4 MR. youatt's veterinary lectures. 
first observe them at the termination of the palatine processes of 
the superior maxillary bones, as it were surrounding, but, in fact, 
locked in and supported by, these bones. They form, in all our 
domesticated animals, a smooth round polished border at the point 
where the cavities of the mouth and the nose would terminate in 
one common passage leading on to the pharynx, and which border 
gives attachment to the velum palati, or soft palate, presently to 
be described, that partially or completely separates those cavities. 
If w 7 e trace this bone posteriorly in the horse , we find that it forms, 
on either side, the wall of the continuation of the nasal cavity 
from both nostrils, and which, now undivided, is called the ductus 
communis narium. It is separated from the mouth by the velum 
palati, and leads on towards the larynx. We here observe two 
processes on either side of this canal, one behind the last molar, 
and being the pterigoid process of the sphenoid bone, the other 
further back, and being a styloid, or sharpened process of the pa¬ 
latine bone, and having, in the recent subject, a beautiful carti¬ 
laginous hook or pulley, round which plays the tendon of the 
stylo-palatine muscle, or principal tensor muscle of the velum 
palati. Externally we trace the connexion of this bone with the 
tuberosity of the superior maxillary; and, lying as it were be¬ 
tween these two bones, that singular and important depression or 
hollow leading to the anterior and posterior palatine foramina, and 
the infra-orbital canal. 
The principal difference in the construction of these bones in 
our other patients, consists in their relative bulk. In the ruminant 
the palatine bones occupy a far greater portion of the palate and 
the floor of the nose than they do in the horse. They particularly 
do so in the ox; and the walls of the ductus communis narium 
are considerably deeper. In the hog and the dog the palatine 
bones throw an elliptical portion of no little development down 
the palate. 
The Vomer .—The last bone to be described is the vomer. It 
cannot be said, strictly speaking, to form a part of the floor of 
the cavity of the nose, but it lies along the centre of it, denti¬ 
culated with, and supported by, the suture which unites the pala¬ 
tine processes of the superior maxillary. It is called the vomer, 
from its resemblance to a ploughshare. It reaches from the pala¬ 
tine processes of the anterior maxillary to the sphenoid bone, and 
is composed of a groove which embraces and supports the carti¬ 
lage that divides the nostrils. It continues in contact with the 
floor of the cavity through its whole extent, and when it arrives 
at the ductus communis, it pursues its course along the centre of 
it, unconnected with either of the sides, until it arrives at the 
sethmoid bone, on the body of which it expands, seemingly em- 
