of Ancient Antarctic Life. 119 



prolongation of Tasmania in the direction of R^yal Company 

 Island is suggested by the Tasmanian axes described * by 

 Prof. David. 



The evidence collected tends to show Antarctica as an 

 unstable area, at one time dissolving into an archipelago, at 

 another resolving itself into a continent. 



How this would affect the marine shallow-water fauna has 

 not been previously considered. Under tlie circumstances I 

 have described, the South Pacific would stretch within a few 

 degrees of the Pole into a deep bight or gulf extending from 

 Tasmania to Cape Horn. Into the western extremity would 

 open the long and narrow tongue of what is now the Tasman 

 Sea. When the climate cooled, the fauna at the head of this 

 Antarctic Gulf, as I propose to call it, would be driven north- 

 wards to milder zones. By diverging meridians a similar 

 fauna would reach New Zealand, New South Wales, and 

 Chili f. In a precisely similar manner Darwin | has shown 

 how the northern Glacial period drove the same Polar fl)ra 

 by radiating paths to the Alps, Himalayas, and AUeghanies, 

 where they now survive stranded on mountain-tops. 



If, when this northward migration occurred, continuous land 

 had reached from Australia to Cliili, then none of the fauna 

 of the Antarctic Gulf could have entered either the Indian or 

 the South Atlantic Oceans. We have, however, no warrant 

 for believing that the Antarctic bridge long endured as con- 

 tinuous and contemporaneous land ; and that it was pierced 

 by channels is proved by the escape of stray members of that 

 characteristically Antarctic genus Struthiolaria to Patagonian 

 coasts {S. ornata, Sowerby §), on the one hand, and to Ker- 

 guelen {S. mirabilis, Smith) [1 on the other. 



The destruction ^ which the ancient fauna of the Antarctic 

 Gulf has endured, and the length of time which has elapsed 

 since its expulsion, deprives us of much hope of reconstructing 

 it. Since that event, for instance, the genus Haliotis has 

 probably altogether grown up as a characteristic feature of 



* Presidential Addresses, Proc. Linn. Soc. N. S. W. (2) viii. p. 60;3, 

 and vol. x. p. 155. 



t Cf. " The Occurrence of Concholepas, recent only in South America, 

 as a Fossil in Australia," Proc. Roy. Soc. N. S. W. 1893, p. 171, 



I ' Origin of Species,' Chap. xi. 



§ Darwin, Geol. Obs. S. America, pp. 376, 018, pi. iv. fig. 62. 



II Trans. Roy. Soc. vol. clxviii. p. 170, pi. ix. tig. 3. 



^ " We seem [in the Pliocene] to be dealing with the remains of an 

 earlier fauna disappearing rapidly before the conquering host of the 

 recent fauna which had invaded New Zealand some time previously." 

 (Button, Macleay Memorial Vol. p. 36.) 



