go VERTEBRATE ANIMALS OF THE UNITED STATES 



Wyoming; southward to Tennessee and Arkansas; common in larger 

 streams. 



H. kentuckiensis (Raf.)- Horny-head; river chub; jerker (Fig. 38). 

 Length 250 mm.; head 4; depth 4.25; color bluish olive; sides with 

 greenish reflection; fins pale orange; a dusky bar behind the opercle; 

 males in the spring with a crimson spot on the side of the head; scales 

 6-41-5; adults with a swollen crest on the head: Pennsylvania to 

 Wyoming; southward to Alabama; very common in larger streams. 



29. Couesius Jordan. Body elongate; mouth terminal; a barbel on 

 each maxillary; teeth 2, 4-4, 2, hooked; scales small; rays of both dorsal 

 and anal fins 8 : 4 species in the United States, i in Mexico. 



Fig. 38. — Hybopsis kentuckiensis (from Fishes of Illinois). 



C. plumbeus (Agassiz). Length 150 mm.; head 4.5; depth 4.5; 

 color dusky; sides silvery, with a dark lateral band; free margin of the 

 dorsal fin concave; scales 11-60 to 70-7: Lake Superior to northern 

 New York and New Brunswick; very common northwards. 



C. dissimilis (Girard). Like C. plumbeus, but more robust; free 

 margin of dorsal fin nearly straight: upper Missouri and Black Hills 

 region. 



C. greeni Jord. Length 150 mm.; head 4; depth 4; color dark olive; 

 sides reddish silvery; a dark streak under the eye; scales 10-57-7; body 

 robust; back convex: head waters of the Fraser River; Idaho. 



30. Platygobio Gill. Body elongate, somewhat compressed; teeth 

 2, 4-4, 2; head broad and flat; a barbel on each maxillary; rays of both 

 dorsal and anal fins 8; scales large: 2 species. 



P. physignathus (Cope). Length 150 mm.; head and depth 4.6; 

 color olivaceous, with a plumbeous lateral band; belly white; scales 

 6-48-5, 20 before the dorsal fin; body slender: upper waters of the Arkan- 

 sas; very common in the river channels. 



P. gracilis (Richardson). Flatheaded chub. Length 300 mm.; 

 head 4.25; depth 4.75; color pale olive; head white; scales 6-50-5, 23 

 before the dorsal fin: head waters of the Missouri and Yellowstone to 



