33 
ON THE NOSTRILS OF THE HORSE. 
cartilages towards the centre of the nose, and so expand the nos¬ 
tril in that direction. These muscles are not found in the hog, to 
whom they could be of very little use. Then there is the dilata¬ 
tor lateralis, proceeding from the point of the ridge of the supe¬ 
rior maxillary, and inserted on the outer side of the nostril. This 
muscle will draw the side of the nose outwards and backwards, 
and so dilate the nostrils outwardly. Both these muscles acting 
together, and dilating the nostril both outwardly and inwardly, 
will very considerably enlarge the external orifice. The dilatator 
lateralis is an exceedingly powerful muscle in the hog, to give 
flexibility to his nasal spade. The absence of the former, which 
could scarcely be useful to this animal, and the extraordinary size 
and strength of the other, are pleasing illustrations of the adap¬ 
tation of animals to their situation and destiny. Another muscle, 
the nasalis longus, comes from the union of the superior maxil¬ 
lary and malar bones, and is partly inserted into the false nostrils 
and dilates them. 
The False JSostrils. —These are singular contrivances. They 
are duplicatures of the skin, but thinner and more flexible ; they 
are blind pouches or bags which fill up the lower side of the nos¬ 
tril. Their use has never been satisfactorily explained. In some 
measure they give additional expansion to the nostril; but, when 
examined more closely, they serve, and particularly in laborious 
breathing, and, when the current of air would be exceedingly 
strong, to divert it from the superior meatus, the peculiar seat of 
smell, and the most sensitive part of the nostril, and where its 
violence might be injurious, and to direct it into the lower meatus, 
whence it will more readily find its way to the trachea and lungs. 
Another muscle by which the nostrils, both true and false, are 
expanded, is the levator labii superioris alceque nasi , from the 
superior portion of the nasals, and even from the frontal bones 
to the upper lip, and to the skin of the nose, and the false nos¬ 
trils. This muscle is not found in the hog, for in the construc¬ 
tion of his muzzle it would be powerless. 
The nasalis brevis is a triangularly-shaped muscle, occupying 
the unattached sides of the nasal bone, and of the opposite and 
corresponding border of the anterior maxillary, and connected 
with the whole of the interposed substance of the soft nostril; 
evidently tightening this substance, and so somewhat enlarging 
the orifice of the nostril, but more employed in supporting it, and 
preventing it being too much dilated. This is a muscle of little 
development and 
the dog. 
All these muscles are employed in dilating the nostrils, and, in 
rapid progression, they have as much as they can do to dilate 
VOL. V. F 
power in the sheep and hog, and not found iii 
