SOUTH AMERICAN NEMATOGNATHI. 125 



Body short and deep, its greatest Avidth less than its 

 greatest depth. Head short, its width 1| in its length, 

 width, at the angle of the mouth, 2 in its length; the head 

 flat above, covered with very thin skin, the surface of the 

 bones deeply furrowed, striations radiating from the eyes 

 and from the pit at the base of the occipital process. Font- 

 anel a narrow fissure between the frontal bones. Occi- 

 pital process very long, partly concealed under the skin, 

 reaching more than half way to the dorsal spine to near the 

 large, concealed, dorsal plate. Pores scattered over the 

 head. 



Eye round , 2 J in snout, 6^ in head, 2 in the interorbital ; 

 its posterior margin in front of the middle of the head. 



Maxillary barbel (torn on one side) extending to tips of 

 middle caudal rays; mental barbels reaching middle of pec- 

 toral, post-mental to midwa}'^ between tip of pectoral and 

 base of ventral. 



Jaws equal, mouth comparatively small; teeth of the 

 mandible as usual; the intermaxillary band of teeth 

 shallowed and interrupted in the middle, its depth about 9 

 in its width, without backward projecting angles. 



Gill-rakers 3+9. 



Distance of dorsal spine from tip of snout 21 in the 

 length; dorsal fin shorter than high, the highest ray I5 in 

 the head. Distance of adipose fin from the dorsal equal to 

 one-third the length of the latter fin; adipose fin twice as 

 long as the dorsal fin, 3 in the length. 



Caudal deeply cleft, the lobes longer than the head, 

 about 3 in the length. 



Anal fin short and high, its margin narrowly convex, its 

 highest ray 2 in the head. 



Ventrals inserted below the vertical from the last dorsal 

 ray, I5 in head. 



Pectoral spine strong, terete, short hooks on its outer 

 margin near tip and short teeth nearly the entire length of 

 the inner margin; Ih in the head. 



