170 COMPARATIVE DENTAL. ANATOMY 



longed into the form of round, curved tusks, which 

 sweep outward and upward to the length of sev- 

 eral feet. The African Elephant has larger tusks 

 than the Indian species, and they sometimes reach 

 the length of eight feet and weigh one hundred 

 and fifty pounds. The tusks are incisors and not 

 canines, which is shown by the fact that they are 

 inserted in and supported by the premaxillary 

 bones, which are enlarged and prolonged to sup- 

 port them. These tusks grow from persistent 

 pulps, and are subject to disease and injuries. 

 Gunshot and spear wounds sometimes reach the 

 pulp in the immature portion of the tooth, and 

 give rise to abscesses which affect the develop- 

 ment of the dentin. Sometimes resorption of the 

 root is caused by the larva of a dipterous insect 

 in India, and the tusk is so weakened that it 

 breaks off. There are no lateral incisors or ca- 

 nines in the Elephant, and probably no premolars, 

 although from the peculiar mode of succession of 

 the molars the premolars and true molars cannot 

 be distinguished. Six molar teeth (Fig. 73) are 

 developed on each side of each jaw which succeed 

 each other from behind forward, moving in a 

 groove. One molar, or parts of two only, are in 

 use at one time, and when one is worn out it has 

 been pushed up to the anterior end of the groove, 

 where it is partially absorbed and shed. Its suc- 

 cessor then advances slowly to take its place, and 



