The Scottish Naturalist. 197 



the few survivors who were able to outlive the rigour of the 

 latest glacial epoch. But when we come to consider the nature 

 of the conditions which obtained during that latest phase of the 

 Ice Age, it seems hardly possible that any southern species what- 

 soever could have survived them. Few geologists, save those who 

 have specially worked at the subject, have realised the extent of 

 the glaciation that took place toward the close of the glacial 

 period. So far as Scotland and Scandinavia are concerned, the 

 ice-sheet which then covered them seems to have been hardly, 

 if at all, less thick than that which mantled them at the very 

 climax of glacial cold, when the European ice had its greatest 

 extension. Not only were the Scandinavian and Scottish ice- 

 sheets coalescent, but they overflowed the Orkney and Shetland 

 Islands, and the Outer Hebrides were buried in ice to as great a 

 depth as they seem to have been at any previous stage of the 

 glacial period. How far west the mer de glace extended seawards 

 can, of course, only be conjectured, but it is most probable that 

 it reached, at least, to what is now the loo-fathom line. Mr 

 Helland and I found that the Fseroe Islands have been in like 

 manner encased in glacier ice. They supported an ice-sheet of 

 their own, the upper surface of which rose to a height in the 

 northern islands of 1600 feet, and in Suderoe of 1400 feet above 

 what is now the sea-level. Not only so, but the ice was so thick 

 that it filled up all the fiords and sounds between the various 

 islands of the archipelago, thus forming one compact mer de glace 

 which flowed outwards in all directions from the dominant points, 

 and discharged its icebergs into the surrounding ocean. If such 

 were the state of the Fseroe Islands in the concluding cold period 

 of the Ice Age, it is but reasonable to infer that similar extensive 

 ice-sheets flowed outwards from Iceland, Greenland, and Spitz- 

 bergen into the Arctic Ocean — the temperature of which must 

 have been depressed to a very low degree by icebergs and floe- 

 ice, which, indeed, must have wellnigh choked it up. Is it 

 possible that any one of the southern species which occur in the 

 post-glacial beds and present seas of Scandinavia could have 

 survived such conditions ? The answer, I think, must be in the 

 negative. 



Thus we seem driven to the conclusion that the visitors from 

 southern waters which are now living in the northern seas, and 

 which were at one time more plentiful, both as regards species 

 and individuals, must have immigrated long after the severity of 

 the latest glacial period had passed away. Their history is entirely 



