The closely allied Ground-beetles (_Carabidæ_) furnish us with equally interesting and instructive proofs of a migration from Asia. Over 300 species of _Carabus_ are known to science. The number of species inhabiting Asia and Europe are about equal. But the genus does not extend its range to Southern Asia or to South America or Australia. Very few species enter Africa, and only nine North America, of which three also occur in Siberia. The genus is unknown in Madeira, and only represented by three species in the Canary Islands. To judge from its distribution, it has probably originated in Western Asia. Probably some _Carabi_ of European origin have spread into Asia, but the Asiatic--or we might say the Siberian--origin and subsequent migration westward of a number of well-known forms appears to me evident. Such forms as _C. clathratus_, _C. granulatus_, and _C. cancellatus_ are no doubt of European origin, and have only in recent geological times extended their range across Northern Asia, whilst _C. marginalis_, coming from Siberia, can hardly be said to have invaded Europe, since it has never been met with farther west than the eastern provinces of Prussia.
Among the _Carabidæ_ there are altogether very many examples pointing to a migration from Asia to Europe, but I do not wish here to give a list of all such cases, and only refer to a few of the more remarkable ones. One of the European species of Demetrias (_D. unipunctatus_), known to English entomologists as a south-eastern form, seems to have arrived with the Siberian migration, whilst the closely allied _D. atricapillus_, which has been able to reach Ireland, has a wider range and came earlier with the Orientals.
Messrs. Speyer state (p. 68) that almost all those species of Central European Butterflies whose northern limit is deflected southward as we approach the west coast of Europe, inhabit also the Volga country and the adjoining parts of Asia. Many of them are much commoner there than in Central Europe, and it appears probable to the authors of the _Geographical Distribution of Butterflies_ that these species came from the east. Asia and Central Europe have, according to Messrs. Speyer, no fewer than 156 species in common. Mr. Petersen estimates that no less than 91 per cent. of the Arctic-European Butterflies also occur in Siberia. He made a special study of the Arctic _Macro-lepidoptera_, and came to the conclusion that Central Asia, not having been glaciated in the Ice-Age, offered a possibility of existence to both animals and plants. Here, he thinks, was the principal centre to which Europe owed its re-population in post-glacial times. Mr. Petersen is of opinion (p. 40) that the Arctic-European _Lepidoptera_ are composed of two elements--the pliocene relics which persisted in Europe during the Glacial period, and the new immigrants from Siberia.