382 MEMOIRS OF THE CARNEGIE MUSEUM 



which, in addition to the basal band, has a submarginal black band, a narrower 

 margin being hyaline. 



235. Serrasalmo rhombeus (Linnaeus). (Plate LVI, fig. 1.) 

 Salrno rhombeus Linnaeus, Syst. Nat., ed. 12, I, 1766, 514 (Surinam). — Gmelin, 



Syst. Nat., I, iii, 1788, 686, No. 28.—? Bloch, Ausl. Fische, 1795, pi. 383.- 



Bloch and Schneider, Syst. Ichth., 1801, 404. — Pallas, Spic. Zool., VIII, 



1769, 57, pi. 5, fig. 3. 

 Serrasalmo rhombeus Lacepede, Hist. Nat. Poiss., V, 1804, 284. — Cuvier, Mem. 



Mus. d'Hist. Nat., V, 1819, 367.— Cuvier and Valenciennes, Hist. Nat. 



Poiss., XXII, 1848, 272 (Araguay). — Muller and Troschel, in Schomburgk, 



Reisen, III, 1848, 637 (Rupununi; Takutu). — Castelnau, Anim. Am. Sud, 



Poiss., 1855, pi. 37, fig. 3. — Gunther, Catalogue, V, 1864, 369 (Essequibo; 



Surinam; Demerara). — Eigenmann and Eigenmann, Proc. U. S. Nat. Mus., 



XIV, 1891, 60. — Eigenmann, Repts. Princeton Univ. Exp. Patagonia, III, 



1910, 442. 



Three specimens, 70-232 mm. Wismar. (C. M. Cat. No. 1131a-o; I. U. 

 Cat. No. 11648.) 



Six specimens, 150-355 mm. Crab Falls. (C. M. Cat. Nos. 1127 and 1132; 

 I. U. Cat. Nos. 11649 and 11653.) 



Two specimens, 209-295 mm. Packeoo.. (C. M. Cat. No. 2224a; I. U. Cat. 

 No. 11650.) 



One specimen, 110 mm. Twoca Pan. (C. M. Cat. No. 1134.) 



Seven specimens, 137-261 mm. Tumatumari. (C. M. Cat. No. 1120a-b; 

 I. U. Cat. No. 11651.) 



Nine specimens, 39-57, and one 257 mm. Rockstone. (C. M. Cat. Nos. 1126a 

 and 1741a-c; I. U. Cat. No. 11652.) 



Head 3; depth 1.8-2; D. 16 or 17 in the ratio of one to two; A. in two, 31; in 

 four, 32; in two, 33; in five, 34; and in four, 36; lateral line 87-91. Abdominal 

 serrse usually 30-33, rarely 28 or 36, of which there is one bifid before the anus and 

 one grooved behind the anus. Eye 4.5 in head, 2 in interorbital, 1-1.25 in snout. 



Snout pointed, the lower jaw entering the profile; second suborbital covering 

 the entire cheek or leaving a narrow naked margin; opercles and suborbitals pro- 

 fusely striate; gill-rakers minute, about 10 + 10; teeth as in gymnogenys. 



Dorsal obliquely rounded, its base as long as, or longer than, its distance from 

 the posterior end of the base of the adipose; caudal slightly lunate; anal margin 

 very slightly concave, no anal lobe; ventrals not reaching anal groove; pectorals 

 about to ventrals. 



