60 ANTARCTIC EARTHWORMS. [CH. I 



Australian. Perichwta, Megascolex (P), Crypbodrilus, 

 Megascolides, Lichogaster, Microscolex (C), Acantho- 

 drilus, Octochcetus, Deinodrilus (A). 

 The above list shows how well marked the regions 

 are ; but it loses half its significance without further 

 explanation. New Zealand is really very different from 

 Australia; it has practically only Acanthodrilidse ; con- 

 fined to it are the genera Octochcetus, Plagiochceta and 

 Deinodrilus, and out of the eleven species of Acanthodrilus 

 found in the region eight are New Zealand and only three 

 Australian; Microscolex only just gets into Australia, 

 which is characterised by its Perichsetidae (feebly repre- 

 sented in New Zealand), and by the genera Cryptodrilus 

 and Megascolides. The Neotropical region is really 

 divisible into two ; the southern half including the greater 

 part of the Argentine and Chili has only Acanthodrilus 

 and Microscolex, while the Geoscolicidse are confined 

 to the tropical regions. There is thus the closest 

 resemblance between South America and New Zealand 

 which is accentuated by the fact that in intervening 

 localities — South Georgia, the Falklands, Marion and 

 Kerguelen islands — only Acanthodrilus exists. These 

 evidences in favour of an antarctic continent are referred 

 to again later. The tropical regions of Africa and America 

 agree in the presence of the Geoscolicidse which only just 

 reach Europe and the Oriental region ; moreover the 

 African genera fall into a natural sub-family distinct from 

 that which contains the American forms. This fact again 

 has its counterpart in the Edentata among Mammals and 

 in some other groups. 



