440 APPLIED BIOLOGY 



five well-formed toes with claws, and the large canine teeth. 

 A rudiment of the toe which does not touch the ground may 

 be seen in dogs. It is the first, i.e., towards middle of the 

 body. In seals and walruses the limbs are especially adapted 

 for swimming. 



(5) The head and fore feet of moles are well adapted for 

 burrowing in soil. 



(6) The trunk (proboscis) of elephants is an extension 

 of the nose. The* tusks of ivory are enormously developed 

 teeth (incisors) of the upper jaw. The tusks of the walrus 

 are upper canine teeth. 



(7) Nearly all the apes and monkeys are well adapted to 

 arboreal life. This is obvious when we watch the ways in 

 which they use their hands and feet in climbing. 



(8) The pouch (marsupium) of kangaroos and opossums 

 is a special adaptation for protecting the young, which are 

 born in an exceedingly undeveloped condition. Inside the 

 pouch are milk-glands for supplying food. 



(9) The horns and antlers of cattle, sheep, goats, and deer 

 are adaptations for defense. Antlers of male deer are shed 

 annually, and new ones grow rapidly. Both male and female 

 reindeer have antlers. The hollow horns of cattle, sheep, 

 goats, and antelopes are not shed. 



(10) The skin of rhinoceroses, elephants, and hippopotami 

 is enormously thickened, making them difficult to kill even 

 with powerful guns. 



(11) The mass of long hairs forming a mane along the dorsal 

 surface of necks of horses and their near allies protects against 

 bites, for horses can fight more viciously with their jaws than 

 with their hoofs. 



(12) The teeth of the rodents are specially modified for 

 gnawing wood, nuts, and other plant materials. 



(13) The skin of many carnivors is in winter well protected 

 by close-set hairs which form furs. Examples of great 'com- 

 mercial value are seals, foxes, minks, bear. The hairs of 



