416 Journal of the Asiatic Society of Bengal [November, 1914. 



specialized and it appears to be the only one which has spread 

 into the Indian Peninsula and Ceylon. 



* ,, W 5f fcher j* is also dominant in the south-eastern parts 

 \ Oriental Region I cannot say with certainty ; but further 

 east still, in the Australian Region, it has never been recorded, 

 although^ Selenocosmia and some other genera of that type occur 

 there. This may be due to inferior migratory ability in Chilo- 

 brachys which is not, I think, very likely; or to its having 

 originated after the appearance of a more complete separation 

 cl the Oriental and Australian Regions than was in existence 

 when Selenocosmia passed from one to the other. In either 

 of these cases Ghilobrachys should be at least, and Selenocosmia 

 at most, as common m the eastern parts of the Oriental Region 

 as it is in the western. 



There is also however, the possibility that Chilobrachys may 

 have originated in continental Asia, and not in the Archipel- 

 ago, m which case it may still be spreading slowly eastwards as 

 opportunity offers. Although the Archipelago is clearly the 

 mam centre of evolution in the Indo- Australian Thelyphonidae 

 ana i*assalidae,in the former group the numerous species of the 



almost exnlllsi^lTT T* tl ,.™,>„~ rr . r . ■ *♦-*.- 



Hypoctontis 



a secondary centre in Burma, whose secluded valleys are, in 

 aaaition well known to have favoured the evolution of innumer- 

 able small tribes from the various ancient stocks of the human 

 race which have from time to time migrated and settled 



n-i\ [ Ur ™ a has been and 8tiU ia ^e centre of evolution of 

 c^/o6m c % 5 this genus will be less abundant in the Archipelago. 



«™L?'* « ,' mosfc P roba Wy the case, for Simon does not 



record it from the Sunda Islands at all. 



Several stages in the increasing specialization of the stridu- 

 uting organs are to be found in Chilobrachys. The form which 

 most closely approaches that found in Selenocosmia is found 

 in o assamensis and C. fumosus > figured on pi. xxxi, fig 5. 

 m,,!^ Spe ? 16 ! the s t ru ctures borne on the chelicerae are still 

 rntS?T y sp ' mf T m ' tbou g h not mixed with hair as in Seleno- 

 cosma ; and, although the bacilli on the coxae of the palps 



^ rL C °i! e u a 1*°*% oval area, those of the whole length of the 



a,iH 5 / th , e ventral row are more or less sharply distin- 

 guished from the others by their greater size and strongly 

 ^avitorm shape, this being especially marked in three or four 



The 



«S.lX pe °[. this s P eci es is a dned female of uncertain locality- 

 Hirst am, pp s^\ ° Pply this name is thafc identified with it by 



and r 1 ?,!!?* in - S ■ h f mala yana , which is exactly like the C. assamensis 

 does an! „T'c m , thu reSpect - Tt aIso resembles them more nearly than 

 bacilh L thl Sele ™> co ™™ known to me in the structure of the group of 



more tvSca? ^ OX - ° f *^ e Palp- It is, in fact, transitional between the 

 more typ,cal species of Selenocosmia and Chilobrachys. 



