1834.] CAUSES OF EXTINCTION. 165 



It is impossible to reflect oil the changed state of the American 

 continent without the deepest astonishment. Formerly it must 

 have swarmed with great monsters: now we find mere pigmies, 

 compared with the antecedent, allied races. If Buffon had known 

 of the gigantic sloth and armadillo-like animals, and of the lost 

 Pachydermata, he might have said with a greater semblance of 

 truth that the creative force in America had lost its power, rather 

 than that it had never possessed great vigour. The greater 

 number, if not all, of these extinct quadrupeds lived at a late 

 period, and were the contemporaries of most of the existing sea- 

 shells. Since they lived, no very great change in the form of the 

 land can have taken place. What, then, has exterminated so many 

 species and whole genera ? The mind at first is irresistibly hurried 

 into the belief of some great catastrophe; but thus to destroy 

 animals, both large and small, in Southern Patagonia, in Brazil, on 

 the Cordillera of Peru, in North America up to Behring's Straits, 

 AVC must shake the entire framework of the globe. An examina- 

 tion, moreover, of the geology of La Plata and Patagonia, leads to 

 the belief that all the features of the land result from slow and 

 gradual changes. It appears from the character of the fossils in 

 Europe, Asia, Australia, and in North and South America, that 

 those conditions which favour the life of the larger quadrupeds 

 were lately co-extensive with the world : what those conditions 

 were, no one has yet even conjectured. It could hardly have been 

 a change of temperature, which at about the same time destroyed 

 the inhabitants of tropical, temperate, and arctic latitudes on both 

 sides of the globe. In North America we positively know from 

 Mr. Lyell, that the large quadrupeds lived subsequently to that 

 period, when boulders were brought into latitudes at which icebergs 

 now never arrive : from conclusive but indirect reasons we may 

 feel sure, that in the southern hemisphere the Macrauchenia, also, 

 lived long subsequently to the ice-transporting boulder-period. 

 Did man, after his first inroad into South America, destroy, as has 

 been suggested, the unwieldly Megatherium and the other Eden- 

 tata ? We must at least look to some other cause for the destruc- 

 tion of the little tucutuco at Bahia Blanca, and of the many fossil 

 mice and other small quadrupeds in Brazil. No one will imagine 

 that a drought, even far severer than those which cause such 

 losses in the provinces of La Plata, could destroy every individual 

 of every species from Southern Patagonia to Behring's Straits. 



