1918.] NATURAL SCIENCES OF PHILADELPHIA. 143 



Gill-opening forward to front eye edge. Rakers 10 + 10, lanceo- 

 late, slender, about f of filaments, and latter 2 in eye. Pseudo- 

 branehiie about half of gill-filaments. Isthmus slender. 



Scales cycloid, rather narrowly imbricated, in lengthwise rows 

 parallel with 1. 1. and become slightly smaller along ventral edge. 

 Caudal with broad basal scaly area, also whole basal extent of anal. 

 L. 1. complete, slightly decurved, and each scale with short tube, 

 exposure about half of each scale exposure. Ventral with scaly 

 axillary flap about | length of fin. 



Dorsal origin about midway between snout tip and hind edge of 

 adipose fin, first branched ray longest and depressed fin half way to 

 caudal base. Origin of adipose fin little nearer depressed dorsal 

 tip than caudal base, adipose fin about long as eye. Anal with 

 long base, first branched ray highest and fin edge nearly straight, 

 so anal origin nearly opposite hind dorsal edge or about midway 

 between hind preopercle edge and caudal base. Caudal well forked, 

 pointed lobes similar, with, lower slightly longer. Pectoral low, 

 reaches slightly beyond ventral origin though not quite to that 

 of dorsal. Ventral inserted nearer anal than pectoral origin, fin 

 reaching latter. Vent close before anal. 



Color in alcohol faded dull brownish generally, though back slightly 

 darker than other regions. A pale sheen, as if silver}^ in life, along- 

 middle of side, though narrowing on caudal peduncle side where 

 giving place to slight dusky tint and then continued out on caudal 

 medianly to liind edge as blackish streak. Iris pale slaty. Black 

 ellipsoid spot, little smaller than eye, at shoulder. Dorsal slightly 

 tinged with dusky, and fins otherwise pale. 



Length 97 mm. 



Type No. 47, 686, A. N. S. P. Puerto Bertoni, Paraguay. Senor 

 A. De W. Bertoni. 



Only the type known, quite distinct from the allied species of 

 Bnjconamericus and Markiana, etc. The dentition, shown to the 

 left below in the accompanying figure, is enlarged a little over twice 

 that of the indicated line of proportion for the profile drawing. 



