SOUTH AMERICAN CHARACID FISHES — ^WEITZMAN 147 



branchiostegal rays, three associated with the ceratohyal and one with 

 the epihyal. All members of the Erythrininae have five branchiostegal 

 rays, fom* on the ceratohyal and one on the epihyal. 



The branchial arches of the Erythrininae and Lebiasininae are like 

 those of the Characinae and differ mainly in general proportions cor- 

 related with different head shape. 



Hoedeman (1950a, pp. 17, 19, 25) stated that pharyngeal teeth are 

 absent in three species of his Nannostominae. All specimens of the 

 Nannostomina, however, that I have examined have small, conic 

 pharyngeal teeth much like those illustrated for Poecilobrycon harrisoni 

 (fig. 8). The gill rakers of members of the Lebiasininae are simple; 

 however, in the Erythrininae the gill rakers are rather complex. The 

 bony cores of those of the upper limb are truncate with small conical 

 "teeth" along their distal margins while those of the lower limb are 

 serially graduated from truncate ones anteriorly to elongate sharp- 

 pointed laminae of bone posteriorly. The dorsal edges of these 

 laminae bear small conic "teeth" while the anterior truncated gill 

 rakers have "teeth" along their distal borders. 



Weberian APPARATUS (fig. 9). — The Weberian apparatus of the 

 Lebiasininae and Erythrininae is, in all major respects, like that of the 

 genus Brycon and the Characinae, differing only in a few aspects of 

 shape and in the proportions of some of the parts. The tripus of 

 Poecilobrycon harrisoni is slightly different in shape from that of 

 Brycon meeki but still retains the basic characid structure. Its 

 dorsal proximal portion is placed slightly higher and more anterior on 

 the body of the third vertebra. In some specimens of the Nan- 

 nostomina examined there are small contingencies of bone across 

 the joint between the neural pedicel and the neural complex. 



Pectoral girdle (fig. 10). — The pectoral girdle of Poecilobrycon 

 harrisoni is much like that of the Characinae, having a large medial 

 coracoid lamina. The main body of the cleithrum, like that of the 

 Characinae, is a sickle-shaped lamella; however, the large foramen 

 between the coracoid and the cleithrum, so typical of the Characinae, 

 is absent or at best only a slight opening. The supracleithrum lacks 

 a sensory canal in all members of the Nannostomina and the post- 

 temporal is not forked, the lower spinous process found in the 

 Characinae being absent. The relationships of the postcleithrum, 

 mesocoracoid, and scapula are not markedly different from those of 

 the Characinae. 



In the Pyrrhulinina, sensory canals are lacking in the post-tem- 

 poral and supracleithrum, and the post-temporal is not forked. The 

 rest of the pectoral girdle is typical of that of characids. Unlike the 

 Nannostomina, the Pyrrhulinina have a large foramen between the 

 coracoid and the cleithrum. In speicmens of Lebiasina and Pia- 



