Natural History 453 



1 



The Egg-laying Mammals 



There are three strange Australian mammals that occupy a 

 position quite by themselves the Duckmole (Ornithorhynchus) , 

 the Spiny Ant-eater (Echidna), and another ant-eater (Proe- 

 chidna). They differ from all other mammals inasmuch as they 

 lay eggs, thereby harking back to the habit of many reptiles. 

 In the form of their shoulder-girdle, in their relatively large eggs 

 with much yolk, in their very variable temperature, and in many 

 other ways they betray their affinity with reptiles, and they must 

 be regarded as very primitive mammals persisting from ancient 

 days. 



The Duckmole, or Duck-billed Platypus (18-20 inches in 

 length) lives beside lakes and streams, and grubs at the bottom 

 or among water-weed for small animals, which it collects in 

 cheek-pouches and chews at leisure with its eight horny tooth- 

 plates. For its true teeth do not last for more than a year. Its 

 fore-feet are webbed, and it is a clever swimmer and diver. But 

 the feet are also clawed, and the quaint creature makes a long 

 burrow in the bank, with two openings, one above and one under 

 the water. The jaws are flattened like the bill of a duck and 

 covered with soft sensitive skin, expanded into a flexible collar 

 where the bill joins the rest of the skull. The eyes are small; 

 the ear-holes are closed by a flap ; the tail is strong and helps in 

 swimming; the brownish fur is short and soft; the animal can 

 roll itself up into a living ball, and sleeps in this attitude. In 

 the recesses of the burrow two eggs are laid, each about three- 

 quarters of an inch long, enclosed in a flexible white shell, through 

 which the young one has to break its way. There are no teats 

 or mamma? for the young one to suck, and the milk simply oozes 

 out by numerous pores on a bare patch of skin on the ventral 

 surface of the mother. It is licked up by the offspring a very 

 primitive arrangement. 



The Spiny Ant-eaters live in rocky regions and burrow 



