eigenmann: the FRESHWATER FISHES OF BRITISH GUIANA 349 



posed of but four teeth. D. 9 or 10, rarely 11; second suborbital expanded, cov- 

 ering the entire space between the eye and the lower limb of the preopercle; no 

 naked area below the surface of the first and second suborbitals. Maxillary with 

 not more than five teeth on its upper anterior edge; caudal naked. 

 A single species has been taken in Guiana. 



209. Bryconamericus hyphessus Eigenmann. (Plate XLV, fig. 2.) 



Bryconamericus hyphesson Eigenmann, Ann. Carnegie Mus., VI, 1909, 32; Repts. 



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



Type, 37.5 mm. Tumatumari, Lower Potaro. (Carnegie Museum Catalog 

 of Fishes No. 1070.) 



Cotypes, ten specimens, 34-3G mm. Tumatumari. (C. M. Cat. No. 1071a-6; 

 I. U. Cat. No. 11755.) 



Most closely related to stramineus. 



Head 4.5; depth 4; D. 9; A. 16; scales 4-36-2; eye 2.66-2.75; interorbital 

 equal to eye. 



Slender, but compressed, greatest depth over tip of pectorals; ventral and 

 dorsal outlines equally arched; preventral area rounded, with normal scales; post- 

 ventral area short, compressed; predorsal area rounded, with a regular series of 

 ten scales. 



Occipital process very short, only about one-eighth of the distance between its 

 base and the dorsal, bordered by two scales on the sides; skull convex, smooth, a 

 groove above the eye just within the orbital rim; frontal fontanel very short, tri- 

 angular, not half as long as the parietal; snout blunt, the lower jaw included; 

 mouth small, the maxillary a little more than half the length of the eye; cheeks not 

 very wide, entirely covered by the second suborbital; maxillary with three or four 

 broad, five-pointed teeth; premaxillary with two series of five-pointed teeth, four 

 teeth in the inner row, four to six in the outer, the teeth of the outer row smaller 

 than those of the inner row, the inner series parallel with the outer, except that the 

 third tooth is withdrawn from the line of the rest; dentary with seven or eight 

 graduated, five-pointed incisors. 



Scales very regularly imbricate, without interpolated or omitted scales; about 

 three scales on the base of each caudal lobe; scales of the sides usually without, 

 those of the tail sometimes with a single ridge or line; anal sheath very narrow, 

 consisting of a single series of minute scales extending along the greater part of the 

 base of the fin ; lateral line decurved. 



Origin of dorsal a little behind the middle of the body, over the middle of the 



