140 FISHES OF WESTERN SOUTH AMERICA 
serrae; dorsal spine smooth anteriorly, similar to the pectoral spine, slightly shorter, 
its distance from snout 2.33 in standard length; caudal deeply forked; origin of the 
anal nearer base of middle caudal ray than to origin of pectoral spine; edge of anal 
not faleate; ventral reaching beyond origin of anal. 
Lower side of head and belly white; sides and back dusky; anterior half of 
pectoral black; ventrals dark; tip and anterior half of dorsal dark; caudal un- 
marked; tympanum slightly shaded; dark area across frontal. 
Air bladder nearly as long as snout; no coeca. 
Family VI: Hypophthalmidae 
Nematognath fishes with divided vestigial air bladder, a lobe on either side of 
the Weberian apparatus, and enclosed by a capsule of bone which is formed of 
(a) the lateral processes of the fused vertebrae, (b) the scapula, and (c) the processes 
connecting the scapula with the basioccipital. The external opening of the cap- 
sule is enclosed by the scapula and the lateral processes. 
Dorsal fin on the anterior half of the body and over the very long anal, which 
has its origin near the origin of the second third of the body. The eye very low, 
the optic nerve descending to the eye beneath the skin. Gill membranes free. 
Genus 51: HYPOPHTHALMUS Spix 
Hypophthalmus Spix, 1829, Sel. Gen. et Spec. Pisce. Bras., 16, pl. ix, sp.; 
Bleeker, 1863, Nederl. Tijdsch. Dierk., I, 109, edentatus; 
BHigenmann and Eigenmann, 1890, Occ. Papers Cal. Acad. Sei., I, 313; 
Eigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, III, 398; 
Eigenmann, 1912, Mem. Carnegie Mus., V, 208. 
Type: Hypophthalmus edentatus Spix 
The Amazons and northward 
Jaws and vomer edentulous; eye posterior to and lower than the rictus; adipose 
small; dorsal fin short, with a slightly spinous ray inserted posterior to the level of 
the ventrals; anal long; premaxillary very small; barbels six, conspicuous; gill- 
openings wide and nearly reaching the symphysis; ventrals with six rays; branchi- 
ostegals 13-14; gill-rakers long and slender; first two gill-arches with a single series 
of rakers and a broad membrane; fourth gill-arch free. 
105. HypopHTHALMUS EDENTATUS Spix 
Hypophthalmus edentatus Spix, 1829, Sel. Gen. et Spec. Pisc. Bras., 16, pl. ix, equatorial Brazil; 
Giinther, 1864, Cat. Fish. Brit. Mus., V, 67; 
Cope, 1878, Proe. Amer. Phil. Soe., XVII, 673, Peruvian Amazon; 
EKigenmann and Higenmann, 1890, Occ. Papers Cal. Acad. Sci., I, 313; 
Higenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, III, 398; 
Eigenmann, 1912, Mem. Carnegie Mus., V, 209; 
Fowler, 1939 (1940), Proc. Acad. Nat. Sci. Phila., XCI, 232, Contamana, two. 
