ScHARFF — On the Origin of the European Fauna. 477 



540). He adds (p. 542) : " If the cause of the Glacial cold was con- 

 nected with the closing of the Arctic regions against the tropical 

 currents of the Atlantic, the I^orth Atlantic Ocean would have 

 had greater warmth than now, and this would have produced unusual 

 evaporation, and hence unusual precipitation on its cold herders." 

 Croll, on the other hand, in referring to this harrier of land, says : 

 " I have never been able to find any evidence that any such harrier 

 did exist during the Glacial Period." 



In a Paper on the history of the vegetation of Greenland (61ft, p. 

 185), Prof. Nathorst speaks of Spitsbergeii as a northern continuation 

 of Europe — not only geographically, but also botanieally and geologi- 

 cally. All the flowering plants of Spitsbergen, with the excejjtion 

 of but three species, are also found in I^orthern Europe and jS'ovaya 

 Zemlya. He is of opinion that Spitsbergen must have been partially 

 connected with Europe during the Glacial Period. On the other 

 hand, the occurrence of a number of American plants on the west 

 coast of Greenland seems to point to a former land-connexion between 

 the latter country and jS'orth America. Prof. Engler observes (26, p. 

 12) that, as Spitsbergen, Eranz-Joseph's Land, and ISTovaya Zemlya 

 lie on a sub-marine plateau which is less than 200 fathoms below sea- 

 level, and is probably continued northward, the insular position of 

 these islands might only be a temporary one. These islands might, 

 he says, have formed a connexion between Greenland and Arctic 

 Europe, by means of which a migration of plants from North America 

 and Greenland to Northern Europe became possible. At any rate, he 

 continues, the reasons in favour of this Arctic connexion of America 

 vdth Europe are stronger than those of a connexion between Green- 

 land, Iceland, the Faroes and Great Britain. He thinks too 

 (p. 143) that many species of plants belonging to the Alpine flora of 

 Arctic Siberia seem to have travelled from Scandinavia via Greenland 

 and North America to Eastern Asia, and not direct from Scandinavia 

 to Siberia. Among Irish naturalists I may mention the late Dr. 

 Moore and Mr. A. G. More, who were both of opinion (58, p. xx.) 

 that the presence in the west of Ireland of several American plants in- 

 dicated a former land-connexion between Europe and North America. 



The most important geological contribution which has been 

 published on this problem of a former northern land-connexion is 

 tliat hy Professor Petterson (68). He tells us that, according to 

 recent surveys, a high su.b-marine plateau, with a sharp fall of 1000 

 fathoms towards the Atlantic Ocean, rises from Northern Norway, 

 and continues as far as Spitsbergen. From this plateau arise several 



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