94 AUSTEALASIA. 



square miles, with a collective pojjulation estimated at three hundred thousand. 

 On the other hand, the islands of the east coast, resting on the common Indo- 

 nesian submarine plateau, are for the most part distinct from Sumatra, and 

 require to be studied apart. The low-lying alluvial lands separated by shallow 

 channels from the scarcely emerged plains which have been created by the 

 Sumatran rivers, are certainly natural dependencies of the great island. Such 

 are Rupat, Bengkalis, Padang, Rangsang, Rantau, and others lying about the 

 mouths of the rivers. But those situated farther seaward, and of a hilly and even 

 mountainous character, are of different origin, belonging physically to the Malay 

 Peninsula. Like that region, they are of granitic structure, with surrounding 

 latérite beds. Moreover they lie exactly in a line with the main axis of the 

 peninsula, of which they constitute a southern extension now broken into frag- 

 ments by marine erosions. 



But while the sea destroys in one direction, the rivers reconstruct in another. 

 They carry in solution the débris of the Sumatran highlands, depositing the 

 sediment to the right and left in beds steadily advancing seawards, and thus 

 graduall}^ enlarging the great island towards the east. Unless the marine 

 currents undo this work and keep the straits open by their scouring action, these 

 must at last be silted up, and then the eastern archipelagoes of Piouw and 

 Lingga, with Bangka and its satellites, will become attached to the Sumatran coast, 

 lost as its were, like erratic boulders, amid the sands and clays of recent formation. 



Flora and Fauna of Sumatra. 



Like the rest of Indonesia, Sumatra lies within the zone of alternating mon- 

 soons, the south-eastern or regidar trade wind from May to September, and the north- 

 western, bringing most of the moisture, and prevailing from November to March. 



The Suniitran flora and fauna are distinguished from those of the adjacent 

 lands by a large number of curious species. Such are the great rafflesiœ, the 

 gigantic arum {amorphophalhis titœrmm^, growing to a height of over 16 feet ; 

 and those astonishing fig-trees, whose branches bury themselves in the ground, 

 and then throw off their fruit, like so many small mushrooms. The character of 

 the flora changes gradually southward. Thus, while the Merkus pine prevails in 

 certain highland districts north of the Equator, no conifers at all are met farther 

 south. Nevertheless, certain contrasts between Sumatran and Javanese floras on 

 either side of the Sunda Straits are still striking enough to have attracted the 

 attention of botanists. Characteristic of Sumatra, as compared with Java, is the 

 great relative extent of the tracts overgrown with akuxj and gluga, grasses over 

 three feet high, which stifle the young arboreal growths, and exhaust the soil 

 wherever they become predominant. In Java they are arrested at about 3,000 feet, 

 but in Sumatra they descend to within 800 feet of sea-level, and during the 

 historic period their range has been much increased by careless husbandry. 



Of all the Indonesian lands, this island abounds most in graminiferous species 

 possessing great economic value. Here flourishes the majestic dryabahoiops 



