302 THE AMERICAN CHARACIDAE. 



four scales on the side. Interorbital evenly rounded; frontal fontanel narrow, 

 I5 in the parietal fontanel; maxillary equal to the snout, much shorter than the 

 eye; second suborbital roimded, leaving a considerable naked area all around, 

 which is widest at the ends of the bone; fom* or five teeth in the front row of 

 the premaxillary, five in the second; a single tooth in the maxillary, fom- large 

 slightly graduate teeth and a number of small ones in each dentary. 



Gill-rakers 8, 16, the longest a little more than ^ of the eye. 



Scales thin, cycloid, somewhat caducous, those above the lateral line with 

 2-8 striae, regularly imbricate, no interpolated rows below the lateral line and 

 but few extra scales at base of anal; ^ anal sheath low, of a single series of scales; 

 caudal naked except just at the base; a large axillary scale; lateral Une but 

 little deciirved, the scales below it parallel with it. 



Origin of dorsal midway between tip of snout and base of upper caudal lobe, 

 or a little nearer the former; origin of ventrals and third scale in front of the 

 dorsal equidistant from tip of snout ; origin of anal a little behind vertical from 

 base of last dorsal ray ; dorsal more than 4 in the length ; anal slightly emarginate, 

 its base equal to the distance from the base of the last dorsal ray to the origin 

 or tip of the adipose ; pectorals reaching ventrals; ventrals not to anal. 



A silvery lateral band; a faint vertical humeral spot over the 3rd and 4th 

 scales of the lateral line; the silvery band becoming black on the caudal 

 peduncle and continued as a black streak to the end of the middle rays; anal 

 hyaline, with minute chromatophores toward the ends of the membranes, its 

 anterior ray and tips of a few succeeding ones milk-white. 



Some specimens, 20875, probably from Lagoa Santa have a comparatively 

 short and thick body; A. 25 and 26. Small specimens from Villa Rica, 10296 I, 

 Arroyo Pypucu, 10112 I, and Arroyo Chagalalina, 9998 I, have no differentiated 

 humeral spot, the chromatophores being evenly distributed. 



In the larger of two specimens from Tiete (10788 I. cf 77 mm.) the scales 

 are greatly striate (10-17 striae), the depth is 2.5; A. 23; scales 5-35-4 to base 

 of ventral, 5 to anal; in the small (59 mm.), the scales have from 3-7 striae; 

 depth 2.66; A. 25; scales 5-35-4 to base of ventral. Caudal nearly plain. 



In specimens from the Rio Novo, 21078, the most frequent number of anal 

 rays is 27 (25-29) instead of 32 in those from the Parahyba, and the most fre- 

 quent number of scales in the lateral line is 35 or 36 with 5 between the lateral 

 line and the ventrals, instead of 39 and 40 with 6 or 7 between it and the ventrals 

 in A. parahybae. 



' In two of the specimens from the Uruguay there are interpolated rows. 



