344 PALEONTOLOGY AND EVOLUTION xi 



the weighty evidence which M. Barrande has 

 accumulated, and have admitted the doctrine of 

 colonies. But the admission of the doctrine of 

 colonies implies the further admission that even 

 identity of organic remains is no proof of the 

 synchronism of the deposits which contain 

 them. 



4. The discussions touching the Eozoon, which 

 commenced in 1864, have abundantly justified the 

 fourth proposition. In 1862, the oldest record of 

 life was in the Cambrian rocks ; but if the Eozoon 

 be, as Principal Dawson and Dr. Carpenter have 

 shown so much reason for believing, the remains 

 of a living being, the discovery of its true nature 

 carried life back to a period which, as Sir William 

 Logan has observed, is as remote from that during 

 which the Cambrian rocks were deposited, as the 

 Cambrian epoch itself is from the tertiaries. In 

 other words, the ascertained duration of life upon 

 the globe was nearly doubled at a stroke. 



5. The significance of persistent types, and of 

 the small amount of change which has taken place 

 even in those forms which can be shown to have 

 been modified, becomes greater and greater in my 

 eyes, the longer I occupy myself with the biology 

 of the past. 



Consider how long a time has elapsed since the 

 Miocene epoch. Yet, at that time there is reason 

 to believe that every important group in every 

 order of the Mammalia was represented. Even the 



