68 THE TRIAS AND OOLITE. 



Creatures who, in his infinity of device, was to turn it all to 

 his use the historical being of the world ! It has been sup- 

 posed by some geologists, that there was a special adaptation 

 of the earth at this time to its predominating tenants, as 

 if it presented only low muddy coasts and marshes fit for the 

 residence of reptiles. And it has been thought that this state 

 of the earth is what led to the existence of so many reptiles. 

 But all such speculations rest on insecure grounds. When 

 we consider that the Age of Reptiles, as it has been called, is 

 interposed between an age of fishes and an age of mammals, 

 reptiles being also intermediate to these in the animal scale, 

 we cannot but surmise that the fact depends on some organic 

 law, rather than upon one in physical geography. An obser- 

 vation of some importance to this question is made by Mr. 

 Darwin in his Journal. Describing the Galapagos islands in 

 the Pacific Ocean, where turtles and lizards replace the her- 

 bivorous mammalia, and are the predominating forms of life, 

 he says " The geologist, on hearing this, will probably refer 

 back his mind to the secondary epochs, when lizards, some 

 herbivorous, some carnivorous, and of dimensions comparable 

 only with our existing whales, swarmed on the land and in 

 the sea. It is, therefore, worthy of his observation, that this 

 archipelago, instead of possessing a humid climate and rank 

 vegetation, cannot be considered otherwise than extremely 

 arid, and, for an equatorial region, remarkably temperate." 



