EIGENMANN: the freshwater fishes of BRITISH GUIANA 191 



spines with hooks of equal size in front and behind, the anterior antrorse, the 

 posterior retrorse. Adipose fin low, gradually merging into the back in front. 

 Caudal short and broad, its length equal to snout and eye. 

 Slaty black, with lighter markings below; fins black. 



Leptodoras Boulenger. 



Leptodoras Boulenger, Ann. and Mag. Nat. Hist., (7), II, 1898, 477. 



Type, Oxydoras acipenserinus Glinther. 



No teeth; maxillary barbel fringed; anal 15-18; eye large. 



Boulenger creates the genus Leptodoras on account of the longer body and the 

 longer anal fm, 15-17 rays. In another place (Trans. Zool. Soc, XIV, 1898,423) 

 he rejects the genus Hemidoras as indistinguishable from Oxydoras. As the type 

 of Hemidoras has thirteen anal rays and Hemidoras brevis has thirteen or fourteen 

 it might be doubted whether Leptodoras can be separated from Hemidoras on the 

 score of anal rays. Since, however, Leptodoras has no teeth it maybe kept distinct. 



The extralimital species of this genus are acipenserinus, juruensis and probably 

 stubelii. I have been able to examine the types of the two former in the British 

 Museum. 



Key to the Species of Leptodoras. 



a. Dorsal spine short, pungent, serrate in front. 



b. Eye 3.5 in the head; pectoral spine longer than snout and eye; reacliing near middle of ventrals. 



linnelli. 

 (66. Eye 5 in the head; pectoral spine longer, equal to snout and eye; reaching scarcely beyond origin 



of ventrals acipenserinus. 



aa. Dorsal spine prolonged, not pungent, roughened near its base; eye 6. .5 in the head; pectoral 

 spine reaching ventrals, head depressed juruensis.) 



61. Leptodoras linnelli sp. nov. (Plate XVII, fig. 1; Plate XVIII, fig. 1.) 



Leptodoras linnelli Eigenmann, Repts. Princeton Univ. Exp. Patagonia, III, 1910, 



395 (name only). 



Type, 190 mm. Tumatumari. (Carnegie Museum Catalog of Fishes 

 No. 1626.) 



Cotji^es, twenty-seven specimens, 64-209 mm. Tumatumari. (C. M. Cat. 

 No. 1627a-e; I. U. Cat. No. 12022.) 



Cotypes, two specimens, 64 and 182 mm. Rockstone. (C. M. Cat. No. 1628; 

 I. U. Cat. No. 12024.) 



Cotypes, six specimens, 75-103 mm. Crab Falls. (C. M. Cat. No. 1629a; 

 I. U. Cat. No. 12023.) 



