The Malay Archipelago, by Alfred Russel Wallace

Chapter 39

The Natural History of the Papuan Islands.

New Guinea, with the islands joined to it by a shallow sea, constitute the Papuan group, characterised by a very close resemblance in their peculiar forms of life. Having already, in my chapters on the Aru Islands and on the Birds of Paradise, given some details of the natural history of this district, I shall here confine myself to a general sketch of its animal productions, and of their relations to those of the rest of the world.

New Guinea is perhaps the largest island on the globe, being a little larger than Borneo. It is nearly fourteen hundred miles long, and in the widest part four hundred broad, and seems to be everywhere covered with luxuriant forests. Almost everything that is yet known of its natural productions comes from the north-western peninsula, and a few islands grouped around it. These do not constitute a tenth part of the area of the whole island, and are so cut off from it, that their fauna may well he somewhat different; yet they have produced us (with a very partial exploration) no less than two hundred and fifty species of land birds, almost all unknown elsewhere, and comprising some of the most curious and most beautiful of the feathered tribes. It is needless to say how much interest attaches to the far larger unknown portion of this great island, the greatest terra incognita that still remains for the naturalist to explore, and the only region where altogether new and unimagined forms of life may perhaps be found. There is now, I am happy to say, some chance that this great country will no longer remain absolutely unknown to us. The Dutch Government have granted well-equipped steamer to carry a naturalist (Mr. Rosenberg, already mentioned in this work) and assistants to New Guinea, where they are to spend some years in circumnavigating the island, ascending its large rivers a< far as possible into the interior, and making extensive collections of its natural productions.

The Mammalia of New Guinea and the adjacent islands, yet discovered, are only seventeen in number. Two of these are bats, one is a pig of a peculiar species (Sus papuensis), and the rest are all marsupials. The bats are, no doubt, much more numerous, but there is every reason to believe that whatever new land Mammalia man be discovered will belong to the marsupial order. One of these is a true kangaroo, very similar to some of middle-sized kangaroos of Australia, and it is remarkable as being the first animal of the kind ever seen by Europeans. It inhabits Mysol and the Aru Islands (an allied species being found in New Guinea), and was seen and described by Le Brun in 1714, from living specimens at Batavia. A much more extraordinary creature is the tree-kangaroo, two species of which are known from New Guinea. These animals do not differ very strikingly in form from the terrestrial kangaroos, and appear to be but imperfectly adapted to an arboreal life, as they move rather slowly, and do not seem to have a very secure footing on the limb of a tree. The leaping power of the muscular tail is lost, and powerful claws have been acquired to assist in climbing, but in other respects the animal seems better adapted to walls on terra firma. This imperfect adaptation may be due to the fact of there being no carnivore in New Guinea, and no enemies of any kind from which these animals have to escape by rapid climbing. Four species of Cuscus, and the small flying opossum, also inhabit New Guinea; and there are five other smaller marsupials, one of which is the size of a rat, and takes its place by entering houses and devouring provisions.

The birds of New Guinea offer the greatest possible contrast to the Mammalia, since they are more numerous, more beautiful, and afford more new, curious, and elegant forms than those of any other island on the globe. Besides the Birds of Paradise, which we have already sufficiently considered, it possesses a number of other curious birds, which in the eyes of the ornithologist almost serves to distinguish it as one of the primary divisions of the earth. Among its thirty species of parrots are the Great Pluck Cockatoo, and the little rigid-tailed Nasiterna, the giant and the dwarf of the whole tribe. The bare-headed Dasyptilus is one of the most singular parrots known; while the beautiful little long-tailed Charmosyna, and the great variety of gorgeously-coloured lories, have no parallels elsewhere. Of pigeons it possesses about forty distinct species, among which are the magnificent crowned pigeons, now so well known in our aviaries, and pre-eminent both for size and beauty; the curious Trugon terrestris, which approaches the still more strange Didunculus of Samoa; and a new genus (Henicophaps), discovered by myself, which possesses a very long and powerful bill, quite unlike that of any other pigeon. Among its sixteen kingfishers, it possesses the carious hook-billed Macrorhina, and a red and blue Tanysiptera, the most beautiful of that beautiful genus. Among its perching birds are the fine genus of crow-like starlings, with brilliant plumage (Manucodia); the carious pale-coloured crow (Gymnocorvus senex); the abnormal red and black flycatcher (Peltops blainvillii); the curious little boat-billed flycatchers (Machaerirhynchus); and the elegant blue flycatcher-wrens (Todopsis).

