DISTRIBUTION OF THE TERRICOLOUS OLIGOCHAETES 



147 



distribution, and the ancient history of soil types as summarized by Wilcke 

 (1955, 1960). 



As I have already mentioned, the validity of the Wegenerian hypothesis can 

 be confirmed only by geophysicists but it seems reasonable for me to under- 

 line the extreme simplicity and completeness with which it resolves certain 

 zoogeographical problems, something which other Oligochaetologists, 

 Michaelsen (1922, 1928) and Cernosvitov (1936), have already done with 

 greater authority. 



<^ 



Fig. 12. Distribution oi AUolobophora longa and A. liinicola. 





But putting aside these purely conjectural solutions, let us return to the 

 first zoogeographical problem: the sameness of north European and North 

 American earthworm faunas. Gates (1929, 1959) thought he had solved the 

 questions by stating that all European species in North America were intro- 

 duced by European settlers during the last two centuries; Lindroth (1957) 

 accepts this point of view without reservations. 



I am very skeptical of this solution and feel obliged to ask : is it possible 

 that a whole continent was almost entirely devoid of earthworms up till 200 

 years ago? Or, is it possible that the European Lumbricidae annihilated the 

 autochton taxa almost everywhere in North America ? 



To the first question the answer is: no. Any pedologist would refuse to 



