SKELETON. 703 
Anomodont reptiles only, The fact that in Rodents the madar does 
not form part of the face is of considerable systematic importance. The 
squamosals form a great part of the posterior side walls of the skull, and 
articulate with the pardetals, frontals, orbitosphenoids, and alisphenoids. 
At the posterior end of the zygomatic arch is the longitudinally elon- 
gated glenoid fossa in which 
the mandible moves back- 
wards and forwards. 
In connection with the floor 
of the skull and the roof of 
the mouth, there lie from be- 
hind forwards the following 
components: — The median 
basioccipital; the median 
basisphenoid, which lodges 
the pituitary body in « dorsal 
depression called the sella 
turcica; the paired alisphen- 
oids fused to the sides of the 
basisphenoid ; the median pre- 
sphenoid, which forms the i 
lower margin of the optic PT. i 
foramen between the two’ * | 
orbits; the paired orbitosphen- G 
oids, fused to the presphenoid, \ 
sutured to the alisphenoids 
and sguamosals, and surround- TB 
ing the optic foramen; the 
vertical pterygoids attached A 
at the junction of basisphenoid 
and alisphenoids; the partly 
vertical padatines, united above : 
to the presphenoid and behind Fyg, 38¢,Under surface of rabbit’s 
to the plerygodds and alisphen- skull. 
oids, separating the posterior inc. I., First incisors; Jc. /7., second in- 
nasal passages from the orbits, “"Cjsorss PALX., premaxilla: PA. PICY., pala. 
and uniting to a slight extent tal process of premaxilla; JZX., maxilla; 
in front to form the posterior are ne 32.5 aieomalic anne ee 
. asisphenoid ; /., posterior part of jugal; 
part of the bony apeeira the BO., basioccipital ; PAR.OCC., paroccipital 
median vertical mesethmoid _ process of exoccipital ; SOC., supraoccipital ; 
cartilage extending in front  C., one of the cendsless Se ae audi: 
1 i tory meatus ; .» tympanic bulla; . 
of the presphenoid, Separating glenoid fossa ; Pr: pterygoid. : 
the two nasal cavities, pos- : aes 
teriorly ossified and expanded into the sieve-like cribriform plates 
through the apertures of which the branches of the olfactory nerves 
pass to the nose; the paired vomers along the ventral edge of the 
mesethmoid ; and lastly, the anterior bony palate (formed from inward 
extensions of maxz//le and premaxitle), which in the rabbit is very 
incomplete. a ; 
Wedged in between the occipitals, the sgzamosals, and the bones of 
the basisphenoid region, there is on each side a periotic bone surround- 
1 
