44 THE FOOD OF ANIMALS 



EGG-LAYING MAMMALS (MONOTREMES) 



Australia (with New Guinea and Tasmania) is also the home 

 01 the very lowest existing Mammals, the egg-laying Monotremes, 

 of which there are three kinds, the Duck-Mole or Duck-billed 

 Platypus (Ornithorhynchus)) limited to the Australian continent, 

 and two Spiny Ant- Eaters, of which the commoner, Echidna 

 (fig. 335), ranges from New Guinea to Tasmania. Echidna, with 

 its narrow, toothless snout, mobile tongue^ well-developed salivary 

 glands, and powerful digging claws, presents an insectivorous type 

 of structure with which we are now familiar. 



Comparison of the various insect-eating Mammals shows that 

 similar habits are associated with similar peculiarities of structure, 

 and this furnishes a good instance of the same kind of classifica- 

 tory pitfall as the one which led the old zoologists, and still leads 

 the unskilled observer, to consider the whale as a fish. Natural- 

 ists are now beginning to doubt the propriety of grouping the 

 old-world Edentates with those of the new, and it has been pro- 

 posed to create a new mammalian order the Effodientia (i.e. 

 Diggers) for the reception of pangolins and aard-varks. 



