ELEPHANTS 713 



head rather than from the withers, owing to the higher car- 

 riage of the head. Other differences are the presence of a 

 nipple on the lower edge of the tip of the trunk as well as 

 the one on the upper, the larger tusks, and the lesser number 

 of hoof-like nails on the margin of the hoof in the African. 

 The genus Loxodonta is a much less specialized group than 

 Elephas^ as shown by the lesser number of enamel plates 

 in the molar teeth and the rounded outline of the dorsal 

 surface of the skull. The enormous size of the ears, the 

 additional nipple on the tip of the trunk, and the lesser 

 number of hoof-like divisions in the feet of Loxodonta are, 

 however, specializations not found in the living representa- 

 tive of the genus Elephas. In skull shape the African is, 

 however, decidedly like the genus Mastodon^ being evenly 

 rounded over the parietal or occipital part, and also convex 

 in profile on the forehead above the nasal opening, instead 

 of concave as in Elephas. In tooth structure it is somewhat 

 intermediate between Mastodon or Stegodon and Elephas, the 

 number of plates being intermediate in number and the teeth 

 narrower and often showing, when unworn, a want of cement 

 on the crown, so that the enamel plates project when unworn 

 as ridges similar somewhat to the condition found in Mastodon. 

 The teeth, however, are long-crowned, as in Elephas, and very 

 different in this character from the short-crowned teeth of 

 Mastodon. The Indian elephant, although having as many 

 as twenty-four plates to its last molar tooth, is not the most 

 highly specialized form in this regard, but such distinction 

 belongs to the recently extinct hairy elephant, or mammoth, 

 Elephas primigenius, of the boreal regions. The plates in 

 the mammoth number as many as twenty-seven in the last 

 molar and were narrower, much more crowded, and longer 

 than in the Indian. The molar teeth of all elephants have 

 progressively more and more ridges as we advance from 

 the first to the last tooth in the order of their succession. 

 Usually only the formula of the last three, or permanent 

 set, is considered. In the African elephant the ridge formula 

 in the permanent molars is: first, 6 or 7; second, 8 or 9; 

 and last, 10 or 12. In the Indian this formula runs usually: 

 first, 12; second, 16; and third, 24. The two living ele- 

 phants are both less specialized than some of the extinct 

 forms belonging to the same genera. In a broader way. 



