158 NATURAL HISTORY. 



merely means that they have remained unchanged for the 

 last two or three thousand years ; but every one who has 

 been in the position to appreciate the antiquity of Nature, 

 will readily give the proper value to such a period, as 

 compared with the age of the world. 



Apart from his views as to ' species,' it is to Cuvier that 

 we owe the establishment of a really scientific basis to 

 palaeontology. Cuvier showed that the only method by 

 which the remains of fossil animals could be scientifically 

 investigated, was by comparing them morphologically with 

 the known living forms. In other words, he applied to 

 palaeontology those principles of comparative anatomy 

 which he had used with such brilliant results in his purely 

 zoological investigations. There is, however, an obvious 

 difficulty in the way of the application of the laws of 

 comparative anatomy to fossils in the same way as they 

 can be applied to animals now in existence. In the case 

 of the latter, we have the entire organism before us ; we 

 have not only its skeleton, but also its muscles, nerves, 

 blood-vessels, and internal organs generally. Moreover, 

 in systematic zoology, it is from the soft parts, rather than 

 from the skeleton, that we in many cases draw our most 

 weighty conclusions. In fossil animals on the other hand, 

 with very few exceptions, only the hard parts are preserved 

 for our inspection and examination. If we are to draw 

 any conclusions at all as to the relationships and 

 systematic position of extinct animals, we must do so 

 from the characters and structure of the skeleton alone. 

 Besides, in the case of a great many fossil animals, it is 

 not usual that even the entire skeleton is preserved. In 

 the case of all the Vertebrate animals, at any rate, the 



