312 MAMMALS 



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

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

 row. AVhile yovuifi, the aniinal has four or Hve teeth on 

 each jaw; Ijut 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 "f all, nmssels,-' 

 that live on the bottoms of streams. l<'or a home, the ani- 

 mal digs a liurrow in the liank of some sti'eani. The burrow, 

 which has one opening aJ)0\'e and one f)el(jw the surface 

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

 ward, and finally ends in a largt' ca\'ity made l)y the parent 

 for the nest, which is several feet abo\'e the level of the water 

 and, conse<|uently, dry. The duckljill lays two or three 

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

 the eggs, and are fed l)y the milk secrete(l in the manuiiary, 

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

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

 horse, and f)tliers, the milk glands of the duckfiill and the 

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

 no teats or nipijles. 



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

 but is smaller than the dnckbill and differs markedly from 

 the latter in habits and a|)|X'arance. The ant-eati'r has 

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

 upper surfac(> of the body is co\'ered with strong, pointed 

 spines, bet\\'ecn which are coarse hairs. The limbs are 

 short and sti'ong while e\-ery foot has K\'e toes, each of 

 which ends in a strong claw which enables the animal to 

 burrow in the ground raiiidly and efficiently. 



