The =nostrils= are situated on the muzzle, with which the upper lip
blends. They are shaped somewhat like a comma, with the broad part next
to the septum and the narrow part directed backward and outward. The
skin around the nostrils is bare, usually black, and in health moist and
cool. The muzzle is marked by a median furrow (philtrum) or a deep
fissure in some breeds. The cartilaginous framework is formed
essentially by the septal cartilage and the parietal cartilages which
proceed from it. The septal cartilage projects beyond the premaxilla,
and is much thickened at its extremity; it gives off from its upper and
lower margins the two parietal cartilages, which curve laterally and
toward each other. A grooved plate extends outward from the septal
cartilage in the floor of the nostril, and another lamina supports the
alar fold of the inferior turbinal bone.
The length of the =nasal cavity= varies greatly in different breeds,
corresponding, of course, to the length of the face. The cavity is
roomy, but is very largely occupied by the turbinals and the lateral
masses of the ethmoid bone. The =middle meatus= is short and narrow, and
divides posteriorly into two branches; the upper branch leads to the
ethmoidal meatuses; the lower branch joins the inferior meatus. The
=inferior meatus= is very small in its middle part, owing to the great
development here of the inferior turbinal. The posterior part of the
nasal cavity is divided by a horizontal plate, the lamina transversalis,
into an upper olfactory part and a lower respiratory part. The sinuses
have been described (_vide_ Osteology).
[Illustration: