THE TEETH OF MAMMALS 117 



cial forms of teeth are developed for the per- 

 formance of special functions. Thns there are 

 teeth for prehension, for cutting, for crushing, 

 and for mastication. The grinding teeth are 

 highly elaborated, for mastication has become an 

 important factor in the more highly complicated 

 digestive system. The teeth are important to the 

 alimentary system, for by them food is secured 

 and reduced to prepare it for digestion, so that 

 their office is indispensable. 



The teeth vary in number among mammals, — 

 from the single tooth of the Narwhal to the hun- 

 dreds of teeth of the Dolphins. The primitive 

 form of teeth, the simple cone, is presented by the 

 fishes and reptiles, with but little variation, but 

 in the Mammalia there is wide departure from 

 the primitive typal cone. This is modified and 

 duplicated to an extensive degree to furnish the 

 many forms found among mammals. The primi- 

 tive cone is modified to adapt the teeth to the per- 

 formance of their various functions, — i.e., pre- 

 hension, cutting, and mastication. 



The attachment of the teeth in mammals is by 

 but one method, — that of implantation in a bony 

 socket, or Gompliosis. The roots are single or 

 divided into two or more fangs. Sometimes the 

 roots are completed and the apex closed except 

 the small foramen for the vessels supplying the 

 pulp with nutrition, or again the pulp may be 



