WCP4871

[1]

9 St. Mark’s Crescent, N.W.

March 19th. ¹

Dear Sir Charles

I send you herewith a paper on the "Birds of Timor[,] Flores and Lombock [Lombok]"², — the introduction to which will I think answer some of your questions³ and explain some of your difficulties. A. Murray⁴ has made a similar objection as to Darwin’s⁵ theory of Oceanic Island⁶ but he quite misunderstands the questions. (Geog[raphical]. Dist[ribution]. of Mammalia [sic] p. 17. 18. 19.)⁷ I quite agree with Darwin & Hooker⁸ on this point, and I think the case of the Timorese group of islands an admirable illustration of their views. I am pretty sure there is much more similarity of the plants to Javaneese[sic] species, than the animals. The Plants of Timor are tolerably known & I believe show a good proportion of species identical with Java.

[2] There remains only a Sorex and the very rare Felis megalotis, — the only difficulty, (found in Timor only.) When we consider there are over 50 species of land mammals in Java this is not allowing much for introduction by what Murray contemptuously calls "flotsam & jetsam"⁹.

The absence of a fair proportion of the land mammals of an adjacent country is I think an almost absolute proof of there having been no land connection.

For this reason I consider it certain that Madagascar has never been united with Africa since the Miocene period, and the same with the Philippines.

I make no doubt that in a few centuries or thousands of years, the cockatoos of Lombock may establish themselves in Baly [Bali] and thence push on into Java [3] [p. 2] and then in time spread on & on, if favourable changes in organic & physical conditions occur, till they overrun Java[,] Sumatra[,] Malacca [Melaka] & spread into India. And in the same period no doubt many of the birds of Java will spread over the islands to Timor, as some have already done. But Mammals will always spread much more slowly, because they only pass by water, & between Baly & Lombock & ⁱⁿ all the others straits to the Indian Ocean, there are tremendous currents which render crossing very difficult.

I gave 100 fathoms in round numbers as the outside, but 50 fathoms will unite Java to Borneo and to Baly.¹⁰

The depth of the Straits of Lombock [4] carried a hundred times before they effect a permanent settlement in a new country.

The insects as far as known in Lombock & Timor agree with the birds but present perhaps rather less decided affinities with Australia & more with the Moluccas or Java. I think rather a larger proportion of the species have become modified into new and very distinct forms.

The two largest mammals of Lombock the Macacus Cynomolgus and the wild pig, as well as the Moluccan deer found in Timor, may all have been introduced by man. The Parodoxuru<s> musanga is also often domesticated and might have been introduced. [5] The mammalia [sic] are, as they ought to be, very few, only some half dozen terrestrial species and several of these plainly derivative. The insects are too little known to draw any conclusions from. The birds are sufficiently numerous and sufficiently well known, and I think they prove a great deal.

I feel certain, that the islands from Lombock to Timor have a wholly derivative fauna & flora, — that Timor is the oldest portion and was peopled from Australia to which it was once much nearer, but never united, — that Lombock is the most recent, and is geologically very new indeed, as is also Baly. The fusing of their faunas is now going on, but it is a slow process. Very weak flying birds may be carried over wide spaces of sea, but they may be so [6] is unknown, but it is very deep.

I consider the case of Borneo and Celebes [Sulawesi] a much more difficult one than that of Baly & Lombock. The sea is wider but there is a great extent of opposing coasts; the islands must be both much older; — Celebes I believe to bevery old, — yet there is hardly a land bird and very few insects identical, and I believe the plants of Celebes are highly peculiar.

I send also another paper¹¹ which you may like to have by you. I shall be happy answer any further questions on the subject.

Believe me |Yours very faithfully | Alfred R. Wallace [signature]

Sir C[harles]. Lyell.¹²

This would show that pre-occupancy has great effect.