142 NORTHERN FISHES 



postorbital length of head, about half In largest adults; spot at caudal base 

 round and blackish; caudal fin red in living young; teeth typically 1, 4 — 4, 1 



Hornyhead Chub, Nocomis hiquttatas (Kirtland) 



Mouth horizontal and strictly inferior, upper lip considerably overhung by 

 snout; eye longer than upper jaw; body without definite spots (beware of 

 parasite specks); teeth tj^pically 1, 4 — 4, 1; color silvery, without a dark 

 lateral band; size large, 4-10 inches when adult; dorsal fin inserted distinctly 

 in advance of pelvic fin Silver Chub, Hybopsis storeriantis (Kirtland) 



13. A black spot on dorsal fin near front of base, indistinct in young; mouth 

 large, upper jaw extending at least to below front of eye; sides not mottled 



by specialized dark scales; scales in lateral line fewer than 60 



.Northern Creek Chub, Semotilua atromaculatus atromacidatus (Mitchill) 

 No black spot on dorsal fin; mouth small, ujiiJer jaw not extending to below 

 front of eye; sides mottled by specialized dark scales; scales in lateral line 



about 65-75 



Northern Pearl Dace, Margari.sctis margarita nachtriebi (Cox) 



14. Lateral line scales more than 60 15 



Lateral line scales fewer than 55 19 



15. Litestine short, with a single main loop, and less than twice as long as body; 

 body with a single dusky lateral band; teeth in main row typically 5 — 4, 



sometimes 5 — 5, 4—5, or 4 — 4 16 



Litestine elongate, with two crosswise coils in addition to the primary loops, 

 and riiore than twice as long as body; body with two black lateral bands; 

 teeth 5—5 or 5—4 \ ' 18 



16. Peritoneum black; lateral line incomplete; scales minute, more than 80 in 



lateral line, each with radii on all fields 



Finescale Dace, PfriUe neogaea (Cojie) 



Peritoneum pale; lateral line complete, except in young of Margariscus; 

 scales fewer than 80 in lateral line, with radii only on exposed field 17 



17. Head narrow; gape very wide, the upper jaw extending as far back as the 

 front of the eye; nuptial tubercles small but numerous, developed on head 



and often also on nape; snout sharp 



Redside Dace, CUnostomus elongatus (Kirtland) 



Head width moderate; gape much smaller, the upper jaw not extending as 

 far back as the front of the eye; nuptial tubercles minute or undeveloped; 

 snout blunt Margariscus margarita nachtriebi: see 13 



18. IVIouth strongly oblique and more curved; length of upper jaw less than one- 

 fourth length of head; distance from tip of snout to back of eye usually 



about equal to rest of head 



Northern Redbelly Dace, Chrosonui^ eos Cope 



Mouth little oblique, little curved; length of upi>er jaw more than one-fourth 

 length of head; distance from tip of snout to back of eye distinctly longer 



than rest of head 



Southern Redbelly Dace, Chrosomus erythrogaster Rafinesque 



19. Alxlonien behind jjelvic fins with a fleshy keel over which the scales do not 



])ass: lateral line much decurvcd; anal fin falcate 



. . .Western Golden Shiner, Notcniigonus crysoleucas auratus (Rafinesque) 

 Abdomen beliind pelvic fins rounded over and scaled; lateral line not greatly 

 decurved; anal fin scarcely falcate "^0 



20. First dorsal ray more or less thickened, separated by membrane from first 

 well-(levelo|)e(l ray, and with a tliicker coating of adipose tissue: a dark 



