PACIFIC CONTINENT 427 



New Zealand with Chile, which, as he maintains, ceased to 

 exist at the close of the Eocene Period. 



Certain geological features no doubt point to a former west- 

 ward extension of Chile. Dr. Burckhardt * showed that in 

 western Chile there are enormously thick deposits of porphy- 

 ritic conglomerates which become more attenuated and com- 

 posed of lighter sandy material as we proceed eastward. 

 Hence he argues that these deposits were laid down on an 

 ancient shore-line of a vast western land-mass of which the 

 existing coast cordillera of Chile is the last remnant. He 

 advocates, in fact, nothing short of what we might call a 

 Pacific Continent which lay mainly to the westward of Chile. 

 That land formerly extended in that direction I have en- 

 deavoured to demonstrate from purely faunistic evidence, but 

 I believe that it was part of a great circum-Pacific belt of 

 land which stretched mainly northward, communicating from 

 time to time with Central America and the Antilles, and also 

 with Mexico and western California, and then eventually bend- 

 ing across to eastern Asia in a great loop and thus joining 

 New Guinea, Australia and New Zealand. That Central 

 America ,and western North America must have been thus 

 connected by land with the Australian region has been urged 

 above on several occasions when dealing with the North 

 American fauna. It might be argued that if such a northern 

 land connection once existed, uniting Chile with the Austra- 

 lian region, there would no longer be any necessity for postu- 

 lating an antarctic land bridge. Professor Dahl has recently 

 taken ,up this attitude,; illustrating his adverse criticism against 

 the antarctic theory by means of the distribution of spiders. 

 He does not adopt, of course, my view of a northern semi- 

 circular land belt because this theory has never before been 

 published and is entirely my own. His contention is that the 

 continents and oceans have remained within the lifetime of 

 the present fauna what they are now, that is to say, within 

 the more recent geological periods, except that the great land- 

 masses were joined in the north. A powerful centre of dispersal 

 existed in the arctic regions, according to Professor Dahl.f 



* Burckhardt, 0., " Traces d'un ancien continent," pp. 186 190. 

 t Dahl, F., " Die Yerbreitung der Spinnen." 



