170 LIFE ON THE EARTH. 



ary of the Mesozoic and Paleozoic Deposits, not many 

 closely related forms passing the limits in either case. 

 The present age is in fact a part of the great 

 Csenozoic period. 



The attention of Linnaeus was drawn to the other 

 question regarding the succession of forms on the 

 land, and in the Amoenitates Academicce, which con- 

 tain some essays from his own hand, and many con- 

 tributed by his pupils, we find an interesting dis- 

 course on the subject of the extension of life from 

 the centres of mountainous districts 1 . It is easy to 

 find examples of parallel forms of Mammalia now 

 living, with some of the Tertiary quadrupeds once 

 denizens of the same regions, or regions formerly 

 connected by land ; the affinities thus traced being 

 feebler in proportion to the antiquity of the earlier 

 forms. Thus, in England the Beaver is extinct, but 

 yet lives in Germany ; our Red Deer is apparently 

 the same as some Pleistocene fossils, and very similar 

 to others of earlier date ; and our European Wolf 

 is found in the ossiferous caverns of England, Ger- 

 many and France. Sometimes, without this close 

 affinity, a considerable resemblance is found between 

 special tribes now living and others fossil in the same 

 region. In a part of the Continent of America this 

 is remarkable, among the Edentata, which thougli 



1 De telluris orbis increment*). 



