CYPEINID^. 59 



XX. Teeth one-rowed, with grinding surface, and the edges crenate- 

 serrate ; belly sub-carinate ; alimentary canal elongate, 



NOTEMIGONUS, 27. 

 XXX. Teeth two-rowed, entire, without grinding surface ; alimentary 



canal not elongate Eichardsonius, 28. 



8S, Both jaws with a hard or cartilaginous brown horny plate, large 

 and conspicuous; mouth inferior {Chondrostomatince) : 

 — . Teeth 5-4, club-shaped, entire, terminating in a hook, with the 

 inner (grinding) surface obliquely cut; aual fin elongate; 

 dorsal tin over veutrals ; caudal fin with the accessory rudi- 

 mentary rays very largely developed ; alimentary canal elon- 

 gate (?) : ACROCHILUS, 29. 



fff. Teeth usually 6-6, compressed, lanceolate, erect, very slightly bent inward, 

 one-rowed; body elongate; jaws even; scales small; dorsal 

 over ventrals ; basal caudal rays largely developed ; lower jaw 

 sharp-edged, with a knob at the symphysis ; no pseudobran- 

 chise; intestinal canal elongate ; size large. ..Orthodon, 30. 

 ffff. Teeth in the principal row 3-3, without grinding surface; isthmus very 



wide ; dorsal behind ventrals Tiaroga, 31. 



ee. Maxillary provided with a small barbel : 

 y. Premaxillaries not projectile, the skin of the lip and front continuous ; 

 teeth in the principal row 4-4, without grinding surface ; 



scales small; dorsal behind ventrals; barbel terminal : 



Ehinichthys, 32. 



yy. Premaxillaries projectile, a groove separating the upper lip from the 

 forehead : 

 0. Teeth without grinding surface : 



a. Teeth in the principal row 4-4 ; barbels terminal : 

 b. Dorsal behind ventrals ; scales small : 



c. Lateral line incomplete Apocope, 33, 



cc. Lateral line complete (Subgenus!) Ekitrema, 34. 



Ih. Dorsal fin over veutrals; lateral line complete NocoMis, 35. 



aa. Teeth in the principal row 4-5 ; barbels lateral : 

 d. Dorsal fin over ventrals ; scales large, equal, 



(Subgenus ?) Leucosomus, 36. 

 dd. Dorsal fin beginning over last rays of ventrals ; scales smaller, 



crowded forward Semotllus, 37. 



sz. Teeth with developed grinding surface : 



e. Dorsal fin behind ventrals; scales small ■--. Agosia, 38. 



ee. Dorsal fin directly over ventrals; scales large: 



/. Head compressed, rounded above Pogonichthys, 39. 



ff. Head broad, much depressed, nearly flat or concave above, resem- 

 bling the head of a Cyprinodont Plat ygobio, 40. 



dd. Teeth molar, of the grinding type, without grooves or ridges, in three rows, 



the outer deciduous, 2 or 3, 2, 5—4, 2, 2 or 3 ; two or three of 



the teeth blunt and ranch enlarged; body elongate; head 



tapering: 



— . Angle of mouth with a barbel ; upper jaw freely protractile ; dorsal over 



ventrals Mylochilus, 41. 



. No barbel ; upper jaw not protractile ; dorsal beginning behind ven- 

 trals Mylopharodon, 42. 



**. Opercular and mandibular bones with external cavernous chambers ; air-bladder 

 normal; deutary bones not united; fins without spines 

 {Ccelojihori) : 



