434 OBIGIN OF LIFE IN AMERICA 



insects from the antarctic regions, Dr. Enderlein comes to 

 the conclusion that the existing features of distribution are 

 best explained by means of Dr. Simroth's pendulation theory. 

 That theory is founded on the supposed pendulation or shifting 

 of the poles in the course of time. As the South Pole gradu- 

 ally travelled northward, the present antarctic regions would 

 have slowly moved into more favourable climatic regions, and 

 have thus become habitable for such temperate animals and 

 plants as were able to reach them. When the Pole once more 

 moved back towards its present position, the antarctic fauna 

 and flora would again have endeavoured to regain suitable 

 climatic regions by any other land connections then available. 

 In this manner it is perfectly conceivable how, by a combina- 

 tion of serviceable land connections and a shifting Pole, the 

 present geographical distribution of the animals and plants 

 alluded to could have been brought about. We need not 

 imagine the former existence of a huge continent from which 

 long peninsulae projected, simultaneously joining all the 

 southern continents with one another. More slender land 

 bridges uniting one continent after another during succes- 

 sive geological ages with an antarctic land-mass would be 

 sufficient. Dr. Enderlein supposes that probably towards the 

 end of Cretaceous or in Eocene times the antarctic " Heard- 

 Marion," area was connected by land with Madagascar and 

 indirectly with South Africa. Tierra del Fuego extended 

 beyond the Falkland islands, South Georgia, South Orkneys 

 and Shetlands to Antarctica about the same time, and also, 

 perhaps during the Oligocene and Miocene Periods. Australia 

 was joined to the same area in Oligocene or Miocene times. 

 Dr. Enderlein,* on the other hand, believes New Zealand to 

 have been completely isolated from all other regions since the 

 Eocene Period. 



The theory appears simple and plausible, and if it should be 

 proved that the Poles shift their position to the extent assumed 

 by Professor Simroth, it would explain the causes of some of 

 the great movements of animal life in a satisfactory manner. 

 Nevertheless, we cannot, as Dr. Enderlein acknowledges, dis- 



* Enderlein, Gunther, " Biologische Bedeutung der Antarktis," 

 pp. 333350. 



