It might be urged that the peculiar little blue Magpie of Spain--_Cyanopolius Cooki_--should find a place among the Lusitanian species, since there is no bird like it anywhere else in Europe. But in Eastern Siberia there lives a bird so closely allied as to be barely distinguishable from it. Nevertheless, since there are some distinguishing characters, it has received a distinct name--_C. cyanus_. This is a most interesting and remarkable case of discontinuous distribution, which may perhaps be explained by the supposition that the genus is of Oriental origin, and has died out at its former headquarters in Southern Asia and all along the line of migration, except at the extreme limits of the range in both directions--east and west.
As we go down in the scale of life--among the lower vertebrates and invertebrates--we meet with a greater number of prominent members of the Lusitanian migration. The Bullfinch, Dipper, and Chough, which might be thought to be of Lusitanian origin, are, as I have shown in the last chapter, Asiatic.
The European snakes seem to be all of eastern origin, unless _Tropidonotus viperinus_ might be claimed as a Lusitanian form. Of very great interest from a zoogeographical point of view is our only European member of the South American and African family _Amphisbænidæ_. This species--_Blanus cinereus_--is of the size and shape of an ordinary earth-worm, from which, however, it may be distinguished by its snake-like wriggling motions. It lives under stones in Spain and Portugal, North-west Africa, and Greece. It has, therefore, a somewhat similar distribution to that of many of the animals and plants referred to in the last chapter. But here we have an animal which has evidently utilised the old Mediterranean route described on p. 271, from west to east. Two other species of _Blanus_ inhabit Asia Minor and Syria, but most of its nearest relations either live in South America or tropical Africa. In migrating to North and West Africa, its ancestors probably made use of the land-bridge which spanned the Atlantic in early Tertiary times. Another Lusitanian Lizard--belonging not to an aberrant group, but to the typical Lacertidæ--is _Psammodromus hispanicus_. It is rather variable in colour--generally of a brown or green--and grows to a length at about four or five inches. It occurs throughout the Spanish peninsula and also in Southern France. One of the handsomest European Lizards, which reaches almost a foot in length,--of an olive colour with greenish or mother-of-pearl reflection, and with two yellow stripes along each side of the body,--is an allied species (_P. algirus_). From the Spanish peninsula it passes into Southern France and North Africa. Two other species of the genus are confined to North-west Africa.