74 



THE AMERICAN CHARACIDAE. 



Specimens examined. 



This species has hitherto been known from the types only. It is the only 

 species of Moenkhausia in the coastwise streams of eastern Brazil, south of the 

 Rio San Francisco. 



There can be no doubt about the identification, although Steindachner says 

 that the entire maxillary border is toothed. 



Head 3.7; depth 2 + -2.4; D.ll (rarely 12); A. 34-38 l ; scales mostly 

 removed, 7 or 8-34 to 37-6 or 7. Eye 2.14-2.5; interorbital 2.7-3.25. 



Much compressed, the ventral profile regularly arched from the chin to 

 the end of the anal; dorsal outline arched as much as the ventral, but less 

 regularly; the occipital process rising rapidly, the profile of the head corre- 

 spondingly concave; preventral area rounded, with a median series of scales; 

 predorsal area trenchant, with a median series of about eleven scales. 



Occipital process a little less than one third of the distance from its base to 

 the dorsal, bordered by about five scales on each side; interorbital convex; 

 frontal fontanel not much shorter than the parietal exclusive of the groove on 

 the occipital process; second suborbital leaving a naked area about one fourth 

 as wide as the covered portion ; length of maxillary equals the distance from tip 

 of snout to pupil; mandible equals distance from tip of snout to end of maxil- 

 lary; usually five teeth in the front row of the premaxillary, the third tooth 

 removed from the line, more rarely three or four teeth; five, more rarely six, 

 teeth in the second series; maxillary most frequently with five teeth; of the 

 maxillaries examined two have three, four have four, twelve have five, six have 

 six, six have seven, and two have eight teeth; mandible with four large teeth, 

 frequently a smaller one on the side, and then a series of minute ones. 



Gill-rakers about 8 + 13, one third the diameter of the eye. 



Scales caducous, entire, with a few diverging striae, regularly imbricate; 

 anal sheath of a single series of scales; caudal lobes scaled for a third of their 

 distance at least; lateral line very little decurved, the scales below it parallel 

 with it, a few auxiliary scales over the muscles of the anal. 



1 Of seventeen specimens examined two have thirty-four, one thirty-five, six thirty-six, seven thirty- 

 seven, and one thirty-eight rays. 



