276 THE AMERICAN CHARACIDAE. 



The types in the British Museum are shrunken. The three larger ones 

 appear to be different from the five smaller, which may be A..rutilus. Giinther's 

 formula is certainly wrong. The scales are 8^5-6, 9-45-8, 9-43-8 in the three 

 larger, w-hich may be taken as the types of the species. 



Head 3.75; depth 3; D. 11 ; A. 27; scales 8 or 9^3 to 45-7 or 8; eye 3.75; 

 interorbital 2.6 ; snout about equal to the eye. 



Elongate, but little compressed, deepest just behind axil; caudal peduncle 

 deep, much compressed, its depth ^ of the greatest depth; .ventral profile, from 

 the origin of the pectorals to the anal, nearly straight ; dorsal profile steepest to 

 the tip of the occipital process. Preventral area broadly rounded; the scales 

 of the median series very irregular, reduced in places to rudimentary Uttle flaps; 

 postventral area narrowly rounded. Predorsal area narrowly rounded; its 

 scales regularly imbricate, there being a complete median. series of scales. 



Occipital process a httle less than i of the distance of its base from the 

 dorsal, bordered by four scales on each side. Interorbital broadly and evenly 

 convex. Frontal fontanel very short, 2^ in the length of the posterior exclusive 

 of the occipital groove, extending forward to above middle of eye. Second sub- 

 orbital leaving a wide naked area all aroimd its free border. Maxillary very 

 oblique, equal to the eye. Mandible 2.5 in the head. Four teeth in the outer 

 row of the premaxillary, five in the inner; teeth of the inner series very thick, 

 the denticles arranged in a U-shaped series; four large, irregularly graduated 

 teeth in the lower jaw. No maxillary teeth. 



Gill-rakers 10 + 15, the longest not quite equal to pupil. 



Scales regularly imbricate, except on the preventral area, the rows not 

 deflected toward the anal; no auxiliary rows; lateral line but Uttle decurved, 

 the row of scales below it parallel with it; many concentric, few radial striae; 

 caudal naked ; anal sheath weak ; axillary scale well developed. 



Origin of dorsal one scale nearer tip of the snout than the ventrals, about 

 midway of the length, penultimate ray but little less than half the length of the 

 highest, which equals the length of the head. Anal scarcely emarginate, its 

 origin one or two scales behind the base of the last dorsal ray. Ventrals not 

 reaching anal. Pectoral not to ventrals. 



Plumbeous, an ill-defined lateral band; a vertical humeral spot across the 

 third and foiuth scales of the lateral line; middle caudal rays dark. 



Vertebrae 14 -|- 18. 



Posterior air-bladder pointed, more than twice as long as the anterior, its 

 diameter but little more than | of its length, regularly curved, without angular 

 turns. Alimentary canal about equal to the total length. 



