eigenmann: the FRESHWATER FISHES OF BRITISH GUIANA 325 



Cotype, one specimen, 65 mm. Tumatumari, Lower Potaro. (C. M. Cat. 

 No. 1011.) 



Very similar to M. oligolepis, but without trace of caudal spot and with the anal 

 falcate. 



Head 3.75-4; depth 2.3 -2.6; D. 11; A. 23 or 24; scales 5-30 to 34-3 ; eye 2.4- 

 2.5; interorbital 2.8-3. 



No caudal spot; a large, horizontally oval, humeral spot continued below to 

 the origin of the pectoral; a dark band from origin of dorsal obliquely downward 

 and forward to the lateral line; a dark median lateral line; white below, dark along 

 back; each scale of the side with a conspicuous dark crescent along its middle. 



In life all fins but the adipose strongly tinged with red; middle of adipose 

 yellow. 



This species, abundant in the Potaro River above and below the Kaieteur, 

 is dedicated to the memory of C. Barrington Brown, the discoverer of this most 

 beautiful fall. 



180. Moenkhausia megalops Eigenmann. 

 Tetragonopterus grandisquamis (not of Muller and Troschel) Ulrey, Ann. N. Y. 



Acad. Sci., VIII, 1895, 281 (Itaituba). 

 Astyanax megalops Eigenmann, Proc. U. S. Nat. Mus., XXXIII, 1907, 29 (Itai- 

 tuba, Brazil). 

 Moenkhausia megalops Eigenmann, Repts. Princeton Univ. Exp. Patagonia, III, 



1910, 438. 



One specimen, 57 mm. Rockstonc. (C. M. Cat. No. 2488.) 



Head 3.6-3.7; depth 2.5-2.66; D. 9-11; A. 28-30. Scales 5-35-4; eye 2-2.2 

 in head, twice as long as snout; interorbital 2.8-3 in head. 



A vertical humeral spot above the space between the third and fifth scales 

 of the lateral line, faint; no caudal spot; a silvery lateral line; some metallic reflec- 

 tions. 



181. Mcenkhausia shideleri Eigenmann. (Plate XLVII, fig. 4.) 

 Moenkhausia shideleri Eigenmann, Ann. Carnegie Mus., VI, 1909, 15; Repts. 



Princeton Univ. Exp. Patagonia, III, 1910, 438. 



Type, 65 mm. (Carnegie Museum Catalog of Fishes No. 1012.) Bartica. 



Cotype, 73 mm. Bartica. (I. U. Cat. No. 11716.) 



Cotype, 63 mm. Tumatumari. 



This species has the largest eye of any in the genus. 



Head 3.7-3.8; depth 2.5-2.7; D. 10; A. 26; scales 5-34-3 or 4; eye 2.1 in head; 

 interorbital 2.4 or 2.5 in head. 



