392 INTRODUCTION TO ZOOLOGY. 



Another appendage to the head, and of great value in a 

 commercial point of view, is that which is popularly, though 

 not very correctly termed " whale-hone. " It is not bone, hut 

 a series of horny plates, the substitutes of the true teeth, which 

 in the whale are altogether wanting. The position of these 

 plates is shown in the annexed figure (Fig. 295); they form 



a complete fringe suspended 

 from the margin of the upper 

 jaw, and when the whale 

 closes its enormous mouth, they 

 act as a seive, permitting the 

 water to pass through, and 

 enabling the animal to retain 

 the small gelatinous and mol- 

 luscous creatures on which it lives. The " Baleen' ' or Whale- 

 bone, is so important an article of trade, that hundreds of 

 tons are annually brought into Britain, won by her intrepid 

 mariners among the perils of the Arctic seas. 



Teeth. We now pass on to the teeth, viewed as instruments 

 for the mastication of food. In man they are thirty-two in 

 number, when the series is complete; and the number is the 

 same both in the Orang and Chimpanzee,* They are of three 



Fig. 295. SKULL OF WHALE. 



Fig. 29S. TEETH OF MAN. 



Molars. 



Premolars. Canine. Incisors. 



kinds, the incisor or cutting teeth, the canine which attain a 

 large development in the Dog and carnivorous animals, and 

 hence derive their name;t and the molar or grinding teeth. 



* Owen's Odontography, 

 f Latin cam's, a dog. 



