THE AMERICAN TETRAGONOPTERINAE. 121 
Dorsal rounded, its highest ray shorter than the head, its origin equl- 
distant from snout and middle caudal rays. Caudal lobes longer than the 
head; origin of anal behind the vertical from the last dorsal ray; ventrals 
not reaching anal, their origin nearer base of last anal ray than snout: pec- 
torals not reaching ventrals. 
Scales very regular, with two or three striae; caudal with a few scales 
on the base of the lobes, extending further on the lower lobe than on the upper. 
Anal with a sheath of a single series of scales. Maxillary scale small. 
Highly iridescent, a silvery lateral band; tip of dorsal hyaline, an oblique 
dusky streak through its middle. A dark spot on the base of the middle caudal 
rays, continued faintly to the tip of the middle rays and then obliquely across 
the lobes. A very faint humeral spot. 
It is more than probable that the single specimen at hand is the K. vic- 
toriae described by Steindachner. His specimens have the silvery band bor- 
dered by dark above. A cherry-red spot at base of each caudal lobe in life. 
6. KNODUS CHAPADAE (Fowler). 
Plate 10, fig. 1. 
Astyanax chapadae Fow Er, Proc. Acad. nat. sci. Phil., 1907, p. 350, fig. 33 (Santa Anna da Chapada). 
Bryconamericus chapadae ErGENMANN, Rept. Princeton univ. exped. Patagonia, 1910, 3, p. 434. 
21829 Paratype. Acad. Nat. Sci. Phil. 44 mm. to base of caudal. Santa 
Anna da Chapada, Matto Grosso, headwaters of the Paraguay. Known only 
from the types. 
Very closely related to K. breviceps, but with much longer head. Like K. 
breviceps except in the characters noted below. 
Head about 3.75; depth about 3; D. 10; A. 20; scales 6—42-4.5; eye 3, 
equals interorbital. 
Elongate, without prominent elevations or depressions in the profiles, 
the median series of scales in front of the dorsal not quite complete, replaced 
by the overlapping scales of the two sides from the occipital process to about 
the fourth seale behind the occipital process. 
Maxillary equals snout, three and a half in head; mandible two and four 
tenths. Five teeth (three on one side) in the front row of the premaxillary, 
the second is withdrawn from the line, three several pointed teeth on the maxil- 
lary; mandible with four large teeth and several small ones on the side. 
