160 THE AMERICAN CHARACIDAE. 
defined, not quite extending to the end of the middle caudal rays, lower half 
of the caudal with many pigment-cells and blackish, upper half hyaline; basal 
two thirds of anal dusky. 
17. HemiGcrRamMus 1oTA Durbin. 
Plate 22, fig. 7. 
Hemigrammus iota Dursin, Ann. Carnegie mus., 1909, 6, p. 60 (Gluck Island); Ergenmann, Rept. 
Princeton univ. exped. Patagonia, 1910, 3, p. 436. 
Haxirar.— Essequibo River. 
Specimens examined. 
Number of 
Catalogue number specimens Size in mm. Locality Collector 
1458 C. Type 1 18 Gluck Island Eigenmann 
1460 C. 11914 I. dq 19-21 Rockstone Eigenmann 
Paratypes 
1459 C., 11913 I. 7 18-21 Gluck Island Eigenmann 
Paratypes. 
Head 3.6; depth 3.4; D. 11; A. 15-17; scales 5-30-3; eye 2.33-2.5; 
snout 1.67 in the eye. Interorbital slightly less than the eye, 2.8 in the head. 
Compressed; depth of head at the base of occipital process 1.33 in the 
greatest depth. Preventral region rounded, usually without complete series 
of median scales. Predorsal region rounded, usually with complete series of 
9 to 11 median scales. 
Occipital process 7 or 8 in the distance from its base to the dorsal, bordered 
by 2 seales on each side. Interorbital convex. Frontal fontanel much nar- 
rower than the parietal, triangular, three fourths of the parietal without the 
occipital groove. Second suborbital covering the entire cheek. Snout short, 
mouth comparatively large. Maxillary 1.4 in the eye. Mandible a little 
longer than the eye, 2+ in the head. Premaxillary with five, 3- to 5-pointed 
teeth in the inner row and two or three narrow tricuspid teeth in the outer 
row. Maxillary with one or two broad teeth with 4 or 5 points. Dentary with 
a graduated series of four or five large, 5-pointed teeth, followed by four or five 
minute conical ones on the side. 
Gill-rakers about 9 + 7. 
Anal sheath short, of 7 scales, covering the base of the first 8 or 9 anal rays. 
Lateral line with pores on the first 6 to 8 scales. 
