THE PECULIAR 'POSSUM 



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of the 'possum, show that it is a very primitive 

 mammal, one of the very oldest mammals, so close 

 to the beginning of the mammalian line that there 

 are only two other living " animals " (we can hardly 



call them mammals) older and more primitive the 

 porcupine ant-eater, and, oldest of all, the duck-bill, 

 not " older " at all perhaps, but only more primitive. 

 For the duck-bill, though classed as a mammal, 

 not only has the bill of the duck, but also lays eggs 

 like the birds. The porcupine ant-eater likewise 

 lays eggs, and so seems almost as much bird or rep- 

 tile as mammal. And as the birds and reptiles lived 

 upon the earth before the age of mammals, and are 

 a lower and more primitive order of creatures, so 

 the duck-bill, the porcupine ant-eater, and the 'pos- 

 sum, because in their anatomy they are like the birds 



