456 Oil the hand and Fresh Water 



dence and re-upheaval of the continents of Europe and America, 

 have been effected. We shall do well to remember the brilliant 

 generalizations of the late Edward Forbes, after a close study of 

 the distribution of animals and plants in Great Britain, and of 

 their connection with the tertiary deposits of the same country. 



On the tops of the mountains near the lakes of Killarney, in 

 the south of Ireland, occur a few plants, entirely different from 

 those of the Scotch and Welsh mountains, but nearly agreeing 

 with those of the Asturian mountains in the north of Spain. Ac- 

 cording to Forbes, the southern character of these Irish plants, 

 and their extreme isolation, point to a period when a great moun- 

 tain barrier extended across the Atlantic, uniting Ireland with 

 Spain. Soon after this, arguing from similar data, he infers that 

 another barrier connected the west of France with the south-west 

 of England and thence to Ireland : — and a little later Eno-land 

 and France were connected by dry land, towards the eastern part 

 of the Channel. Upon this supposition it is easy to understand 

 why two small snails (the Helix incarnata and Bithinia margi- 

 nata,) which abound as Pleistocene fossils in the valley of the 

 Thames, although extinct in Great Britain, are still found living 

 in France. 



At the time of the glacial drift, what are now the summits of 

 the Scotch and Welsh mountains were then — Forbes argues — low 

 islands, or members of chains of islands, extending to the area 

 of Norway, through a glacial sea — clothed with an Arctic vege- 

 tation, which in the gradual upheaval of those islands, and conse- 

 quent change of climate, became limited to the summits of the 

 new formed and still existing mountains. After this upheaval it 

 is believed that Ireland was connected with England, and England 

 with Germany, by vast plains, fragments of which still exist, and 

 upon which lived the Irish elk, two-horned rhinoceri, the 

 Arctic elephant (Elephas primigenius), and other quadrupeds now 

 extinct, but which have left behind them in the gravels of our 

 English drift, unmistakeable evidence of their having at one time 

 roamed in great numbers over what is now Great Britain. 



The array of facts which tends to corroborate Forbes's theories 

 would occupy too much time to explain in detail; — I have merely 

 stated his general views in so far as they affect the question at 

 issue. Carrying out these well known generalizations, Sir Charles 

 Lyell after visiting this country and studying the peculiar distri- 

 bution of Pleistocene fossils in Lower Canada, published a theory 

 which he thought would account for these phenomena. This 



