SOUTH AMERICAN NEMATOGNATHI. 113 



divided for more than half their length and the basal 

 portion covered with very thick skin; unless the skin is 

 removed, the rays, in large specimens, would appear to 

 be more, rather than fewer than ten, the number stated 

 by Humboldt. Mangurus is covered with spots which 

 are smallest on the head; if then, we attribute to the per- 

 sonality of the artist the regularity of the spots in the 

 figure of zungaro the identity of that species with 

 mangurus must be conceded. 



Width behind the head decidedly greater than depth, 

 the body wedge-shaped, compressed at the caudal. Head 

 as wide as long; frontal reduced to a very narrow slit 

 between the frontal bones above the eyes; occipital pro- 

 cess short, deeply notched at the tip, receiving the point 

 of the much longer dorsal plate. 



Profile straight, nearly horizontal. 



Eye small; distance from the anterior edge of the eye 

 to the tip of snout 3 in head, distance between the eyes 2 

 in head. 



Maxillary barbels not as long as the head; mental bar- 

 bels reaching to the base of postmentals which extend 

 to the edge of the branchiostegal membrane, or shorter. 



Jaws sub-equal; intermaxillary band 

 of teeth very wide, its depth at the sym- 

 physis 3-4 in its width, the teeth all villi- 

 form, the inner ones slightly longer; 

 mandibulary band of teeth very deep in 

 front, tapering to a point backward, the 

 widest part equal at least to 2 diameters of 

 the eye. 



Humeral process very oblique, scarcely projecting be- 

 yond the arch. 



Distance of dorsal spine from tip of snout 2|-3 in the 

 length. 



Dorsal spine perfectly straight, 2-2J in head, the 

 8 



