268 BIG ANIMALS 



dominant type of the whole planet. In the trias we get 

 the first remains of mammalian life in the shape of tiny 

 rat-like animals, marsupial in type, and closely related to 

 the banded ant-eaters^of New South Wales at the present 

 day. Throughout the long lapse of the secondary ages, 

 across the lias, the oolite, the wealden, and the chalk, we 

 find the mammalian race slowly developing into opossums 

 and kangaroos, such as still inhabit the isolated and anti- 

 quated continent of Australia. Gathering strength all the 

 time for the coming contest, increasing constantly in size 

 of brain and keenness of intelligence, the true mammals 

 were able at last, towards the close of the secondary ages, 

 to enter the lists boldly against the gigantic saurians. 

 With the dawn of the tertiary period, the reign of the rep- 

 tiles begins to wane, and the reign of the mammals to set 

 in at last in real earnest. In place of the ichthyosaurs we 

 get the huge cetaceans ; in place of the deinosaurs we get 

 the mammoth and the mastodon ; in place of the domi- 

 nant reptile groups we get the first precursors of man 

 himself. 



The history of the great birds has been somewhat more 

 singular. Unlike the other main vertebrate classes, the 

 birds (as if on purpose to contradict the proverb) seem 

 never yet to have had their day. Unfortunately for them, 

 or at least for their chance of producing colossal species, 

 their evolution went on side by side, apparently, with that 

 of the still more intelligent and more powerful mammals ; 

 so that, wherever the mammalian type had once firmly 

 established itself, the birds were compelled to limit their 

 aspirations to a very modest and humble standard. Ter- 

 restrial mammals, however, cannot cross the sea ; so in 

 isolated regions, such as New Zealand and Madagascar, the 

 birds had things all their own way. In New Zealand, there 

 are no indigenous quadrupeds at all ; and there the huge 



