DERIVATION OF THE FLORA AND FAUNA 275 



flora, spread from pole to pole before any temperate zones had become sharply 

 delimited and when the distribution of land and sea was quite different from what 

 it is now. With the appearance of distinct climatic belts a sorting out of meso- 

 and microthermic groups followed, and these belts, both north and south, started 

 to produce their own particular new groups which dispersed toward the equatorial 

 zone and eventually met and passed it where mountain ranges offered a passage. 

 This is in agreement with Florin's opinion (pj) that the temperate floras, angio- 

 sperms as well as gymnosperms, developed independently throughout the Tertiary 

 period in the north and south hemispheres. The march of Antarcto-tertiary types 

 north corresponds to the march of Arcto-tertiary types south. 



Recently Antarctica and the far south in general as the birthplace of the world's 

 floras has found an eloquent advocate in Ll^ON Croizat (yi), who throws all other 

 speculative authors in the shade. His ideas were criticised by Sparre (2j6), but, 

 as Juan Fernandez is regarded by Croizat as "one of the most interesting domains 

 of general phytogeography", I cannot pass him in silence. 



The original southern plant world, Croizat says, spread over the globe in 

 a way not to be deducted from the present map; we have to go back to the map as 

 it looked during the Cretaceous, but he does not tell which of the constructions 

 he prefers, only that he dismisses Wegener's theories; that everybody who devotes 

 himself to the study of plant migrations should pay attention not only to the present 

 configuration of the continents goes without saying. His own ideas of Cretaceous 

 geography in the south are expressed on p. 252: 



It is most probable, sure we would venture to say, that an ancient shore connected 

 every land in the deep south of our maps, not only, but that the lands, now vanished, 

 but once extant between the approach of Kerguelen Islands and Magellania are the ultimate 

 hub of angiospermous dispersal. 



Here extends the Patagonian-Mascarene baseline with its two triangles, Natal-Ker- 

 guelen-Tristan da Cunha (the Afro-antarctic triangle) and Ceylon-Madagascar- 

 Mascarenes, the "hub" spoken of above. Croizat points at South Georgia as a 

 proof of the existence of an old Antarctic flora: 



The theory that a nebulous 'Glacial Epoch' killed off very nearly all the ancient 

 vegetation of the antarctic islands is shown to be false by the comparatively large plant- 

 world still endemic in South Georgia, indeed a sizeable flora if we consider that it thrives 

 in what is now hardly better than a glaciated mountain straight out of the ocean (p. 255). 



Now, Croizat otherwise deals with the phanerogams only; there is not a single 

 endemic species in South Georgia, but there are many endemic bryophytes and 

 lichens. And he forgets to mention that the "nebulous" glacial epoch has left its 

 very distinct marks there, because we know that the lowland was ice-covered where 

 the phanerogams now form closed communities and that it is very improbable that 

 the higher flora survived. It is surprising that, in this connection, he does not men- 

 tion Kerguelen where endemic genera such as Pringlea and Lyallia surely survived. 

 A second baseline indicates the extension of an Antarcto-Gondwana in the 

 S. Indian Ocean, a third lies along 60° S. and runs from south and east of Chatham 

 Is. to contact S. America. From these centres the angiosperms started to disperse 



