EIGENMANN: the freshwater fishes of BRITISH GUIANA 407 



Premaxillary horizontal, its teeth strictly conical, in a single series, the second 

 (or first) tooth and the next to the last strong, sharp, canine; anterior upper part 

 of maxillary little oblique, with teeth similar to those of the premaxillary, the first 

 and fourth or fifth being canines ; the posterior part of the maxillary abruptly much 

 oblique, with the exception of the teeth entirely concealed by the first suborbital 

 when the mouth is closed; back part of mandible with minute, recurved teeth, 

 preceded by three widely spaced canines, the middle one largest. 



Pectorals not overlapping the far remote ventrals; scales cycloid; lateral line 

 complete; tongue long and free. 



Key to the Guiana Species of Acestrorhynchus. 

 a. A conspicuous vertical black humeral blotch; caudal spot small and circular, or larger and continued on 



the middle caudal rays. Lateral line 79-95; A. 25-29 falcatus. 



aa. Shoulder-girdle wdth a minute spot in front of the origin of tlie lateral hue; anal long, with 28-33 rays. 



Lateral line 93-114 micrdepis. 



aaa. No shoulder-spot, opercle margined with dark; A. 23-26. Lateral line 144-152 falcirostris. 



aaaa. A black band from the tip of the snout to the caudal ; A. 27; scales 79, eight between lateral Unc and anal. 



nasutus. 

 261. Acestrorhynchus falcatus (Bloch). (Plate LXI, fig. 3.) 



Salmo falcatus Block, Ausl. Fische, VIII, 1794, 120, pi. 385 (Surinam). 

 Xiphorhynchus falcatus Cuvier and Valenciennes, Hist. Nat. Poiss., XXII, 1848, 



337, part (Surinam). — Castelnau, Anim. Am. Sud, Poiss., 1855, 75 (Amazon). 

 Xiphorhamphus falcatus MtJLLER and Troschel, Horaj Ichth., I, 1845, 17; in 



Schomburgk, Reisen, III, 1848, 635 (Essequibo; Pomeroon). — GIjnther, 



Catalogue, V, 1864, 354.— Vaillant, Bull. Mus. d'Hist. Nat., V, 1899, 154 



(Carsevenne) . 

 Acestrorhynchus falcatus Eigenmann and Ogle, Proc. U. S. Nat. Mus., XXXIII, 



1907, 34 (Surinam). — Eigenmann, Repts. Princeton Univ. Exp. Patagonia, 



III, 1910, 447. 

 Xiphorhamphus ferox GtJNTHER, Ann. and Mag. Nat. Hist., (3), XII, 1863, 443 



(Essequibo); Catalogue, V, 1864, 355 (Essequibo). 



One specimen, 182 mm. Barima. (C. M. Cat. No. 1960.) 



One specimen, 270 mm. Lama Stop-Off. (C. M. Cat. No. 1995.) 



Nine specimens, 96-120 mm. Lama Stop-Off. (C. M. Cat. No. 1964a-c; 

 I. U. Cat. No. 12232.) 



Two specimens, 102-111 mm. Malali. (C. M. Cat. No. 1905a; I. U. Cat. 

 No. 12242.) 



Eleven specimens, 85-114 mm. Maduni Creek. (C. M. Cat. No. 1966a-c; 

 I. U. Cat. No. 12233.) 



