Cockerell: Scales of Characinid Fishes. 109 



the figure, the base strongly bilubed, much as in Leporiniis. The ex- 

 posed part is shining silvery-green, and is without distinct sculpture, 

 except for a single median radius, with perhaps rudiments of others. 

 This radius is joined in the centre by others, namely one which 

 continues in the same straight line to the basal notch, and one on 

 each side, which soon branches, giving rise to a lateral V, the lower 

 fork of which usually branches again. The circuli, covering all 

 except the exposed part, are exceedingly dense, and are very largely 

 moniliform, or broken into minute bead-like elements, as in Sclero- 

 pages. The broad area just apicad of where the radii meet is 

 covered with labyiinthine markings. In the region of the nucleus 

 there are numerous scattered translucent spots. 

 Chalcinus elongatiis Gunther. Smaller, proportionately broader 

 scales, without angles: length about four mm., width slightly over 

 five mm.; structure quite as in Gasteropelecus, with the same sort of 

 radii, but often with a fine basal radius. The region apicad of the 

 nucleus, narrowing on each side, so far as the sculpturing goes, is 

 densely covered with labyrinthiform markings, the inner basal 

 circuli become largely moniliform. This is intermediate between 

 C. rotundatus and Gasteropelecus. 



Stethaprionin.e. 



Foiderina orbicularis (Cuvier & Valenciennes). The scales are 

 entirely of the character and pattern of the lepidiirus-section of 

 Moenkhausia. Apical radii usually three or four, arranged in a 

 fan-like manner. 



Agoniatin.^. 



Piabucus dentatus Kohlreuter (British Guiana). Small, transversely 

 oval scales; no radii; nucleus about twice as far from apex as from 

 base; basal circuli fine, close together; apical circuli widely spaced, 

 continuous with basal, meeting in the middle line at about a light 

 angle just above the nucleus, the angle becoming wider and wider 

 apicad, until near the margin it is virtually absent. A characteristic 

 little scale. 



StI CH ANODONTIN^. 



SticJianodon insignis Steindachner. (Specific identity not quite 

 certain.) (Collected by William James at Manacapouru, Thayer 

 Expedition.) Scale agrees with that of Moenkhausia dichruriis. 



