xxix. 4 TEETH 711 



elephants, forming the two enormous upcurved tusks, up to 11^ ft 

 long in Loxodonta, composed of solid dentine except for a temporary 

 cap of enamel at the tip. This mass of ivory is no doubt useful for 

 defence and perhaps in food collection, but it seems to be a consider- 

 able waste of calcium and phosphorus, not to mention of the energy 

 necessary to carry the 350 lb weight. This weight is balanced against 

 that of the body, upon the pillar-like front legs, and it is perhaps not 

 fantastic to suggest that the tusks serve partly as counterweights, for 



/77./ rn.m.4 



Fig. 474. Skull of young Indian elephant. The roots of 



the teeth have been exposed. 

 al. alisphenoid; bo. basioccipital; eo. exoccipital ; /. frontal; 

 j. jugal; m. maxillary; m.i. first molar; tn.m. J and 4. third and 

 fourth milk molars; p. parietal; pm. premaxillary ; so. supra- 

 occipital; sq. squamosal. (After Reynolds, The Vertebrate 

 Skeleton, Cambridge University Press.) 



purposes of balance (see p. 697), extravagant though such an arrange- 

 ment may be. However, the weight of the head is reduced by extensive 

 development of air sinuses between the inner and outer tables of the 

 bones of the skull. The tusks are smaller in females and in the Indian 

 than in the African elephant; in the female Indian elephant they do 

 not project beyond the lips. This difference may be connected with 

 the relatively small size of these females. 



The essential features of the grinding apparatus are the immensely 

 large molars (Fig. 473), with numerous sharp transverse ridges, by 

 which all sorts of plants, including hard grasses, are chopped into 

 small fragments. There are three small premolars, which are soon 

 shed, and the three molars are then developed in a series and used 

 one after the other. By a special arrangement of the palate (Fig. 474) 

 the teeth are allowed to form high up in the skull, so that each tooth 

 has a very great area, made up by the fusion of as many as twenty- 



