1899] DISTRIBUTION OF THE ARACHNID A 225 



Carboniferous beds (Anthracoscorpii) survived that period, and none 

 that the group of Neoscorpii, which comprises all recent forms, had 

 come into existence at that time. Hence it is possible that the latter 

 only date back to the earlier Secondary epoch. They may, in fact, 

 be coeval with the Mammalia. If this be so, the similarity in 

 distribution between the two classes is not a surprising fact. 



It is believed by Dr. Blanford that India was connected with 

 South Africa, by way of the Seychelles and Madagascar, throughout 

 Upper Cretaceous (perhaps during Eocene) times, and that the con- 

 necting land was broken up into islands at an early date in the 

 Tertiary period. This view is in accordance with the suggestion 

 already made, that the scorpions took possession of the Afro-Mascarene 

 continent during the Oligocene and Miocene epoch, that is to say, 

 after the severance of Madagascar from South India. Otherwise there 

 would be, one may suppose, a much greater resemblance than actually 

 obtains between the scorpions of Indo-Ceylon and Madagascar. Clearly 

 also the absence of Indian scorpions and of Amblypygous and Uro- 

 pygous Pedipalps from Madagascar, and their presence in South India 

 and Ceylon, shows that they entered these areas of the Oriental region 

 after the submergence of the land uniting this region with the 

 Mascarene portion of the Ethiopian ; in other words, not before, and 

 probably after, the Eocene period. 



It is stated by Mr. Lydekker that during the Pliocene India and 

 Africa were zoologically identical, the identity being due to the 

 derivation of the mammalian population of the two countries from a 

 common source, namely, the so-called Siwalik fauna of Lower Pliocene 

 age, which has been traced from the frontiers of Baluchistan along the 

 Himalayas into Burma, and for some distance to the north, south, and 

 east of that country. Here, again, there appears to be no evidence 

 against the supposition that the ancestors of the existing Indian, and 

 most of the existing African, Scorpions and Pedipalps, also formed 

 part of the Siwalik fauna. At all events, as a working hypothesis 

 this may be assumed to be the case. 



If the Amblypygous Pedipalp of the genus Tarantula was widely 

 distributed over the area occupied by the Siwalik fauna, its existence 

 at the present day in Siani, India and Ceylon, Arabia, and East Africa 

 becomes intelligible, because it appears certain that in Pliocene times 

 there was a broad, and in part forest-covered, tract of land uniting 

 Africa with South- Western Asia. Probably the scorpions of the genera 

 lomachus and Archisometrus, both of which occur in India and East 

 Africa, entered the latter area at the same time as Tarantula. 



So far as the genera just mentioned are concerned, the fauna of 

 Africa and India are at the present time identical. The differences 

 between the two that obtain in other respects appear to be explicable 

 on the hypothesis that new forms have sprung up within two areas 

 since the Pliocene epoch, and that others, like the scorpions of the 



16 NAT. SO. VOL. XIV. NO. 85. 



