1902.] AND ANCIENT GEOGRAPHY. 375 



Europe was established north of the Aralo- Caspian basin over 

 Southern Russia (Scharff, 1897, map p. 466). 



The gradual origin of Europe, beginning with the formation of 

 the chief mountain chains in the Oligocene, its connection first of 

 the southern and central parts with Western Asia across the Balkan 

 Peninsula (Miocene and Pliocene) and with Northern Africa over 

 Spain (end of the Miocene), and subsequently the connection of 

 the central and northern parts with Siberia (over Russia), by which 

 processes Europe assumed the shape of a continent (part of Asia), 

 have been largely used by previous authors for the explanation of 

 the zoogeographical conditions of Europe. 



Osborn (1900, p. 569) mentions a repeated immigration of 

 Mammals into Europe and indicates the Upper Eocene, the 

 Miocene and the Pliocene times as most important in this respect. 

 But we must always bear in mind that during the Older Tertiary- 

 Europe was not a unit at all — in fact did not exist as a zoogeo- 

 graphical section. The Old Tertiary Mammalian faunas of Europe 

 (chiefly in the Northwest, in France) probably belong to the British- 

 Scandinavian mass, which was connected, as has been mentioned 

 incidentally, with North America. 1 Then, in the Miocene, we 

 have in Europe, which assumes a more consistent shape, a fauna of 

 new character, the origin of which is to be sought in the East and 

 Southeast (Asia), and possibly during this time the first African 

 types reached Europe, either by the roundabout way over Western 

 Asia or more directly over Algiers and Spain. 



Kobelt (1897) also assumes an isolation of Europe at the begin- 

 ning of the Tertiary, and discusses the immigration of an Indo- 

 Chinese fauna from the East in Pliocene times, while the Nile 

 valley formed a route by which freshwater animals immigrated 

 from the South (Africa). 2 



The most detailed investigations on this question have been pub- 



1 As to this connection, which is not treated here, I refer the reader to Nen- 

 mayr (1890, Vol. 2, pp. 497 and 504) and to Scott {An Introduction to 

 Geology, 1897, P- 5°5)- 



3 Contrary to this, Pilsbry (1894) is inclined to assume, for the Helices, a Cre- 

 taceous immigration from Southeastern Asia into Europe and Africa. But 

 according to the present state of our knowledge, as set forth above, the history o* 

 the development of Africa and Europe, as well as of Asia, does not warrant ihis 

 assumption. There was no possibility, on geological grounds, for the old Siaic 

 fauna to reach Europe and Northern Africa before the Miocene. 



