60 COMPARATIVE DENTAL ANATOMY 



of simple conical shape and are employed for pre- 

 hension only. The "sheep-head" possess an- 

 terior teeth which resemble the incisors of a sheep 

 and ronnd crushing teeth in the posterior region. 

 Most of the lower mammals are deficient in regard 

 to cutting teeth, the teeth being all of the molar 

 type for grinding. The higher forms possess 

 well-marked typical incisors. Thus the incisors 

 of the Herbivora are well developed for cutting 

 purposes. In the Camivora the incisors are re- 

 duced, for the cutting function is usurped by the 

 long blades of the sectorial premolars and molars. 

 In the Marsupials, Insectivora, Rodentia, Cheirop- 

 tera, and others the incisors are specially devel- 

 oped for special purposes. In the Quadrumana 

 they foretell the form of these teeth in man, which 

 they resemble, in whom incisors are formed by 

 the modification of the single cone,— the base be- 

 ing flattened to form a cutting edge. 



The Canines. This tooth is the first succeeding 

 the incisors, and is immediately distal to the inter- 

 maxillary suture. It is implanted in the maxil- 

 lary bone proper above, and is probably modified 

 from the premolar series. It is called the Canine 

 from being extra well developed in the dog and 

 other carnivorous animals. It is the principal 

 prehensile tooth in mammals, and is therefore 

 first in function, though second in position in the 

 dental series. It is implanted by a single root, 



