president's address. 831 



decides in favour of a former land connection Ijetween South- 

 eastern Australia and South America, through what is now 

 Tasmania, and thus adds his support to a theor}^, the objections 

 to which are continually losing weight. 



In my Address last year I pointed to the necessity of this 

 connection in former times in order to account for the affinities 

 of a portion of the floras of Australia, New Zealand and South 

 America, and the occurrence in a fossil state in South America of 

 marsupials allied to our own. The chief objections are — first, 

 that an ocean of considerable depth lies between these countries, 

 the bottom of which, it is therefore supposed, could never have 

 been above the surface. As a matter of fact, even if Wallace's 

 1000 fathom limit of possible elevation or depression could be 

 acknowledged, it is to be remarked that not enough soundings 

 have been taken in the higher latitudes to prove the non-existence 

 of submerged plateaux. The lowest continuous line of soundings 

 seems to have been made by the officers of the Challenger; it lies 

 near latitude 50\ and there is to the south of that parallel 

 plenty of room for extensive plateaux to show themselves 

 or even quite shallow depths when soundings are taken. The 

 other objection, that the temperature and climate would have 

 been too severe, can scarcely have weight. In the early and 

 middle Tertiary mild temperatures existed in the northern hemi- 

 sphere up to latitude 79° in Spitzbergen, and 81|° in Grinell 

 Land, and there is no reason why, at the same epochs, if the 

 disposition of the land was suitable, there should not have been 

 temperatures favourable to life in the corresponding latitudes 

 near the south pole. Fossil remains from the Straits of Magellan 

 indicate tropical conditions. During the Pliocene, temperature 

 generalh^ became lowei-ed, and the vegetation of the temperate 

 zone had Ijegun to retreat from the North Pole ; but even if the 

 same process took place at the South Pole, there might still be 

 abundant warmth between, say, 55° and 70°, to permit of the 

 existence of a luxuriant vegetation and fauna. 



