196 HISTORY OF THE EUROPEAN FAUNA. 



the Mediterranean dates therefore from early pleisto- 

 cene or late pliocene times. 



In referring to the sixty-five species of Land and 

 Freshwater Mollusca which have been described from 

 the continental "Loess," Dr. Kobelt states (p. 166) 

 that this fauna has certainly not a steppe-character. 

 It does not therefore strengthen Professor Nehring's 

 view that Europe during the deposition of the loess 

 had a climate comparable to that of the Siberian 

 steppes. The Glacial period had hardly any effect 

 on the molluscan fauna of Europe. Dr. Kobelt 

 believes in a certain movement of that fauna from 

 the least favourable areas, with a subsequent 

 re-immigration; but even that could not have 

 taken place on a large scale. Nothing like a 

 destruction of the fauna occurred, as far as we 

 know from fossil evidence. 



Not a single species of land or freshwater mollusc 

 can be quoted as having migrated to Europe from 

 Siberia in recent geological times. The molluscan 

 fauna of the latter country is so closely connected 

 with that of Europe, that it is quite impossible to 

 elevate it to the rank of a sub-region of the Holarctic 

 Region. Dr. Kobelt insists that Siberia cannot even 

 claim to be placed into a distinct province. Accord- 

 ing to the same authority, we find no species in the 

 whole Siberian molluscan fauna which we might 

 regard as having immigrated since the close of the 

 Glacial period. Even to attempt the location of 

 the original homes of many of the species which 



