus, this 

 appearance aided by converging longitudinal lines formed by connecting 

 cross-marks of light color on the scales of some of the rows; lateral line 

 gently decurved anteriorly. 



Sexual differences slight; upper surface of pectoral rays in spring males 

 with verv fine pectinately disposed tubercles; no sexually mature females 

 in our collections; some rather young females with ovaries just beginning 

 to enlarge taken about May 20. 



A fish of the larger streams and lowland lakes, v^idely distrib- 

 uted in Illinois, though rare with us throughout its range. Our 

 28 collections carry it from Cairo to Jo Daviess county and from 

 the Wabash to the Mississippi. None of them, however, are from 

 the lower Illinoisan glaciation. One collection is from the Rock 

 River near Milan, seven come from the Illinois and its larger trib- 

 utaries, an equal number are from the Mississippi and its neighbor- 

 ing lakes and bayous, five from the Wabash and its tributaries, 

 three from the Saline River, and two from the Ohio. Outside 

 Illinois it is generally distributed from Lakes Erie and Ontario to 

 Wyoming, Nebraska, and Arkansas, ranging southward also to 

 Tennessee. 



HYBOPSIS KENTUCKIENSIS (Rafinesque) 

 (river chub; horny-head) 



Rafinesque, 1820, Ichth. Oh., 48 (Luxilus). 



G., VII, 178 (Ceratichthys biguttatus and C. cyclotis) and 179 (C. stigmaticus and C. 

 micropogon) ; J. & G, 212 (Ceratichthys biguttatus and C. micropogon) ; M. V., 

 65; J. & E., I, 322; N., 45 (Ceratichthys biguttatus); J., 62 (Ceratichthys bigut- 

 tatus;) F. F., I. 6, 89 (Ceratichthys biguttatus); F. 75 (Semotilus biguttatus); 

 L., 19. 



A large species, with a general resemblance in form to Semotilus, 

 but the snout more pointed, mouth less oblique, and with no caudal spot 

 (except in young) . Length 6 to 8 inches ; body subfusiform, very little com- 

 pressed, robust anteriorly, the body deepest' in front of the dorsal fin; pro- 

 file scarcely declined from front of dorsal to occiput in adults, the descent 

 from that point to muzzle rapid ; depth 3.9 to 4.5; caudal peduncle less 

 than head, its depth 1 .9 to 2 . 1 in its length. Color of top of head and 



