i 7 o THE POPULAR SCIENCE MONTHLY. 



of a block of stone to the pelvis of the same animal which lay hidden 

 in it, it was not because either he, or anybody 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 ad- 

 vance of paleontology 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 ter- 

 restrial or fresh-water 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. More- 

 over, 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 every- 

 body, from the time of Xenophanes downward, who believed that fos- 

 sils were really organic remains. Steno discusses their value as evi- 

 dence of repeated alteration of marine and terrestrial conditions upon 

 the soil of Tuscany in a manner worthy of a modern geologist. The 

 speculations of De Maillet in the beginning of the eighteenth century 

 turn upon fossils, and Buffon follows him very closely in those two 

 remarkable works, the " Theorie de la Terre " and the " Epoques de 

 la Nature," with which he commenced and ended his career as a natu- 

 ralist. 



The opening sentences of the " Epoques de la Nature " show us 

 how fully Buffon recognized the analogy of geological with archaeolog- 

 ical inquiries. " As in civil history we consult deeds, seek for coins, 

 or decipher antique inscriptions in order to determine the epochs of 

 human revolutions and fix the date of moral events, so, in natural his- 

 tory, we must search the archives of the world, recover old monu- 

 ments from the bowels of the earth, collect their fragmentary remains, 

 and gather into one body of evidence all the signs of physical change 

 which may enable us to look back upon the different ages of nature. 

 It is our only means of fixing some points in the immensity of space, 

 and of setting a certain number of way-marks along the eternal path 

 of time." 



Buffon enumerates five classes of these monuments of the past his- 

 tory of the earth, and they are all facts of paleontology. In the first 

 place, he says, shells and other marine productions are found all over 

 the surface and in the interior of the dry land ; and all calcareous 

 rocks are made up of their remains. Secondly, a great many of these 

 shells which are found in Europe are not now to be met with in the 

 adjacent seas ; and, in the slates and other deep-seated deposits, there 

 are remains of fishes and of plants of which no species now exist in 



