R. S. Lull — Evolution of the Elephant. 



175 



greatly when given improper food. The number of plates in 

 the largest teeth varies from ten or eleven in the African ele- 

 phant 'to twenty-seven in the Indian. The hairy mammoth 

 had the most numerous and finest plates of all, representing in 

 this respect the culmination of evolution. 



The tusks are merely modified incisor teeth of the upper 

 jaw which continue to grow throughout life. They are com- 



5 a 



56 



Fig. 5. Crown view and section of a molar tooth, original. 



posed entirely of dentine or ivory of a superlative quality, the 

 enamel being reduced to a small patch at the tip which soon 

 becomes worn away. The tusks have various uses, but their 

 primitive purpose is for digging. The African elephant is so 

 industrious a digger that the right tusk is always the shorter, 

 as it has to bear the brunt of the work. Tusks are so small 

 as to be apparently absent in the female Indian elephant and 

 often in the male, while they are present in both sexes in the 

 African species. In size they are always much smaller in the 

 Indian form, as seventy-six pounds is the maximum weight for 

 a single tusk, while the greatest recorded size of those of the 

 African elephant is 10 feet f inches in length by 23 inches in 

 circumference at the base, with a weight of 221 pounds for 

 the right tusk, while the left measured 10 feet 2>\ inches in 



