SOUTH AMERICAN NEMATOGNATHI. 247 



c. Lateral scutes 29; dorsal and ventral surfaces of the caudal peduncle 

 shielded; humeral process extending to the last fourth of the pectoral 

 spine; maxillary barbels not reaching the gill-opening; Dorsal and 

 caudal fins with dark spots. (Kner.) d'orbiyny 187. 



cc. Lateral scutes 40; dorsal and ventral surfaces of the caudal peduncle 

 naked; humeral process extending little beyond middle of pectoral 

 spine; maxillary barbels reaching considerably beyond base of 

 pectoral spine. (Steindachner.) amazonum 188. 



185. Oxydoras niger, 



Doras niger Val. in Humb. Observ. Zool. ii, 184; Cuvier & Valen- 

 ciennes xv, 291, 1840 ( ?); Schomburgk, Fish. Guiana, part i, 165, 

 1841; Miiller & Troschel, Schomburgk, Brit. Guiana, 629, 1848 

 (Eivers of Guiana); Bleeker, Nederl. Tijd. Dierkunde, i, 14, 

 1863 (name only). 



Rhinodoras niger Giinther, Cat. Fish. Brit. Mus. v, 209, 1864 (Ama- 

 zons); Cope, Proc. Am. Philos. Soc. xvii, 678, 1878 (Nauta) ;, 

 Vaillant, Bull. Soc. Philom. Ser. 7, iv, 1880 (Calderon). 



Oxydoras niger Eigenm. & Eigenm. Proc. Cal. Acad. 2d Ser. i, 159 % 

 1888 (Teffe; Gurupa; Manacapuru; Coary; Obidos). 



Doras humboldti Agassiz, Gen. et Spec. Pise. Bras. 14, 1829 (Kio. 

 San Francisco, Brazil); Agassiz, A Journey in Brazil, 1868. 



Corydoras edentatus Spix, Gen. et Spec. Pise. Bras. pi. v, 1829. 



Rhinodoras prionomus Cope, Proc. Acad. Nat. Sci. Philad. 1874,, 

 134 (Nauta); id., Proc. Am. Philos. Soc. xvii, 678, 1878 (Nauta) 



Rhinodoras teffeanus Steindachner, SB. Ak. Wien, Ixxi, 145, pi. iii, 



1875 (Teffe). 

 Habitat: Amazon and northward; Kio San Francisco? 



We have examined two specimens from Teffe agree- 

 ing in all particulars with the plate of D. teffeanus Stein- 

 dachner; the first spine-bearing lateral plate is partially 

 concealed under the skin, but touches the dorsal plate 

 above as in the typical niger. As we cannot consider 

 the marbled color (traces of which are also seen in some of 

 our larger specimens), of specific value, we have identi- 

 fied it with niger. Ox. teffeanus was identified by Dr. 

 Cope with his prionomus it is therefore also placed in 

 the synonymy of niger. The remaining synonymy 

 needs no explanation. 



Elongate, slender; depth beneath the dorsal spine 

 about equal to the width; caudal peduncle depressed. 

 Head long and pointed, its width about equal to its 



