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 animaFs 
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. 
