SOUTH AMERICAN NEMATOGNATHI. 87 



at the mouth 2J in the length of the head. Top of head 

 granular, the granulations forming striae nearly every- 

 where; occipital process as broad as long, with a median 

 ridge, the margins concave. Middle of the fontanel over 

 the posterior margin of the pupil, continued backward 

 as a triangular groove to near base of occipital process; 

 interorbital area with the usual four smooth ridges; hu- 

 meral process roughened, covered with skin; sides of 

 the head with reticulating mucous canals. 



Eye 1J in snout, 5J in head, about 3 in interocular, 2 

 in interorbital space. 



Maxillary barbels about reaching gill-opening; men- 

 tals extending about half way to gill-opening, the post- 

 mentals not much longer. 



Upper jaw projecting; teeth villiform in the jaws, sub- 

 granular or bluntly conical on the palate, small; no gran- 

 ular teeth in the inner series of the mandible; the palatine 

 patches smaller and more diverging than in spixii. 



Gill-membranes united, joined to the isthmus. Gill- 

 rakers 8+14. Pectoral pore moderate. 



Distance of dorsal spine from snout 2J in the length, 

 the spine 1J in head, serrate on its posterior margin, 

 granulate in front along basal half, becoming nearly 

 smooth above. 



Space between dorsal and adipose fins 3J in the length; 

 the adipose shorter than the dorsal fin, free posteriorly. 



Caudal forked, 4| in the length. 



Anal fin a little longer than high, its highest rays about 

 half length of head. 



Ventral fins about 2 in the head. 



Pectoral spine as long as the dorsal spine, but stronger, 

 serrate on its inner margin, granular along its outer 

 margin. 



Dorsal surface brown; sides and ventral surface sil- 

 very; fins smutty. 



