eigenmann: the FRESHWATER FISHES OF BRITISH GUIANA 451 



teeth; broad bands of rasp-like teeth on vomer, palatines, pterygoids, sphenoid, 

 tongue, and hyoid; pectorals of moderate length; ventrals scaly; gill-membranes 

 separate." (Gunther.) 



294. Arapaima gigas (Ciivier). 



Sudis gigas Cuvier, Regne Animal, II, 1817, 180. — Agassiz, Selecta Gen. et Spec. 

 Pise. Bras., 1829, 31, pi. B. — Schomburgk, Fishes Brit. Guiana, I, 1841, 

 198, pi. 11 (Rupununi; Rio Branco; Rio Negro; Amazon). 



Arapaima gigas Muller, Abhand. Akad. Wiss. Berlin, 1846, 191. — Muller and 

 Troschel, in Schomburgk, Reisen, III, 1848, 638 (British Guiana). — Gunther, 

 Catalogue, VII, 1868, 379 (British Guiana; Bahia). — Eigenmann, Repts. 

 Princeton Univ. Exp. Patagonia, III, 1910, 453. 



Sudis pirarucu Spix, Selecta Gen. et Spec. Pise. Bras., 1829, pi. 16. 



Vastres cuvieri Cuvier and Valenciennes, Hist. Nat. Poiss., XIX, 1846, 441, pis. 



579, 580. 



Vastres mapce Cuvier and Valenciennes, Hist. Nat. Poiss., XIX, 1846, 449, pis. 



580, 581. 



Vastres agassizii Cuvier and Valenciennes, Hist. Nat. Poiss., XIX, 1846, 461. 



This species has been taken near the mouth of the Potaro River and from there 

 up into the Rupununi. It is said to reach fifteen feet in length and four hundred 

 and ten pounds in weight. Head nearly 4; D. 34-37; A. 30-32; scales 6.5-56-6. 

 B. 16. 



Order MICROCYPRINI. 



Family XVII. PCECILIIDjE. 



"Four-eyes"; "Cockabilly," etc. 

 Head scaly above; mouth terminal or superior; premaxillary protractile; 

 sides of the mouth formed by the premaxillary; teeth small, various; dorsal fin 

 single, placed far back; caudal symmetrically or obliquely rounded, rarely forked. 



Key to the Guiana Genera of Pceciliid^e. 



a. Males similar to the females except in color; oviparous; dorsal smaller than anal, its origin behind that of 



anal; eyes normal; teeth conical, in several series; body subcylindrical. (Fundulince.) Rivulus. 



aa. Anal of the male modified; viviparous. 



6. Eyes elevated, the upper part adjusted to see in the air, the lower in the water; dorsal behind the anal 



in both sexes. (Anablepina.) Anableps. 



bb. Eyes normal. 



c. Caudal peduncle without a knife-like ridge below; anal fin of the male normal, on the lower 

 surface of the abdomen. (Pceciliince.) 

 d. Intromittent organ not spine-bearing, composed of simply modified anal rays; males at least 

 as large as the females Poecilia. 



