14 
Mr. Home's Lecture 
terminating of one abruptly in the other ; but the two edges 
are bevilled off, and laid over each other for nearly one-tenth 
of an inch in the eye of the goose, and more where the eye is 
larger. In the recent state, the thin edge of the cornea is 
readily torn off from the inner surface of the sclerotic coat to 
which it adheres, so as to show this mode of union. This cir- 
cumstance was known to Haller, and is particularly de- 
scribed in his works. 
There is a bony rim surrounding the basis of the cornea in 
the eyes of birds, which is peculiar to this class of animals. It is 
made up of a number of different parts, very commonly 13 in 
number; some of these are lapped over each other, but some 
have an irregular union, one part passing before, and the 
other behind the bony scale next to it. This bony circle, 
thus made up, is not equally broad in its different parts ; it 
is broadest where it covers the upper and outer part of the eye, 
and narrowest where it covers the cornea towards the inner 
canthus. 
This bony rim does not give an origin to the cornea, as 
might appear to a superficial observer, but is a bony hoop laid 
over the junction between the sclerotic coat and cornea ; and 
as the thin edge of the cornea passes within the sclerotic coat, 
the principal attachment of the bony rim must be to that coat. 
The bony rim is adapted to the surface upon which it lies ; 
the greatest part of its breadth is firmly connected to the scle- 
rotic coat ; and where the cornea projects, the anterior edge 
of the rim is turned forwards to correspond with that projec- 
tion ; here the scales are extremely thin, they terminate in a 
fine edge, and admit of being forced a little asunder, to adapt 
them to the stretched state of the cornea ; but no such effect 
