EIGENMANN: the freshwater fishes of BRITISH GUIANA 169 



Without opening the question whether the specimens recorded by Eigenmann 

 and Eigenmann as cristatus and wesselii belong to distinct species, I am inchned 

 to consider the ivesselii of Steindachner as a sj-nonym of the cristatus of Miiller 

 and Troschel. I have examined the type of cristatus and: 



Twelve specimens, 81-137 mm. Tumatumari. (C. M. Cat. No. 1686a-d; 

 I. U. Cat. No. 12062.) 



One specimen, 145 mm. Below Packeoo Falls. (C. M. Cat. No. 1687.) 



One specimen, 105 mm. Rockstone. (C. M. Cat. No. 1688.) 



Two specimens, 115-150 mm. Konawaruk. (C. M. Cat. No. 1689; I. U. 

 Cat. No. 12063.) 



Twelve specimens, 160-205 mm. Creek below Potaro Landing. (C. M. Cat. 

 No. 1690o-(?; I. U. Cat. No. 12064.) 



Two specimens, 133-158 mm. Twoca Pan. (C. M. Cat. No. 1691«; I. U. 

 Cat. No. 12065.) 



Essequibo and creeks of the interior, most abundant in the lower Potaro River. 



Head 4.5; depth 4.5-5.75; D. 1,6; A. 13-15; adipose fin 2.25-2.4; eye 3.5-4 

 in the head, interorbital 4.25-5; half the eye or all of it in the posterior half of 

 the head. 



Occipital crest more than three times as long as wide, reaching the dorsal 

 plate; fontanels of about equal width, the posterior becoming verj^ narrow behind; 

 maxillary barbels extending to the base of the caudal or slightly beyond its tip; 

 outer mental barbels reaching ventrals or in the largest specimens a little shorter. 



Dorsal rounded, the spine slender, about equal to the fourth ray in height; 

 anterior margin of the dorsal spine with recurved notches on its distal half or less, 

 posterior margin with small recurved hooks; interspace between the dorsals about 

 equal to the eye; caudal deeply forked, frequently split to the base, the lower lobe 

 much the broader; ventrals not reaching anal; pectoral not to ventral; pectoral 

 spine with small hooks along the posterior margin, its anterior margin rough, with 

 recurved notches on distal half. A narrow blue-black stripe from below origin 

 of dorsal, disappearing near caudal, and becoming obscure with age; dorsal 

 with the usual hyaline band. 



45. Pimelodella megalops sp. nov. (Plate XV, fig. 2.) 



Pimelodella viegalops Eigenmann, Repts. Princeton Univ. Exp. Patagonia, III, 

 1910, 389. 



Type, 100 mm. Tumatumari. (Carnegie Museum Catalog of Fishes No. 1692.) 

 Cotj^pes, fifty-six specimens, 67-96 mm. Tumatumari. (C. M. Cat. No. 



1693o-e; I. U. Cat. No. 12066.) 



