and organs of hearing of the dugong. 153 
nicated, through the bony connections that have been men- 
tioned, to the ossicula, and from thence to the cochlea, and 
semicircular canals. 
Thi animal, although the tail is horizontal, possesses the 
sense of smell, since there are orifices in the cerebriform 
plate of the skull for the olfactory nerves. 
While this paper was in the press, I have been so fortunate 
as to receive from Sir Thomas Stamford Raffles, another 
skull belonging to a dugong, 8 feet long, in which the milk 
tusks had been shed, and the permanent ones had acquired 
sufficient length to show the degree they project beyond the 
bony sockets, and the manner in which they are worn down, 
by rooting up the plants while feeding. They are consider- 
ably broader than the milk tusks, even at their points, ex- 
plaining the use of the cup at the end of the milk tusk being 
wider than the tusk itself, to admit of the point of the perma- 
nent one having this encreased breadth. 
These tusks bear a near resemblance to those of the hog, 
the points being turned a little outwards, and they wear down 
in the same manner. 
It is not a little remarkable, that in writing this paper upon 
the milk tusks, I should have an opportunity, during an acci- 
dental delay in the press, of being furnished with materials to 
show the appearance of the permanent tusks, which forms so 
essential a character of the animal, and also to prove that 
while young, there are incisors in the lower jaw ; two of 
them in the jaw of this skull having been accidentally en- 
tangled (while shedding,) in the new bone that was closing 
