284 FISHES. 



grinding surface; alimentary canal elongate, four 

 times the length of body or more ; pi'emaxillaries 

 projectile; lips attenuate, without sheath; scales 

 large. 



/. Lateral Hue almost wanting; mouth oblique; dor- 

 sal in front of ventrals. . . . Coliscus, 4. 



ff. Lateral line complete ; mouth horizontal ; dorsal 

 over ventrals. . . . Hybognathus, 5. 

 ee. Teeth raptatorial, more or less strongly hooked; ali- 

 mentary canal usually short, about as long as body 

 (in Notemigonus and Ghro8omu8 somewhat elongate.) 



g. Lateral line complete (rarely obscure or wanting on 

 the last five or six scales.) 



h. Teeth in the principal row 4 — 4. 



i. Teeth with masticatory surface developed. 



j. Dorsal fin beginning above some part of base 

 of ventrals ; anal basis short, its rays seven 

 to nine. 



k. Teeth 4-4 ; scales normal. Hudsonius, 6. 



kk. Teeth 2, 4-4, 2; scales closely imbricated. 



LuxiLus, 7. 



jj. Dorsal fin beginning entirely behind ventrals, 

 between ventrals and anal ; anal elongate, of 

 ten to twelve rays ; (small, elongate species 

 wdth the mouth oblique, the teeth 2, 4 — 4, 2, 

 and a black soot at base of dorsal fin in front.) 



Lythburus, 8. 



ii. Teeth without masticatory surface. 



I. Lips thin, normal ; opercular and mandibul- 

 ary bones without externally visible muc- 

 ous chambers. 

 m. Dorsal fin beginning entirely behind 



