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is met with. Eastward of Sikkim, however, as has already been shown, it is very difficult to draw a definite line, chiefly in consequence of our defective knowledge; but the boundary already adopted in the case of the Oriental Region seems, on the whole, to be a suitable one—namely, that of the northern water-parting of the Yang-tse-Kiang —thus leaving Moupin, and the district of Eastern Tibet explored by the French missionary, Pere David, within the confines of the Palaearctic Region.

There are only two important groups of islands connected with this Region; these are the British Islands in the West, and the Japanese Islands in the East. The faunas of both these insular groups are of the true "continentalisland" type, and differ very slightly from that of the neighbouring mainland. This is more especially the case with the British Isles, where we find among the Mammals no peculiarities worthy of mention, with the exception, perhaps, of a recently discriminated stoat (Mustela hibernica), said to occur only in Ireland.

Section II.—General View Of The Mammal-fauna Of The Paluearctic Region

The Palaearctic Region, although covering a larger area than any of the other Regions, comes out only fourth as regards the number, both of species and of genera, of mammals represented in it, being surpassed in this respect by the Neotropical, Ethiopian, and Oriental Regions. The total number of such genera is one hundred and three, out of which twenty-five are absolutely confined within its limits, while four others are highly characteristic of it, though they just pass over its frontiers. The remainder, seventy-four in number, are mostly widely spread. When these figures have been reduced to percentages, it will be found that only 24 per cent, of the genera are endemic, which is considerably less than in any other of the Regions hitherto treated of. Reviewing the Fauna in detail, we find that of the nine

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Fig. 35.—The Bactrian Camel.
(Camelus bactrianus.)

terrestrial Orders, six only are represented in the Palaearctic Region, the Edentates, Marsupials, and Monotremes being completely absent. Among the Ungulates, of which a considerable number of forms are found within the Palaearctic sphere, there is a fair percentage of peculiarities. The Bactrian, or Two-humped camel (Fig. 35), is known to exist still in a wild state only in certain districts of Central Asia, while the Arabian, or One-humped camel, has never yet been met with in a truly wild condition, so that the genus Camelus may be considered as truly Palaearctic.

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Fig. 36.—The Musk-deer.
(ifoschus motchifcrvs.)
[LItt of Vert. An. 1S!)6, p. 171.l

Two other endemic genera belonging to the Deer-family (Cervidm) are Moschus, the Musk-deer, a small hornless deer found only in the higher mountain ranges of Central Asia (Fig. 36); and Capreolus, the Roe-deer, fairly well spread over the whole extent of the Region.

Among the Bovidm, Saiga, an Antelope found on the steppes of Russia and Western Asia, Pantholops, another

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Fio. 37.—The Chamois.
(Rupicapra tragus.)

Antelope of the Central-Asiatic mountains, and Rupicapra, the Chamois of the European mountain ranges (Fig. 37) are confined to this Region. The important genera of Sheep (Ovis) and Goat (Capra) must be considered as especially characteristic of this Region, although stragglers of these forms are found in the confines of the Nearctic and Oriental Regions. They are all mountain animals, one of the best marked forms being the Barbary Sheep

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(Ovis tragelaphus) of Northern Africa (Fig. 38). Of the Rodents, the two most characteristic Palrearctic families are the Dormice (Myoxidm) and the Jerboas (Dipodidie). Of the former family two genera, and of the latter four, are all confined to this Region. There are also two very

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