358 POLAR PROBLEMS 



On the last point, however, Wood* has since reached the opposite con- 

 clusion. 



During the last few years several Australians have attacked the 

 question of earlier distribution, with rather full discussion of the 

 literature. Jones^ and Anderson^ support in general the hypothesis 

 of immigration from paleo-Arctic centers, without actually denying 

 the possibility of effective Antarctic land connections. Harrison,^ 

 on the other hand, flatly espouses the cause of a southern route for the 

 pre-Tertiary constituents of the flora and fauna. In building his 

 bridges, however, this author postulates an elevation which would 

 come near to draining the permanent ocean basins. He seems to 

 ignore the fact that, one after another, many of the resemblances be- 

 tween varied elements of the South American and Australasian faunas 

 have proved illusory, and that more and more the testimony is re- 

 duced to groups of animals of whose past history we still know nothing. 

 Indeed, as Anderson holds, the more closely the zoological props of 

 Antarctic land-bridge theories are examined, the weaker they appear, 

 while similarity of floras, by analogy from present conditions, affords 

 but poor evidence. 



The real proof, or at least the data to shift the burden, would be 

 forthcoming only through the discovery of marsupials or other per- 

 tinent material in fossiliferous beds of Antarctica. Here, beyond doubt, 

 lies one of the most fascinating and important opportunities for 

 south polar investigation, as pointed out by the paleontological finds 

 of the Swedish expedition. The mere fact that all or parts of Ant- 

 arctica once enjoyed a mild climate, a diversified rain forest, etc., does 

 not, as Harrison seems to believe, imply the presence of a mammalian 

 fauna; the region may even then have possessed some proportion of 

 its modern geographic isolation, without terrestrial vertebrates other 

 than birds. 



Contrasts Between Arctic and Antarctic Life 



The striking contrasts between conditions in the Arctic and Ant- 

 arctic Regions have been well expressed in many aspects but perhaps 

 never more simply and clearly than by Darwin in his journal of the 

 cruise of the Beagle, where, in a section devoted to the climate and 

 productions of the Antarctic islands, he writes : 



3 H. E. Wood: The Position of the "Sparassodonts," With Notes on the Relationships and 

 History of the Marsupialia, Bull. Amer. Museum of Nat. Hist., Vol. Si, 1924, pp. 77-101. 



* F. W. Jones: The Mammals of South Australia, Part I: The Monotremes and the Carnivorous 

 Marsupials (Handbooks of the Flora and Fauna of South Australia), British Science Guild, South 

 Australian Branch, Adelaide, 1923; reference on pp. 20-28. 



5 Charles Anderson: The Australian Fauna, Journ. and Proc. Royal Soc. of New .South Wales, 

 Vol. 59, 1925, pp. 15-34- 



6 L. Harrison: The Migration Route of the Australian Alarsupial Fauna, Austral. Zoologist 

 (Royal Z06I. Soc. of New South Wales), Vol. 3, Part V, 1923, pp. 247-263. 



