392 FISHES OF WESTERN SOUTH AMERICA 
Type: Acara tetramerus Heckel 
All South America Panama to La Plata 
Gills without a lobe, rakers small; mouth small and moderately protractile; 
lateral line low; soft fins scaled slightly or not at all; lateral line scales of the same 
size as others. 
501. ARQUIDENS TETRAMERUS (Heckel) 
Acara tetramerus Heckel, 1840, Ann. Wiener Mus., IH, 341; 
Miller and Troschel in Schomburgk, 1848, Reisen, III, 624; 
Ginther, 1862, Cat. Fish. Brit. Mus., IV, 277; 
Cope, 1871, Proc. Acad. Nat. Sci. Phila., XXIII, 255, R. Ambyiacu; 
Steindachner, 1882 (1883), Denksch. KIx. Akad. Wiss. Wien, XLVI, 2, Iquitos; Rio Huallaga; 
Pellegrin, 1902, Bull. Mus. Hist. Nat., VIII, 182; 
Pellegrin, 1903 (1904), Mém. Soc. Zool. France, XVI, 171; 
Regan, 1913, Ann. Mag. Nat. Hist., (8), XII, 282, Rio Ucayali. 
Astronotus tetramerus Eigenmann and Eigenmann, 1891, Proc. U.S. Nat. Mus., XIV, 68. 
Astronotus (diquidens) tetramerus Eigenmann and Bray, 1894, Ann. N. Y. Acad. Sei., VIT, 617. 
Aiquidens tetramerus Eigenmann and Kennedy, 1903, Proc. Acad. Nat. Sci. Phila., LV, 534; 
Eigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, III, 471; 
Eigenmann, 1912, Mem. Carnegie Mus., V, 491. 
Chromys uniocellata Castelnau, 1855, Anim. Amér. Sud, Poiss., 15, pl. vi, fig. 1, Rio Ucayali. 
Acara flavilabris Cope, 1870, Proc. Amer. Phil. Soc., XI, 570, Pebas; 
Cope, 1871 (1872), Proc. Acad. Nat. Sci. Phila., X XIII, 255, pl. x, fig. 4, Rio Ambyiacu; 
Cope, 1878, Proc. Amer. Phil. Soc., XVII, 696, R. Marafion. 
British Guiana, Amazons, Rio de Janeiro, Paraguay 
17735, 11, 19-80 mm., creek, Rio Itaya, Allen, September, 1920. 
17738, 2, 26 and 37 mm., Gosulimacocha, Allen, October, 1920. 
17739, 3, 21-45 mm., brook, Iquitos, Allen, November, 1920. 
17740, 12, 22-41 mm., Yarinacocha, Allen, August, 1920. 
One of these juveniles has a complete longitudinal band. 
17741, 7, 79-121 mm., Iquitos pond, Allen, September, 1920. 
7742, 79, 22-138 mm., creek, Pto. Bermudez, Allen, July, 1920. 
Apparently this number is incorrectly recorded. 
17742, 4, 46-126 mm., Iquitos, Morris, 1922. 
17743, 4, 95-163 mm., Lago Cashiboya, Allen, August, 1920. 
17744, 3, 71-94 mm., creek, Yurimaguas, Allen, November, 1920. 
17745, 4, 103-138 mm., creek, Rio Morona, Allen, October, 1920. 
—, 2, 175 and 185 mm., Yarinacocha, Allen, August, 1920. 
17789, 2, 165, 232 mm., Manaos, Allen, December, 1920. 
The pond specimens, especially 17741, deeply colored. They show faintly 
the vertical color bands and a lateral band from the eye to the caudal basis. This 
is interrupted by the lateral spot. 
Of the specimens from the Itaya, 17735, one of three largest has four anal 
spines, otherwise the same. 
Color notes made in the field on the Puerto Bermudez specimens, 17742, show 
the dorsal half of the body deep blue, shading to grey ventrally. Ocellated spot on 
the peduncle blue-black, bordered with yellow; irregular blue-black markings on 
the caudal fin; fins washed with yellow; five or six longitudinal stripes of yellow on 
