754 BIRDS [DISTRIBUTION, ward somewhere "between lat. 30" and 35 N. till it meets the Pacific Ocean, besides Japan and the Kurile Islands. The propriety of comprehending this enormous tract in one Zoological Region was first shown by Mr Sclater, in the paper to which reference has before been made, 1 and as regards the distribution of most classes of animals there have been few to doubt that it is an extremely natural one. jmo- Not indeed altogether so homogeneous as the Nearctic ueity of .Region, it presents however even at its extreme points no fauua. VQY y striking difference between the bulk of its Birds. Though Japan is far removed from Western Europe, and though a few generic forms and still fewer families inhabit the one without also frequenting the other, yet there is a most astonishing similarity in a large portion of their respective Birds. ; In some cases the closest examination has failed to detect any distinction that may be called specific between the members of their avifauna ; but in most it is possible to discover just sufficient difference to warrant a separation of the subjects. Nevertheless it is clear that in Japan we have as it were a repetition of some of our most familiar species the Redbreast and the Hedge- Sparrow for example slightly modified in plumage or otherwise so as to furnish instances of the most accurate representation. The limits of the western portion of the Region are definite enough, for except in its African province it is girt by the sea, but even there we find a boundary hardly inferior to a coast-line in the precision with which it may be recognized and in the influence it exerts. This is the Great Desert, commonly known as the Sahara, which, though yearly crossed by innumerable multitudes of many of the more migratory species, just as the sea itself is traversed by them, acts as a complete barrier to the less migratory and to the residents, cutting off the denizens of Morocco, Algeria, and Tunis from the rest of the continent to which they are geographically attached. Further to the eastward, however, the limits of the Region are if in any way marked at least but little known, though indications are not wanting to show that the avifauna of Tripoli is rather Ethiopian than Palsearctic in its character. When we reach Egypt we have a state of things which may be compared to that debatable land in Central America wherein the Neotropical and Nearctic avifaunas meet but hardly mingle. During winter the bird-population of the Nile-valley is formed almost exclusively of the hordes of European migrants of nearly all Orders and families which there seek refuge. "When spring returns these begin to troop across the Mediterranean, and their place is taken by the indigenous Birds of Egypt which had been either reduced to comparative insignificance by, or actually thrust out before, the northern invaders. The seaboard of Palestine, and even its interior, until the western limits of the Jordan-basin are touched, are on the contrary almost purely Pataarctic, but the depressed valley of the Ghor, part of which is sunk about 1300 feet below the level of the Mediterranean, seems to be an outlier of the Ethiopian Region, and though the scanty avifauna of the Mountains of Moab may possess a northern phase, the desert, with its characteristic, and in the main Ethiopian, forms of animal- life almost immediately succeeds, and it is not until the fertile plains of Mesopotamia are approached or attained that we can feel assured we have again entered the Palse- arctic area, which may be considered to reach the head of the Persian Gulf. Coasting this inlet on its eastern side we have a fauna the character of which it is as yet impossible to declare, and this difficulty becomes greater still when we emerge into the Indian Ocean. It seems most probable 1 Journal of the Proceedings of the Linnean Society, Zoology, oL ii. pp. 134-138. that Beloochistan belongs to the Palseartic Region, but if not then the line of demarcation must run inland and so continue between that land and Afghanistan till, ascend ing the right bank of the valley of the Indus, it turns the shoulder of the Great Snowy Range and thence proceeds in the direction already traced parallel to the southern frontier of Thibet, and across the intervening portion of the Chinese Empire, once more to the ocean. Arrived here the remaining limits of the Region are as well marked by the coast-line as they were in Europe. They extend to Kamchatka, and rounding the furthest verge of Asia, within the Arctic Circle, they return by the north coast of Siberia till the confines of Europe are again reached. To separate this vast area into subsidiary districts Sub< according to the zoological properties of each is perhaps a Slonf less easy task than is the same operation with regard to the Nearctic Region, and, as in that case, the mapping-out of the whole into Subregions is almost impossible except it be done arbitrarily. Nevertheless the attempt must be made, and, though in the Asiatic half considerable assist ance is to be derived from a careful essay by Mr Elwes, 2 respecting the European moiety much doubt may be reasonably entertained. The very fulness of the information which we possess as to the ornis of some countries of Europe makes the scarcity of it in respect to others all the more conspicuous, and renders any really comprehensive view of the whole all the more difficult. Grounds are not wanting at first sight in favour of a longitudinal or approximately longitudinal division of this quarter of the globe, in which case the line of demarcation might be taken to run up the Adriatic Sea, and starting from the neighbourhood of Trieste, to cross the Carnic Alps, descend the valley of the Inn till it falls into the Danube, and thence follow the angular mountain frontier of Bohemia as far as the head-waters of the Niesse, along which it would proceed to their junction with the Oder,.and so to the Baltic a little to the westward of Stettin. Thence it might be continued northward be tween (Eland and Gottland up the Gulf of Bothnia to the confines of Sweden and Finland, where cutting the Scandinavian peninsula to the westward of the Lower Tornea and its affluent the Muonio it would strike the shores of the Arctic Ocean perhaps on the Lyngen Fjord. Though undoubtedly most species of Birds are common to both sides of this imaginary line, yet it would be found to divide the breeding-range of a few which are very character istic of the east and west of Europe respectively. But on further consideration it would seem that though such a division as has just been suggested may be convenient if not natural for the countries lying north of the Mediter ranean basin, those, such as the three principal peninsulas which project into the great inland sea, together with the portion of North Africa which was at one time known as Mauritania, form a group which have much in common, and collectively differ more from the countries lying further to the north than the two (Eastern and Western) divisions of Central and Northern Europe, just suggested, do from one another. Accordingly it seems best to adopt primarily a latitudinal division of the Western part of the Palaearctic Region. This done we should have as our first Liiui Subregion all Europe north of the Pyrenees, the Alps, the Subr Balkan, the Black Sea, and the Caucasus, and since it would thus comprehend by far the greater portion of this quarter of the globe, we may not inappropriately call it the " European " Subregion, further subdividing it if we think fit into a Western and an Eastern Province, accord ing to the boundary above traced the eastern boundary of the last being indeed very uncertain, though perhaps to
J Proceedings of the Zoological Society, 1873, p. 615.