270 THE AMERICAN CHARACIDAE. 



So far as known, this character is found among other characins only in some 

 specimens of A. stilbe from the Atrato and in some of the Cheirodontinae. The 

 preventral surface in the male is very narrow, the scales of the two sides are 

 straight edged below and joined by a series of narrow median scales. 



Head 4.25; depth 3; D. 11; A. 38; scales 7-38-6; eye 1- in snout, 3+ in 

 head; interorbital 2.9 in the head; depth of caudal peduncle equals its length 

 or the length of the postorbital portion of the head. 



Slender; ventral profile a nearly regiilar segment of a circle from the man- 

 dible to the end of the anal ; dorsal profile a little less regular, less deeply arched. 

 Preventral area narrow, rounded, with a narrow median series of scales; post- 

 ventral area narrow. Predorsal area rounded, with about six median scales in 

 front of the dorsal, and about six irregular scales farther forward. 



Occipital process unusually long and slender, its length equal to nearly 

 a third of the distance from its base to the dorsal. Interorbital very convex. 

 Mouth terminal, snout pointed. Maxillary about .6 as long as eye; maxillary- 

 premaxillary border equal to the eye in the length ; greatest width of the second 

 suborbital about two thirds of the length of the eye ; five teeth in the front row 

 of the premaxUlary on one side, fom- on the other, five teeth in the inner series 

 of the premaxUlary. One tooth on the maxillary, fom* large teeth in the mandible 

 in front, minute ones on the sides. 



Scales regularly imbricate except over the anal muscles where they are 

 much smaller and the rows are deflected toward the anal. Caudal naked, anal 

 with a sheath of a single series of scales which are continuous with those above 

 its base ; axillary scale long ; lowest row of scales of the sides with their ventral 

 margin straight, those of the two sides nearly meeting in front of the ventrals; 

 a narrow median series between them. 



Origin of dorsal an orbital diameter nearer tip of snout than end of last 

 scale of the lateral line, the second ray prolonged in a filament, 3.33 in the 

 length. Caudal deeply forked, the lobes about 3.5 in the length. Anal low, 

 but httle emarginate, its origin equidistant from middle of eye and end of last 

 scale of the lateral line, on the vertical from the last dorsal ray. Outer ventral 

 ray prolonged, reaching to base of fifth anal ray. Pectorals reaching two scales 

 beyond origin of ventrals. 



Easily distinguished by the fiUform dorsal and ventrals, the position of 

 the dorsal ; the five teeth in the inner series of the premaxUlary and the peculiar 

 scaHng of the preventral and predorsal areas, as well as by the small scales 

 covering the anal musculature. 



The type is a male with retrorse hooks along the first ten anal rays. 



