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 ( luvier and Valenciennes. 

 " Saurauwari," "Yarauira." 

 Doras costata (not of Linnseus) 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-t; I. U. Cat. No. 12033.) 



Ten specimens, 65-123 mm. Maduni Creek. (C. M. Cat. No. 1444a-6; 

 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-6; 

 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. IT. 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 



