THEORY OF THE EARTH. 



collected, it is easy to recognise a considerable 

 number of Fresh-water Tortoises, or Emydes, 

 which further discoveries can alone determine, 

 but of which several are already distinguished by 

 their size and peculiar forms, from all the species 

 hitherto known *. 



It is among these innumerable oviparous 

 quadrupeds, of all sizes and forms ; in the midst 

 of these crocodiles, tortoises, flying reptiles, huge 

 megalosauri, and monstrous plesiosauri, that some 

 small Mammifera are said to make their appear- 

 ance for the first time ; and the assertion is so 

 far authenticated by the occurrence of jaws, 

 and some other bones discovered in England, 

 which undoubtedly belong to this class of ani- 

 mals, and particularly to the family of Didel- 

 phides, or to that of the Insectivora. 



It may, however, be supposed, that the stoney 

 matters which encrust these bones, owe their origin 

 to some local recomposition, posterior to the ori- 

 ginal formation of the strata. However this may 

 be, it is still found for a long time that the class of 

 Reptiles predominates. 



The ferruginous sands, placed in England 

 above the chalk, contain abundance of crocodiles, 

 tortoises, megalosauri, and especially a reptile 



Researches, vol. v. part ii. p. 225. 



