FISHES 63 



ki Minute barbel present 25. Margariscus. 



k2 No barbel present; lateral line 



short 26. Hemitremia. 



J3 Lateral line wanting 27. lotichthus. 



£2 Teeth i-rowed, being either 4-5 or 5-5. 



gi In the extreme western States 28. Siphateles. 



29. Hesperoleucus. 

 g2 In the central and southeastern States. 



hi Mouth vertical 30. Opsopceodiis. 



\\2 Mouth horizontal 31. Opsopoea. 



62 Abdomen behind ventral fins compressed to an 



acute edge which is scaleless; central States 32. Xotemigonus. 



C2 Teeth in main row 4-4, the lesser row being often absent, 

 di Lower jaw normally formed. 



ei Barbies absent; eastern and central States, 

 fi Mouth not hke that of a sucker. 



gi First (rudimentary) ray of dorsal fin sepa- 

 rated from next ray, to which it is joined 



by a membrane 2,2,. Ceratichthys. 



g2 First ray of dorsal fin closely joined to next, 

 hi No cavernous channels in mandible and 

 opercle. 



ii Teeth in i or 2 rows, 4 being in the 

 main row and i or none in the 

 short row on each side or both, 

 ji Dorsal fin nearly above the 



ventrals 34. Hybopsis. 



J2 Dorsal fin mostly behind the 



■ ventrals 35. Cyprinella. 



i2 Teeth in 2 rows, being 2, 4-4, 2, or 

 rarely i. 

 ji Size moderate; length mostly 



125 mm. to 200 mm 36. Luxilus. 



37. Hydrophlox. 

 J2 Size very small; length 50 mm. to 



100 mm 38. Notropis. 



39. Lythrnrus. 

 h2 Conspicuous cavernous channels in 



mandible and opercle 40. Ericymba. 



U Mouth and lower lips fleshy hke a suckers. . . .41. Phenacobius 

 e2 Barbels present. 



fi Scales very small, 60 to 90 in the lateral hne. 



gi Premaxillaries not protractile 42. Rhinickylhys 



g2 Premaxillaries protractile. 



hi Barbels minute; Rocky Mountain region 43. Apocope. 



hz Barbels well developed 49. Coucsius. 



£2 Scales large, 35 to 50 in the lateral line, 

 gi Size small or moderate. 



