eigenmann: the FRESHWATER FISHES OF BRITISH GUIANA 353 



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 tips of the seventh 

 and eighth; tip of adipose black; a minute spot at the base of the middle caudal 

 rays, their tips 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. 



213. Astyanax mutator Eigenmann. (Plate LI, fig. 3.) 



"Punkay." 

 Astyanax mutator Eigenmann, Ann. Carnegie Mus., VI, 1909, 18; Repts. Princeton 



Univ. Exp. Patagonia, III, 1910, 434. 



Type, 53 mm. Savannah Landing, L'pper Potaro. (Carnegie Museum Cat- 

 alog of Fishes No. 1023.) 



Cotypes, one hundred and twenty specimens, 23-58 mm. Savannah Landing, 

 Upper Potaro. (C. M. Cat, No. 1024r,- 2 ; I. U. Cat, No. 11724.) 



Head 4; depth 2.75-3; D. 11; A. 21-24, most frequently 22; scales 6-33 to 

 35-4.5; eye 2.75-3; interorbital equal to eye. 



Compressed; dorsal and ventral profiles equally curved; snout narrow, pointed; 

 profile not depressed over the eye; preventral area rounded, without a distinct 

 median series of scales; postventral area narrowly rounded; predorsal area keeled, 

 with a median series of nine or ten scales. 



Occipital process very narrow, about one-fifth as long as the distance of its 

 base from the dorsal, bordered on each side by three scales; interorbital convex; 

 frontal fontanel much shorter than the parietal; second suborbital narrow, leaving 

 a naked area, which is more than half as wide as the bone itself; maxillary equal to 

 snout in length, its front margin very convex; width of lower jaw about half the 

 orbit ; premaxillary with two to four teeth in the front series, five five-pointed teeth in 

 the second series; maxillary with three teeth, of which one is minute; dentary with 

 five or six five-pointed teeth, graduate; abruptly a series of minute conical teeth 

 on the sides. 



Gill-rakers 11 + 18. 



Scales regularly imbricate, no interpolated or omitted series; anal sheath of a 

 single series of scales along anterior part of anal; lateral line little decurved, some- 

 times broken or interrupted on the tail, each scale with several radiating striae. 



Origin of dorsal midway between tip of snout and base of middle caudal rays; 

 highest dorsal ray nearly 4 in the length; origin of anal and ninth to eleventh dorsal 

 rays equidistant from snout; anal very slightly emarginate; ventrals considerably 



