18 Annals of the Carnegie Museum. 



Head about 4; depth 3.33; D. 11; A. 20-22; scales 5-33 to 

 35-4; eye 2.3; interorbital 3. 



Elongate, ventral profile regularly arched ; dorsal profile with an 

 angle at the origin of the dorsal, profile not depressed over the eye ; 

 preventral area flat, postventral narrowly rounded, predorsal area 

 rounded, with a median series of eight or nine scales. 



Occipital process about \ of the length from its base to the dorsal, 

 bordered by three scales; interorbital nearly flat, with marginal grooves ; 

 fontanel narrow, longer than the parietal ; second suborbital leaving 

 a triangular naked area below its junction with the first ; maxillary 3 

 in the head ; premaxillary with two to four teeth in the front series, 

 which is parallel with the second series ; five teeth in the second tow, 

 their denticles arranged in a distinct crescent ; maxillary with three 

 teeth ; mandible with four graduated teeth and abruptly smaller ones 

 on the sides. 



Scales as in gutanensis, but fewer scales on the base of the caudal 

 lobe. 



Dorsal and ventrals equidistant from tip of snout ; highest dorsal 

 ray about 3.75 in the length ; origin of dorsal about equidistant from 

 tip of snout and tip of adipose ; anal emarginate ; ventrals not quite 

 reaching anal ; pectorals to ventrals. 



Highly iridescent, a few chromatophores on cheek and opercles ; an 

 oblique dark band crosses the second, third, and fourth scales of the 

 lateral line, another one parallel to it in front of the dorsal shades into 

 the thickly punctate sides ; a punctate band extends from the base of 

 the first dorsal ray to the tip of the seventh and eighth ; tip of adipose 

 black ; a minute spot at the base of the middle caudal rays, tip of the 

 rays dusky, all of the membranes punctate, a punctate band from the 

 middle of the first anal rays along the tips of the rest of the rays, 

 other parts of the fin hyaline ; pectorals and ventrals slightly punctate. 



Astyanax mutator sp. no v. 

 (Native name, Punkay.*) 



Type 53 mm. (No. 1023 Carnegie Museum Catalog of Fishes.) 

 Savannah Landing, Upper Potaro. 



Cotypes, 120 specimens, 23-58 mm. Savannah Landing, Upper 

 Potaro. (C. M. Cat. 1024, a-z ; I. U. Cat. 11 724.) 



Head 4; depth 2.75-3; D. n; A. 21-24, most frequently 22; 

 Scales 6-33 to 35—4^- ; eye 2.75-3 > interorbital equals eye. 



