Some of the Wagtails (_Motacilla_), as I mentioned in the last chapter, have certainly come to us with the Siberian migration; but others seem to be Oriental, such as _Motacilla melanope_, which is resident in Southern Europe and migratory in the North. _M. campestris_--the Yellow Wagtail--has a most peculiar discontinuous range. One colony breeds in the British Isles and Western Europe generally, where it is known as a summer visitor, retiring to West Africa during winter; another is found from South-east Russia to Turkestan in summer, and winters in Southern Africa. This fact may possibly be due to two distinct migrations from Asia having taken place: an earlier one from the South-east--that is to say, an Oriental one--and a Siberian one more recently. In this case the members of the two migrations have not become sufficiently differentiated to be regarded as distinct varieties. Though most of the Wagtails have a somewhat northern range, none (except perhaps _M. borealis_) are truly Arctic; and indeed, as almost all of them pass the winter in southern latitudes, it may be assumed that they are of southern and not of northern origin. The Dippers (_Cinclus_) are practically unknown in the Central European plain, but they occur in Western Europe as far north as Scandinavia, also in the Alps, Carpathians, and Southern Europe, including Sicily and Sardinia. Some authorities distinguish three species, others only one. As a matter of fact, the difference between the three forms is very slight, and their nests and eggs are undistinguishable. Eight other species have been recognised, and all these are either Asiatic or American. As one of the American forms is peculiar to Peru and another to Ecuador and Columbia, and since the genus as a whole is a mountain-genus, it probably is an ancient one. Its European range alone, however, implies that it has inhabited our continent for a considerable time and is no new-comer. We may look upon it as of Asiatic origin. The ancestors have spread east and west, the European species having arrived with the earlier Oriental migrants, and wandered along the Mediterranean at a time when the geographical conditions of that sea were vastly different from what they are to-day.