The naturalist will obtain a clearer idea of the variety and interest of the productions of this country, by the statement, that its land birds belong to 108 genera, of which 20 are exclusively characteristic of it; while 35 belong to that limited area which includes the Moluccas and North Australia, and whose species of these genera have been entirely derived from New Guinea. About one-half of the New Guinea genera are found also in Australia, about one-third in India and the Indo–Malay islands.

A very curious fact, not hitherto sufficiently noticed, is the appearance of a pure Malay element in the birds of New Guinea. We find two species of Eupetes, a curious Malayan genus allied to the forked-tail water-chats; two of Alcippe, an Indian and Malay wren-like form; an Arachnothera, quite resembling the spider-catching honeysuckers of Malacca; two species of Gracula, the Mynahs of India; and a curious little black Prionochilus, a saw-billed fruit pecker, undoubtedly allied to the Malayan form, although perhaps a distinct genus. Now not one of these birds, or anything allied to them, occurs in the Moluccas, or (with one exception) in Celebes or Australia; and as they are most of them birds of short flight, it is very difficult to conceive how or when they could have crossed the space of more than a thousand miles, which now separates them from their nearest allies. Such facts point to changes of land and sea on a large scale, and at a rate which, measured by the time required for a change of species, must be termed rapid. By speculating on such changes, we may easily see how partial waves of immigration may have entered New Guinea, and how all trace of their passage may have been obliterated by the subsequent disappearance of the intervening land.

There is nothing that the study of geology teaches us that is more certain or more impressive than the extreme instability of the earth’s surface. Everywhere beneath our feet we find proofs that what is land has been sea, and that where oceans now spread out has once been land; and that this change from sea to land, and from land to sea, has taken place, not once or twice only, but again and again, during countless ages of past time. Now the study of the distribution of animal life upon the present surface of the earth, causes us to look upon this constant interchange of land and sea — this making and unmaking of continents, this elevation and disappearance of islands — as a potent reality, which has always and everywhere been in progress, and has been the main agent in determining the manner in which living things are now grouped and scattered over the earth’s surface. And when we continually come upon such little anomalies of distribution as that just now described, we find the only rational explanation of them, in those repeated elevations and depressions which have left their record in mysterious, but still intelligible characters on the face of organic nature.

The insects of New Guinea are less known than the birds, but they seem almost equally remarkable for fine forms and brilliant colours. The magnificent green and yellow Ornithopterae are abundant, and have most probably spread westward from this point as far as India. Among the smaller butterflies are several peculiar genera of Nymphalidae and Lycaenidae, remarkable for their large size, singular markings, or brilliant coloration. The largest and most beautiful of the clear-winged moths (Cocytia d’urvillei) is found here, as well as the large and handsome green moth (Nyctalemon orontes). The beetles furnish us with many species of large size, and of the most brilliant metallic lustre, among which the Tmesisternus mirabilis, a longicorn beetle of a golden green colour; the excessively brilliant rose-chafers, Lomaptera wallacei and Anacamptorhina fulgida; one of the handsomest of the Buprestidae, Calodema wallacei; and several fine blue weevils of the genus Eupholus, are perhaps the most conspicuous. Almost all the other orders furnish us with large or extraordinary forms. The curious horned flies have already been mentioned; and among the Orthoptera the great shielded grasshoppers are the most remarkable. The species here figured (Megalodon ensifer) has the thorax covered by a large triangular horny shield, two and a half inches long, with serrated edges, a somewhat wavy, hollow surface, and a faun median line, so as very closely to resemble a leaf. The glossy wing-coverts (when fully expanded, more than nine inches across) are of a fine green colour and so beautifully veined as to imitate closely some of the large shining tropical leaves. The body is short, and terminated in the female by a long curved sword-like ovipositor (not seen in the cut), and the legs are all long and strongly-spined. These insects are sluggish in their motions, depending for safety on their resemblance to foliage, their horny shield and wing-coverts, and their spiny legs.

