20 ORIGIN OF LIFE IN AMERICA 



of the ancient north Atlantic land connection, and are sup- 

 posed to have subsequently become extinct on the intermediate 

 stations between the two continents, particular attention may 

 be drawn to the range of the " running beetles " of the genus 

 Carabus. They are of great value in aiding us to solve pro- 

 blems of this nature, because, being usually found under 

 stones and clods of earth, they are not liable to occasional 

 transport by floods. Being wingless they cannot be carried 

 to distant lands by winds ; and lacking any kind of means by 

 which they might become attached to a mammal or bird they 

 would not be conveyed in such an accidental manner from one 

 locality to another. The great importance of the species of 

 Carabus has been recognised, and their distribution brought 

 to bear upon zoogeographical problems by Mr. Born.* He cites 

 two of the species, viz., Carabus catenulatus and Carabus 

 nemoralis, as evidences of a former land bridge between 

 northern Europe and North America, although they no longer 

 occur in Iceland or in Greenland. Both these running beetles 

 are typically European species, being quite absent from Asia. 

 The conspicuously ornamental Carabus memoralis is confined 

 in North America, to Nova Scotia and New Brunswick. Hence 

 it somewhat agrees in its American range with that of Helix 

 hortensis. The other species of Carabus has a wider dis- 

 tribution in boreal North America. 



Such instances lead us to believe, therefore, that the faunas 

 of Greenland and Iceland were richer in pre-Glacial times 

 than at present. They are certainly suggestive also of a sur- 

 vival of species having taken place through the Ice Age within 

 the glaciated area of North America. We possess no evidence 

 that these beetles and the snail Helix hortensis, and many 

 other animals belonging to the same group of European in- 

 vaders, were pushed south during Pleistocene times into the 

 United States, and that they then regained their former 

 northern habitat, after having become extinct again in their 

 more southern stations. 



The extinction of a large part of the former beetle fauna 

 of Greenland may be inferred from the fact that Greenland 

 only possesses forty-one species of beetles, while there are 



* Born, P., " Zoogeographisch-carabologiache Studien," p. 8. 



