124 Bulletin 47, United States National Museum. 



body; pectoral spine 1 in head. Plumbeous above, with blue luster ; fins 

 dotted with brown. (Eigenmann.) West Indies from Porto Rico to Suri- 

 nam and south to Pernambuco. (^po, before; w^, eye.) 



Bagrus proops, CUVIER & VALENCIENNES, xiv, 457, 1839, Guiana; Porto Rico. 



Arius proops, GUNTHER, Cat., v, 148, 1864. 



Netmna proops, BLEEKER, Silures de Suriname, 62, 1864. 



Tachisurus proops, EIOENMANN, S. A. Nematognathi, 57, 1890. 



171. SCIADEICHTHYS PASSANY, (Cuvier & Valenciennes). 



D. I, 7 ; A. 17. Palatine patches of teeth with a backward projecting 

 angle ; dorsal plate notched in front, receiving the point of occipital pro- 

 cess. Eye nearer snout than to preopercle. Lower jaw longer ; occipital 

 process wider and shorter than in S. proops, its tip reduced ; "dorsal plate 

 more or less crescent-shaped. Eye nearer snout than in S. proops. Head 

 flat, especially forward; opercle strongly granular; humeral process 

 obtuse, higher than long, granular ; dorsal and pectoral spine granular 

 in front, weakly serrate behind; ventrals longer than pectorals. (Cuvier 

 &, Valenciennes.) Cayenne, (passany, the vernacular name at Cayenne.) 



Bagrus passany, CUVIER & VALENCIENNES, xiv, 458, 1839, Cayenne. 



Arius passany, GUNTHER, Cat., v, 149, 18C4. 



Tachisurus passany, EIGENMANN, S. A. Nematognathi, 58, 1890. 



172. SCIADEICHTHYS ALBICANS, (Cuvier & Valenciennes). 



D. I, 7; A. 19. Palatine bands of teeth with an angle behind, the teeth 

 villiform ; dorsal plate notched in front, receiving the point of occipital 

 process. Eye nearer snout than to preopercle. Jaws equal ; dorsal plate 

 large, almost as wide as the skull behind eye ; opercle striate ; top of head 

 granular forward to between eyes ; a triangular smooth area in front ; 

 humeral process, dorsal plate, and outer margins of dorsal and pectoral 

 spines granular. Snout 3 in space from eye to preopercle ; eye 5 in inter- 

 ocular space. Maxillary barbels scarcely reach gill opening. Adipose 

 almost as long as anal. Caudal lobes subequal, 5 in the total length. 

 Head 4| in the total, its width H in its length. (Cuvier & Valenciennes.) 

 Guiana to the Amazon, (albicans, whitish.) 



Bagrus albicans, CUVIER & VALENCIENNES, xiv, 461, pi. 420, 1839, Cayenne. 



? Bagrus valenciennesi, CASTELNAU, Anim. Amer. Sud., 31, pi. xin, f. 1, 1855, Amazon. 



Arius valenciennesi, GUNTHER, Cat., v, 150, 1864. 



Tachisurus albicans, EIGENMANN, S. A. Nematognathi, 59, 1890. 



71. SELENASPIS, Bleeker. 



173. SELENASPIS HERZBERGII, (Bloch). 



Head 3g to 3| ; depth, 5 to 6. D. 1,7; A. 18. Palatine bands of teeth 

 with a backward projecting angle ; teeth all villiform. Posterior nasal 

 openings connected by a membrane ; dorsal plate and occipital process 

 truncate where they meet, at least in the adult; in the young the dorsal 

 plate is somewhat convex in front, the backward projecting angles of the 

 palatine patches not developed. Occipital process i as wide at tip as at 

 base; its length more than i its width; its middle scarcely keeled; gill 

 rakers 5 + 10. Body elongate, the head longer than wide ; plates on head 



