316 MEMOIRS OF THE CARNEGIE MUSEUM 



Piabucus Cuvier. 

 "Les Piabuques" Cuvier, Regne Animal, II, 1817, 166 (argentinus). 

 Piabucus Oken, Isis, 1817, 1183. 



Type, Salmo argentinus Linnaeus. 



With the character of Iguanodectes, but with the preventral area sharply 

 trenchant. 



Three species, of which one was taken in Guiana. 



171. Piabucus dentatus Koelreuter. 



"Piabuca" Marcgrave, Hist. Rer. Nat. Bras., IV, 1648, 170. 



Trutta dentata Koelreuter, Nov. Comm. Petropoli, VIII, 1761, 413, pi. 14, fig. 4. 



Piabucus dentatus Eigenmann, Repts. Princeton Univ. Exp. Patagonia, III, 1910, 

 440. 



Salmo argentinus Linnaeus, Syst. Nat., ed. 12, 1766, 511. — Bloch, Ausl. Fische, 

 1785, pi. 382, fig. 1. —Bloch and Schneider, Syst. Ichth., 1801, 403. 



Characinus argentinus Lacepede, Hist. Nat. Poiss., V, 1790, 272. 



Piabuca argentina Cuvier, Regne Animal, II, 1817, 310 (fide Miiller and Troschel).— 

 Muller and Troschel, Hor. Ichth., I, 1845, 9, pi. 1, fig. 1; in Schomburgk, 

 Reisen, III, 1848, 633 (Lake Amucu and Savannah swamps). — Cuvier and 

 Valenciennes, Hist. Nat. Poiss., XVII, 1848, 108. — Gunther, Catalogue, V, 

 1864, 344. — Eigenmann and Eigenmann, Proc. U. S. Nat. Mus., XIV, 1891, 

 57. — Steindachner, " Ichthyologische Beitrage," xv, 1891, 22 (Iquitos). 

 Eight specimens, 102-138 mm. Koreabo Rubber Plantation. (C. M. Cat. 



No. 1891a-6; I. U. Cat. No. 12169.) 



Two specimens, 149-155 mm. Wismar. (C. M. Cat. No. 1892; I. U. Cat. 



No. 12170.) 



Head 5.66-6.3; depth 3.6-3.66; D. 10 or 11; A. 43-45; scales 11-84-7. Eye 



1 in snout, 3.25 in head, 1.5 in interorbital. 



Elongate, compressed; profile depressed over the nape and eyes; ventral profile 



exaggerated in front of the ventrals; predorsal area narrowly rounded, preventral 



area compressed to an edge, the region between the bases of the pectorals stiff, the 



region just in front of the ventrals with a flexible ridge of scales. 



Occipital crest narrow, reaching about one-seventh of the distance from its base 



to the dorsal; parietal fontanel broad, more than twice as long as the frontal, which 



is nearly equilaterally triangular; mouth small, terminal, the jaws subequal, pre- 



maxillary meeting the minute maxillary at an angle. Six or seven pluricuspid 



teeth in the inner row of the premaxillary, the outer row composed of a single 



