On Some South African Aviculariidae (Arachnida). 129 



Idiosoma. In 1897 Pocock records the two African species of Idiops 

 (thorelli and meadii) described by Cambridge in 1870 as Acanthodon, 

 and describes a new species of the genus from ? specimens. Sub- 

 sequently Simon makes Acantliodon a synonym of Idiops, and con- 

 stitutes the synonymy of the latter genus as on p. 889, Hist. Nat. des 

 Ar. 1903 ; apparently re-establishing Ausserer's Idiosoma. The 

 generic type for Idiops thus reverts to Perty's I. friscus, and Acantliodon 

 disappears ; A. petiti becoming I. petiti. For species other than 

 American, Simon makes new genera, Pachyidiops and Titanidiops ; 

 which Hewitt, however, does not think valid (Ann. Durb. Mus. vol. i, 

 pt, 3, p. 225, note). 



Purcell in 1904 removes all his species from Acantliodon, placing 

 some in a new genus, Ctenolophus, and the rest in Idiops. About 1910 

 Hewitt describes the supposed $ of Acantliodon pretoriae, of which 

 the J 1 was described by Pocock in 1898, and subsequently describes 

 other species under the genus Acantliodon, although the name 

 had lapsed. Amongst species which finally come to rest under 

 Acantliodon are forms with 3 pairs of small marginal sternal sigilla, 

 which Hewitt considers genetically the same as Purcell' s Gorgyrella ; 

 further, having examined Grucriu's type on which Acantliodon was 

 originally based, he finds that Ctenolophus is congeneric with the original 

 Acanthodon (which, however, is Idiops) ; hence Ctenolophus, Gorgyrella, 

 and an apparently new form are all included by him under the lapsed 

 Acanthodon. If sternal sigilla are thus considered valueless for generic 

 separation, Idiops itself has little support ; hence it is not surprising 

 that Hewitt considers it probable that " Acanthodon and Idiops will 

 eventually be united " (Ann. Durb. Mus. vol. i, pt. 3, p. 225, footnote) ; 

 in fact the subfamily Idwpeae would practically become one big genus. 



A possible solution is suggested in the previous and following pages 

 in which the name Segregara shall be applied to forms with 3 pairs 

 of small marginal to [submargiual sigilla, from which fresh genera, 

 Gorgyrella and Idiops (including Ctenolophus), have branched off. 



SYTEMATIC VALUE OP STERNAL SIGILLA (Text-figs. 12 and 13). 



In connection with the genus Pelmatorycter, Hewitt states (Ann. 

 Durb Mus. vol. i, pt. 3, p. 223) that "the character of the position of 

 the posterior sternal sigilla is only of specific importance, for in the 

 genus Pelmatorycter these sigilla may be small and submargiual, or 

 very large and submedian." This may perhaps be because specimens 

 of the genus Ancylotrypa have been included as Pelmatorycter. In 

 specimens of both genera available for examination great similarity 

 exists, and the posterior sternal sigilla show less divergence than in 



