ix] GEOGRAPHICAL DISTRIBUTION 131 



geology that it was only at a very recent date that 

 England was cut off from union with the continent. 

 Thus an identity of fauna was to be expected. On 

 the other hand we are confronted with a very great 

 difference between the earthworms of eastern tropical 

 Africa and of the adjacent island of Madagascar. 

 In the latter we have as a prevalent form the genus 

 Kynotus ; in the former continent many Geoscolecidae 

 but no Kynotus. It is believed that the separation 

 of Madagascar from the mainland was at an earlier 

 date than that of Great Britain from Europe. We 

 must however be cautious before slipping into what 

 might seem a case of arguing in a circle. It will 

 however probably not be disputed that Madagascar 

 was severed earlier than England. 



We will now attempt to map out the world into 

 a series of regions characterised by their earthworm 

 inhabitants and see how far these regions agree with 

 those rendered necessary by the distribution of some 

 other animals. 



We can to begin with accept the Palaearctic 

 region. The region however will be a little different 

 from that usually accepted. For we must probably 

 exclude Japan, whose earthworm fauna contains the 

 characteristically Eastern genus Pheretima. Other- 

 wise we have a region characterised by the family 

 Lumbricidae, which is really limited to it, and by just 

 a few traces of other genera such as Hormogaster 



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