34 PROGRESS OF PALEONTOLOGY n 



working, you will find that his method is neither 

 more nor less than that of Steno. If he was able 

 to make his famous prophecy from the jaw which 

 lay upon the surface of a block of stone to the 

 pelvis of the same animal which lay hidden in it, 

 it was not because either he, or any one else, 

 knew, or knows, why a certain form of jaw is, as a 

 rule, constantly accompanied by the presence of 

 marsupial bones, but simply because experience 

 has shown that these two structures are co- 

 ordinated. 



The settlement of the nature of fossils led at 

 once to the next advance of palaeontology, viz. its 

 application to the deciphering of the history of 

 the earth. When it was admitted that fossils are 

 remains of animals and plants, it followed that, in 

 so far as they resemble terrestrial, or freshwater, 

 animals and plants, they are evidences of the 

 existence of land, or fresh water; and, in so far 

 as they resemble marine organisms, they are 

 evidences of the existence of the sea at the time 

 at which they were parts of actually living animals 

 and plants. Moreover, in the absence of evidence 

 to the contrary, it must be admitted that the 

 terrestrial or the marine organisms implied the 

 existence of land or sea at the place in which they 

 were found while they were yet living. In fact, 

 such conclusions were immediately drawn by 

 everybody, from the time of Xenophanes down- 

 wards, who believed that fossils were really 



