SOUTH AMERICAN NEMATOGNATHI. 169 



teeth very deep, its depth 4 in its width; 

 mandibulary band of teeth at the sym- 

 physis about one-half as wide as the in- 

 termaxillary band. Gili-rakers 4+10. 



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

 the spine high and slender, 2 in head; its anterior mar- 

 gin smooth, the posterior margin verrucose. Distance 

 of adipose fin from the dorsal equal to the length of the 

 dorsal. Adipose fin 5| in the length. 



Pectoral spine about 2 in head, its anterior margin 

 with short blunt teeth, the posterior margin with long 

 teeth. 



Head 3J; Br. 9-10; D. I, 6; A. 13. 



A single specimen in poor condition .18 m. Goyaz. 



122, Fimelodus albicans, 



Arius albicans Valenciennes, Voy. d'Orb. pi. iii, fig. 2, 1847. 

 Arius albicans Cuv. & Val. Hist. Nat. Poiss. xv, 80, 1840 (Bueno* 



Ay res). 

 Piramutana albicans Giiiither, Annals & Mag. Nat. Hist. 1880, !) 



(Kio Plata). 



Arius moroti Valenciennes, Voy. d'Orb. 6, 1847 (La Plata). 

 Pimelodus albicans Eigenm. & Eigenm. Proc. Cal. Acad. 2d Ser. 



i, 134, 1888 (La Plata). 

 Habitat: Kio Plata. 



Dr. Giinther is the first to have rediscovered this 

 species. All the specimens referred to albicans by Liitken, 

 Steindachner and others belong to P. clarias. 



As Valenciennes and Giinther state, this species has 

 no teeth on the pterygoids; it always has teeth on the 

 vomer. In the smallest and largest specimens exam- 

 ined they are present on one side only. It is further dis- 

 tinguished by its small eye and depressed head. 



The vomeriiie teeth are scarcely sufficient to separate 

 this species from Pimelodus generically. 



Head rather broad, granulose. Eye small 3J-4J in 

 snout, 7J-9 in head, 2-3 in interorbital, 1 in interna- 

 sal space. 



