ELEPHANTS. 87 



The nasal aperture is on the top of the skull, and directed nearly 

 vertically upwards ; but in the living animal it forms the base of 

 the elongated trunk, at the extremity of which are the real external 

 nostrils. The great size of the skull, which is necessary for the 

 support of the heavy tusks and trunk, is produced by an unusual 

 development of air-cells in the cranial bones, so that the outer 

 surface of the skull of an old elephant is often nearly a foot 



Fig. 46. 



Skull of African Elephant (Elephas africanus). 



distant from the inner wall of the brain-case, the latter increasing 

 but little in size as the animal gets older. These air-cells may be 

 seen in the longitudinal section of an Indian Elephant's skull in 

 Division B ; or, through the bullet-holes, in the skull of the old 

 " rogue" Elephant mounted in the Saloon. 



Elephants possess no lower incisors, and the single upper pair 

 form the great ivory tusks ; there are no canines ; the molars are 

 remarkable in that their succession does not take place in a ver- 

 tical direction, as is usual among mammals, but from behind for- 

 wards. Never more than one, or portions of two, molars are in use 

 at any one time, and as that is pushed forwards and finally falls 

 out, the next one behind it takes its place. In this way six molars 

 are successively brought into use and shed during the animal's 

 life. The inverted skull in the Saloon shows the manner of this 

 succession very well, the fifth tooth of the series being in place 

 both above and below, with the sixth and last one ready formed 

 behind to take its place. 



