8 MR. YOUATTS VETERINARY LECTURES. 
stated, under the valve-like structure of the prolongation of the 
lower cell of the oethmoid bone. 
In oxen the superior turbinated bone is small and simple, and 
is almost destitute of convolutions. It is evidently merely sup¬ 
plementary to the sethmoid, and its function is diminished and 
rendered unnecessary by the development of that bone. This is 
more particularly so in the dog , where the turbinated bones are 
reduced to utter insignificance by the bulk of the sethmoid. 
The inferior turbinated bone in the horse is more porous 
than the superior one; it is also more convoluted, and the con¬ 
volutions are not a little complicated. The gauze-like structure 
of this bone is worthy of notice, and also the different manner in 
which the two cornets are convoluted ; the upper portion of the 
superior bone being most closely attached to the walls of the 
cavity, and the lower border lying comparatively loose;—the re¬ 
verse taking place with the lower turbinator. The inferior turbi- 
nator lies along the superior maxillary, below its union with the 
nasal. Neither of them can be separated from the bony parietes 
of the cavity by maceration, but they are too readily broken off 
in our dry preparations. A prolongation of the lower turbinator 
extends over the inner ala of the false nostril, and may be readily 
seen by lifting the nostril. It has, sometimes, been mistaken for 
a morbid tumour, or minute polypus. The hollow pedicle which 
runs down thus far has no outlet, but seems designed to give sup¬ 
port to the inner ala of the false nostril. Comparative anatomists 
speak of the connexion between the two turbinated bones, but I 
have never been able satisfactorily to trace it. 
In the ruminants , the inferior turbinated bone is more deve¬ 
loped, and particularly in the sheep, so as to fill up, as it were, 
the whole of the cavity, accounting for the readiness with which 
that animal is blown when he is a little hurried. In the dog this 
bone is very small, but is curiously complicated. We need in 
him both speed and scent; this bone is also unusually convo¬ 
luted, and the nasal cavity is left more open. 
The Meatus. —You will perceive that these bones divide the 
cavity into three distinct meatuses or channels; the superior one 
lies between the superior turbinated one and the nasal bone, con¬ 
stituting the roof of the cavity, and it even extends above, and 
by the side of the sethmoid bone, to the cribriform plate, and it is 
closed at its superior termination. It is defended from the access 
of the external air, or, at least, from any violent current of air, 
by the development of the false nostril at its lower part. It is 
an interposed space to defend the sethmoid bones from injury if 
the nasals should be fractured: and the air, loitering as it were 
