170 . MICKOSCOLEX. [CH. Ill 



from America is identical with any New Zealand form; 

 but they are all closely related. This however does not 

 exhaust the antarctic region. During the voyage of the 

 " Challenger " and the transit of Venus expedition a few 

 earthworms were collected at Kerguelen and at Marion 

 Island. These amounted to only a single species, which 

 is common to both islands, and is a member of the genus 

 Acanthodrilus. The same genus also occurs in South 

 Africa ; but Africa so far as concerns the family Acantho- 

 drilidce chiefly abounds in the genus Benhamia,. which 

 differs in a few small though constant points from 

 Acanthodrilus. The genus Benhamia in the opinion of 

 Dr Michaelsen, is really limited to Africa. Species have 

 been described from America, the West Indies, and from 

 India and Malaya; but it is possible, as Dr Michaelsen 

 thinks, that, they have .been imported by man. The 

 family Acanthodrilidce indeed is almost exclusively ant- 

 arctic, and in any case by far the majority of its species 

 and genera are limited to the antarctic area. Microscolex 

 passes into North America, has been met with in Europe 

 and the Azores and Canaries, and also occurs in Australia. 

 But with the exception of America all the species found 

 outside the antarctic area are identical with species living 

 within it 1 ; this suggests importation from abroad. This 

 series of facts is a very remarkable one, and deserves more 

 consideration than has been devoted to it in forming any 

 theory about a possible former antarctic continent of greater 

 dimensions than the present shrunken land mass. The 

 facts seem also to point to a more recent communication 

 i Excepting M. poultani from Teneriffe and M. algeriensis from Algeria. 



