334 MAMMALS 



Tlie gorilla is the largest of the manlike aj^es, often reach- 

 ing a height of five feet, four or six inches. It lives in deep 

 forests, in a very restricted portion of western Africa in the 

 Congo district. Its forehead retreats strongly, its expres- 

 sion is brutal, and the body is more uniformly covered with 

 hair than that of the chimpanzee. The gorilla naturally 

 walks on all fours, but it can walk erect although rather 

 clumsily. Its ferocity has been exaggerated. 



Man. — As an animal, man belongs to the family Homin- 

 ida' and is known scientifically as Homo sapien.'<. As an 

 animal, he is distinguished for his erect posture, very com- 

 plete o]:)position of the thumb to the fingers, short canine 

 teeth, greater length of hind, as compared with fore limbs, 

 and the great size and complexity of the brain. 



Characteristics of the mammals. — As we ha\'e already 

 learned, the name of the class is derived from the fact that 

 the young are nourished foi- a longer or shorter time on milk, 

 which is a fluid secretion from certain specialized glands 

 known as mammie. Secondly, it may be said that the 

 bodies of mammals, at some period of their existence, are 

 more or less covered with hair, ^^'e have seen from bur own 

 study and observation that many are completely covered 

 with hair, except the nose and soles of the feet. On the 

 other hand, the whales are wholly destitute of hair, or ver\' 

 sparsely clothed with it, in the adult stage : but it is present 

 on portions of the body in eiidiryoiiic whales. Moreovei', 

 the heart, as in birds, cfiiisists of four chatnbei's, the two 

 on one side being comjjletely separated from the two on the 

 other side. Hence, there is a, double circulation. The 

 thorax is se|.xarated from the alxlomen by a strong muscular 

 partition known as the diaphragm. This aids greatly in 

 respiration. The mammals, in general, bring forth theii' 



