104 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



small, \yell-defined humeral spot of about ten chroinatopliores ; tip of anal lobe 

 sometimes milk-white. 



Many specimens, 30 to 50 mm. long. 19a. 



Moenkhausia lepidurus gracilimus, sp. nov. 



Anal averaging 22 rays ; depth 4 or nearly 4. 



Color of caudal as in typical individuals of lepidurus but faint, with a duskiness 

 extending upon the lower caudal lobe. 



Humeral spot, even in the smallest examples, of over 20 chromatophores, not 

 well defined. 



Also seventeen specimens, 47-59 mm. long, from Villa Bella. 



Middle caudal rays and distal part of the other rays, and upper and lower edges 

 of the fin, dusky ; tip of anal lobe sometimes milk-white ; humeral spot of many 

 chromatophores, extending upward from second and third or third and fourth 

 scales. 



These specimens are appreciably different from the typical M. gracilimus, but 

 gradations between them are almost perfect. 



Twenty-one specimens, about 39 to 57 mm. Serpa, 



Moenkhausia cotinho, sp. nov.i 



Distinguished by the slender form combined with the broad, basal caudal bar. 



Head 3f-3|; depth 3-i-; D. 11 ; A. 20 or 21 ; scales 5-32-3.5. 



Elongate, not strongly compressed or elevated. 



Occipital process short, reaching one-sixth the distance to dorsal. 



Three or four teeth in outer series of the premaxillary, five teeth in the second ; 

 two teeth in the premaxillary. Lower jaw with four large teeth followed Jay a much 

 smaller, recurved tooth and a number of minute teeth. 



Brassy, the fins dusky ; a very large and very conspicuous vertically oval black 

 spot on base of caudal, bordered behind by milk-white. 



Three cotypes 67-71 mm. from Para, Thayer Expedition, are much paler; the 

 caudal spot, although covering the same area, is very faint except that part not 

 covered by the caudal scales. 



Two specimens, 46 and 54 mm. Dr. Justa, by Major Cotinho. 



Moenkhausia ceros, sp. nov. 



Distinguished by the caudal spot and the short anal. 



Head 4 ; depth 3.25 ; D. 11 ; A. 19; scales 5-33-3. 



Elongate, compressed ; dorsal and ventral profiles gently curved. Occipital 

 process short, reaching about one-sixth to dorsal, bordered by three scales on 

 each side. 



Eour teeth in the front series of the premaxillary, inner series of six graduated 

 teeth ; four large, graduated teeth in the lower jaw, and numerous small ones. 



1 For Major Cotinho, Brazilian attache of the Thayer Expedition. 



