[[p. 308]] [We have great pleasure in assisting to give publicity to the following letter, which has been addressed by Mr. A. R. Wallace to The Reader--and we trust that there will be no difficulty in raising the small sum necessary to enable the important object of which it treats to be carried out.]

5, Westbourne Grove Terrace, W.

    I ask permission to lay before your readers a few facts and suggestions on the above subject. Some weeks since I was informed by an old acquaintance, Mr. Robert Coulson, a mining engineer who has explored a good deal of North-Western Borneo, that he had found a quantity of bones in a cave in that country; and, having read, during his stay in London, Sir Charles Lyell's "Antiquity of Man," he thought the fact might be of some interest. On inquiring particulars, I found that the cave in question was situated in the district between Sarawak and Bruni, on a mountain some distance inland. Mr. Coulson had been searching for tin and other ores, which were reported to exist in these caves, and in this particular one he found the floor covered with a kind of fossil guano, very hard, and about two feet thick. He had some of this broken up with picks, and found it to contain abundance of bones, especially at the bottom, next the rocky floor of the cave. He assured me there were great numbers of bones of many sorts, and numbers of teeth of all sizes. The guano was so hard that they did not break up much of it. There were also some human skulls lying on the surface, about which the natives who accompanied him could tell him nothing.

    The presence of this layer of solid guano in a cave is not easy to account for. If it is the accumulated dung of the small bats, and perhaps a few swifts or goatsuckers that may now frequent the caves, it would indicate a long period of time. There are now no animals in Borneo that would be likely to frequent caves, the only moderately large carnivora, the Malay bear and the tiger-cats (Felis macrocelis and F. javensis), being arboreal animals. The mere fact, therefore, of large quantities of bones found in a cave with the accumulated dung in which they are buried, indicates a state of things which has [[p. 309]] now passed away; and the examination of those bones might throw light upon the changes which have resulted in the peculiar zoological character which the productions of the island present.

    It may, perhaps, be advisable, in connexion with this subject, briefly to point out the chief characteristics of the fauna of Borneo, the anomalies which it presents, and which a knowledge of its most recent changes may assist us in explaining; as well as the promise it holds out of richly rewarding the researches of palæontologists. The natural productions of Borneo resemble on the whole so closely those of the other Indo-Malayan countries (Java, Sumatra, and the Malay Peninsula), that there can be little doubt of there having been a geologically recent connexion between them all. Of about seventy mammals known to inhabit Borneo, only ten are peculiar to it, the remaining sixty occurring, with but slight differential characters or none, in one or other of the adjacent islands. In birds and insects about the same proportion are really distinct, though there are many more which offer slight but constant peculiarities, and have, therefore, received distinct specific names. Notwithstanding, however, this great and very general similarity, there are in Borneo certain peculiarities and certain deficiencies which give it a marked character. Several genera are peculiar to it, as Nasalis, Dendrogale and Ptilocercus, and that singular bird Pityriasis. The tiger, which abounds on all the other islands and in the peninsula of Malacca, is absent, and yet several of the large herbivora, which, being free from the attacks of such a ferocious beast, one would expect to find in greater abundance, are very local and scarce, and apparently dying out. The elephant and rhinoceros, which in Sumatra and the Malay Peninsula exist in company with the tiger, are so local and scarce in Borneo that their very existence has been for some time doubtful, and even the tapir is by no means so plentiful as in the places mentioned above. The wild ox, also (Bos sondaicus), only exists in the north-east extremity of the island.

    The most striking feature of Borneo is, however, undoubtedly the presence and comparative abundance of the great anthropoid ape, Simia satyrus, as well as a second species, Simia morio, Owen. One or both of these is met with over the whole extent of Borneo, whereas, though there can be no doubt that the former occurs also in Sumatra, it seems confined to a limited district, and in the whole southern half of the island is entirely unknown. Another important consideration is, that the Malayan region (of [[p. 310]] which Borneo forms an important section), though of limited extent, has a highly characteristic and peculiar fauna. It possesses many genera entirely restricted to it, and many families which attain their greatest development in it, and also presents us with some of the most singular and interesting forms in the animal kingdom.

    From the foregoing facts the following conclusions are, I think, rendered very probable:--(1st) A great geological antiquity for the Malayan region as a whole; (2nd) a considerable antiquity for that portion of it which now forms the island of Borneo; and (3rd) great and varied changes in physical geography, and great concomitant changes in animal life, which have resulted in the present condition of that island's fauna;--and we may, I think, be certain, that the remains of the animals which inhabited Borneo at a comparatively recent period will be of great interest, and may serve to indicate the nature of the changes that have been recently, and are probably still, going on.

    Quite independently, however, of the fact that bones are known to exist in a particular cave in Borneo, it appears to me that that island offers a field for exploration unequalled perhaps in the globe. Limestone caverns abound in it. There are several very extensive ones in the Sarawak territory itself, and Mr. St. John mentions others in the Bruni country. The character of the existing fauna, as well as the extent of the land and the height of the mountains, all prove it to be of some geological antiquity. Now, in every other country which has been explored, the animals which have recently become extinct are always allied to those now living in the same region, and are often of gigantic size or remarkable forms. Europe gives us elks, bears, and hyenas, Australia extinct kangaroos and wombats, South America giant sloths and armadillos; according to all analogy, therefore, we may expect that the caves of Borneo would reward a persevering explorer, not only with fossil tapirs, Malay bears, and scaly ant-eaters, but also with the precursors of the extraordinary lemuroid forms now inhabiting the country--Galeopithecus, Nycticebus, and Tarsius--and with fossil proboscis-monkeys, gibbons, and orangs, more or less resembling those which now abound in its vast and luxuriant forests. It is not improbable that some human remains may also be found to throw light upon the question of the origin of the Malayan races, and to prove whether a Negrito or some still lower race was formerly spread over the whole archipelago.

    [[p. 311]] Should the naturalists of this country be willing to make an effort to carry out this most promising work, I can inform them that Mr. Coulson, who is now on his way to Singapore, is willing to undertake it, if he receives instructions within the next month or two, after which time he will probably have other engagements. The necessary expenses of going to such a remote part of the country would be rather heavy, as he must engage a native boat and crew, as well as labourers, at Sarawak; but I estimate that £150 would cover expenses and his remuneration for getting a good sample of the contents of the cave he described to me; and, if an additional £100 could be raised, he would be able, while in the country, to explore several other caves and ascertain whether any of them contain remains of greater antiquity and higher interest. It is needless to observe that to carry out a thorough examination of all the caves or recent deposits in the country (which would be necessary to reap the full benefits of any exploration) would require a much larger sum than I have mentioned.

Alfred R. Wallace