GEEENLAND-EUEOPE LAND BEIDGE 13 



of the theory from the oceanographical, geological and 

 biological standpoints.* 



A second land bridge apparently united northern Greenland 

 and Lapland at about the same time. This I described on a 

 previous occasion. It will not be necessary for me to repeat 

 all the arguments I advanced for and against the hypothesis, 

 and I must content myself with a short statement of the main 

 facts. The theory of the Greenland-Iceland-Scotland land 

 bridge (Pig. 2) had been put forward by quite a number of 

 authorities on independent grounds. Yet while some maintain 

 that it merely existed in early Tertiary times, others contend 

 that it couldionly have been made use of by the members of our 

 present fauna and flora after the Glacial Epoch, because the 

 latter had not yet come into^ existence before that time. 



One of the most important facts in favour of the existence of 

 this land bridge is presented, in my opinion, by the geographi- 

 cal distribution of the land snail known as Helix hortensis. 

 I have quoted many other instances in my paper on this 

 subject, but this no doubt affords the most striking biological 

 support for the belief in a land connection between Scotland, 

 Iceland, Greenland and Labrador. 



Helix hortensis is a typically west European species, being 

 quite unknown in the eastern parts of Europe or in Asia. 

 Beyond the mainland of Europe we find it in Great Britain, 

 in Ireland, the Shetland Islands, the Faroes, Iceland, in 

 southern Greenland, Labrador, the islands off the north-east 

 coast of North America, and part of the opposite mainland. 



Biologists are often too ready in invoking human agency 

 when endeavouring to explain the occurrence of certain 

 common European species in unexpected localities abroad. 

 When this snail was first discovered in North America, its 

 presence there was universally attributed to the action ,of man, 

 and was often cited as a good instance of the facility with 

 which terrestrial moUusks are introduced into foreign coun- 

 tries and become established there. Until the year 1864 no 

 other theory was even thought of. During that year, however, 



* Scharff, E. F., " On a former Land Bridge between Europe and 

 North America." 



