1899] DISTRIBUTION OF THE ARACHNIDA 229 



marsupials entered their respective areas of distribution in Eocene 

 times, the lands connecting these two continents with South America 

 must, according to the hypothesis, have been in existence some time 

 between the Eocene and the end of the Miocene periods. 



Apart, however, from dates, since land connections between the areas 

 in question are believed to have existed, it is necessary, when discussing 

 the question of the origin of the Neotropical scorpion and Pedipalp 

 fauna, to examine the evidence for or against the view that any elements 

 of the fauna have been derived from Australia or South Africa. 



Since the Solifugae and the two groups of Pedipalpi with which 

 we are dealing do not occur in Australia at the present time, and there 

 is no reason to suppose they have existed there in the past, the 

 question of the Australian origin of the Neotropical members of these 

 orders need not be further discussed. But seeing that both 

 Amblypygous and Uropygous Pedipalps extend in Polynesia as far as 

 Samoa, it may be deemed possible that they passed into South 

 America by a land connection in more northern latitudes. No justi- 

 fication for this hypothesis, however, is supplied by the existing fauna. 



With regard to the scorpions, the question of a trans-Pacific 

 migration bears a different aspect. As already stated, the Australian 

 genus Ccrcoplwnius belongs to the typically South American family 

 Bothriuridae (Telegonidae). Hence Australia may have supplied South 

 America with this portion of its fauna. But, ceteris paribus, the 

 migration may equally well have taken place the other way, that is to 

 say, from South America to Australia, and this view of the matter is 

 supported by the richness of the Neotropical and the poverty of the 

 Australian fauna in genera and species of this family. If this supposition 

 be correct, and if the assumption already made, that the ancestors of the 

 Neotropical Bothriuridae did not enter South America before the end 

 of the Miocene be also correct, there must have been a land connection 

 between the two countries, probably in Pliocene times. It seems 

 evident, however, that New Zealand formed no part of this trans- 

 oceanic continent. 



Turning now to Africa, it is clear that since the Thelyphonidae do 

 not exist in that country, the Neotropical genera of the group cannot 

 have come from there. The Neotropical Solifugae, too, are in no way 

 closely related to the Ethiopian members of this Order, but to those of 

 the Mediterranean region, and no special relationship is traceable between 

 the African Amblypygous Pedipalpi of the family Tarantulidae and the 

 Neotropical Admetidae. The scorpions, too, of the two regions are, on 

 the whole, very distinct. There is, however, one genus of scorpions, 

 Opisthacanthus, which at the present time is found only in tropical Africa, 

 Madagascar, and South America, and one genus, Damon, of the family 

 Tarantulidae, which occurs only in East Africa and South America. 



The occurrence of the genus Opisthacanthus in Madagascar as 

 well as in South Africa, indicates that it entered Madagascar before the 



