FOSSILS. t>7 



The Succession of Life. 



The oldest geological deposits in the Cam- 

 brian p< ire no indication of a commen 

 ment of life on the earth. The assemblage of 

 r eliminating the types which have be- 

 ttinct, is comparable to such as might be 

 nd upon an existing sea-bed. The most an- 



5t ratified rocks lend 

 no support to the hypothesis that they 



ss by which animal- s iccessively 



m the order of their grades of 

 organisation. I ups 



of an i m 1 dated with each other 



upon an exist;: I »:i many 



it the present day tl ety in life is not 



than the j in a quarry or 



xamining a few yard- of rock. 



h f tli- • he animal king- 



dom sentatives in very old rocks. Man 



sent known, to the 



ch has 



shed further and further backward in time, the 



Ch in which each of the highest types— mam- 



-is first met with. 



cks are fancifully 



SpOr °f the 



middle peri tamed the age of reptiles; and 



the latest r e termed t: :' mammals. 



animals puts on a - 

 ;e diversity of organisation in the epochs 

 which it is supposed to characterize; and each 

 includes some extinct groups which are not met 

 with at the present day ; or subsequent to the 

 epoch which the group characterizes. On the 

 other hand, mammals are not only not limited 



