THE ANIMAL KINGDOM. 



MAMMALIA. 



THE first characteristic of the great class called 

 Mammalia is that from which their name is derived,* 

 viz., that they suckle their young, which are born alive. 



They all breathe air by means of lungs, and have 

 hearts with four compartments two auricles, and two 

 ventricles. The most perfect form of lungs and heart 

 have been shown in the description of those possessed 

 by human beings f for man stands at the head of all 

 created things, and animals are termed "higher" or 

 " lower," according as they approach him in organisation. 



When we speak of the lower animals, however, we do 

 not mean that any one of them is imperfect in its 

 structure, for all are equally fitted for the position in 

 which they are placed, and every created thing, however 

 small or apparently insignificant, bears evidence of the 

 wisdom and design of the merciful Creator of all. 

 Throughout creation we find the most wonderful harmony 

 existing between all the organs of animals and their 

 habits and instincts, so that none of them could ex- 

 change any portion of its structure with another and be 

 equally fitted for its sphere of action. 



So perfect is this organisation, that from a single tooth 

 the student of science can discover the class of the animal 

 to which it belonged, and can speak with certainty of its 

 structure and general habits. 



The teeth, indeed, are organs of great importance in 

 Mammalia, being specially adapted to the food on which 

 the animal is to live, and to its habits of life. Thus man, 

 who is said to be omnivorous (or everything eating), has 

 some teeth of each of the kinds possessed by the other 



* Mamma, the breast. 



t "Our Bodies," Cassell's Primary Series. Pages 6 1 and 68. 



