THE AMERICAN TETRAGONOPTERINAE. 55 



Key to the Species. 



A. 36 or 37; depth 1.6-1.8 rarely 2; eye in adult less than interorbital; scales toward occiput 

 decreasing in size; occipital process bordered by 5-7 scales on each side; caudal lobes scaled 

 for about half their length; distance of dorsal from tip of snout greater than the distance of 

 the ventrals from tip of snout; ventrals equidistant from tip of snout and last third or last 

 fourth of anal; pectorals reaching beyond origin of ventrals; 12 to 16 azygous, predorsal scales. 



1. argenteus Cuvier. 



A. 32 or 33; depth 1.66-2; eye in adult at least equal to the interorbital; occipital process bor- 

 dered by 3 or 4 scales on each side; caudal lobes densely scaled to near their tip; dorsal and 

 ventrals about equidistant from tip of snout; ventrals equidistant from tip of snout and 

 end of anal; pectorals usually not reaching origin of ventrals; 8 or 9 azygous predorsal 

 scales. Scales 7-29 to 34-3.5; a caudal spot 2. chalceus Agassiz. 



A. 32; depth 1.66; eye 2.7 in the head, a little less than the interorbital, which is 2.33 in the 

 head; pectorals reaching a little beyond origin of the ventrals; scales 8.5-31-4.5; caudal 

 scaled to its tip 3. huberi Steindachner. 



A. 31-33; depth 1.66-1.8; eye 2.2-2.4 in the head, greater than interorbital; ventrals nearer 

 the snout than the dorsal, equidistant from snout and last fourth of the anal; pectorals reach- 

 ing past origin of ventrals; scales 7-28 to 29-3.5 to 4 4. gibbosus Steindachner. 



1. Tetragonopterus argenteus Cuvier. 

 Plate 2, fig. 1; Plate 4, fig. 2. 



Tetragonoplerus argenteus Cuvier, Mem. Mus. hist, nat., 1848, 4, p. 455 (Bahia?) ; Muller & Troschel, 



Horae ichthyol., 1845, 1, p. 13 (Brazil & Guiana); Fische British Guiana, 1848, p. 634 (Amucu); 



Cuvier & Valenciennes Hist. nat. poissons, 1848, 22, p. 132 (Bahia?) ; Kner, Characinen, 1S59, 



p. 38 (Cujaba; Guiana); Gunther, Cat. fishes Brit, mus., 1864, 6, p. 318; Steindachner, Ichthyol. 



beitr., 1876, 6, p. 46 (Santarem); Flussf. Sudamer., 1879, 1, p. 7 (Orinoco, near Ciudad Bolivar); 



1S82, 4, p. 13 (Amazons, Iquitos); Eigenmann & Eigenmann, Proc. U. S. N. M., 1891, 14, p. 52; 



Ulrey, Ann. N. Y. acad. sci., 1895, 8, p. 273; Boulenger, Trans. Zool. soc. London, 1896, 14, p. 



35 (Descalvados, Northern Paraguay); Pellegrin, Bull. Mus. hist, nat., 1899, 6, p. 157 (Apurc; 



Manaos) ; Boulenger, Boll. Mus. univ. Torino, 1900, 15, no. 370, p. 2 (Urucum) ; Eigenmann, Ann. 



Carnegie mus., 1907, 4, p. 126, fig. 10 (Puerto Murtinho; Bahia Negra); Rept. Princeton univ. exped. 



Patagonia, 1900, 3, p. 439; Mem. Carnegie mus., 1912, 6, p. 319, fig. 37 (Tumatumari) ; Fowler, 



Proc. Acad. nat. sci., Phil., 1914, p. 242 (Rupununi). 1 

 Tetragonoplerus rufipes Valenciennes, d'Orbigny, Voy. Amer. Merid. Poissons, 1847, pi. 11, fig. 1 



(Buenos Aires); Cuvier & Valenciennes, Hist. nat. poissons, 1848, 22, p. 136 (Buenos Aires); 



Gunther, Cat. fishes Brit, mus., 1864, 6, p. 318 (Buenos Aires); Eigenmann & Eigenmann, Proc. 



U. S. N. M., 1891, 14, p. 52; Perugia, Ann. Mus. civ. storia nat. Genova, 1891, ser. 2, 10, p. 42 



(Candclaria, Rio Parana; Rio Paraguay at Asuncion); Lahille, Rev. Mus. de la Plata, 1895, 6, 



p. 7 (Punta Lara, Isla Santiago); Ulrey, Ann. N. Y. acad. sci., 1895, 8, p. 272. 2 



1 Tetragonopterus argenteus about 100 mm. Cuvier's type (said to contain thirty-four anal rays by 

 Cuvier and forty by Valenciennes) has thirty-seven and a half anal rays; dorsal broken. Lateral line 

 30; a dark vertical bar at origin of caudal; two vertical bars behind the head. 



2 The types, three specimens, of T. rufipes in the Jardin des Plantes from Buenos Aires are in bad 

 condition; they are 100, 110, and 118 mm. long. Those are evidently the ones figured and described 

 by Valenciennes who wrote the label. They have A. 37; interorbital slightly convex. It is impossible 

 in their state of disintegration to distinguish them from T. argenteus, with which they are very probably 

 identical. I have not seen the type of T. sawa. 



