THE VOYAGE OF THE BEAGLE 101 



pletely frozen, that the carcass of an animal embedded in it 

 is perfectly preserved. With these facts we must grant, as 

 far as quantity alone of vegetation is concerned, that the 

 great quadrupeds of the later tertiary epochs might, in most 

 parts of Northern Europe and Asia, have lived on the spots 

 where their remains are now found. I do not here speak of 

 the kind of vegetation necessary for their support; because, 

 as there is evidence of physical changes, and as the animals 

 have become extinct, so may we suppose that the species of 

 plants have likewise been changed. 



These remarks, I may be permitted to add, directly bear 

 on the case of the Siberian animals preserved in ice. The 

 firm conviction of the necessity of a vegetation possessing 

 a character of tropical luxuriance, to support such large 

 animals, and the impossibility of reconciling this with the 

 proximity of perpetual congelation, was one chief cause of 

 the several theories of sudden revolutions of climate, and of 

 overwhelming catastrophes, which were invented to account 

 for their entombment. I am far from supposing that the 

 climate has not changed since the period when those ani- 

 mals lived, which now lie buried in the ice. At present I 

 only wish to show, that as far as quantity of food alone is 

 concerned, the ancient rhinoceroses might have roamed over 

 the steppes of central Siberia (the northern parts probably 

 being under water) even in their present condition, as well 

 as the living rhinoceroses and elephants over the Karros 

 of Southern Africa. 



I will now give an account of the habits of some of the 

 more interesting birds which are common on the wild plains 

 of Northern Patagonia; and first for the largest, or South 

 American ostrich. The ordinary habits of the ostrich are 

 familiar to every one. They live on vegetable matter, such 

 as roots and grass; but at Bahia Blanca I have repeatedly 

 seen three or four come down at low water to the extensive 

 mud-banks which are then dry, for the sake, as the Gauchos 

 say, of feeding on small fish. Although the ostrich in its 

 habits is so shy, wary, and solitary, and although so fleet 

 in its pace, it is caught without much difficulty by the In- 

 dian or Gaucho armed with the bolas. When several horse- 



