FOSSILS. 63 



to about six successive epochs, during which the 

 life gradually became higher in the details of its 

 organization. This theory was not suggested by 

 examination of the rocks and their contents, be- 

 cause divisions which separate strata in Europe 

 are differently placed in America. The hypothe- 

 endeavoured to forestall results at which 

 science might arrive. The species of fossils 

 found in each stratum were supposed to have 

 been created in the period of time when they 

 St met with; and to have become extinct 

 when they disappeared with the succession of 

 newer stral 



found that existing life varies with 

 elevation above the sea level, and that there 1- a 

 relation between distribution in height and in 

 horizontal area. While some of the plants found 

 in Great Britain are identical with those of Ger- 

 many, there are a few, living on high ground, 



which are Scandinavian types. In the south-west 



of Ireland there are a few Spanish and Portuguese 

 types. The Scandinavian life was accounted for 

 on the hypothesis that, in a recent period of geo- 

 logical time, those plants spread over land which 

 is now the North Sea, when the temperature was 

 lower than it is now. When the German types of 



plants subsequently spread over England, the 

 Scandinavian species, which could endure greater 

 cold, survived upon the hills; much as the Celtic 

 population may have receded to the high ground 

 before the invading Saxon peoples. 



Considerations of this kind indicate two great 

 laws. First, that the existing life which occupies 

 the earth's surface is grouped in series of geo- 

 graphical assemblages, each of which may be 

 termed a life province; and secondly, that these 



