GREENLAND-EUROPE LAND BRIDGE 
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-Ieeland-Scotland land 
bridge (Fig. 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 could only 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 mollusks 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, B. F., “ On a former Land Bridge between Europe and 
North America.” 
