48 WHAT EVOLUTION IS 



active state. Two of them, however, 

 the Australian porcupine and the 

 duckbill, lay eggs. These two mam- 

 mals, in addition to the habit of 

 laying eggs, have many primitive char- 

 acteristics. They constitute the low- 

 est group of this class of animals. 

 They are commonly designated as 

 monotremes. The remarkable feature 

 about them, from the standpoint of 

 the present discussion, is that they are 

 not found broadcast over the earth 

 but are limited to a very distinct zoo- 

 geographical area, the Australian 

 region. Thus the total representation 

 of this striking group of forms is re- 

 stricted to a small part of the globe. 



The Australian region is not only 

 the habitation of the monotremes; it 

 is also the home of the marsupials. 

 These are mammals, such as the pha- 

 langers, the wombats, and the kan- 

 garoos, the females of which are 



