312 MAMMALS 



webs of the front feet project beyond the claws, but can be 

 folded back out of the way when the animal digs its bur- 

 row. While young, the animal has four or five teeth on 

 each jaw; but in the adult these are replaced by horny 

 plates. 



The duckbill spends . much of its time in the water, 

 searching for grubs, worms, snails, and, most of all, mussels 

 that live on the bottoms of streams. For a home, the ani- 

 mal digs a burrow in the bank of some stream. The burrow, 

 which has one opening above and one below the surface 

 of the water, extends in a winding manner gradually up- 

 ward, and finally ends in a large cavity made by the parent 

 for the nest, which is several feet above the level of the water 

 and, consequently, dry. The duckbill lays two or three 

 true eggs, with soft, leathery shells. The young hatch from 

 the eggs, and are fed by the milk secreted in the mammary, 

 or milk, glands of the mother. Hence this animal is a true 

 mammal like the horse or the cow. But unlike the cow, 

 horse, and others, the milk glands of the duckbill and the 

 following closely related animal, the spiny ant-eater, have 

 no teats or nipples. 



Spiny ant-eater. — This animal is also found in Australia, 

 but is smaller than the duckbill and differs markedly from 

 the latter in habits and appearance. The ant-eater has 

 its jaws produced into a narrow, bill-like structure and the 

 upper surface of the body is covered with strong, pointed 

 spines, between which are coarse hairs. The limbs are 

 short and strong while every foot has five toes, each of 

 which ends -in a strong claw which enables the animal to 

 burrow in the ground rapidly and efficiently. 



