294 Fretp Museum or Natura History — Zoéxoey, Vor. X. 
large, premaxillary with 3 or 4 series of teeth, each tooth with from 3 to 
5 cusps; teeth in lower jaw in 2 series, the first composed of large tri- 
cuspid teeth, the second series with 2 canine teeth situated behind ante- 
rior teeth in first series; maxillary with small tricuspid teeth; nostrils 
close together; gill-openings wide, the membranes slightly united, free 
from the isthmus; gill-rakers slender; fontanel present. 
The species of this genus range from Guatemala, south. Four 
species are found in the region of the Canal Zone. 
KEY TO THE SPECIES. 
a. Scales small, 64 to 80 in lateral series; anal fin long, its base much 
longer than head, with 32 to 37 rays. 
b. Teeth in lower jaw very large and strong, usually 8, rarely only 
7 and occasionally 9, in outer series; teeth on outer edge of maxil- 
lary very small, 9 to 10 in number; 18 to 21 vertical rows of 
scales crossing back between dorsal and adipose. 
striatulus, p. 294. 
bb. Teeth in lower jaw notably smaller, 13 to 14 in outer series; teeth 
on outer edge of maxillary moderately developed, 12 to 13 in 
number; 21 to 25 vertical rows of scales crossing back between 
dorsal and adipose. chagrensis, p. 295. 
aa. Scales larger, 43 to 58 in lateral series; anal fin short, its base 
about equal to length of head, with 24 to 30 rays. 
c. Scales moderate, 53 to 58 in lateral series, 16 to 18 vertical rows 
crossing back between dorsal and adipose; upper jaw strongly 
projecting, exposing two series of premaxillary teeth anteriorly. 
. petrosus, p. 297. 
ec. Scales large, 43 to 48 in lateral series, 12 to 14 vertical rows cross- 
ing back between dorsal and adipose; upper jaw only slightly in 
advance of the lower, the second series of premaxillary teeth well 
covered by lower lip. argenteus, p. 298. 
40. Brycon striatulus (Kner). 
Chalcinopsis striatulus Kner, Sitzungsb. K. Bayer. Ak. Wiss. Miinchen, 
1863, 226 (Panama); Kner & Steindachner, Abhandl. K. Bayer. 
Ak. Wiss. Miinchen, 1866, 38, Pl. V, fig. 2 (New Granada and 
Panama on the Pacific slope ); Ginther, Cat. Fish. Brit. Mus., V, 
1864, 337: 
Brycon striatulus (in part) Jordan & Evermann, Bull. U.S. Nat. Mus., 
XLVII, 1896, 337. 
Head 3.6 to 4.45; depth 3.05 to 3.6; D. 11; A. 32 to 35; scales in 
lateral series 64 to 73. 
