TUSKS. 195 



INCISORS. 



There are six incisors in each jaw, known as the pinchers, 

 intermediate, and corner teeth. Those of the upper jaw are 

 larger than those of the lower ; the corner teeth are the largest, 

 the intermediate are next in size, and the pinchers are the small- 

 est. The incisor teeth have a large crown, on the extremity of 

 which there are three eminences or tubercles, that in the centre 

 being the largest, which gives it somwhat the form of a clover- 

 leaf, or fleur-de-lis. The internal face is beveled off and sepa- 

 rated from the root of the tooth by a distinct ridge. The external 

 face is convex in both directions, and is smooth and shiny. The 

 root is very large, it is flattened from side to side, and is sepa- 

 rated from the crown by a well-developed neck. The root is 

 very firmly imbedded in the deep alveolar cavities. The virgin 

 root contains a large dental pulp-cavity, whicli, however, be- 

 comes obliterated at an early period. When the incisors are 

 worn by the friction of food and the thousand-and-one foreign 

 bodies which the dog '' handles " with its mouth, the central 

 tubercle is first used, then the lateral tubercles, and last the 

 whole crown is worn, showing an irregular table of dentine, 

 surrounded by enamel, and having in its centre a dark spot 

 corresponding to the obliterated dental cavity. 



The surface of the teeth is of a brilliant white, as, in the 

 dog, they are not covered with cement as in the other animals. 

 The temporary and permanent incisors are alike in form and 

 shape, but the former are very much smaller than the latter, 

 and, as the head and jaw of the young dog are relatively large, 

 the temporary incisors cannot occupy the whole arch, and so 

 have spaces between them showing the gum, while the larger, 

 permanent teeth, when virgin, are just in contact with each other 

 by their free extremities. 



TUSKS. 



The dog has four tusks, which are very prominent and 

 give the name of canine teeth to the corresponding teeth which 

 resemble them in the other animals. They are placed one each 

 side of each jaw, dividing the space between the incisive arch 



