28 



ZOOLOGY. 



animals, even mammals, are wholly wanting, as in the ant- 

 eater (Fig. 29). 



52. In animals which do not masticate, but merely 

 seize their prey with the teeth, as in crocodiles, and many 

 other reptiles, all the teeth resemble each other : they have 



Fig. 17. Head of the Gavial or Gangetic Crocodile. 



the form of hooks or cones : but in animals which masticate, 

 the teeth have different forms and uses. 



Fig. 18. Mouth of Balsenoptera 

 Kostrata, or smaller Korqual.* 



Fig. 19. Skull of the Lion. 



Thus, in man and most mammals there exist three kinds 

 of teeth : 1. The teeth called incisive, which have a sharp 

 cutting edge. 2. Conical teeth, which in many animals pro- 

 ject beyond the plane of the others ; these are the canine 

 teeth. 3. Others, called molar, whose broad and irregular 

 surface points out their use in the trituration of the food. 



The mode of implantation of these teeth in the jaws differs, 

 as well as the form of the corona, being, in fact, in accordance 



* The mouth of the smaller Rorqual; it has no teeth in either jaw ; the 

 food is caught , by the whalebone in the upper jaw. From a sketch made 

 from life by my former assistant, E. J. Forbes. 11. K. 



