176 Annals of the Carnegie Museum. 



Head 3.5-3.75; depth 2.8-3.2; D. 11 ; A. 27 or 28; scales 7-35-5; 

 eye 2.5; interorbital 3. Slender, dorsal and anal profiles gently and 

 equally curved; ventral areas rounded, preventral area without a 

 distinct median series of scales; predorsal area with about ten scales; 

 occipital process about one-fifth of the space between its base and the 

 dorsal; interorbital but slightly convex; frontal fontanel very little 

 shorter, but much narrower than the parietal; second suborbital leav- 

 ing a narrow naked margin; maxillary slender, one-half the length of 

 the snout and eye; four teeth in the front row of the premaxillary, 

 five in the second row; maxillary with one small tooth; mandible 

 with four large teeth in front and several abruptly minute ones in 

 each dentary. Gill-rakers 8 + 15. Scales regularly imbricate, no 

 interpolated rows; lateral line somewhat decurved; anal with a sheath 

 of a single row of scales along the base of the anterior rays; scales 

 with a few faint radial stria?. Origin of dorsal about equidistant from 

 snout and caudal, highest dorsal ray 4 in the length; caudal lobes about 

 3.5 in the length; origin of anal under last caudal ray; ventrals vary, 

 reaching the anal ; pectorals scarcely to the ventrals. Highly iridescent 

 silvery; a bright silvery lateral band, a faint humeral band, no caudal 

 spot. 



Differing from guianensis in the partially naked cheek, etc' 

 Named for Mrs. Marion Durbin Ellis, collaborator in monographing 

 the minute Tetragonopterinoe. 



14. Astyanax guaporensis sp. nov. 



Plate VII, fig. 4. 



Type. — One specimen, 49 mm. C. M. No. 3351. Maciel, Rio Guapore, July 

 23-26, 1909. 



Colypes. — Two specimens, 36 and about 40 mm. C. M. No. 3352. Same place 

 and date. 



Head 3.75; depth 2.75-2.9; D. 11 ; A. 27, 29, 31; scales 6-35-5; 

 eye 2-2.2^ in the head, interorbital 3. Compressed; ventral area 

 rounded, predorsal area with about 8 scales; occipital process J^ in 

 the distance from its base to the dorsal; second suborbital leaving but 

 a small triangle below its anterior corner naked, its surface pitted. 

 Three or four teeth in the outer row of the premaxillary, five in the 

 inner; about seven teeth on the maxillary; five large and several 

 minute teeth on rach dentary. Gill-rakers 7 + 12, those of the lower 

 arch large and strong. Scales with an interpolated row over the anal, 



