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 accompanying 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, comparatively 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 members 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 really noticeable break in distribution comes with the Aru Is., for while the Tenimber group (Timor Laut, etc.) are decidedly Malay, and the Ké 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. [Illustration: FIG. 207.--_Ariophanta Rumphii_ v. d. B., Java.] The Malay peninsula is practically another island of somewhat 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 with Siam. Points of connexion between Ceylon and Sumatra, and Ceylon and Borneo, have already (p. 304) been brought out. [Illustration: Map to illustrate the GEOGRAPHICAL DISTRIBUTION of the Land Mollusca of the EAST INDIAN ARCHIPELAGO _The red line marks the 100 fathom line_ London: Macmillan & Co. _London Stanford’s Geog^l. Estab^t_.] It seems not impossible, from the point of view of the land Mollusca only, that the Sunda Islands may at one time have stretched much farther into the Bay of Bengal, prolonged, perhaps, into what are now the Andaman and Nicobar groups, while Ceylon and the western side of the Deccan, united into one continuous piece of land, and possibly separated from N. India by a wide stretch of sea, extended farther eastward in a long island, or series of islands.