CHAPTER XIV 



THE ELEPHANTS AND SEA COWS 



Distribution of the Elephants— Characters of the Elephant 

 dentition — Evolution of the Elephant — Features of the 

 Sireniaii dentition — Origin and relationships of the 

 Sirenia. 



PROBOSCIDEA 



Five species of Elephant exist today, four of them in Africa 

 and a single one in Asia but though the varieties and range 

 of this animal are now greatly restricted, it was distributed in 

 former times over the whole world except Australia, even pene- 

 trating into South America and Avas in consequence adapted 

 for every kind of climate from subarctic to tropical. The 

 Elephant gives striking conformation of a general principle in 

 mammalian structure, namely, that teeth and skull are much 

 more progressive than the skeleton in general: Elephants of 

 middle Miocene times are scarcely distinguishable in skeletal 

 features from those of the present day although very marked 

 changes have occurred in the dentition and skull. 



To look at the example of young Indian Elephant figured 

 (Elephas maximus, Fig. 79) one would Avonder from Avhat 

 sort of ancestral form its teeth have been dem^ed, for they are 

 among the most specialized of all teeth, consisting as they do 

 of a number of transverse plates of dentine coated on both sides 

 Avith enamel and held together by cementum. Further in mode 

 of eruption the Elephant molars differ from those of all other 

 Mammals in that the successional tooth does not displace its 

 predecessor vertically but erupts obliquely from behind and 

 above in the maxilla, behind and below in the mandible. 



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