30 ORIGIN OF LIFE IN AMERICA 



Labrador fauna is largely composed of indigenous American 

 species, which have not penetrated to Greenland. This seems 

 to suggest that the points of resemblance in the fauna of 

 Labrador and Greenland may have been more marked in 

 remoter times, before the influence of the continental fauna 

 had impressed itself upon the outlying peninsula of Labrador. 

 Considering the extreme probability of Labrador having been 

 connected by land with Europe by way of Greenland and 

 Iceland in Pliocene times, we might expect some Euro- 

 pean mammalian types to have occurred in north-eastern 

 North America. The little evidence we possess tends to 

 show that the mamtaialian life of the extreme north of 

 western Europe was always poor. We cannot assume 

 that insurmountable barriers prevented European mammals 

 from invading America, because certain species such as the 

 reindeer and lemming seem to have passed from America to 

 Europe across a North Atlantic land bridge. It might be 

 argued that European animals did cross over, but were unable 

 to maintain themselves in America, a fate which has largely 

 befallen the American immigrants in Europe. For such a 

 supposition, however, we still lack evidence. If no examples 

 of European animals or plants were known from the American 

 side of the water, we might assume the land bridge to have 

 been a discontinuous one, as Mr. Hedley suggested to me, 

 connecting Greenland alternately with Labrador and Scotland. 

 But one of our strongest supports for the North Atlantic- 

 land bridge is, as I said, the presence of the European 

 Helix hortensis in North America. It still occurs in 

 Labrador. From Labrador it travelled southward along the 

 coast. Is it possible tfoat the whole strip of coast was at 

 'that time cut off by some barrier from the interior of 

 North America ? 



Supposing the western parts of the Labrador plateau had 

 become covered by glaciers as soon as the North Atlantic land 

 bridge was formed, it might have produced an effectual barrier 

 against western invaders and yet have allowed eastern forms 

 to reach Labrador. 



Later on I intend to return to this problem again. Mean- 

 while, let us journey westward across the high plateau of 

 Labrador towards Hudson Bay and Central Canada. As we 



