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There are three very remarkable types in this list, which indicate that Celebes has, at some past period, remained much more isolated than is at present the case—for it cannot be doubted that, as we believe time to be the great worker in the creation of new species— the period of isolation of any land may be approximately measured by the eccentricity of its indigenous forms of life. The three eccentric Celebesian types are Cynopithecut, Babirussa, and Anoa. The Cynopithecus is apparently most nearly allied to the African Cynocephali, and the Anoa has been sometimes classed as an Antelope—also an ^Ethiopian type. The presence of these two form's in Celebes has led Mr. "Wallace, for whose opinions in matters of geographical distribution we hare a great respect, to imagine that there must havo formerly been some mysterious connection by means of a large (now submerged) continent between Africa and Celebes.* But it does not seem to us necessary to have recourse to such an hypothesis. Cynopithecus is certainly a difficulty. But granting, what we believe • is not positively settled, that its nearest relative is the African Oynocephalus, we must still recollect that a species of this latter genus exists in Arabia (C. hamadryas)—and that it is not impossible that the "missing links" along the Asiatic shores may have died out. Again, the Anoa is arranged by the late Mr. Turner, who paid very great attention to the osteology of the Buminants with Bubal us, from which it is stated not to be separable generically.f And Bubalus is a form that is to be found all over the Indian region. The Babirussa is merely a Sus with the canines abnormally developed, and Sus is again an Indian type—peculiar species of which are found in the islands of Sumatra, Java, and Borneo. Although, therefore, we are decidedly inclined to include Celebes in the Australian region —more on account of the absence of characteristic Indian forms than because of the presence of many Australian types, it must be admitted that the special peculiarities of Celebes (Cynopithecus, Anoa, and Babirussa) point rather towards the Asiatic main as the place of their derivation. It might also have been stated that Cynopithecut also occurs in the Philippines,}: where the general aspects of the Zoology are most unequivocally Indian.

Tarsius —a Lemuroid form—very isolated in structure, also occurs

* See Joarn. Proc. Linn. Soc. Zool. iv. p. 178. t Sec Proc. Zool. Soc. 1850, p. 164.

J We are very imperfectly acquainted with the Mammals of the Philippines. Is it not pofcuble the Anna, or some allied form, may bo found there too?

in Celebes. But it is evidently a Bornean type that has crossed the boundary-line—being also met with in the little island of Banca.

"We have now glanced at the four subdivisions of the AustroMalayan province of the Australian Fauna, in all of which Cuscus is the most prevalent form of Marsupials. As far as the present state of knowledge will enable us to form an opinion, it would appear to be very poor in Mammals—the whole number of species known as belonging to it, including several which are in all probability recent introductions, not exceeding 50. There is no doubt that future explorations in New Guinea and the adjacent terrce incognita will hereafter somewhat increase the number; but, however this may be, the grand features of the Mammal-fauna, embodied in the absence of all large and highly developed forms except in a few isolated cases of erratic species, and the presence of Marsupials', will remain the same.

Of the Mammals of the islands immediately adjacent to New Guinea on the east—New Ireland, New Britain, New Caledonia, Ac. —we know but little. A species of Guscus is found in New Ireland,* and another in the Solomon Islands,! and the Mammals of these countries probably do not materially differ from those of New Guinea. Farther eastwards, in the Polynesian subregion, no Mammals, as far as we are aware, except Chiroptera, are known to exist. Several species of Pteropu* X have been procured from theso islands, and Dr. Gray has lately described a very singular new form belonging to the same family, from the Fee-jee Islands.§ New Zealand has as yet yielded to us only two species of Bats—one a Vetpertilio, the other an endemic form, but probably belonging to the American family Phyllosiomidee—although traces of some terrestrial Mammal (which if existing is no doubt a Marsupial) are said to have been recently discovered in the Middle Island.

We conclude this hasty sketch of the Mammals of the Australian Begion, with a table which will serve to show approximately the number of species of each terrestrial order of Mammals found in its three principal divisions of Austro-Malaya, Australia, and Polynesia.

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In conclusion we may be permitted to offer the following speculations concerning the possible mode of origination of some of the peculiarities presented by the Australian Mammal-Fauna, founded upon the theory of the descent of allied species from a common stock—this being, as we must recollect, at present the only hypothesis upon which any solution of the otherwise inexplicable problems of geographical distribution can be attempted.

