THEORY OF THE EARTH. 289 



water-rat and domestic mouse *. In the caves 

 of England two species are also found f. 



The osseous brecciae even contain bones of 

 shrew-mice and lizards f . 



In certain sandy strata of Tuscany, there are 

 teeth of a porcupine ||, and in those of Russia 

 heads of a species of beaver, larger than ours, 

 which M. Fischer has named Trogontherium . 



But it is more particularly in the class Edenta- 

 ta that these races of animals belonging to the pe- 

 riod before the last assume a size much superior 

 to that of their present congeners, and even rise 

 to a magnitude altogether gigantic. 



The Megatherium unites a part of the generic 

 characters of the armadilloes, with some of those of 

 the sloths, and is in size equal to the largest rhino- 

 ceros. Its claws must have been of a monstrous 

 length, and prodigious strength; its whole skeleton 

 possesses an excessive solidity. It has only as yet 

 been found in the sandy strata of North Ame- 

 rica^. 



* See my " Researches," vol. iv. p. 1 78, 202, and 206 ; 

 vol. v. part i. p. 54-. 



t Id. vol. v. part i. p. 55. 

 { Id. vol. iv. p. 206. 

 || Id. vol. v. part ii, 517. 

 Id. part i. p. 59- 



IT Id. p. 174; and part ii. p. 519. 



T 



