62 MEMOIRS OF THE CARNEGIE MUSEUM. 



Head 4-4.25; depth 2.5-2.75; D. 10 or 11; A. most frequently 19, ranging 

 from 17-20; scales 34-35, rarely 32, eight or nine scales with pores, ten scales 

 between dorsal and ventral; eye 2.6-3 in head, about equal to the interorbital ; 

 depth of caudal peduncle about equal to its length. 



Compressed, dorsal and ventral outlines evenly and equally curved. Pre- 

 ventral area rounded with a median series of eleven scales; predorsal area rounded 

 with a median series of nine scales, extending to within two scales of the occipital 

 process; occipital process broad and short, reaching about one-seventh to the dorsal, 

 bordered by two and one-half scales on each side; skull convex, frontal fontanel 

 only about one-fourth as long as the parietal; mouth very short and small, maxillary 

 very little, if any, more than half as long as the eye; teeth broad-tipped, five- or 

 seven-pointed, median point largest, projecting; four teeth on the premaxillary, 

 two on the maxillary, eight or nine on the mandible, those on the side of the man- 

 dible graduate, the last one may be minute and single pointed, all the rest of the 

 teeth similar in size and shape; third suborbital strong, in contact with the pre- 

 opercle below and partly behind; postorbitals thin, ill defined, leaving a considerable 

 naked area. Gill-rakers 4 + 8, very short, only about one-fifth as long as eye. 



Origin of dorsal a little nearer tip of snout than base of caudal, the fin pointed, 

 the highest ray about equal to the head; adipose fin small; caudal forked, the 

 lobes about equal to the length of the head; origin of anal behind the vertical 

 from the last dorsal ray; anal fin but slightly emarginate, its base little shorter 

 than the head; all but the last three or four of the divided anal rays of the male 

 with seven or eight strong recurved hooks. Pectorals of the male reaching the 

 ventrals; ventrals of the male truncate, reaching the anal, ventrals of the female 

 pointed, not reaching the anal; the pectorals in the female not reaching the ventrals. 



Scales thin, regularly imbricate, very few diverging strise; anal with about 

 three scales forming a sheath at the base of the anal; base of caudal in the male 

 scaled, the scales covering the caudal fulcra and forming a lobe along the middle 

 of the fin. 



Tip of dorsal and upper part of membrane between the rudimentary, and first 

 full ray black; tip of anal in the male black; a conspicuous triangular caudal spot 

 not quite extending to the end of the middle rays; a black band extending forward 

 to below the dorsal. 



Genus XVIII. Mixobrycon^^ gen. nov. 



Type: Mixobrycon ribeiroi (Eigenmann). 



Closely resembling Hyphessobrycon; teeth heavy, few, in a single series; third 



" pi^is = a mixing; Brycon, a genus of Characins. Name chosen because tlie teeth show some of the 

 characters of Hyphessobrycon. 



