128 Annals of the South African Museum. 



equivalent to saying that Ctenolophus is congeneric with Idiops, which 

 is borne out by the diagrams (c) and (D). 



But in Ann. Durban Mus. vol. i, pt. 3, p. 225, Hewitt considers the 

 " South African species now referred to this genus (Acanthodon) con- 

 generic with the genotype of Acanthodon (G-uerin) from Brazil," and 

 gives a short diagnosis of Acanthodon, in which he states that there 

 are " either 2 or 3 pairs of sternal sigilla, the 1st pair marginal or 

 sometimes (= Gorgyrella, Pure.) a little separate from the margin." 

 He thus includes all 3 forms A. B, and c, as one genus under the name 

 Acanthodon; which, if Gruerin's type is identical with Purcell's Cteno- 

 lophus as he maintains, has but 2 sternal sigilla as in (c), and does 

 not apply to forms (A) and (B), but did and still does apply to 

 forms (D) now known as Idiops. Thus, as the following will tend to 

 show, the name Acanthodon disappeared once in 1870 (Cainbr.) and 

 once again in 1903 (Sim.), and was accepted as synonymous with 

 Idiops by Pocock in 1903. Hewitt, however, still uses the name, and 

 further includes under it the 3 forms as above ; whereas it would seem 

 more fitting to keep Gorgyrella separate, unite Ctenolophus with Idiops, 

 and substitute Segregara for the form (A) hitherto described under the 

 lapsed name Acanthodon. The creation of a new name seems neces- 

 sary, since Simon's Titanidiops does not appear to be the same as form 

 (A), but rather should agree with form. (D). It may be mentioned 

 that Ctenolophus and Idiops differ in one respect, namely, the latter 

 has two rows of teeth on the cheliceral groove, whilst the outer row 

 is represented in Ctenolophus by minute denticles only ; this by itself 

 is perhaps hardly sufficient for separation, though fairly constant, but 

 would no doubt serve to divide the group into two main classes. 



From the above resume, it would seem that M. Perty founded the 

 genus Idiops. Guerin, not having referred to this, subsequently 

 founded the genus Acanthodon on a specimen, A. pet it i, which was con- 

 generic with Perty 's Idiops. Walckenaer subsequently not only adopted 

 Gruerhrs Acanthodon, but erroneously concluded that Perty's Idiops 

 was really a Sphasus. This mistake was rectified later, but Acanthodon 

 was left standing. Cambridge then (P.Z.S. 1870) states definitely 

 that Acanthodon is identical with Perty's Idiops, and describes a series of 

 species for this genus, from South America, Syria, Africa, and Australia; 

 unfortunately he thus describes species which were geuerically 

 different from Idiops. Hence Ausserer puts the Australian species 

 I. sigillata into a new genus Idiosoma, and Simon subsequently reduces 

 Idiops to the South American species and places the rest under 

 Acanthodon, in which genus he includes as a synonym Ausserer's 



