LIXNEAN SOCIETY OF lONDOX. 89 



may be that Australia was then too poor to afford emigrants. 

 Another and more probable explanation is that Antarctica having 

 received a fauna and flora from Arcbiplata was severed fi-om it 

 before joining Australia. Thus a stream of migration would be 

 forced forward and checked backwards. 



The austral fauna and flora appears extending m successive 

 zones from the far south to the tropics. In New Zealand the 

 warmth-loving plants and animals, such as the Kauri pine (a 

 relation of Araucaria) and Placostylus snail, have been thrust to a 

 northern refuge, while diminished temperature has probably exter- 

 minated others. The Araucaria and iguanas, the freshwater fish 

 Osteof/lossum , are examples of tropical austral forms of which a 

 long list could be compiled. 



It is unhkely that the Antarctica that bore this tropical and 

 subtropical assembly reached much more broadly to the tropics 

 than does the present continent. Had it done so, more traces 

 would have been left of such extension in the South Sea Islands on 

 the one side or in South Africa on the other. 



But if the subtropical flora and fauna had in the Tertiary 

 extended unbroken across the pole from Fuegia to Tasmania, what 

 then became of tlie ancestors of the present subantarctic and south 

 alpine life ? Why were not these frigid forms driven from off the 

 face of the earth when the heart of the Antarctic itself enjoyed a 

 genial climate ? 



The discovery by Sir E, Shackleton of a plateau 10,000 feet high 

 near the south pole, suggests a solution of the difficulty. If such 

 a plateau existed ^hen the climate was at its warmest, then the 

 tropical migrants could have found a congenial climate on the 

 coast, while the ancestors of the Kosciusko and Kerguelen plants 

 and animals took refuge on the plateau heights. The inference is 

 that such a plateau did then exist. 



If the land-connection between the Antarctic and Tasmania had 

 broken down during the warmest period of the interglacial phase, 

 it would have isolated the flora and fauna at a time when the cold 

 elements were gathered together on the central plateau heights, 

 while the temperate and subtropical elements possessed the 

 Antarctic periphery. In that case the cold forms would have had 

 no opportunity to escape to the alpine stations of New Zealand or 

 Australia, or to occupy the subantarctic islands. 



The conclusion is therefore drawn that the land link was main- 

 tained during the period of refrigeration, and that from the 

 Antarctic focus first the subtropical, then the temperate, lastly the 

 alpine forms were expelled, each to gain a fresh footing in lower 

 latitudes. 



Possibly associated with the formation of great ice masses, a 

 paroxysm of diastrophic energy ensued. This, which perhaps has 

 not yet subsided, effected the destruction of the antarctic bridge, 

 and to it may be due the recent disarticulation of the Dominion 



