THE AMERICAN TETRAGONOPTERINAE. 147 
Occipital process 5 or 6 in the distance from its base to the dorsal, bor- 
dered by 3 scales. Interorbital slightly convex. Frontal fontanel triangular, 
almost as wide as the parietal and as long as the parietal without the occipital 
groove. Second suborbital little more than half the eye in width, usually with 
narrow naked margins behind and below. Mouth large; snout little more 
than half the length of the eye. Maxillary slender, just, or not quite, equal to 
the eye; 2 to 2.3 in the head. Mandible equal to the eye. Premaxillary 
with three or four tricuspid teeth in the outer row, and four or five, rarely six, 
3- to 5-pointed teeth in the inner row. Maxillary with two or three, less often 
four, 3- to 5-pointed teeth, the posterior one sometimes conical. Dentary 
with a graduated series of four or five 3- to 5- and 7-pointed teeth, followed 
by a series of seven to twelve minute, conical ones on the sides. 
Gill-rakers 6 + 10. 
Caudal scaled over the basal one half. Anal sheath short, consisting of 
about 6 scales over the bases of the first 10 rays. Lateral line with pores devel- 
oped on 5 to 14 scales. 
Origin of the dorsal equidistant from the snout and caudal; penultimate 
ray short, one fourth of the longest, which is 3.67 in the length. Origin of the 
anal on the vertical from the first scale behind the dorsal. Anal emarginate, 
the longest ray 1.25 in the length of the base. Ventrals on the vertical from 
the first scale in front of the dorsal. Ventrals just reaching the anal. Pec- 
torals just, or not quite, reaching the ventrals. 
No humeral spot. Caudal spot faint or lacking. A heavy leaden lateral 
stripe often somewhat expanded near the end of the caudal peduncle, nar- 
rowed in the region just below the dorsal. Dorsal and anal somewhat dusky. 
A broad black marginal or submarginal band across the caudal lobes. When 
this band is submarginal the middle caudal rays are black also. The base of 
the caudal lobes hyaline, probably orange or red in life. Seales of the back 
and sides, above the lateral stripe outlined with dusky. Sides below the lateral 
stripe with pale bluish iridescence. 
7. HEMIGRAMMUS NANUS (Liitken). 
Plate 18, fig. 1; Plate 78, fig. 2, 7. 
Tetragonopterus nanus LiitKEn, Overs. K. Dan. selsk. Forh., 1874, p. 133 (Lagoa Santa); Vidensk. selsk., 
1875, 12, p. 218, pl. 5, fig. 17 (Rio das Velhas); ErgeNMANN & EIGENMANN, Proc. U.S. N. M., 1891, 
14, p. 282; Unrey, Ann. N. Y. acad. sci., 1895, 8, p. 286. 
