1899] DISTRIBUTION OF THE ARACHNIDA 231 



3. Oriental, including India, Ceylon, Burma, and the countries 



and islands east and south-east of this point as far as 

 " Wallace's line." 



4. Australian, including the Australasian islands east of "Wallace's 



line " and Australia. 



5. Sonoran, including the Southern States of North America south 



of about the 40th parallel and the central plateau of Mexico. 



6. Neotropical, including the rest of Central America, the West 



Indies and South America, nearly as far south as the 50th 

 parallel of latitude. 



Subsequent studies in the same group have not materially affected 

 these conclusions. But the discovery that species of typically Arabian 

 and Persian types extend as far as Gwalior in India will make it 

 necessary to draw the line of demarcation between the Mediterranean 

 and Oriental regions considerably to the east of the Indian frontier. 



The known facts connected with the distribution of the Solifugae 

 and the Pedipalpi agree in the main with those that the scorpions 

 supply. A notable exception is furnished by India, which, while 

 clearly belonging to the Oriental region so far as scorpions and whip- 

 scorpions (Uropygi) are concerned, forms part of the Mediterranean 

 region in the case of the Solifugae, and of the Ethiopian in the case 

 of the Amblypygi. Taking the four groups into consideration, how- 

 ever, the balance of evidence is in favour of classifying it with the 

 Oriental region. On the other hand, the Austro-Malayan Islands, 

 which in the case of the scorpions were referred to the Australian 

 region, belong, in the case of both Amblypygous and Uropygous Pedi- 

 palpi, and also in the case of the Solifugae, if the record of Dinorhax 

 from the Moluccas be correct, to the Oriental region without doubt ; 

 and since, even in the case of the scorpions, these islands are perhaps 

 as much Oriental as Australian, the evidence points to their inclusion 

 in the former region. 



One last word about the Sonoran region. The absence of any 

 barrier between this region and the Neotropical makes its exact 

 southern limit a matter of doubt, on account of the intermixture of 

 the faunas of the two areas. The genera that may be regarded as 

 characteristic of the region are Hadrurus, Vcjovis, Uroctonus, and 

 Anuroctonus amongst the scorpions, and Datames amongst the Solifugae. 

 These forms extend into Mexico, but are absent from the West Indies. 

 But the region also contains species of Uropygous and Amblypygous 

 Pedipalpi, scorpions of the genera Diplocentrus and Centrums, and prob- 

 ably Solifugae of the genus Clcobis. Since, however, these genera extend 

 far into the Neotropical region, and are met with in the West Indies, 

 they must be regarded as Neotropical elements, which have pushed 

 their way to the north since the final union between North and South 

 America took place. 



