NOTES ON THE GEOGRAPHICAL DISTRIBUTION OF ANIMALS. 263 
would be at least 1,000 feet lower than at present, and pro- 
bably 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 sur- 
vived 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 Palsearetic 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 then 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 geo- 
logical 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.* 
* 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.” 
