ANNOTATED LIST OF THE SPECIES 255 
Type: [guanodectes tenuis Cope 
Range that of the unique species 
Upper Jaw with two series of pluricuspid incisor-like teeth, the outer series 
having a single tooth on each side; origin of the long anal beneath the dorsal; 
pectorals low, with a nearly horizontal base; preventral area rounded with breast 
broad between the pectorals, and with a perceptible median ridge; gill-membranes 
united, free from the isthmus; lateral line complete. 
317. IGUANODECTES TENUIS Cope 
Iguanodectes tenuis Cope, 1871 (1872), Proce. Acad. Nat. Sei. Phila., X XIII, 260, pl. viii, figs. 1 and 
la, Rio Ambyiacu; 
Eigenmann and EKigenmann, 1891, Proc. U.S. Nat. Mus., XIV, 54; 
Eigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, IIT, 430; 
Bigenmann, 1912, Mem. Carnegie Mus., V, 314; 
Kigenmann and Myers, 1929, Mem. Mus. Comp. Zool., XLIII, v, 494, pl. lxxi, figs. 3 and 6; 
pl. xevu, fig. 14. 
Rio Ambyiacu and British Guiana 
Genus 121: PIABUCUS Oken 
Les Piabuques Cuvier, 1817, Régne Anim., II, 166, Salmo argentinus. 
Piabucus Oken, 1817, Isis, 1183; 
Eigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, III, 440; 
Eigenmann, 1912, Mem. Carnegie Mus., V, 316. 
Type: Salmo argentinus Linnaeus 
Guiana to basin of La Plata 
Slender, smelt-like; mouth minute; teeth incisors with numerous cusps, in 
single series, except that the premaxillary may bear an anterior series of two teeth; 
gill-membranes united across, but free from the isthmus; preventral contour sharply 
compressed and little expanded; pectorals large, low, with oblique bases; origin of 
anal forward of the vertical from the dorsal fin. 
318. PraBucuS DENTATUS (IKoelreuter) 
Piabuca (native name) Maregrave, 1648, Hist. Rerum Nat. Bras., IV, 170. 
Trutta dentata Woelreuter, 1761, Nov. Comm. Petropoli, VIII, 413, tab. 14, fig. 4. 
Piabucus dentatus Kigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, III, 440; 
Eigenmann, 1912, Mem. Carnegie Mus., V, 316; 
Eigenmann and Myers, 1929, Mem. Mus. Comp. Zool., XLII, v, 497, pl. xxi, figs. 2 and 4; 
pl. xevii, fig. 15. 
Salmo argentinus Linnaeus (in part), 1766, Syst. Nat., ed. xi, 511. 
Piabuca argentina Cuvier, 1817, Régne Anim., IT, 310; 
Cuvier and Valenciennes, 1848, Hist. Nat. Poiss., XXII, 108; 
Giinther, 1864, Cat. Fish. Brit. Mus., V, 344; 
Steindachner, 1891, Sitzb. Kk. Akad. Wiss. Wien, ©, 364, Iquitos; 
Eigenmann and Higenmann, 1891, Proc. U.S. Nat. Mus., XIV, 57. 
Iquitos to Para and the Guianas 
