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Show 14 ISLAND LIFE. (PART, I, -------··-------------------- the Alps. There are of course numerous instances in which species occur in two or more islands, or in an island and continent, and are thus rendered discontinuous by the sea, but these involve questions of changes in sea and land which we shall have to consider further on. Other cases are believed to exist of still wider separation of a species, as with the marsh titmice and the reed buntings of Europe and Japan, where similar forms are found in the extreme localities, while a distinct variety, race, or sub-species, inhabits the intervening district. Extent and Limitations of Specific Areas.-Leaving for the present these cases of want of continuity in a species, we find the most wide difference between the extent of country occupied, varying in fact from a few square miles to almost the entire land surface of the globe. Among the mammalia, however, the same species seldom inhabits both the old and new worlds, unless they are strictly arctic animals, as the reindeer, elk, and arctic fox, the glutton, the ermine, and some others. The common wolf of Europe and Northern Asia is thought by many naturalists to be identical with the variously coloured wolves of North America extending from the Arctic Ocean to Mexico, in which case this will have perhaps the ·widest range of any species of mammal. Little doubt exists as to the identity of the brown bears and the beavers of Europe and North America; but all these species range up to the arctic circle, and there is no example of a mammal universally admitted to be identical yet confined to the temperate zones of the two hemispheres. Among the undisputed species of mammalia the leopard has an enormous range, extending all over Africa and South Asia to Borneo and the east of China, and thus having probably the widest range of any known mammal. The winged mammalia have not usually very wide ranges, there being only one bat common to the Old and New Worlds. This is a British species, V esperugo serotinus, which is found over the larger part of North America, Europe and Asia, as far as Pekin, and even extends into tropical Africa, thus rivalling the leopard and the wolf in the extent of country it occupies. Of very restricted ranges there are many examples, but some of these are subject to doubts as to the distinctness of the ~HAP. II.] THE ELEMEN'J;ARY FACTS OF DISTRIBUTION. 15 species or as to its geographical limits being really known. In Europe we have a distinct species of ibex (Capra Pyrenaica) confined to the Pyrenean mountains, w bile the true marmot is restricted to the Alpine range. More remarkable is the Pyrenean water-mole (Mygale Pyrenaica), a curious small insectivor? us animal found only in a few places in the northern valleys of the Pyrenees. In islands there are many cases of undoubted restriction of species to a small area, but these involve a different que~tion from the range of species on cpntinents where there is no apparent obstacle to their wider extension. Specific range of Birds.-Among birds we find instan·ces of much wider range of species, which is only what might be expected considering their powers of flight; but, what is very curious, we also find more striking (though perhaps not more frequent) examples of extreme limitation of range among birds than among mammals. Of the former phenomenon perhaps the most remarkable case is that afforded by the osprey or fishing-hawk, which ranges over the greater portion of all the continents, as far as Brazil, South Africa, the Malay Islands, and Tasmania. The barn-owl (Strix .flammea) has nearly as wide a range, but in this case there is more diversity of opinion as to the specific difference of many of the forms inhabitino- remote . 0 countnes, some of which seem undoubtedly to be distinct. Among passerine birds the raven has probably the widest ranget extending from the arctic regions to Texas and New Mexico in America, and to North India and Lake Baikal in Asia; while the little northern willow-wren (Phylloscopus borealis) ranges from Norway across Asia to Alaska, and southwa:rd to Ceylon, China, Borneo, and T1mor. Of very restricted continental ranges tbe best examples in Europe are, the little blue magpie ( Cyanopica cooki) confined to the central portions of the Spanish peninsula; and the Italian sparrow found only in Italy and Corsica. In Asja, Palestine affords some examples of birds of very restricted rap.o-e-a beau~ifu~ sun-~ird (.1..Vectarinea osea) a peculiar starling tA.mydrus Tnstran!J~~) and some others, being almost or quite confined to the warmer portions o~ the valley of the Jordan. In |