308 MALACCA — SUMATRA chap. 



This want of individuality in the land Mollusca of the Malay 

 islands is accounted for by a consideration of the sea depths 

 which separate them from the Asiatic mainland. The accom- 

 panj^ing map, the red line on which is intended to show what 

 would be the result of an elevation of the sea bottom for no 

 greater amount than 100 fathoms, exhibits clearly the fact that 

 these islands are practically a part of Asia, a large stretch of 

 very shallow sea extending between Siam and the greater part 

 of the north-west coast of Borneo. 



In all probability the three great islands of Sumatra, Java, 

 and Borneo were united with the mainland of Asia, and 

 with one another, at a period, geologically speaking, com- 

 paratively recent. This follows from the general uniformity of 

 their land Mollusca, both as regards one another and as regards 



the mainland. Nor do the smaller mem- 

 bers of the island series — Bali, Lombok, 

 Sumbawa, Flores,Timor, and Timor Laut 

 — show any marked individuality in the 

 possession of peculiar genera. Wallace's 

 line is absolutely non-existent, so far as 

 the land Mollusca are concerned. The 

 Yv3r.20i. — Ariophanta Rum- really noticeable break in distribution 

 p II y. . .,.a^a. comes with the Aru Is., for while the 



Tenimber group (Timor Laut, etc.) are decidedly Malay, and the 

 Ke Is., in the poverty of our information, uncertain, the Aru Is. 

 are as Papuan as New Guinea itself. The profound depths of 

 the Banda Sea to the north, and the Timor Sea to the south, 

 appear to have kept the islands from Flores to Timor Laut 

 free from the intrusion of any Moluccan or any considerable 

 Australian element. The Moluccas, as has been already 

 remarked, besides possessing considerable peculiarities of their 

 own, unite a mixture of the Malay and Papuan elements, and 

 serve as a sort of debatable ground for the meeting of the two. 



The Malay peninsula is practically another island of some- 

 what the same shape and general trend as Sumatra, and about 

 one-half the size. Its general relations — and the remark applies 

 to the great Sunda Islands as well — appear to be rather more 

 with Burmah, Tenasserim, and even the Cingalese district, than 

 wdth Siam. Points of connexion between Ceylon and Sumatra, 

 and Ceylon and Borneo, have already (p. 304) been brought out. 



