kigenmann: the FRESHWATER FISHES OF BRITISH GUIANA 371 



226. Brycon falcatus Muller and Troschel. (Plate LIV, fig. 2.) 

 ? Chalceus labrosus Schomburgk, Fishes Brit. Guiana, I, 1841, 212 (Paduiri). 

 Brycon falcatus Muller and Troschel, Horse Ichth., I, 1845, 29, pi. 6, fig. 1; 

 in Schomburgk, Reisen, III, 1848, 635 (all rivers). — Gunther, Catalogue, V, 

 1864, 334 (Essequibo; Surinam). — Eigenmann and Eigenmann, Proc. U. S. 

 Nat. Mus., XIV, 1891, 55. — Eigenmann, Repts. Princeton Univ. Exp. Pata- 

 gonia, III, 1910, 431. 

 Brycon schomburgkii Muller and Troschel, Horse Ichth., I, 1845, 29, pi. 6, fig. 2 

 (Essequibo); in Schomburgk, Reisen, III, 1848, 96 (Lower Essequibo).— 

 Eigenmann and Eigenmann, Proc. U. S. Nat. Mus., XIV, 1891, 55. 

 One specimen, 114 mm. Rockstone. (C. M. Cat. No. 1816.) 

 Three specimens, 115-130 mm. Locality ? (C. M. Cat. No. 1817; I. U. Cat. 

 No. 12109.) 



Twelve specimens, 223-275 mm. Tukeit. (C. M. Cat. No. 1818a-b; I. U. 

 Cat. No. 12107.) 



Head 3.5-4; depth 2.6-2.8; D. 11; A. 26 or 27; scales 9-52-53-4; eye 3.4-3.75 

 in head, 1.66-2 in interorbital, about equal to the length of the snout. 



Elongate oval, the dorsal and ventral outlines about equally convex; pre- 

 ventral area broad, flattish; postventral area narrowly rounded; predorsal area 

 narrowly rounded, without a definite median series of scales; head broad, the convex 

 profile in front of the dorsal but little depressed over the eyes; second suborbital 

 in contact with the angle of the preopercle, a narrow naked margin between it and 

 the upper and lower limits of the preopercle. 



Upper jaw but slightly projecting, only the outer row of the premaxillary 

 exposed; seven to ten teeth in the outer series in each premaxillary, six in the inner 

 row and four between the two series; three large teeth on each side of the mandible, 

 with graduated teeth on the sides. 



Origin of dorsal equidistant from tip of snout and base of middle caudal rays; 

 dorsal obliquely truncate or slightly emarginate. Adipose fin well-developed. 

 Caudal emarginate when opened, the middle rays forming a small projecting lobe; 

 anal slightly emarginate in front; ventrals reaching beyond vent, but not to anal, 

 pectorals not quite to ventrals. 



A humeral spot just behind the opercle above the lateral line. A conspicuous 

 V-shaped black band on the caudal; base of anal black; sides highly iridescent, 

 darker above; dark lines along the middle of the rows of scales above the lateral 

 line; dorsal, adipose, and upper caudal margin rosy; an orange band parallel with 

 the black band on caudal and anal in the smaller specimens in life. In the larger 

 the dorsal, adipose, caudal and anal are dirty orange. 



