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THE PALÆARCTIC REGION
(PLATE VII., p. 196)
SECTION I-BOUNDARIES OF THE PALEARCTIC REGION
THIS, the last of the six great Regions, consists, as its name implies, of the whole northern part of the Old World. Its boundaries have already been defined in previous articles dealing with the Ethiopian and Oriental Regions, these being the only Regions with which it marches. Speaking generally, it may be said to consist of the whole of Europe, the northern border of Africa, and Asia north of the Himalayas. Its southern boundary in Africa was taken, in the article on Ethiopia, as the Tropic of Cancer, but this, of course, is a purely arbitrary line, and runs through the centre of the Sahara Desert. It would, perhaps, be more accurate to put in its place the northern edge of the Sahara as the limit, and to include all the desert country both of Africa and Arabia in the Ethiopian Region.
The question of Egypt is a difficult one, as its fauna undoubtedly contains a mixture of forms characteristic of both the Palearctic and Ethiopian Regions; on the whole, however, Egypt, up to the First Cataract, is best included in the Palearctic Region.
In regard to the boundary line between the Palearctic and Oriental Regions, there can be no doubt that at the higher elevations of the Himalayas a true Palearctic fauna
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, Père David, within the confines of the Palearctic 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 PALEARCTIC REGION
The Palearctic 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
terrestrial Orders, six only are represented in the Palearctic Region, the Edentates, Marsupials, and Monotremes being completely absent. Among the Ungulates, of which a considerable number of forms are found within the Palearctic 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 Palearctic.
Two other endemic genera belonging to the Deer-family (Cervida) 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.