The Mammals and Man 



intelligent of the animal kind. They show refinements of the 

 senses of sight, hearing, and smell such as are met with nowhere 

 else. They range from the Equator to the coldest regions of the 

 earth in which any food is to be found ; they people alike the 

 forest and the plain, and have their representatives both in the 

 air and in the sea. 



The most lowly of the mammals are the Monotremes, which 

 include the well-known Australian duck-mole or duck-billed 



Fig. 105. — The Australian Duck-mole or Duck-billed Platypus. 



platypus, and two species of spiny ant-eaters, one of which is 

 found in Austraha, the other in New Guinea. The two types are 

 shown in Figs. 105 to 107. The best-known and most striking fact 

 concerning these is that, hke the birds and reptiles, and unlike 

 all other mammals, they lay eggs. Beyond this feature they 

 show many affinities with the reptiles, in their skeleton for ex- 

 ample, and particularly in their reproductive organs. Another 

 interesting fact is that the blood temperature, of the ant-eater at 

 least, is low, and varies considerably. It has been found to 



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