THE AMERICAN TETRAGONOPTERINAE. 183 
with two or three teeth of from 7 to 9 cusps each. Dentary with a graduated 
series of about ten teeth, the five in front with 5 to 7 cusps, those on the sides 
tricuspid. 
Gill-rakers about 6 + 10. 
Anal sheath represented by 6 scales diminishing in size from the anterior 
two. Lateral line with pores on 5 to 9 scales. 
Origin of the dorsal equidistant from the snout and the last anal ray or 
tip of the adipose; the penultimate ray almost half as long as the longest, 
which is 4.16 to 4.25 in the length. Caudal a little longer than the head. 
First anal ray on the vertical from the fourth to eighth dorsal ray. Ventrals 
directly below the second scale in front of the dorsal. Pectorals reaching the 
ventrals. 
First six dorsal rays tipped with chalky white their submarginal half 
covered with a black bar; another bar of chalky white covering one half 
or two thirds of the remaining distance to the base of the rays; anal usually 
plain, sometimes tips of the second, third, and fourth anal rays white, a black 
line passing from just proximal of the white to the tips of fifth and sixth rays. 
The tips of all the other anal rays touched with black which deepens a little 
upon the last rays. A vertical humeral spot crossing the third and fourth, 
sometimes the fourth and fifth scales of the lateral line; margin of caudal dusky; 
sides, excepting over the body-cavity, with chromatophores. Outer rays of the 
ventrals and pectorals chalky white. 
7. HyYPHESSOBRYCON BENTOSI Durbin. 
Plate 25, fig. 3; Plate 79, fig. 9, 9a. 
Hyphessobrycon bentosi DurRBIN, Bull. M. C. Z., 1908, 52, p. 101 (Obidos); Ercenmann, Rept. Princeton 
univ. exped. Patagonia, 1910, 3, p. 436. 
Hapirat.— Amazon. 
Twenty-one specimens 20842 Cotypes 30-38 mm. Obidos Bentos 
Head 3.3 to 3.5; depth 2.8-3.2; D. 11; A. 27-30; scales about 30-33; 
eye 2.5 in head; interorbital much less than the eye. 
Compressed; depth of the head at the base of the occipital process 1.33 
to 1.5 in the greatest depth. Preventral region rounded. Predorsal region 
slightly keeled. 
Occipital process 5 in the distance from its base to the origin of the dorsal. 
