THE EUROPEAN SEAS. 



63 



direction from north to south, and that since then 

 their direction has been changed to that now pre- 

 vailing, from south to north. The consequence of 

 this was the migration of southern (Mediterranean) 

 species northward, until they reached our coasts, 

 and of the original Arctic species also to the north- 

 ward, till some of them were actually driven from 

 the 6 land of their fathers ' to the cold seas of Spitz- 

 bergen — migrations that are going on, perhaps, at 

 this day, though of course very slowly. But before 

 the Mediterranean species arrived, our shores were 

 peopled with a number of species probably from the 

 Celtic regions, which, being at present neither Medi- 

 terranean nor Arctic, and obtaining in the Germanic 

 region their maximum of development, appear to 

 have finally settled in that sea, quibus mare Germa- 

 nicum germana patria. So I get in each of my two 

 regions, Eegio Germanica and Regio Arctica, three 

 tribes, Hospites e mari Siculo, cives Germani and 

 aborigines." 



Some years must elapse before we can determine 

 the category (according to the ingenious distinctions 

 suggested by Professor Loven), to which each animal 

 form (and vegetable also) should be referred. When 

 a stranger species of prolific habits, and capable of 

 adapting itself readily to the new conditions under 

 which it is placed, has colonized an area for some 

 time, it is exceedingly difficult to distinguish between 

 it and a true aboriginal. 



Throughout the Boreal region Cetacea are abun- 



