24 CALIFORNIA ACADEMY OF SCIENCES. 



surface plain light shading into light purple or pinkish; 

 dorsal fin dusky, usually with a dusky median stripe on 

 the interradial membrane; caudal dark except the outer- 

 most rays; pectoral smutty, ventrals usually white, the 

 posterior half sometimes dusky; anal fin white anteriorly 

 becoming dusky backward; maxillary barbels more or 

 less dusky. 



Greatest width, before pectoral fins, 5f-6 in the length; 

 A. 51-55. 



Twelve specimens .14-. 19 m. Para; Arary. Agassiz & 

 Bourget. 



13. Platystacus sicuephorus. 



Asjrredo sicuephorus Ciiv. & Val. Hist. Nat. Poiss. xv, 439, 1840 



(Mana). 

 Aspredo sicyejjhorus Giintlier, Cat. Fish. Brit. Mus. v, 269, 1864 



(copied). 

 Platystacus sicuejjhorus E. & E. Proc. Cal. Acad. Sci. 2d Ser. ii, 



1889, 50. 

 Habitat: French Guiana. 



14. Platystacus filamentosus. 



Aspredo ^^fflametitosus Cnv. & Val. Hist. Nat. Poiss. xv, 437, pi. 450, 

 1840 (Cayenne); Giinther, Cat. Fish. Brit. Mus. v, 270, 1864 

 (Demarara) . 



Platystacus jilamentosus E. & E. Proc. Cal. Acad. Sci. 2d Ser. ii, 

 1889, 50. 



Habitat: Guianas. 



15. Platystacus tibicen. 



Aspredo tibicen (Temmiuk) Cuv. & Val. xv, 438, 1840 (Surinam); 



Gunther, Catal. v, 270, 1864 (Brit. Guiana). 

 Platystacus tibicen E. & E. Proc. Cal. Acad. Sci. 2d Ser. ii, 1889, 50 



(Curuca; Eio Muria). 

 Habitat: Guiana; Curuca, Eio Muria. 



This species may readily be distinguished by the nasal 

 spines. 



Head somewhat elongate, subconical. Interorbital 

 width 5 in the distance between base of pectoral and tip 

 of snout. Mouth narrow, the snout little projecting; 

 teeth fine and long-, the intermaxillary band continuous. 

 Maxillary barbel about reaching to gill-opening, an ac- 



