190 THE AMERICAN CHARACIDAE. 
tricuspid teeth in the inner row and two conical or tricuspid ones in the outer 
row. Maxillary with four small conical and 3-pointed teeth. Dentary with 
a graduated series of about eight very small tricuspid teeth followed by four 
minute conical ones. 
Gill-rakers 8 + 14. 
Anal sheath probably obsolete. Lateral line with pores on about the 
first half of the scales. 
Origin of the dorsal equidistant from the snout and the caudal, its penulti- 
mate ray 2.33 in the longest which is 3.33 in the length. Origin of the anal 
on the vertical from the first scale behind the dorsal. Anal slightly faleate. 
Base of ventrals on the vertical from the second scale in front of the dorsal. 
Ventrals barely reaching to the anal. Pectorals not reaching the ventrals by 
half the width of the eye. 
A small black spot at the base of each caudal lobe. No humeral spot or 
lateral stripe. Seales of the dorsal surface and basis of the anal rays outlined 
with dusky. Fins all a little dusky. 
A single specimen, 1248 C. M., 23 mm. from Rockstone, probably H. riddlei 
or very near it, differs as follows from the type of H. riddlei from Los Castillas. 
Dorsal profile straight. Maxillary with six conical teeth, premaxillary with 
twelve small teeth in the inner row and two in the outer. Depth 3.8; eye 3 in 
the head; D. 11; A. 20; scales 4-31-3. 
13. HyPpHESSOBRYCON STRAMINEUS Durbin. 
Hyphessobrycon stramineus Dursin MS. E1ceNMANN, Rept. Princeton univ. exped. Patagonia, 1910, 3, 
p. 436 (Tabatinga). 
One specimen 20772 Type 38 mm. Tabatinga Bourget 
Head 4; depth 2.8; D. 10; A. 27; scales 5-32-3; eye 2.7 in the head, 
interorbital just equal to the eye. 
Compressed; depth of head at the base of the occipital process 1.75 in the 
greatest depth. Preventral and predorsal regions rounded, without complete 
regular series of median scales. 
Occipital process 6 in the distance from its base to the dorsal, bordered 
by 2+ seales. Interorbital slightly convex. Frontal fontanel small, triangular, 
narrower than the parietals, little more than one half the parietal without the 
occipital groove. Second suborbital in contact with the preopercle. Snout 
shorter than the eye, mouth comparatively small. Maxillary about equal to 
