SECTIONS. 51 
part of the anterior portion of the cranial 
cavity. 
The facial portion of the skull is separated from 
the cranial cavity by the cribriform plate, 
which is lodged between the _ pre-sphenoid, 
orbito-sphenoids, and frontals. It is further 
divided into two tube-like portions (better seen 
in tranverse section), which constitute the nasal 
cavities. The median partition is formed by 
the mesethmoid cartilage, which is situated in a 
eroove of the vomer, the dorsal portion of which 
is produced into a thin vertical plate and also 
enters into this dividing septum, in the ventral 
portion. The sides of the vomers are laterally 
produced and form a partial division between 
the nasal cavity and the olfactory chamber (see 
transverse section D). The anterior and pos- 
terior portions of the nasal cavities are filled 
by a series of infolded laminze of bone—the 
maxillo-turbinals and ethmo-turbinals ; inferi- 
orly are a similar series—the naso-turbinals. 
Enclosing the nasal cavities and _ olfactory 
chamber, and forming the outer wall of the 
facial portion of the skull, are the nasals, 
maxilla, premaxilla, palatines, and pterygoids. 
Viewed in longitudinal section, only a small 
portion of these bones are visible. The nasals 
form the dorsal portion of the nasal cavities, 
and articulate with the frontals; they are situ- 
ated immediately above the ossified mesethmoid 
