eigenmann: the FRESHWATER FISHES OF BRITISH GUIANA 391 



It is very probable that the anal in the males of all of the species, certainly in 

 some of them, is bilobed, i. e., the anterior rays and those near the middle of the fin 

 are prolonged. The anal in the female is falcate in all of the species so far placed 

 on record. 



Key to the Guiana Species of Myloplus. 

 a. Sides with an oblique cross-band; serrse 33-35; D. 23-25, the anterior rays filiform in the male; the anal 



bilobed, falcate in female schomburgki. 68 



aa. Sides plain. 



b. D. 26-31; depth 1.25-1.6 in the length, distance between origin of anal and origin of dorsal 1.3 in the 

 length without the head; adipose fin .5 or .6 of the length of the eye; base of last dorsal ray 

 about equidistant from end of lateral line and base of fourth to eighth ray. Anal falcate, 36-44; 



serrae 37-49. Origin of dorsal nearer to snout than to end of lateral line rubripinnis. 



bb. D. 24 or 25; A. 35 or 36; depth 1.5 in the length; adipose fin .8 of the length of the eye or equal to it; 

 base of dorsal 3.5-3.8 in the length; base of last dorsal ray equidistant from the base of the first 



ray and the eleventh scale from the end of the lateral line; seme 37-41 rhomboidalis. 



acta. Sides with orange spots; D. 27-31; A. 35-40; depth 1.66 in the length; distance from origin of ana! to 

 origin of dorsal 1.5 in the length, much less than length of head; origin of the dorsal nearer to end 

 of lateral line than to tip of snout. Serroe 36-38; anal falcate in the female, bilobed in the male. 



asterias. 



247. Myloplus rubripinnis (Mtiller and Troschel). (Plate LVII, fig. 2.) 



Myletes rubripinnis Muller and Troschel, Horse Ichth., I, 1845, 28, pi. 9, fig. 3 



(Essequibo); in Schomburgk, Reisen, III, 1848, 637 (Essequibo). — Gunther, 



Catalogue, V, 1864, 373 (Essequibo). — Eigenmann and Eigenmann, Proc. 



U. S. Nat. Mus., XIV, 1891, 60. 

 Myleus rubripinnis Eigenmann, Repts. Princeton Univ. Exp. Patagonia, III, 1910, 



443. 



Five specimens, 72-97 mm. Crab Falls. (C. M. Cat. No. 1121a-6; I. U. 

 Cat. No. 11662.) 



Six specimens, 124-365 mm. Crab Falls. (C. M. Cat. Nos. 1128 and 1129; 

 I. U. Cat. No. 11657.) 



Three specimens, 139-252 mm. Rockstone. (C. M. Cat. No. 2218; I. U. 

 Cat. No. 11656.) 



68 Mylophus schomburgki (Jardine) . 



Tetrago?wpterus schomburgkii Jardine, in Schomburgk, Fishes Brit. Guiana, I, 1841, 243, pi. 22 (Rio Negro). 



Myletes schomburgkii (not of Muller and Troschel) CuviERand Valenciennes, Hist. Nat. Poiss., XXII, 1848, 

 212 (Surinam). — Steindachner, " Ichthyologische Beitrage," v, 1876, 86. — Eigenmann, Repts. Prince- 

 ton Univ. Exp. Patagonia, III, 1910, 443. 



Myletes palometa Cdvier and Valenciennes, Hist. Nat. Poiss., XXII, 1848, 214 (Orinoco). — Gunther, 

 Catalogue, V, 1864, 372. 

 No specimens were secured and there is no authentic record of its having been taken in the Essequibo. 



