124 THE AMERICAN CHARACIDAE. 
1. MARKIANA NIGRIPINNIS (Perugia). 
Plate 13, fig. 3-5. 
Tetragonopterus nigripinnis Peructa, Ann. Mus. civ. storia nat. Genova, 1891, ser. 2a, 10, p. 643 (Rio 
de la Plata); 1897, ser. 2a, 18, p. 25 (Reyes; Rio Beni); ErgenMANN, Proc. U.S. N. M., 1893, 16, 
p. 53; Unrey, Ann. N. Y. acad. sci., 1895, 8, p. 263, 273. 
Markiana nigripinnis E1GeENMANN, Smithsonian misc. coll. quart., 1903, 45, p. 145; Rept. Princeton 
univ. exped. Patagonia, 1910, 3, p. 438. 
Astyanax nigripinnis EIGENMANN & Oct», Proc. U.S. N. M., 1907, 33, p. 30 (Paraguay). 
Tetragonopterus anomalus STEINDACHNER, Anz. K. akad. wiss. Wien, 1891, p. 173; Ichthyol. beitr., 1891, 
15, p. 27; Sitzungsb. K. akad. wiss. Wien, 1891, 100, p. 173, 369, pl. 3 (Rio Parana); ErGenmMann, 
Proc. U. S. N. M., 1893, 16, p. 53. 
Hasitat.— La Plata Basin. 
2. MArKIANA GBAyt (Pellegrin). 
Tetragonopterus (Markiana) geayi PELLEGRIN, Bull. Mus. hist. nat., 1908, 14, p. 347 (Apuré). 
Markiana geayi E1GENMANN, Rept. Princeton univ. exped. Patagonia, 1910, 3, p. 438. 
Known from a single specimen 104 mm. long, in the Jardin des Plantes. 
6. GymNocoryMBus Eigenmann. 
yuurds, naked; xépuvufos, summit. 
Gymnocorymbus EIGENMANN, Bull. M. C. Z., 1908, 62, p. 94. 
Typre.— Gymnocorymbus thayeri Eigenmann. 
Very deep, compressed, Tetragonopterini form; anal long, its margin nearly 
straight, its origin behind the origin of the dorsal; mouth moderate, the maxil- 
lary reaching below eye; first and second suborbital leaving a moderate naked 
area all around its lower margin; scales all cyeloid; lateral line complete, caudal 
and anal largely scaled; maxillary with one or two teeth; premaxillary with 
an outer series of tricuspid teeth and an inner series of many pointed teeth. 
Hasrrar.— Amazons and Paraguay. 
Key to the Species. 
a. Scales in lateral line 33-36; parietal fontanel arched over at base of occipital process; anal sheath 
of three or four series of scales; anal margin straight; anal and area above it not notably dark. 
1. thayeri Figenmann. 
aa. Scales in lateral line 30-35; parietal fontanel not arehed over; anal sheath of five or six series 
of scales; anal margin rounded; anal and area above it dark.......... 2. ternetzi (Boulenger). 
