48 MEMOIRS OF THE CARNEGIE MUSEUM. 



not to ventrals. Scales of the back margined with dark; a black median line; 

 some black at base of ventrals and base of anal. 



Genus XII. Macropsobrycon-^ gen. nov. 



Type: M acropsobry con Uruguay ance mgenmsinn. 



Related to Parecbasis, but having even fainter dentition, and an incomplete 

 lateral line; related to Aphyodite, but with a naked caudal and a well developed 

 pseudo tympanum; also to Leptobrycon, but with a long anal. It is possible that 

 some of the species of Megalamphodus should be placed in this genus. 



Teeth minute, conical, or but few of them with a lateral notch; six to eight in 

 the premaxillary, five or six in the front part of the mandible, none on the side of 

 the lower jaws, none on the maxillary, premaxillary feeble, maxillary several times 

 as large, nearly as long as eye, its outer margin very convex, inner margin concave, 

 not thickened; sides of mandible much raised; adipose fin well-developed; caudal 

 apparently naked; cheeks entirely covered by the third suborbital; postorbitals 

 covering abovit half the width of the postorbital space; frontal fontanel short or 

 medium; a well marked pseudotympanum. 



23. Macropsobrycon uruguayanae, sp. nov. (Plate VI, fig. 2.) 



6895a, C. M., type, 46 mm., paratypes 6896a-d, C. M., four, about 45 mm. 

 Feb. 1, 1909. Haseman. 



6897a, C. M., 26 mm. Uruguayana. Haseman. 



Head 4.5; depth 3; D. 11; A. 23-25; scales about 30-33, of which about five 

 are with pores. Eye 3 in head, greater than the very convex interorbital. 



Dorsal and ventral profiles both regular, without humps or depressions, the 

 ventral profile a little more arched than the dorsal; preventral area with about 

 thirteen scales; predorsal area narrowly rounded. with a median series of about 

 thirteen scales. Occipital process reaching about one-sixth to one-seventh to the 

 dorsal; frontal fontanel as broad, and less than half as long, as the parietal; the 

 skull very convex, the third suborbital in contact with lower limb of the pre- 

 opercle; without a naked angle under its anterior margin, leaving a wide naked 

 wedge behind its posterior margin; postorbitals narrow and feeble, leaving about 

 half of the postorbital area naked. Gill-rakers 7 + 15 to 17, very long and slender, 

 the longest more than one-half the eye. 



Premaxillary very feeble, one specimen examined has six slightly graduate 

 conical teeth, of which only one has a slight notch on one side; another has seven 



'^^ liaKpo^ii with a long face, i. e., maxillary. 



