LIFE ON THE EARTH. 19 



lutions that we must ascribe the detached aspect 

 of the distribution of many plants and animals ; 

 these great changes having divided what was once 

 a continuous area, and interrupted what was once 

 a free communication between the regions in which 

 the species occur. Thus we may comprehend the 

 occurrence of Scandinavian plants in the mountains 

 of Scotland, and the north of England ; as Myosotis 

 alpestris, on Micklefell 2400 ft. high, in Yorkshire ; 

 Cornus Suecica on the eastern moorland, and Tri- 

 entalis Europa3a, in the western part of the same 

 county. We must suppose land once continuous 

 between Scotland and Norway, and a climate more 

 severe than the present. Under such circumstances 

 the plants might spread southward ; and afterwards, 

 when the countries were divided and the climate 

 became milder, they might remain in a few and 

 especially cold or elevated situations 1 . 



In the same way we may attempt to explain the 

 remarkable fact that not only a very considerable 

 number of European plants is found in the Himalaya 

 mountains, but also many of the accompanying birds. 



The late Dr Royle long since called attention to 



this remarkable fact, and Dr Hooker, recently, has 



stated that no less than 222 species of British plants 



extend to India, and oblige us to look to a common 



1 E. Forbes, in Memoirs of Geological Survey, Vol. I. 



C2 



