306 Frerp Museum or Naturat History — Zoétocy, Vo. X. 
4.25 in head; snout 3.7 to 4.37; eye 4.65 to 6.8; mouth large; lower jaw 
projecting; maxillary reaching past posterior margin of eye, mostly 
slipping under suborbital; teeth as in preceding species; gill-rakers 
poorly developed, 5 below angle on anterior arch; lateral line complete, 
straight, occupying median line of side; scales large, regularly placed, 
cycloid, 15 to 17 on median line in advance of dorsal; 9 scales across 
caudal peduncle from one lateral line to the other; 4 complete rows of 
scales between lateral line and anal fin; dorsal fin inserted midway 
between tip of upper jaw and base of caudal or slightly nearer the 
former; adipose fin wanting; caudal fin convex; anal fin inserted poste- 
riorly, the longest rays not quite reaching base of lower caudal rays; 
ventral fins inserted under base of dorsal, a little nearer base of caudal 
than tip of lower jaw; pectoral fins inserted behind margin of preopercle, 
failing to reach base of ventrals by 4 or 5 rows of scales. 
Color as in preceding species. 
Of this species 8 specimens were preserved. They range in length 
from 85 to 295 mm. All are from the Rio Tuyra Basin. 
This species is closely related to the preceding, differing mainly in 
the slightly larger scales. Our specimens were compared with specimens 
from the Rio Atrato Basin, with which they appear to agree perfectly. 
Habitat: Rio Tuyra Basin; both slopes of Colombia; Ecuador, and 
south to Brazil. 
Family VII. Gymnotide. 
Body elongate, more or less eel-shaped; with or without scales; 
vertebre many; skull with or without a frontal fontanel; parietal fon- 
tanel always present; mouth with or without teeth; margin of upper 
jaw formed by maxillaries and premaxillaries; air-bladder in 2 parts, 
connected by a small tube; vent well forward, never behind tips of 
pectorals, usually under head; dorsal fin wanting, or represented by a 
filament; caudal fin present or more usually absent, the tail terminating 
in a pointed appendage when fin is wanting; anal fin very long; ventral 
fins wanting; pectoral fins present, small. 
KEY TO THE GENERA. 
Frontal fontanel wanting. Gymnotus, p. 307. 
. Frontal and parietal fontanels present. 
Caudal fin and dorsal filament wanting. 
Orbital margin free; teeth present in both jaws, in 2 more or less 
distinct patches in upper jaw and in a single patch in lower jaw. 
Sternopygus, p. 308. 
eo P 
