THE AMERICAN TETRAGONOPTERINAE. 187 
In addition to these on which the description is based, I have series of speci- 
mens from the Patia, San Juan, Atrato, and Magdalena Basins. 
Head 3.25 to 4; depth 2.75 to 2.8; D. 11; A. 23-25; scales 7-34 to 36-6; 
eye 2.1—2.4, in the head; interorbital less than the eye, 3 in the head. 
Very compressed; dorsal profile about equally arched with the ventral 
profile. Preventral region rounded, without a complete series of median scales. 
Predorsal region obscurely keeled, with a median series of 10 to 13 scales. 
Occipital process little more than 4 in the distance from its base to the 
dorsal, bordered by 3 or 4 scales. Interorbital slightly convex. Frontal fon- 
tanel elongate, triangular, narrower than the parietal, as long as the parietal 
without the occipital groove. Second suborbital leaving a very narrow naked 
margin around its entire edge. Snout short, about 2 in the eye; mouth large. 
Maxillary slender, its anterior margin nearly straight to near the posterior 
angle where it is rounded, a little less than the eye, about 2.67 in the head. 
Mandible considerably longer than the eye, 2 in the head. Premaxillary with 
an outer row of three tricuspid teeth and an inner row of five 3- to 5-pointed 
teeth. Maxillary with three tricuspid or conical teeth. Dentary with four 
large teeth and a series of about seven abruptly smaller teeth on the side. 
Gill-rakers 7 + 11. 
Anal sheath short, with about 7 scales covering the base of the first 7 or 8 
anal rays. Lateral line with pores developed on 9 to 13 scales.’ 
Origin of the dorsal equidistant from the snout and caudal, the penulti- 
mate ray two fifths of the longest, which is 3.25 in the length. Caudal about 
half the length of the eye shorter than the head. Origin of the anal on the 
vertical from the eighth or ninth dorsal ray. Anal long, somewhat emarginate, 
the longest ray about 1.5 in the base. Base of ventrals on the vertical from 
the first scale in front of the dorsal. Ventrals reaching the second or third 
anal ray. Pectorals reaching the first or second scale beyond the base of 
ventrals. 
No humeral spot, no caudal spot. A few of the anal rays sometimes tipped 
with black, the other fins unmarked with black. Scales of the back and upper 
half of the sides broadly outlined with dusky. A very narrow lateral stripe. 
Numerous inconspicuous chromatophores everywhere on the body except over 
the body-cavity and a small area just behind the humeral region. A pale blue 
iridescence on the cheek and sides below the lateral stripe. 
1 In at least some of the Pacific slope specimens the line approaches completeness, 
