eigenmann: the FRESHWATER FISHES OF BRITISH GUIANA 187 



in a marginal row behind; median spines strong, recurved; caudal peduncle entirely 

 covered with a median series of plates above and half-way to the anal below. 



Slaty blue, a light band from the fontanel along the middle to the tip of the 

 caudal; lower surface and margin of head to near the eye light. Barbels dark, 

 dark streak back from the maxillary barbel; dorsal with a dark band across its 

 upper part; center and margins of caudal light, a pair of submarginal dark bands; 

 anal with a dark streak; ventrals hyaline; pectoral dusky. 



58. Doras hancocki Cuvier and Valenciennes. 



" Saurauwari," "Yarauira." 



Doras costata (not of Linnaeus) Hancock, Zool. Journ., IV, 1828,242 (Demerara). — 



Schomburgk, Fishes Brit. Guiana, I, 1841, 156. 

 Doras hancockii Cuvier and Valenciennes, Hist. Nat. Poiss., XV, 1840, 279. — 



Gunther, Catalogue, V, 1864, 202 (Demerara; Rio Cupai). — Eigenmann and 



Eigenmann, Occasional Papers Cal. Acad. Sci., I, 1890, 234. — Eigenmann, 



Repts. Princeton Univ. Exp. Patagonia, III, 1910, 393. 



One hundred and ninety-five specimens, 9-120 mm. Lama Stop-Off. (C. M. 

 Cat. No. 1443a-i; I. U. Cat. No. 12033.) 



Ten specimens, 65-123 mm. Maduni Creek. (C. M. Cat. No. 1444a-o; 

 I. U. Cat. No. 12034.) 



One specimen, 28 mm. Wismar. (C. M. Cat. No. 1445a). 



Nine specimens, 26-41 mm. Rockstone. (C. M. Cat. No. 1446a-6; I. U. 

 Cat. No. 12035.) 



Twelve specimens, 28-36 mm. Gluck Island. (C. M. Cat. No. 1649a-o; 

 I. U. Cat. No. 12038.) 



Four specimens, 68-98 mm. Tumatumari. (C. M. Cat. No. 1447a; I. U. 

 Cat. No. 12036.) 



Eight specimens, 30-45 mm. Rupununi Pan. (C. M. Cat. No. 1448a-6; 

 I. U. Cat. No. 12037.) 



Head 4-4.3; depth 4.25; width at tip of humeral process 3.66; D. 1,6; A. 11- 

 13; lateral plates 1+25; eye 1.5 in snout, 4.5 in head. 1.5 in interorbital. 



Coracoid and its process exposed below, striate; nuchal area with a blunt 

 median keel, roof-shaped ; head granular to the anterior nares; movable nasal bone 

 large, forming part of the orbit; maxillary barbel reaching tip of humeral process, 

 outer mental barbel to its middle; jaws equal, mouth terminal, its width less than 

 half the space between the gill-openings. 



Pectoral spine strongly serrate on its anterior and posterior margins, its upper 



