THE AMERICAN TETRAGONOPTERINAE. 59 



tip of snout and last fourth of anal. Ventrals reaching to anus or anal; pectorals 

 beyond the origin of the ventrals. 



Two oblique dark bars, one from in front of the dorsal to the pectoral, the 

 other parallel to it from behind the tip of the occipital crest; a dusky predorsal 

 line continued on the first dorsal ray; a dark spot at end of caudal peduncle, 

 inconspicuous in the adult, sometimes extending across the entire peduncle 

 and base of caudal in the young. Anal sometimes margined with dusky. Dorsal 

 membrane thickly punctate. Otherwise bright silvery. 



About twelve of the anterior anal rays of the male with hooklets turned 

 toward the base of the fin, about twelve of the hooklets on the middle half of 

 the first rays, the number decreasing backward. 



Air-bladder very large, each section a cone, their bases contiguous, the 

 posterior section nearly twice as long as the anterior, bent downward and ex- 

 tending to the origin of the anal, the diameter of its large end equaling two thirds 

 the length of the head. Alimentary canal about one and two fifths times the 

 length over all. 



Vertebrae 10 + 19 counting the coalesced as one. Tip of occipital process 

 extending much beyond the posterior face of the skull. 



2. Tetragonopterus chalceus Agassiz. 

 Plate 4, fig. 1; Plate 98, fig. 4. 



Coregonus amboinensis Artedi, Species, 1738, p. 44. 



Tetragonopterus argenteus Artedi, Seba, Lecupl. rerum, 1758, 3, tab. 34, fig. 3, p. 174 (Rio Negro; Suri- 

 nam). 



Tetragonopterus chalceus Agassiz, Spix Selecta gen. et spec. Pise. Bras., 1829, p. 70, tab. 33, fig. 1 (Brazil) ; 

 Cuvier & Valenciennes, Hist. nat. poissons, 1848, 22, p. 140; Kner, Characinen, 1859, p. 38 

 (Rio Negro; Surinam); Gunther, Cat. fishes Brit, mus., 1864, 6, p. 320 (British Guiana, Essequibo); 

 Cope, Proc. Acad. nat. sci. Phil., 1871, p. 260 (Ambyiacu); Steindachner, Ichthyol. beitr., 1876 

 6, p. 47 (Xingu, near Porto do Moz); Eigenmann & Eigenmann, Proc. N. S. N. M., 1891, 14, 

 p. 52; Ulrey, Ann. N. Y. acad. sci., 1895, 8, p. 227; Vaillant, Bull. Mus. hist, nat., 1899, 5, 

 p. 154 (Carsevenne) ; Pellegrin, Bull. Mus. hist, nat., 1899, 6, p. 157 (Apure); Fowler, Proc. 

 Acad. nat. sci. Phil., 1906, p. 440 (Ambyiacu; Maraiion; Pebas); Eigenmann, Rept. Princeton 

 univ. exped. Patagonia, 1910, 3, p. 438; Mem. Carnegie mus., 1912, 6, p. 320, fig. 38 (Wismar; 

 Bartica; Tumatumari; Crab Falls; Rockstone); Fowler, Proc. Acad. nat. sci. Phil., 1914, p. 242 

 (Rupununi). 



t Tetragonopterus artedii Cuvier & Valenciennes, Hist. nat. poissons, 1848, 22, p. 128 (Surinam); 

 Gunther, Cat. fishes Brit, mus., 1864, 6, p. 319; Eigenmann & Eigenmann, Proc. U. S. N. M., 

 1891, 14, p. 52; Ulrey, Ann. N. Y. acad. sci., 1895, 8, p. 272. 1 



1 The type of this species was given to the Paris museum by the Ley den museum. It measures 

 68 mm. to base of caudal. Lat. line 31; A. 32 (Valenciennes says 40). 



