The genus to which our common Goldfinch belongs, viz., Carduelis, is also probably of Oriental origin, and may be looked upon as one of the earlier migrants. That species (C. elegans) breeds throughout Europe, except in the extreme north, but it is especially abundant in Southern Europe and North-west Africa. It is also resident in Madeira and the Canaries. Eastward its range extends to Persia. A larger race (C. major) inhabits Western Siberia and crosses the European border into Russia. It interbreeds in Siberia with C. caniceps, an East Siberian form.
A few instances of Reptiles and Amphibia with a similar range will show that the Oriental migration was not confined to the higher vertebrates.
Two species of the genus Eremias (Podarcis) occur in South-eastern Europe. This is a genus of Lizards with rather a wide distribution, ranging from Central Asia to South Africa southward and China eastward. Altogether there are twenty-four species, two of which just enter Europe; and of the rest half are Asiatic and half African. Even if the genus were of African origin, it is extremely unlikely that the Asiatic species came by way of Europe. We may assume, therefore, with a fair degree of probability that the two European species wandered westward along with the Oriental migrants.
The genus Ablepharus belongs to a family of Lizards in which the legs are either very fully developed, or quite absent as in the Slow-worm (Anguis fragilis). It is an ancient genus, having a wide range from Central Asia to Australia on the one hand, and to South Africa on the other. One species of this Scink-like Lizard, viz., Ablepharus pannonicus, enters Europe in the south-east, inhabiting Greece as far north as Southern Hungary. In Asia it is found in Syria and North Arabia. This clearly signifies that the Lizard is an Oriental migrant.
Among the Snakes which participated in the Oriental migration might be mentioned Eryx jaculus, whose home is probably in Western Asia. It is known in Europe from the Greek islands of Tinos and Naxos, from Turkey and Southern Russia. Another, a peculiar worm-like form, lives underground in damp earth and under stones—Typhlops lumbricalis. This species inhabits the mainland of Greece as well as the Greek islands, and Asia Minor as far as the Caucasus.
A most interesting case of distribution is that of the pretty little Toad so well known on the Continent under the name of "fire-toad" (Bombinator igneus). Though some authorities, such as Boulenger, recognise only one form of Bombinator,[1] others are of opinion that two well-marked varieties exist in Europe. These are looked upon by Dr. von Bedriaga as good species, but he acknowledges that they are rather critical and difficult to identify. No other species of Bombinator occur in Europe. Bombinator pachypus, the western race,—or if we choose to call it species,—occurs in France, Germany, Switzerland, Austria, Sicily, and Greece. B. igneus—the eastern race—is found in Southern Sweden, Denmark, Germany, Austria, and Russia. The latter has therefore a more northerly and easterly range. The species is not known from Siberia, but makes its appearance again in China in a form which, according to Dr. von Bedriaga, does not quite agree with either of the two European races.
Now if we supposed Bombinator to have originated in Europe, its absence from the British Islands, most of the Mediterranean islands, and the greater part of Scandinavia would not be easy of explanation, while as an Asiatic migrant the European range is more readily understood. Its apparent absence from Western Asia might quite likely be due to the fact that the zoology of that part of the Continent is only now being investigated. The latter has, moreover, undergone great physical changes in recent geological times. The supposition that one migration of Bombinator from the south-east has taken place, and then another from the east, seems to explain this case of distribution, as other similar ones, in a most satisfactory manner.
The Tree-Frog (Hyla arborea) must be an ancient species, but it is not of European origin. Few genera of Amphibia have a wider distribution than Hyla. There are only three species in Asia, Europe, and Africa, the remaining 129 being confined to America and Australia. Two of the three Old World Tree-frogs are so closely allied that until recently they were regarded as mere varieties of one another. These are Hyla arborea and H. chinensis. The former is found in Asia Minor, Persia, China and Japan, and in most of the Mediterranean islands and Southern Europe generally. It does not occur in the British Islands, Norway, or North Russia, but in South Sweden, Germany, France, and Spain. It is also known from North Africa and from Madeira, the Canaries, and the Salvages. The occurrence of the Tree-Frog on so many of the Mediterranean islands is of particular interest, especially as four well-marked varieties have been distinguished by our leading herpetologists, so that the more minute features of the various forms can be traced from island to island, adding one more proof—if proof were needed—of their former continuity. Of course, that Hyla arborea must be considered an Oriental migrant seems so evident that it scarcely needs further comment.
A number of mollusca might be mentioned whose range indicates that they have migrated to Europe from Asia Minor. Buliminus pupa is one of these. It is known from Asia Minor, Greece, South Italy, Sicily, and Algeria. Buliminus detritus is perhaps better known, being common in some parts of Germany. From there its range spreads east as far as Asia Minor. Many closely allied species inhabit Western Asia, to which they are confined, while others enter on European territory in some of the Greek islands. B. fasciolatus occurs on the islands of Crete, Rhodes, Cyprus, and in Greece and Syria. Most of the species of Buliminus have a very restricted range, but Buliminus obscurus is found almost all over Europe, from Ireland in the west to the Crimea and Transcaucasia in the east.
Whether the sub-genus Pomatia of the genus Helix—to which the so-called Roman Snail belongs—is of Asiatic origin, or whether some of the species have migrated from Europe to Asia, I am not prepared to say; but there can be no doubt that Helix pomatia has reached Western Europe from the east.