166 GEOLOGICAL SITUATION AND 



Recent The recent annihilation of a great number of species enables us to 



Annihila- 

 tions, realize more fully the changes which are going on in the animal creation. 



For example, a considerable number of animals have been swept off from 

 the British Isles during the historic period. Among these are the bear, 

 the wolf, the elk, &c. Even in America, during the comparatively short 

 period of its history, species have vanished, and others are following them. 

 The beaver, formerly so generally spread over the whole country, is now 

 only to be found in remote regions. The deer and the moose are disappear- 

 ing in the same manner. The buffalo is very much diminished in numbers, 

 and must, ere long, be extirpated. In other parts the Dodo and the Dinor- 

 mis have perished within the last two centuries, and the Apterix is 

 undergoing the same fate. These animals have fallen by the hand of man. 

 But many species are constantly perishing from natural and inevitable 

 causes ; such, for example, as extensive inundations, earthquakes, volcanoes, 

 and the action of the winds. Various species undergo a gradual extinction 

 by changes which deprive them of their accustomed food ; and, finally, others 

 seem to die out from unknown causes. 

 conciu- We have no means of determining, at present, Avhich of these causes 



have destroyed the North American Mastodon. Vegetation appears to be 

 the same as when the latest of the Mastodons lived, since we find, with 

 skeletons of these animals, evidences of food derived from plants which are 

 still existing. Nor is there any reason to believe the climate may have 

 undergone any remarkable alteration at the period of their destruction, or 

 that the winds or floods have had an agency in accomplishing it. 



Notwithstanding, therefore, the possibility of conceiving many causes 

 which may partly account for the destruction of the Mastodon, we cannot 

 point out any one adequate to the annihilation of the 'whole race. 



sion. 



