eigenmann: the FRESHWATER FISHES OF BRITISH GUIANA 521 



Plataxoides Castelnau, Anim. Am. Sud, Poiss., 1855, 21, pi. 11, fig. 3. 



Type, Platax scalaris Cuvier and Valenciennes. 



Greatly compressed and deep; dorsal and anal spines graduated, the last 

 forming parts of elevated lobes; gill-arch without a lobe, rakers stiff, of moderate 

 length. 



353. Pterophyllum scalare (Cuvier and Valenciennes). 



Platax scalaris Cuvier and Valenciennes, Hist. Nat. Poiss., VII, 1831, 237 

 (Brazil). 



Pterophyllum scalaris Heckel, Ann. Wiener Mus., II, 1840, 335 (Barra do Rio 

 Negro). — GtJNTHER, Catalogue, IV, 1862, 316 (River Cupai). — Steindachner, 

 "Chromiden Amazonenstromes," in SB. Akad. Wiss. Wien, LXXI, 1875, 76 

 (Santarem; Montalegre; Villa Bella; Obidos; Coary; Ueranduba; Tonan- 

 tins; Tabatinga; Hyutay; Xingu; Lago Manacapuru; Lago Maximo; Barra 

 do Rio Negro). — Eigenmann and Bray, Ann. N. Y. Acad. Sci., VII, 1894, 624. 

 -Pellegrin, Bull. Mus. d'Hist. Nat., VIII, 1902, 183 (Marajo; Teffe; Tonan- 

 tins; Tabatinga); "Cichlides," 215, in Mem. Soc. Zool. France, XVI, 1903, 251 

 (Peru; Teffe; Amazon).— Regan, Ann. and Mag. Nat. Hist., (7), XVI, 1905, 

 441. — von Ihering, Rev. Mus. Paulista, VII, 1907, 335. — Eigenmann, Repts. 

 Princeton Univ. Exp. Patagonia, III, 1910, 479. 



Plataxoides dumerilii Castelnau, Anim. Am. Sud, Poiss., 1855, 21, pi. 11, fig. 3 

 (Para). 

 Four specimens, 44-77 mm. to the end of the middle caudal rays. Rupununi. 



(C. M. Cat. No. 2355a-6; I. U. Cat. No. 12502.) 



Six specimens, 52-64 mm. to end of middle caudal rays. Rockstone. (C. M. 



Cat. No. 2356a-c; I. U. Cat. No. 12503.) 



Seven specimens, 65-69 mm. to end of middle caudal rays. Crab Falls. 



(C. M. Cat. No. 2357o-d; I. U. Cat. No. 12504.) 



Head 3; depth 1.25; D. XI-XII,24 or 25; A. VI,26; lateral line 18 or 19 + 



13 -f ; scales 36-40 in a median series; eye 2.8 in the head, 1 in interorbital, .1 in 



preorbital. 



Compressed; profile depressed, the snout pointed; maxillary reaching to below 



the eye; maxillary-premaxillary border 3.5 in the head. 



Cheeks with about four series of scales; a series of scales on the lower limb of 



the preopercle and another on the interopercle ; scales ctenoid, about eight scales 



between the lateral line and the dorsal; dorsal and anal with a triangular patch of 



scales, the apex of the triangle on the last spines or first ray. A few scales at the 



base of the caudal. 