The salient feature of the Australian Mammal-fauna is its Marsupials, which elsewhere in the whole world only now occur in America. It follows, therefore, from the principle of the continuity of generic areas, that there must have existed at some former period an area intermediate between America and Australia, peopled by Marsupials. Wo may suppose this to have been the case either by there having existed a south-polar continent by which a branch of the Australian Marsupials reached America, or by these now widelyseparated groups being alike relics of the great Marsupial Fauna which formerly peopled the whole earth, when perhaps Placental Mammals were not as yet developed. However this may be, it seems obvious that the large and varied group of lmplacentals now met with in Australia, must have originated through the complete isolation of that country through a long series of ages. During the time while the great mass of earth on this side of the globe was producing the several Orders of Placentals and their subordinate groups, physical peculiarities in the antipodean continent, to which the Marsupial form of structure was better adapted than the Placental, may have induced a series of concomitant variations of the Implacental type, until the various families of herbivorous, insectivorous, and carnivorous Marsupials were the result. In the meanwhile, corresponding circumstances on this side of the globe may have favoured the development of Placentals, and this form being once firmly established, the Implacentals would ultimately succumb, until their sole lingering remains are to be met with only in the shape of the American family, Didelpkida*

Or, if we adopt the hypothesis of the South-polar continent, which, as is well known, derives strong ground of support from certain observed facts in other branches of Natural History—we may suppose that the American Marsupials are due to a connection of America with Australia, subsequently to the latter having been broken off from the great Paleogean continent. The Didelphidce of the New World being chiefly confined to Southern America (where more than 30 species exist, whereas only 2 occur in North America) would seem to favour the latter hypothesis.

However this may be, we must imagine the Marsupial type to have undergone development in Australia during a long series of ages—during which a broad sea cut off all communication with the great eastern continent. "When New Guinea and the AustroMalayan islands rose from the water they would of course be peopled with Mammals from Australia, and hence receive their Marsupial types. The Macropodida, advancing into a new land within the tropics, densely clothed with vegetation, would be gradually developed into Dendrolagi. The water-strait between Australia and Asia being thus narrowed, such small Mammals as Eodents would easily be conveyed across, and supply the few Mammals of this form now found in the Australian region. As regards the Chiroptera there would obviously be still less difficulty. Mr. R. F. Tomes—a good authority on this subject—says that he has "often been surprised that Australia does not furnish a single form among the Bats that is not common to nearly all the world besides," (Mr. Tomes forgets Nyctopkilu»), "indeed many of the species are found in the Indian Islands, and curiously enough in China." It is, therefore, quite evident that the Bats of Australia have been comparatively recent immigrants from Asia.

* It is perhaps to the non-presence of the Imectivora in South America that the continuance up to the present time of Marsupials in that country is due—for it is a noticeable fact that the only two zoological regions that produce Marsupials are deficient in Insectivores. The latter are mainly an Old-world group, distributed over the Pahearctic, Indian and Ethiopian regions, but most abundant in the latter, and presenting us in these countries with about 13 generic types and some 90 species, while in the New World they have only penetrated into the northern portion to the number of 18 or 20, and, with the exception of the extraordinary Solenodon, exhibit but few generic types different from those of the other hemisphere.

These speculations are merely put forth as a sample of the interesting nature of the results which the study of geographical distribution may hereafter assist us in arriving at. Before anything positive can be attained in such matters, a much more extensive knowledge than we yet possess, not only of the existing Faunas and Floras of the world's surface, but also of the Faunas and Floras of past ages, is necessary. When, in addition to thiB, a minute acquaintance with the geological structure of every portion of the globe shall have been acquired, we may reasonably hope to give a really satisfactory explanation of the predominance of the Marsupial type in Australia, and to solve many other now unmanageable problems of geographical distribution.

III.—Peters's Memoir On Solenodon.

TJeber die Saugethier-gattung Solenodon. Von Wilhelm Peters. Abh. Ak. Wiss. Berlin, 1863.

The singular form of Insectivorous Mammals known as Solenodon was brought to the knowledge of science some thirty years ago by the veteran naturalist, Professor Brandt of St. Petersburg.* Professor Brandt's description was founded upon a single specimen of this animal procured in the island of St. Domingo, which, if we except the imperfect example formerly in the Zoological Society's collection and now in the British Museum, has up to the present time remained unique in Europe.

A short time since Senor Felipe Poey of Havanah,—a gentleman well known for his valuable contributions to the Natural History of Cuba,—sent to Europe a specimen of what he supposed to be this species, which had been obtained in the mountains of Bayamo in that island. Senor Poey, we may add, had previously published some valuable notes upon the habits of this animal, as observed by him in a state of nature, in his Memoirs on the Natural History of the Island of Cuba.f On Senor Poey's specimen coming into the hands of Dr. Peters, the accurate eye of that distinguished naturalist at once perceived its distinction from the previously described

* Dc Solenodonte, novo Mummnlium gencre. Mem. Acad. St. Pet. ii. p. 459. (1833).

| Memorias sobra la Historia Natural de la L>la de Cuba. Vol. I. pp. 23, 431. llabana, 1861.

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