5 
NASAL CAVITY IN THE HORSE, &C. 
bracing it; and two processes like the ears of a cat project still 
more posteriorly, and terminate on the sphenoid bone. It does 
not, however, closely adhere to the eethmoid bone, but there is a 
space between them, towards the centre, through which nerves and 
bloodvessels pass to the nostril, and particularly to the cartilagi¬ 
nous septum. 
The difference between this bone in the horse and in cattle, 
principally consists in its articulating in the latter with the maxil¬ 
lary bones only, and not with the palatine, so that in them the 
nasal cavity is not divided through its whole extent, but there is 
a communication under the vomer, before w r e arrive at the ductus 
communis, and this communication is more or less extensive in 
proportion to the space occupied by the palatine bone in the floor 
of the cavity. In consequence of the vomer being thus separated 
from the palatines, and likewise of the depth of the palatine sur¬ 
faces that line the ductus communis, the vomer seems in cattle 
and sheep to be deeply buried between them. The groove of the 
vomer is likewise deeper in cattle than in the horse ; for if it den- 
ticulates only with a part of the floor, it is necessary that it should 
more deeply embrace the septum, in order to give it sufficient 
support. 
The Septum .—The central w 7 all of division between the cavities 
of the nose is a cartilaginous, and not a bony one. It is of con¬ 
siderable thickness and strength, embedded in the channel of the 
vomer below, firmly adhering to the suture of the nasals above, 
and extending from the points of the nasals anteriorly, to the de¬ 
scending floor of the frontal sinuses, and to the cribriform plate 
of the aethmoid bone posteriorly. It divides the cavity of the 
nose into two equal parts, and is placed in the centre for the pur¬ 
pose of strength. I have stated that the nasal bones are liable to 
injury; they are occasionally fractured ; but this firm and elastic 
cartilage placed under the crown of the arch affords a very con¬ 
siderable support, and a support of a peculiar nature, a gradually 
yielding resistance, that neutralizes almost anv force that can be 
applied. 
We shall see, by and by, that the membrane lining the nasal 
cavity is a highly sensitive one, and peculiarly liable to accident 
and disease. The inflammation excited will rapidly spread, and 
the whole of the cavity may participate in it; thence would arise 
pain and swelling, and difficulty, or impossibility, of breathing 
through a passage previously nearly filled with the apparatus be¬ 
longing to the sense of smell. There is one species of inflamma¬ 
tion, insidious and fatal, to which the horse and his varieties are 
alone exposed, viz. that of glanders. This interposition, then, of 
the septum is a wise and benevolent provision to hinder the spread 
