100 A FOSSIL CONTINENT 



digenoiis culture, were still, to be aure, in their stone age ; 

 but it was a very dillerent stone age from that of the cave- 

 dwellers or mound builders in Britain. Even so, though 

 Australia is still zoologically in the secondary period, it is 

 a secondary period a good deal altered and adapted in detail 

 to meet the wants of special situations. 



The oldest types of animals in Australia are the 

 omithorhynchus and the echidna, the 'beast with a bill,' 

 and the ' porcupine ant-eater ' of popular natural history. 

 These curious creatures, genuine living fossils, occupy in 

 some respects an intermediate place between the mammals 

 on the one hand and the birds and lizards on the other. 

 The echidna has no teeth, and a very bird-like skull and 

 body ; the omithorhynchus has a bill like a duck's, webbed 

 feet, and a great many quaint anatomical peculiarities 

 which closely ally it to the birds and reptiles. Both, in fact, 

 are early arrested stages in the development of mammals 

 from the old common vertebrate ancestor ; and they could 

 only have struggled on to our own day in a continent free 

 from the severe competition of the higher types which have 

 since been evolved in Europe and Asia. Even in Australia 

 itself the omithorhynchus and echidna have had to put up 

 perforce with the lower places in the hierarchy of nature. 

 The first is a burrowing and aquatic creature, specialised 

 in a thousand minute ways for his amphibious life and 

 queer subterranean habits ; the second is a spiny hedge- 

 hog-like nocturnal prowler, who buries himself in the earth 

 during the day, and lives by night on insects which he 

 licks up greedily with his long ribbon-like tongue. Apart 

 from the specialisations brought about by their necessary 

 adaptation to a particular niche in the economy of life, 

 these two quaint and very ancient animals probably 

 preserve for us in their general structure the features of 

 an extremely early descendant of the common ancestor 



