232 CALIFORNIA ACADEMY OF SCIENCES. 



Doras coslattif. 'Lacei:)t'de, Hist. Nat. Poiss. v, 116, 1803 [in part] 

 (South America); Hancock Zoological Journal, iv, 242, 1828 

 (Demarara); Cuv. & Val. Hist. Nat. Poiss. xv, 268, 1840 (Gui- 

 ana); Schomburgk, Fish. Guiana, part i, 156, 1841; Castelnau, 

 Anim. Amerique du Sud. 48, 1855 (Amazon); Giinther, Cat. 

 Fish. Brit. Mus. v, 201, 1864 (British Guiana; Eiver Gupai); 

 Eigenm. & Eigenm. Proc. Cal. Acad. 2d Ser. vol. i, 161, 1888 

 Eio Preto; Eio Puty; San Gougallo; Xiugu Cascade; Obidos; 

 Gurupa; TeSt-). 



Platj/doras cosiatus Bleeker, Nederl. Tijd. Dierkunde, i, 16, 1863 

 (name onlj^); id. Silures de Suriname, 38, 1864 (Surinam). 



Habitat: Eio San Francisco; Parahyba; Amazon and Solimoens; 

 Guiana region. 



The depth under the dorsal spine little less than the 

 width; caudal peduncle about as deep as wide. Head as 

 wide as long, its depth 14 in its length; anterior profile 

 steep; opercles, suborbital, and nasal bones and entire 

 upper portion of the head with radiating series of gran- 

 ules. Dorsal plate with a narrow inward-directed pro- 

 cess behind. Anterior portion of the head flat, poste- 

 rior portion arched. Fontanel wedge-shaped. 



Eye large, I3-23- in the snout, Sh-5h in the head, li-2 

 in the interorbital. 



Maxillary barbel reaching second fourth of the pecto- 

 ral spine; postnientals little beyond base of pectoral, 

 mental about half as long as the postmental barbels. 



Snout narrowly rounded, its width at the rictus 2^ in 

 the head. Upper jaw projecting. Teeth villiforni, in 

 moderate bands. 



Breast entirely covered with skin. 



First and second hook-bearing lateral scutes touching 

 the dorsal plate above, lower than the third scute which 

 is 1^ in the head; between the scapula and the hook- 

 bearing scutes are two granular plates; the hook-bearing 

 scutes covering the entire sides, leaving a naked dorsal 

 and ventral surface between, the scutes becoming lower 

 backward, conforming to the outline of the body, and 

 not meeting the bases of the adipose and anal fins; the 



