1906.] NATURAL SCIENCES OF PHILADELPHIA. 447 



Brycon melanopterum (Cope). 



Megalobrycon melanopterum Cope, Proc. Acad. Nat. Sci. Phila., 1871 (1872), 

 p. 262, PI. 13, fig. 1. Cotypes, Nos. 8,035 (type) and 8,036, A. N. S. P. 

 Ambyiacu River. John Hauxwell. 



Width of head 2 in its length; interorbital space 2|. Body com- 

 pressed, and edges apparently all rounded. Head becoming more or 

 less constricted below. Snout broad, rounded when viewed above. 

 Mouth broad. Outer enlarged mandibular teeth 8, quindentate, and 

 lateral series becoming smaller posteriorly. An inner lateral series of 

 mandibular teeth, small, and at symphysis a small conic tooth inside. 

 Maxillary toothed, its entire edge in a single series. Teeth in upper 

 jaw triserial anteriorly, laterally biserial, and each of inner series at 

 least tridentate, those in third anterior series enlarged and quindentate. 

 Tongue thick, fleshy and little free. Interorbital space broadly con- 

 vex. Gill-opening to about first i of eye. Rakers about 8 + 13, 

 lanceolate, and longest y of longest filaments, which are f of eye. 

 Scales strongly striate and finely ciliate. Color in alcohol pale 

 brownish, back and upper surface of head a little deeper colored. 

 Fins pale brownish, and dorsal, caudal and anal tinted a little 

 brownish. Along middle of upper caudal lobe longitudinally a dusky- 

 brown blotch, deepest at base of lobe. This margined below diffusely 

 with grayish-white. Along base of anal a brownish shade. Iris brassy- 

 brown. Length 6f inches (caudal damaged). Type. 



Also 4 examples from the Peruvian Amazon from Prof, James Orton 

 Coll. 



Though I allow the above specimens of this species as distinct from 

 Megalobrycon cephalus Giinther, it is possible that they may be found 

 identical. Cope pointed out that M. melanopterum differs in the outer 

 series of teeth in the upper jaw being more than double the size of 

 those on the maxillary, as stated for M. cephalus by Dr. Giinther. 

 The apparently uniform coloration is a feature of striking difference, 

 and as Dr. Giinther's examples were 13 inches long, may be one of 

 age. Brycon falcatus Miiller and Troschel, from Guiana, is also related. 



Chalcinus albus (Cope). 



Triportheus albus Cope, Proc. Acad. Nat. Sci. PWla., 1871 (1872), p. 264, 

 PI, 14, fig, 3. Type, No. 21,234, A. N, S. P. Ambyiacu River. John 

 Hauxwell. 



Width of head 2 J in its length ; interorbital space 3 in head measured 

 from tip of upper jaw. Body strongly compressed and preventral 

 region trenchant. Snout with convex surface, and roimded when 

 viewed from above. Teeth in upper jaw mostly biserial, or only 

 irregularly triserial, quindentate, and median inner series expanded 



