been the birthplace of most of the principal groups of animals, including those now confined to tropical Africa, or even to South America. Nor need this surprise us, poor as is the present Palæarctic region, when we consider the great vicissitudes to which this region has been more especially exposed, and the many conditions unfavorable to animal life which it now presents. There is little doubt that the amazingly rich fauna possessed by Europe previous to the glacial epoch was then almost entirely swept out of it, a very large proportion of its original fauna and flora being either wholly exterminated or driven into distant regions, whence, on the abatement of the cold, their descendants would return very slowly, if at all. Besides, it is urged by Mr. Belt that during the glacial period such vast masses of water were locked up in snow and ice that the average level of the sea would be at least one thousand feet lower than at present, and probably far more. This would lay bare great tracts of land possessing a much warmer climate than any other portion of the globe at that time, where many tropical forms may have survived the glacial period, though some would doubtless have been subsequently exterminated by the great floods which Mr. Belt argues would have occurred towards its close, from the melting of the ice. This view receives considerable support from the numerous traditions of submerged countries in the Atlantic, and off the coasts of China, India, Ceylon, and east Africa.
Great changes have recently taken place in the inland seas of the Palæarctic region. It was formerly bounded to the south by a great inland sea, resembling the Mediterranean, occupying the place of the Sahara; and a chain of inland lakes appears to have extended from Spain to the Black Sea. Wallace believes the Mediterranean to have there consisted of two great lakes, while north Africa was connected with Spain and Italy by extensive tracts of land now submerged. At this time, too, much of northern Asia may have been depressed below the sea, or, at any rate, the great lakes, such as the Caspian, Aral, and Baikal, appear to have communicated with the Arctic Ocean. But there is still much obscurity relating to the geological history of northern Asia; and until increased facilities of communication and changes in politics render China and Asiatic Russia more accessible to scientific men, it cannot be entirely cleared up. It is so difficult to account for the total disappearance of such forms as the mammoth from a country like Siberia, that some have suggested that they were destroyed by floods, to which indeed a great part of central and northern Asia was very probably subject, considering the much greater number and extent of the inland seas in former times, even if a large portion of the country was not actually covered by the Arctic Ocean. Much valuable geological information relating to northern Asia in recent times must be still locked up in Chinese annals; and I have not yet met with any history by a competent geologist of the series of great volcanic disturbances, inclusive of earthquakes and floods, which devastated China during the first half of the fourteenth century, and which were felt with great severity at least as far as Austria and Greenland, and indirectly over the whole of the then known world, and there is reason to believe even in America. A history of these extraordinary phenomena, which are unparalleled in modern times for their extent and severity, if collected from the numerous available materials, and worked up by a competent hand, would be of the greatest scientific value.
And here I may remark that I am convinced that great light would probably be thrown on the former state of the world in historic times by the study of Oriental literature by scientific men. There has been much discussion among the Orientalists about the identification of the islands of Wák-wák, mentioned by Arab geographers, as well as in the "Arabian Nights." These are the islands, seven years' journey from Baghdad, where the trees bear fruit in the shape of female heads, suspended by the hair, which cry out "Wák-wák " at sunrise and sunset. Then to connect these islands more distinctly with birds, they are inhabited by jinneeyehs, who fly about in feather dresses, which are sometimes stolen by some enterprising hero. Wallace describes the great bird of paradise (Paradisea apoda) as being very abundant in the Aru Islands, and settling on the trees in flocks at sunrise, uttering a loud and shrill note audible at a great distance, which sounds like "wawk-wawk-wawk-wǒk-wǒk-wǒk." Any
- This is confirmed even by groups of which very few fossil remains exist. Mr. S. H. Scudder, in his recent work on fossil butterflies, only admits nine species, all European; but of these four are preponderating American in their affinities, three Oriental, one Mediterranean, and one African.
- The most accessible account of this period is perhaps that in Hecker's history of the black death, in his "Epidemics of the Middle Ages."