14 6 Sir Everard Home on the milk tusks, 
bones of the ear are not represented; and as in that stage 
of the animal's growth they have no bony connection with 
the skull, there is sufficient evidence of their having belonged 
to a young animal. Another skull is in the collection of 
comparative anatomy belonging to Mr. Brookes, in London. 
In that also the organs of hearing are wanting. The third 
is in my possession, and is the subject of the present obser- 
vations ; in this the bones of the ear on both sides of the skull 
are preserved, although they have acquired no bony connec- 
tion with the skull. 
The first examination which it occurred to me to make, 
was respecting the length of the tusks, the points of which 
were the only parts exposed. For this purpose, one of the 
bony canals, composed of the bones of the face in which the 
tusk is contained, was laid open, and one of the tusks was 
removed from its socket, and a longitudinal section after- 
wards made of it. The whole of its substance was found to be 
solid, showing that it had arrived at its full growth, and was 
therefore only a milk tusk : at the posterior extremity there 
was a small shallow cup composed of the same materials, which 
appeared to be no part of the tusk itself, but, as it were, fixed 
to the end of it. This was contained in a corresponding cavity 
adapted to it, in the skull ; but upon the upper surface, the 
bony table of the skull was entirely removed to some extent 
by absorption, so that the shallow cup at the root of the tusk 
was exposed externally, giving the skull at that part a very 
extraordinary appearance. In Mr. Brookes’s specimen, the 
aperture through the external table of the skull is to a less 
extent, than in my specimen, but exactly of the same kind. 
In M. Cuvier's skull, there is no appearance of any breach in 