The large islands to the east of New Guinea are very little known, but the occurrence of crimson lories, which are quite absent from Australia, and of cockatoos allied to those of New Guinea and the Moluccas, shows that they belong to the Papuan group; and we are thus able to define the Malay Archipelago as extending eastward to the Solomon’s Islands. New Caledonia and the New Hebrides, on the other hand, seem more nearly allied to Australia; and the rest of the islands of the Pacific, though very poor in all forms of life, possess a few peculiarities which compel us to class them as a separate group. Although as a matter of convenience I have always separated the Moluccas as a distinct zoological group from New Guinea, I have at the same time pointed out that its fauna was chiefly derived from that island, just as that of Timor was chiefly derived from Australia. If we were dividing the Australian region for zoological purposes alone, we should form three great groups: one comprising Australia, Timor, and Tasmania; another New Guinea, with the islands from Bouru to the Solomon’s group; and the third comprising the greater part of the Pacific Islands.

The relation of the New Guinea fauna to that of Australia is very close. It is best marked in the Mammalia by the abundance of marsupials, and the almost complete absence of all other terrestrial forms. In birds it is less striking, although still very clear, for all the remarkable old-world forms which are absent from the one are equally so from the other, such as Pheasants, Grouse, Vultures, and Woodpeckers; while Cockatoos, Broad-tailed Parrots, Podargi, and the great families of the Honeysuckers and Brush-turkeys, with many others, comprising no less than twenty-four genera of land-birds, are common to both countries, and are entirely confined to them.

When we consider the wonderful dissimilarity of the two regions in all those physical conditions which were once supposed to determine the forms of life-Australia, with its open plains, stony deserts, dried up rivers, and changeable temperate climate; New Guinea, with its luxuriant forests, uniformly hot, moist, and evergreen — this great similarity in their productions is almost astounding, and unmistakeably points to a common origin. The resemblance is not nearly so strongly marked in insects, the reason obviously being, that this class of animals are much more immediately dependent on vegetation and climate than are the more highly organized birds and Mammalia. Insects also have far more effective means of distribution, and have spread widely into every district favourable to their development and increase. The giant Ornithopterae have thus spread from New Guinea over the whole Archipelago, and as far as the base of the Himalayas; while the elegant long-horned Anthribidae have spread in the opposite direction from Malacca to New Guinea, but owing to unfavourable conditions have not been able to establish themselves in Australia. That country, on the other hand, has developed a variety of flower-haunting Chafers and Buprestidae, and numbers of large and curious terrestrial Weevils, scarcely any of which are adapted to the damp gloomy forests of New Guinea, where entirely different forms are to be found. There are, however, some groups of insects, constituting what appear to be the remains of the ancient population of the equatorial parts of the Australian region, which are still almost entirely confined to it. Such are the interesting sub-family of Longicorn coleoptera — Tmesisternitae; one of the best-marked genera of Buprestidae — Cyphogastra; and the beautiful weevils forming the genus Eupholus. Among butterflies we have the genera Mynes, Hypocista, and Elodina, and the curious eye-spotted Drusilla, of which last a single species is found in Java, but in no other of the western islands.

The facilities for the distribution of plants are still greater than they are for insects, and it is the opinion of eminent botanists, that no such clearly-defined regions pan be marked out in botany as in zoology. The causes which tend to diffusion are here most powerful, and have led to such intermingling of the floras of adjacent regions that none but broad and general divisions can now be detected. These remarks have an important bearing on the problem of dividing the surface of the earth into great regions, distinguished by the radical difference of their natural productions. Such difference we now know to be the direct result of long-continued separation by more or less impassable barriers; and as wide oceans and great contrast: of temperature are the most complete barriers to the dispersal of all terrestrial forms of life, the primary divisions of the earth should in the main serve for all terrestrial organisms. However various may be the effects of climate, however unequal the means of distribution; these will never altogether obliterate the radical effects of long-continued isolation; and it is my firm conviction, that when the botany and the entomology of New Guinea and the surrounding islands become as well known as are their mammals and birds, these departments of nature will also plainly indicate the radical distinctions of the Indo–Malayan and Austro–Malayan regions of the great Malay Archipelago.

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