388 
countenance of the elephant, together with his well-known 
docility, lead to the presumption that this animal must possess 
a brain of considerable magnitude. Although this is really 
the case in a remarkable degree, yet the external skull is by 
no means a measure of the organ within. I now place before 
you a horizontal section of the cranium of this animal; and it 
exhibits two remarkable facts, first, the small space occupied 
by the brain, and secondly, the beautiful and curious structure 
of the bones of the head. To the latter we may first direct our 
attention. The two tables of all these bones, except the oc- 
cipital, are separated by rows of large cells, some from four 
to five inches in size, others very small, irregular, and honey- 
comb-like; these all communicate with each other, and through 
the frontal sinuses with the cavity of the nose, also with the 
tympanum or drum of each ear; consequently, as in some 
birds, they are filled with air, and thus, while the skull attains 
a great size, in order to afford an extensive surface for the 
attachment of muscles, and a mechanical support for the tusks 
or the enormous incisor teeth, it is at the same time very 
light and buoyant in. proportion to its bulk ; a property the 
more valuable, as the animal is fond of the water, and fre- 
quently takes to it, and swims and bathes in deep rivers. All 
these cells are lined by a delicate mucous membrane of a light 
rose colour, being slightly vascular, like that in the frontal 
sinuses, of which cavities these cells may be considered as an 
extension, rather than as analogous to the diploe in other ani- 
mals. The septa between the cells are vertical, and pass from 
the euter table to the inner; they are very hard and vitreous, 
whereas the outer table is of a coarse and porous texture. 
These septa strengthen the whole fabric, the outer table abut- 
ting against them ; some rows are separated from others by 
horizontal shelves. This structure also extends into some of 
the bones of the face, and into those at the base of the era- 
nium, the pterygoid processes, and the condyles of the occipi- 
tal; but all the superior part of the last-named bone is devoid 
of them, the two tables being close and thin, and the bone 
