x.] PERSISTENT TYPES OF LIFE. 197 



sive development, entirely comprised within the time represented 

 by the fossiliferous rocks. 



Contrariwise, any admissible hypothesis of progressive modifi 

 cation must be compatible with persistence without progression, 

 through indefinite periods. And should such an hypothesis 

 eventually be proved to be true, in the only way in which it can 

 be demonstrated, viz. by observation and experiment upon the 

 existing forms of life, the conclusion will inevitably present itself, 

 that the Palaeozoic, Mesozoic, and Cainozoic fauna? and floras, 

 taken together, bear somewhat the same proportion to the whole 

 series of living beings which have occupied this globe, as the 

 existing fauna and flora do to them. 



Such are the results of palaeontology as they appear, and have 

 for some years appeared, to the mind of an inquirer who regards 

 that study simply as one of the applications of the great biological 

 sciences, and who desires to see it placed upon the same sound 

 basis as other branches of physical inquiry. If the arguments 

 which have been brought forward are valid, probably no one, in 

 view of the present state of opinion, will be inclined to think the 

 time wasted which has been spent upon their elaboration. 



