SOUTH AMERICAN NEMATOGNATHI. 153 



comb-like; frontal fontanel open in front, extending back- 

 ward to about the center of the eye. Occipital process 3 

 times as broad as long. Dorsal plate very widely forked in 

 front, its width at the narrowest place more than twice its 

 length on a median line; the posterior portion of the head 

 strongly convex in a transverse section. Four pores on the 

 snout, no conspicuous pores on sides or top of head. 



Eye longer than snout, 3.^ in the head, 1;| in the inter- 

 ocular. 



Maxillary barbel reaching to near tip of pectoral ; mental 

 barbel to base of pectoral, post-mental a little beyond its 

 base. 



Snout rounded, upper jaw longer; teeth all villiform, ar- 

 ranged as in jequitinhonhce. 



Gill-opening extending to base of pectoral. Humeral 

 process covered with thin skin, somewhat roughened on its 

 surface, extending a little beyond middle of pectoral. Pec- 

 toral pore large. Lateral line undulating. 



Distance of dorsal spine from snout 3| in the length; dor- 

 sal spine 1| in the head, its outer margin scarcely rough- 

 ened, its inner margin slightly serrate; first soft ray If in 

 the head. Distance between dorsal and adipose fins 2J in 

 the length. 



Caudal deeply forked, the lobes pointed, 3| in the length. 



Anal emarginate, the first rays (female) not reaching to 

 base of the last rays. 



Ventrals not reaching the anal, 1| in the head. 



Pectoral spine slightly shorter than the head, its outer 

 edge and sides smooth, its inner margin strongly serrate. 



Back brown, the color composed of numerous brown dots; 

 top of head and snout blotched with brown on a yellow 

 ground; opercle and a triangular spot behind the eye yel- 

 low; humeral region covered with numerous conspicuous 

 brown dots; sides and ventral surface yellow; upper caudal 

 lobe dusky, otherwise fins plain yellow, 



Head 4^; depth oi; D. I, 6; A. 20; V. 8; P. I, 6-7. 



