CHART V 



MAMMALS 



In the Mammals we reach the highest forms of animal'Hfe, the final order 

 including Man himself. The lowest forms include the Monotremes, or 

 Egg-Laying Mammals, and the Marsupials, or Pouched Mammals. The 

 gradual ascent upward is shown on the above chart, reading from right 

 to left. Mammals differ from other animals in the following characters: 

 the possession of hair, mammary glands or breasts, a high blood tempera- 

 ture, a four-chambered heart, a diaphragm, and a highly developed nervous 

 system. In the above chart a general world survey is made, except that, 

 under Rodents, only the American families could be included, because 

 of the very large number of these little Gnawers all over the world. 



