THE TRIUMPH OF THE MAMMALS 97 



v/ill give another glimpse into the machinery of 

 nature if we describe it. 



At the time when the earliest mammals appeared, 

 towards the end of tlie Permian Ice Age, South Africa 

 and Australia were, as we saw, connected by land. It 

 was in that part of the world that the little early 

 mammals lived. We find their bones in South Africa 

 and their living representatives in Australia and New 

 Guinea. They wandered from Africa to Australia; 

 or, as is more probable, they were evolved on the lost 

 continent, which is now beneath the waves of the 

 Indian Ocean, and travelled east and west. Anyhow, 

 they overran the country which we now call Australia. 

 But during the Age of Reptiles the land between 

 Africa and Australia foundered. One might almost 

 say that, when the early mammals reached Australia, 

 the gates were closed behind them. Australia became 

 an island. So when, in the course of time, lions and 

 tigers and other carnivorous mammals were evolved 

 in the rest of the world, they could not reach Australia, 

 and its very primitive population slumbered on until 

 early man and his dog came along to disturb them. 



That is why we find primitive mammals in Aus- 

 tralia. The most primitive is a small furry creature, 

 about the size of a rabbit, which is often called in 

 English nature books the "Duckmole," because it 

 has a beak something like the duck's and it burrows 

 in the banks of the streams. Australians generally 

 call it the Platypus, or, if they have been to Melbourne 



