CYPRINHLE. — XXVI. 51 



d. Teeth 5-5 or 4-5; dorsal inserted behind ventrals ; scales very small ; 

 anal short. 



e. Pseudobranchiae none; lower jaw thin, with sharp, hard edge; upper 



jaw protractile, with fleshy covering; lateral line complete; body 



elongate, subterete Oxygeneum, 50. 



ee. Pseudobranchiae present; lips thin, normal; upper jaw protractile; 



lateral line incomplete Chrosomus, 51. 



dd. Teeth 4-4; pseudobranchiae present; dorsal over ventrals; scales 

 rather large. 



f. First (rudimentary) ray of D. slender, firmly attached to the first de- 



veloped ray; jaws sharp-edged, the lower with a slight projection in 

 front; scales before D. large (less than 15). Hybognathus, 52. 

 ff. * First (rudimentary) ray of D. well developed, bluntish, separated 

 from the first developed ray, to which it is joined by membrane 

 (this character never conspicuous except in adult males; often ob- 

 scure in young); scales before D. small (more than 20.) 



PlMEPHALES, 53. 



cc. Alimentary canal short, less than twice length of body; teeth hooked, 

 the grinding surface, if present, narrow and rudimentary; peritoneum 

 usually pale ; species mostly carnivorous. 

 g. Dentary bones parallel, united for their whole length (the lower jaw 

 reduced to a tongue-like projection, which has a fleshy lobe on each 

 side. ( Exoglotrince.) 

 h. Premaxillaries not protractile; upper lip thickened; scales moder- 

 ate ; teeth 1, 4-4, 1, without grinding surface. ExOGLOSSUM, 54. 

 gg. Dentary bones broadly arched, as usual among fishes, and united 

 only at the symphysis. (Leuciscince.) 

 i. Abdomen behind V. not compressed to an edge, the scales passing 



over it; anal basis generally short (the rays 7 to 12). 

 j. Teeth in the main row, 4-4. 

 k. Maxillary without traces of barbel. 

 x. [Premaxillaries protractile.] 

 /. Lower lip thin or obsolete (except in one or two species), not 

 developed as a fleshy lobe on each side. 

 m. Mandible, interopercle, and suborbital not evidently cavernous. 

 n. l First (rudimentary) ray of D. enlarged and bluntish, sepa- 

 rated from the first developed ray by membrane (as in Pime- 

 ph<rtes), this most evident in 6 ; scales before D. small, 

 about 28; teeth 4-4; [black blotch on front of dorsal and 

 one at base of caudal always present.] . . Clioi,a, 55. 

 nn. First (rudimentary) raj' of D. small, closely joined to the 

 first developed ray; teeth 2, 1 orO, 4-4, 2, 1 or 0; scales 

 rather large; scales before D. large or small (12 to 30). 



Notropis, 56. 

 mm. Mandible, interopercle, and suborbital with conspicuous 

 externally visible cavernous areas (like silver}' cross- 

 bars); teeth 1,4-4, 0; scales large; D. above V. 



Ericymba, 57. 

 II. Lower lip developed as a fleshy lobe on each side ; teeth 4-4, 

 without grinding surface; D. before V.; isthmus very broad. 



Phenacobius, 58. 



1 This character is more or less obscure in females and young examples. 



