504 COMPARATIVE ANATOMY AND PATHOLOGY. 
be most useful to him. Most of the breeds of cattle being armed 
with horns, the head, and particularly the forehead, of these animals 
is strongly formed. With this view it is pleasing to compare the 
comparatively thin orbital ridge of the horse with the thickened 
projecting quadrilateral one of the ox. 
In the Sheep. — The bony structure connected with the visual 
organs is very different in the sheep. The frontal bones project 
considerably both forward and laterally, in order to afford in both 
directions sufficient space for the origin of the horn : therefore it is 
that the forehead of the sheep is so much broader, and the eyes 
have so much greater prominence, than in most other animals. 
The Situation of the Eyeball. — That which Mr. Percivall says 
of the horse is true of our other domesticated animals : “ The eye- 
ball is placed within the anterior or more capacious part of the 
orbit — nearer to the frontal than to the temporal side — with a degree 
of prominence peculiar to the individual — and, within certain limits, 
variable at his will. 
The ferocious Look of the Carnivora. — In carnivorous animals 
the orbit is much developed, and in some of them encroaches on the 
bones of the face. A singular effect is also produced on the coun- 
tenance, both when the animal is growling over his prey, as well as 
when he is devouring it. The temporal muscle is violently acted 
upon ; it presses on the cartilage that forms part of the external ridge 
— that again presses upon and protrudes the eye, and hence the 
peculiar ferocity of expression which is observed at that time. The 
victims of these carnivorous animals are also somewhat provided 
against the danger by the acuteness of sight with which they are 
gifted, and which will be spoken of in its proper place. 
The Protections of the Eye. — The eye is well protected by a 
bony socket beneath, and on the inside, but is partially exposed on 
the roof and on the outside. It is, however, covered and secured 
by thick and powerful muscles, to be hereafter described — by a 
mass of adipose matter which is distributed in various parts of the 
orbit, and by the orbital sheath of considerable density and firm- 
ness, and, especially where it is most needed, on the external and 
superior portions. 
This adipose matter exists in a considerable quantity in the orbit 
of the horse, and enables the eye readily to revolve by the slight- 
est contraction of the muscles. By the absorption of it in sickness 
or old age, the eye is not only to a certain degree sunk in the orbit, 
but the roof of the orbit posterior to the frontal bone, being deprived 
of its support, is considerably depressed. I will not disgrace this 
lecture by referring to the rascally contrivance by which this indi- 
cation of age is, in some degree, removed. 
A greater mass of fat is found in the eye of the ox, and renders 
