60 THE SKELETON OF THE CAT. 
bones; its floor by the horizontal plates of the palatines, 
maxillaries, and premaxillaries. 
The nasal cavity opens craniad by the large nares (Fig. 
30, J; Fig. 42, r), which are bounded by the premaxillary and 
Fic. 43.—SKULL, MEpIAN LONGITUDINAL SECTION, SHOWING THE CAVITIES. 
J, cerebellar fossa; LZ, cerebral fossa; ///, olfactory fossa. 1, occipital bone; 2, 
interparietal; 363% parietal; 4 temporal (4, squamous portion; 4’, petrous portion; 
4”, tympanic portion); 5, sphenoid; 6, presphenoid; 7, palatine; 8, frontal; 9, max- 
illary; 10, premaxillary; 11, ethmoid; 12, nasal; 13, incisor teeth; 14, canine; 
15, 16, 17, premolars; 18, molar. a, tondyloid canal; 6, hypoglossal canal; ¢, 
jugular foramen; @, internal auditory meatus; ¢, appendicular fossa; /, tentorium; g, 
dorsum sellz; 4, sella turcica; 7, hamular process; 7, pterygoid process of sphenoid; 
, optic foramen; /, presphenoid sinus; , m', frontal sinus; 7, lamina perpendicu- 
laris of the ethmoid (broken at cranial edge). 
nasal bones. In the natural condition this opening is divided 
by a median cartilage which is continuous with the lamina per- 
pendicularis (Fig. 43, 2) of the ethmoid, thus forming a parti- 
tion which divides the nasal cavity into two separate halves. 
From the floor of the cranial part of the cavity rises a ridge 
formed of the nasal crests of the maxillaries and premaxillaries, 
and the cranial portion of the vomer. Farther caudad the 
vomer spreads out in a horizontal plane and separates from the 
floor of the cavity, so that the nasal cavity is thereby divided 
by a horizontal partition into dorsal and ventral portions. The 
ventral portion is small, forming the inferior meatus of the 
nose; it ends caudally at the choanz (posterior nares, Fig. 
1, 0) which lead into the nasopharynx. That portion. 
of the nasal cavity lying dorsad of the vomer is almost com- 
