270 
THE FRONTAL BONES 
nose, and lodges in the sinus. He suffers more than the sheep 
from this cause, but not so frequently, for the frontal sinuses of 
the ox seem to be more the accidental than natural and regular 
habitation of these insects. 
He is, however, sometimes seen in great pain, holding his 
head low, and carrying it on one side. This is not from the irri¬ 
tation of these insects, but from the pus which has been eff used 
within the sinuses, collecting about the root of the horn. If the 
horn is cut off, a very great quantity of matter often escapes, 
or, at all events, the inflammation is much relieved by the copious 
bleeding that inevitably follows. 
In the sheep the frontal bones are less developed. They are 
more convex both in the homed and polled variety ; and in both 
the parietal bone, as the specimens will shew you, is permitted to 
occupy its usual situation on the roof of the cranium, and the ridge 
is formed by the occipital bone. The ridge or crest is, however, con¬ 
siderably depressed in both. It is so far depressed as to be out of 
all danger when the animals amuse themselves by butting each 
other. A very small portion only of bone, actually covering the 
brain, can receive the concussion of the rude encounter. If these 
bones, and the all important organ they cover, are not protected, 
as in the horse, by the yielding resistance of the temporal muscle, 
they are more effectually preserved by their being depressed out of 
the way of danger. 
The horn, as in the ox, springs from the frontal bone, but much 
nearer to, and a little above the orbit of the eye. The frontal 
sinus in the polled sheep is more confined than in the horse. 
There is a singular and irregular depression on either side where 
the horn should have sprung, which limits the extent of the sinus 
backward; but in the horned sheep the sinus reaches to the horn, 
and through it. In neither is there any separation of the plates of 
the bone at the posterior part of the frontal in the young animal; 
but when the horn is nearly grown, the sinus penetrates through 
the frontal, but never reaches the parietal. This is a singular dif¬ 
ference in the construction of these bones in two homed animals, 
the ox and the sheep. 
The foramen supra-orbitarium passes through the frontal sinus 
in both the polled and the horned variety ; and, as in the ox, 
there is a comparatively greater surface for the vessels to supply, 
there are usually two foramina on either side, and the vessels, 
at their exit from the bone, are defended by a sulcus or trench ; 
and especially as these animals, like the ox, make too free use of 
their heads in combat, and the vessels might be injured. 
In order to afford space for the attachment or origin of the horn, 
the orbitar portion of the frontal bones projects both forward and 
