34 AUSTRALASIA. 



Darwin to occupy a zone of subsidence, are on the contrary now known to belong- 

 to an area of upheaval 



Oceanic Flora. 



An oceanic basin covering over half of the planetary surface from Behring 

 Strait to the Antarctic regions must naturally present every gradation of climate, 

 and consequently also a great diversity of animal and vegetable life. In the 

 neighbovirhood of the continents the oceanic islands partake more or less of the 

 adjacent floras and faunas. Nevertheless the Eastern Archipelago is the only 

 insiJar group which can be regarded as forming part of the Old World from the 

 standpoint of its natural histor}'. The Indian flora, scarcely arrested by the inter- 

 vening shallow waters, continued to advance from island to island towards the 

 south-east. In this insular region it has even developed a marvellous wealth of 

 forms, rivalled only in some few privileged districts of the neighbouring main- 

 land. 



Thanks to the periodical return of the monsoons, the currents and counter- 

 currents, the Indian flora has also spread to the clusters of small equatorial groups, 

 some of which contain an extremely limited number of endemic plants. On the 

 surprising resemblance presented by the native vegetation of remote islands 

 certain naturalists base a strong argument in favour of a former vast expansion 

 of oceanic lands, which are at present broken into a thousand scattered fragments. 



But while widely separated lands offer a great analogy in their plant life, 

 others again lying in close proximit}^ often present the most startling contrasts. 

 Thus Madagascar possesses an independent flora, and in this respect is by no means 

 an African island, as might be supposed from its geographical position. More 

 than half of the local species hitherto discovered are absolutely indigenous. The 

 volcanic Mascarenhas group also possess such a large number of peculiar forms, 

 that these islands may be regarded as so many distinct botanical stations. 



In the Pacific Ocean the Hawaiian Archipelago also constitutes a separate 

 vegetable zone ; of all tropical insular groups it possesses the relatively largest 

 number of endemic plants In the Galapagos group also more than half of the 

 species are of local origin. Although this archipelago lies near the American 

 mainland, and is exposed to the direct influence of the equatorial current setting 

 from the coast of Ecuador, each of its six islands to some extent even constitutes a 

 special centre. Thickets of plants belonging to a single genus and growing on 

 analogous soils are nevertheless formed of different species in the different 

 members of this remarkable group. 



The flora of the Australian continent is one of the most characteristic on the 

 globe, although its northern and noi'th -western shores approach close to the islands 

 forming part of the Indian vegetable zone. The conlrast is very marked between 

 York peninsula in north Australia and the south coast of New Guinea, yet the 

 shallow intervening strait is studded with islands, by which j)lants might with 

 apparent ease have migrated to and fro. Nor is Australia altogether destitute of 

 species of Indian origin, for in the forests of the north-western regions no less 



