ScHAiiFF— Ow the Origin of the European Fauna. 499 



an isolated one. Professor J. Gcikie{o5a, p. 377) tells us that an 

 ice-sheet traversed North Lancashire and the adjacent parts of York- 

 shire and Westmoreland, the general trend of wliich was towards^the 

 south or south-south-east, and that from this might justly be inferred 



8. — Map of the British Islands] dining the latter] part of the Glacial Period, 

 showing approximately the ancient land now covered by sea (lightly 

 shaded). 'The darkly-shaded parts represent the extension of the 

 sea at that time, and the white parts land. 



that some barrier existed in the Irish Sea, by which the Ecglish^ice 

 was prevented from following the slope of the ground, which is 

 towards the soutli-west. 



Here again, I think, the marine theory would explain in a more 

 satisfactorv manner than the terrestrial one, the fact of the erratics 



