SOUTH AMERICAN NEMATOGNATHI. 17 



with the first described by a median ridge, a continua- 

 tion of the nuchal plate. 



Interorbital width greater than length of snout. 



Maxillary barbels reaching somewhat beyond origin 

 of pectoral fins; mental barbels about reaching to the 

 postmentals, postmentals about as long as the width of 

 interorbital. 



Teeth in two patches in each jaw. 



Coracoid processes parallel, as long as the distance be- 

 tween them. Humeral process reaching to middle of 

 pectoral spine. 



A slit-like pectoral pore. 



Skin everywhere covered with warts. 



Distance of dorsal fin from tip of snout 2$ in the 

 length. 



Pectoral spine slightly curved, reaching beyond tip 

 of coracoid process, its margins with recurved hooks 

 which are largest toward the tip. 



Dark brown, dotted and spotted with lighter and 

 darker; belly somewhat lighter, with rather large dark 

 brown spots, all the fins dark brown, the rays with small 

 transparent spots, the tips of dorsal, anal and ventrals 

 transparent. 



A. 6. 



One specimen .llm. Serpa. S. V. R. Thayer. 



4, Bunocephalus gronovii. 



Aspredo verrucosa Gronow, Syst. Ichthyol., 137, 1854 (not of Bloch). 

 Bunocephalus verrucosus Knev. SB. Ak. Wien, xviii, 1855, 96. (Barra do 

 Rio Negro). 



Bunocephalus gronovii Bleeker, Ichthyol. Arch. Iiid. Siluri, 329, 1858. 

 Glinther, Cat. Fish. Brit. Mus. v. 266, 1864 (Demerara). E. & E. 



Proc. Cal. Acad. Sci. 2d Ser. ii, 1889, 48. 

 Habitat: Mouth of Rio Negro and Demarara. 



5. Bunocephalus bicolor, 



Bunocephalus bicolor Steindachner, Flnssf. Sudani, iv, 8, pi. ii, fig. 1, 

 1882, (Rio Huallaga). E. & E. Proc. Cal. Acad. Sci. 2d Ser. ii, 1889, 48 

 (Cudajas; Jutahy). 



Habitat: Amazon and its tributaries from Cudajas to Huallaga. 



2 



