JR. 8. Lull — Evolution of the Elephant. 



173 



The development of the trunk has been accompanied by a 

 marked change in the character and form of the skull, which 

 is merely a mechanical adaptation to provide the leverage 

 necessary to wield so weighty an organ. This has been brought 

 about by a shortening of the skull accompanied by a corre 

 sponding increase in height. The result is that the base of the 

 trunk has been brought much nearer the fulcrum at the neck, 

 thus shortening the weight arm of the lever, while the increas- 

 ing height not only lengthens the power arm but gives more 

 surface for the attachment of muscles and the great elastic 

 Mg amentum nuchce which aids in supporting the head. 



Fig. 4. Sectioned skull of Indian elephant ; after Owen. 



This change in the form of the skull, while it gives to the 

 physiognomy of the animal that dignified, intellectual look, 

 does not imply a similar development of the brain, for the 

 brain case has increased but little, the great size of the skull 

 being largely due to the development of air cells in the cranial 

 bones so that the actual thickness of the roof of the skull is 

 greater than the height of the brain chamber itself, a feature 

 well shown in fig. 4. 



The Teeth. 



It is generally true among mammals that the normal num- 

 ber of teeth in the adult is forty-four, eleven in each half of 



