22 Annals of the Carnegie Museum. 



maxillary equal to the eye ; four or five teeth in the front row of the 

 premaxiilary, the third withdrawn from the line of the rest ; five grad- 

 uated teeth in the second row, their denticles in shallow crescents : 

 maxillary with two or three minute teeth ; dentary with four large teeth 

 abruptly followed by smaller ones on the sides. 



Gill rakers 8 -f n- 



Scales of the sides regularly imbricate, a few interpolated scales over 

 the anal muscles ; anal sheath of a single row of scales along the base 

 of the anterior rays ; caudal naked, a well-developed axillary scale ; 

 lateral line but little decurved. Each scale of the sides with a few 

 nearly parallel striae. 



Dorsal but little farther from snout than the ventral, nearer snout 

 than caudal, its margin rounded, the highest ray about 3.75 in the 

 length, the penultimate a little less than half as long as the highest. 

 Anal emarginate, the second and tenth reaching the base of the eigh- 

 teenth where depressed ; first anal ray below or behind the base of the 

 last dorsal ray. Ventrals not reaching anal, pectorals to ventrals. 



Highly iridescent, blue above, greenish to silvery below ; a club- 

 shaped horizontal humeral spot, its pointed anterior end from the 

 upper margin of the first scale of the lateral line along the row of scales 

 above the lateral line to above the fifth scale of the line ; a dark verti- 

 cal bar crossing the opercle, followed by a light bar, a second dark 

 bar across the posterior part of the humeral spot, a second light bar 

 and then a third dark bar shading into the profusely dotted sides. 

 Cheeks profusely dotted ; a dark median line, most prominent in young 

 specimens preserved in formalin, this line not extending along the sides 

 of the caudal peduncle ; a black spot at the base of the caudal, its 

 margins shading into the dusky caudal but not definitely continued to 

 the end of the middle rays. These markings fading with age. In life 

 all fins but pectorals tinged with orange or brick red. 



Astyanax potaroensis sp. nov. 



Type, 58 mm. (No. 1037 Carnegie Museum Catalog of Fishes.) 

 Amatuk Cataract, Potaro River. 



Cotypes, 12 specimens, 51-64 mm. Amatuk. (C. M. Cat. No. 

 1038, #-<:; I. U. Cat. No. 11733.) 



Cotype, 1 specimen, about 59 mm. Kangaruma, Lower Potaro 

 River. (C. M. Cat. No. 1039.) 



Cotype, 1 specimen, 45 mm. Tukeit, Lower Potaro River. (C. 

 M. Cat. No. 1040.) 



