124 Bulletin ^7, Umted States National Museum. 



body ; pectoral spine \\ in head. Plnmbeous above, with blue luster ; fins 

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

 nam and south to Pernambuco. (Trpo, before ; ii\\), eye.) 



naijrus prooiK, CuviER & Valf.nciennes, xiv, 457, 1830, Guiana; Porto Rico. 



AHm proops, GCnther, Cat., v, 148, 1864. 



Nelnma proops, Bleeker, Silures de Suriname, 62, 1864. 



Tnrhhiitnis proops, Eioknmann, S. .\. Neniatogiiatlii, 57, 1890. 



171. SCIAnEICHTHYS PASS.\.NY, (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.jn-oops, its tip reduced; dorsal plate 

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

 Hat, 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. (Ouvier 

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



Bngiiis passany, Cl'VIER & VALENCIENNES, xiv, 4,')8, 1839, Cayenne. 



Arius passanT), GuNTHER, Cat, v, 149, 18C4. 



Tnchisnnts passany, Eigenmann, S. A. Nematogn-athi, 58, 1890. 



172. SCIADEICHTHTS ALBK'AXS, (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, 5i in the total length. 

 Head 4| in the total, its width liin its length. (Cuvier cV^ Valenciennes.) 

 Guiana to the Amazon, (albicans, whitish.) 



Bagrus albicans, Cuvier & Valenciennes, xiv, 401, pi. 420, 1839, Cayenne. 



f r.agrns valencieiincsi, Castelnau, Anini. Amer. Sud., 31, pi. xiii, f. 1, 18.'>.'i, Amazon. 



Arms valeticiennesi, Gunther, Cat., v, 150, 18G4. 



Tai-hisiinis albicans, Eigenmann, S. A. Nematognatlii, 59, 1890. 



71. SELENASPIS, Bleeker. 



173. SELENASPIS HERZBERGII, (Blorli). 



Head 3? to 3f ; depth, 5 to 6. D. I, 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 dorf^al 

 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 j plates on head 



