THE BEPTILIAN MAMMALS. 



231 

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CHAPTER XXXII. 

 THE REPTILIAN MAMMALS. 



Befoeb we come to the true mammals^ we should notice 

 two very singular forms which in some important respects 

 are intermediate between the 'reptiles and bir ds an d^Jha- 

 Wgher mammals. These are the duck-bill and spinyant-" 

 eaterTi Besides peculiarities in the breastbone and other 

 parts, one of the most obvious distinctions in these animals 

 is the long, toothless jaws (there are eight horny teeth in 



FiQ. 233.— Duck-bill. Australia. (One-fourth natural size.) 



the duck-bill), which are long and narrow in the Echidna, 

 or broad and flat in the duck-bill {Ornithorhynclius para- 

 doxus), where it is covered by a leathery integument; the 

 external ear is wanting; in these respects they resemble 

 reptiles and birds. 



In the aquatic duck-bill (Fig. 333) the feet are webbed, 

 with claws of moderate size. It is covered with a soft fur, 

 and is a-bgut half a metre (17-33 inches) -long. Its habits 



