On some Trapdoor Spiders from Australia. 109 



IX. — On some Trandoor Spiders of the Family Ctenizidje 

 from South and West Australia, contained in the Collection 

 of the British Museum. By R. I. PoCOCK. 



The four genera discussed in this paper, all belonging, as I 

 believe, to the Cyrtaucheniete, form an interesting series 

 wherein the arrangement of the eyes passes from that of 

 Aganippe, which is but a slight exaggeration of the pattern 

 observable in Gyrtauchenius, to that of Tdiosoma, which, as 

 implied by the name, is comparable to the formula found in 

 Idiops and its allies. The gradual assumption, too, of the 

 integumental characters of the abdomen is clearly indicated, 

 the normal hairy clothing of Aganippe passing into the 

 aberrant spinous covering of Idiosomi. through the form 

 called Anidiops, where the hairs are dorsally intermixed with 

 strong spines. 



Genus Idiosoma, Ausserer. 

 Idiosoma, Ausserer, Verb. z.-b. Wien, 1871, p. 150. 



Belonging to the group Cyrtauchenieae of the family 

 Ctenizidae, but characterized by the arrangement of the eyes, 

 which much resembles that of Idiops, and by the coriaceous 

 spinous wrinkled cuticle of the posteriorly truncate abdomen, 

 which approaches that of Cyclocosmia and Chorizops. 



Type /. sigillatum (Cambr.). 



This genus, established by Ausserer for the reception of 

 the peculiar species named Idiops sigillatus by O. P. Cam- 

 bridge, was, by Mons. Simon, regarded as a synonym of 

 Acanthodon (Hist. Nat. Araign^es, p. 91, 1892). The 

 antagonistic opinions of these authors were based upon the 

 characters presented by the type specimen, which belongs to 

 the male sex ; and it may be inferred that whereas Ausserer 

 regarded them as of generic value, to Simon they were 

 merely of sexual importance. The discovery, however, that 

 the female differs greatly from the female of the Idiopeai in 

 the scopulation and spine-armature of its legs, as well as in 

 the form of the labium, abdomen, &c., is sufficient justifica- 

 tion for the re-establishment of Ausserer's genus. 



Idiosoma sigillatum (Carabr.). 



Idiops sigillatus, Cambridpre, Proc. Zool. Soc. 1870, p. lOo, pi. viii 

 «g. 2, 



2 •• — Colour. Cephalothorax and limbs uniform chestnut, 

 cephalic region of the former paler ; abdomen dirty yellow, 

 tinted with black, with a fine yellow longitudinal dorsal band. 



