SOUTH AMERICAN NEMATOGNATHI. 175 



Pectoral spine roughened in front, strong recurved 

 teeth behind. 



Depth of caudal peduncle 2| to 3 in head. 



Head 3J to 4J; depth 3| to 5; Br. 9; D. I, 6; A. 11. 



We have examined about four hundred specimens of 

 this species, some of which have teeth on the vomer and 

 some have not. Some have teeth on the pterygoid and 

 some have not; some have the sides thickly covered with 

 small spots (pantherinus); some have the sides covered 

 with from three to five series of large spots (macrospUa); 

 some have the sides plain (macronema, piscatrix); some 

 have three or four black bands along the sides; some 

 have long maxillary barbels, and some have shorter 

 ones; some have a long or shallow band of teeth on the 

 intermaxillary, and some have a deeper, shorter band; 

 some have a black spot at the base of the dorsal plate 

 and some have not. They are labelled Pimelodus macu- 

 latus. It seems that the species Pimelodus maculatus 

 Auct. goes through a similar variation of color and 

 other characters. The maculatus has been confounded 

 with clarias by Kner, Steindachner (as shown by the 

 labels), and Liitken, and in fact the only difference 

 between the two species is the presence of teeth on the 

 pterygoids and vomer in the one and their absence in 

 the other; and when these teeth in clarias are absent, as 

 they sometimes are, it cannot be distinguished from 

 maculatus, and maculatus, with all its synonyms, may be 

 placed in the synonymy of clarias. 



We should perhaps state in this connection that we 

 have examined almost every specimen in the museum 

 at least four times, that we have several times separated 

 the material according to the variation of the different 

 parts, and that we have been enabled to separate the 

 material into several varieties, some of which have not 

 yet been described. 



