502 PROCEEDINGS OF THE ACADEMY OF [Sept., 



scales in median lateral series 38 to caudal base, and 4 more on 

 latter, sometimes^ ; 10 scales above 1. 1. to dorsal origin; 8 or 9 

 scales below 1. 1. to ventral origin; usually 20 scales, sometimes 19, 

 between anal origin and last dorsal ray base; usually 20 predorsal 

 scales, sometimes 21; usually 17 1. 1. tubes, sometimes 15 or 16; 

 snout 2f to 3| in head; eye 2f to4f; maxillary If to 2; interorbital 

 2f to 3; pectoral 1| to If; ventral If to li; length 2f to 4}f inches. 



Variation with age, as well as individually, is quite noticeable. 

 In the type the right upper teeth forming the cutting edge are all 

 more or less conic and with only obsolete cusps. The other examples 

 have them symmetrically developed, and in the young examples 

 all the cusps are all more on a uniform plane or line in both jaws. 

 Small examples also have no external conic denticles on the upper 

 lip. The smallest paratype also has no maxillary or lateral man- 

 dibular teeth, only the cuspidate anterior teeth being developed, and 

 all the simple conic teeth apparently only appearing with age. The 

 young also have a large eye, a much shorter maxillary, which only 

 reaches back about opposite front edge of pupil, the articulation of 

 the mandible before the hind pupil edge, predorsal scales much 

 smaller than the others, the depressed dorsal fin not reaching adipose 

 fin origin, and without traces of the dark predorsal bands. With 

 advancing age a few conic teeth appear on the maxillary and lateral 

 elevated portions of the mandibular rami, though only in the large 

 examples is this bone elongated and well toothed. 



The accompanying figure has the tail ends represented as restored, 

 and the cut illustrating the dentition shows the left upper teeth as 

 symmetrical. 



(Altus, high; pi?ina, fin; with reference to the elevated dorsal 

 of the adult.) 



TETRAGONOPTERIN^. 

 Brycon scapularis sp. nov. Fig. 3. 



Head 3f ; depth 3; D. m, 9; A. iv, 25, i; P. i, 12; V. i, 7; 



scales in 1. 1. 51 to caudal base and 4 more on latter; 10 scales above 



1. 1. to dorsal origin; 5 scales below 1. 1. to ventral origin; 6 scales 



below 1. 1. to anal origin; 22 predorsal scales; head width 2f in its 



length; head depth at occiput If; snout 4; eye 3f ; maxillary 2\; 



nterorbital 3f; mandible 2f ; first branched dorsal ray If; least 



depth of caudal peduncle 3J; first branched anal ray 2f ; pectoral 



If; ventral If. 

 Body well compressed, contour rather evenly ellipsoid, greatest 



depth at dorsal origin, edges all convexly rounded or with only 



