NEW SCIENCE OF PALEONTOLOGY 



of nature, he will naturally inquire whether there are 

 any means provided for the repair of these losses ? Is 

 it possible as a part of the economy of our system that 

 the habitable globe should to a certain extent become 

 depopulated, both in the ocean and on the land, or 

 that the variety of species should diminish until some 

 new era arrives when a new and extraordinary effort 

 of creative energy is to be displayed ? Or is it possible 

 that new species can be called into being from time to 

 time, and yet that so astonishing a phenomenon can 

 escape the naturalist? 



14 In the first place, it is obviously more easy to prove 

 that a species once numerously represented in a given 

 district has ceased to be than that some other which 

 did not pre-exist had made its appearance assuming 

 always, for reasons before stated, that single stocks 

 only of each animal and plant are originally created, 

 and that individuals of new species did not suddenly 

 start up in many different places at once. 



" So imperfect has the science of natural history re- 

 mained down to our own times that, within the mem- 

 ory of persons now living, the numbers of known ani- 

 mals and plants have doubled, or even quadrupled, in 

 many classes. New and often conspicuous species are 

 annually discovered in parts of the old continent long 

 inhabited by the most civilized nations. Conscious, 

 therefore, of the limited extent of our information, we 

 always infer, when such discoveries are made, that the 

 beings in question had previously eluded our research, 

 or had at least existed elsewhere, and only migrated at 

 a recent period into the territories where we now find 

 them. 



