This is by far the richest portion of the Palæarctic region, for although of moderate extent much of it enjoys a climate in which the rigours of winter are almost unknown. It includes all the countries south of the Pyrenees, Alps, Balkans, and Caucasus mountains; all the southern shores of the Mediterranean to the Atlas range, and even beyond it to include the extra-tropical portion of the Sahara; and in the Nile valley as far as the second cataract. Further east it includes the northern half of Arabia and the whole of Persia, as well as Beluchistan, and perhaps Affghanistan up to the banks of the Indus. This extensive district is almost wholly a region of mountains and elevated plateaus. On the west, Spain is mainly a table-land of more than 2000 feet elevation, deeply penetrated by extensive valleys and rising into lofty mountain chains. Italy, Corsica, Sardinia, and Sicily, are all very {200}mountainous, and much of their surface considerably elevated. Further east we have all European Turkey and Greece, a mountain region with a comparatively small extent of level plain. In Asia the whole country, from Smyrna through Armenia and Persia to the further borders of Affghanistan, is a vast mountainous plateau, almost all above 2000, and extensive districts above 5000 feet in elevation. The only large tract of low-land is the valley of the Euphrates. There is also some low-land south of the Caucasus, and in Syria the valley of the Jordan. In North Africa the valley of the Nile and the coast plains of Tripoli and Algiers are almost the only exceptions to the more or less mountainous and plateau-like character of the country. Much of this extensive area is now bare and arid, and often even of a desert character; a fact no doubt due, in great part, to the destruction of aboriginal forests. This loss is rendered permanent by the absence of irrigation, and, it is also thought, by the abundance of camels and goats, animals which are exceedingly injurious to woody vegetation, and are able to keep down the natural growth of forests. Mr. Marsh (whose valuable work _Man and Nature_ gives much information on this subject) believes that even large portions of the African and Asiatic deserts would become covered with woods, and the climate thereby greatly improved, were they protected from these destructive domestic animals, which are probably not indigenous to the country. Spain, in proportion to its extent, is very barren; Italy and European Turkey are more woody and luxuriant; but it is perhaps in Asia Minor, on the range of the Taurus, along the shores of the Black Sea, and to the south of the Caucasus range, that this sub-region attains its maximum of luxuriance in vegetation and in animal life. From the Caspian eastward extends a region of arid plains and barren deserts, diversified by a few more fertile valleys, in which the characteristic flora and fauna of this portion of the Palæarctic region abounds. Further east we come to the