PHYSICAL GEOGRAPHY.--The Alps, continued on the west by the Pyrenees and the Cantabrian mountains, and carried eastward to the Black Sea by the Balkan range, form an irregular line, that separates the three peninsulas of Spain, Italy, and Greece from the great plain of central Europe. On the north of this plain, there is a corresponding system of peninsulas and islands, where the Baltic answers in a measure to the Mediterranean. This midland sea, which at once unites and separates the three continents, is connected with the Atlantic by the narrow Strait of Gibraltar, and on the east is continued in the Aegean Sea, or the Archipelago, which leads into the Hellespont, or the Strait of the Dardanelles, thence onward into the Propontis, or Sea of Marmora, and through the Bosphorus into the Black Sea, and the Sea of Azoff beyond. From the Red Sea and the Indian Ocean the Mediterranean is parted by a space which is now traversed by a canal. The irregularity of the coast-line is one of the characteristic features of the European continent. Especially are the northern shores of the Mediterranean indented by arms of the sea; and this, along with the numerous islands, marks out the whole region as remarkably adapted to maritime life and commercial intercourse. ITS INHABITANTS.--Europe was early inhabited by branches of the _Aryan_ race. The cradle or primitive seat of the Aryan family --from which its two main divisions, the European and the Asiatic, went forth--is not known. It is a matter of theory and debate. We find the _Graeco-Latin_ peoples on the south, the more central nations of _Celtic_ speech, the more northern _Teutons_, and in the north-east the _Slavonians_. But how all these Aryan branches are mutually related, and of the order and path of their prehistoric migrations, little is definitely known. The _Celts_ were evidently preceded by _non-Aryan_ inhabitants, of whom the _Basques_ in Spain and France are a relic. The _Celtiberians_ in Spain, as the name implies, were a mixture of the _Celts_ with the native non-Aryan _Iberians_. The _Greeks_ and the _Italians_ had a common ancestry, as we know by their languages; but of that common ancestry neither Greeks nor Latins in the historic period retained any recollection; nor can we safely affirm, that, of that earlier stock, they alone were the offspring.