SKELETON. 



703 



Anomodont reptiles only. The fact that in Rodents the malar does 

 not form part of the face is of considerable systematic importance. The 

 sqtiamosals form a great part of the posterior side walls of the skull, and 

 articulate with fazparietals^f rentals > 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 a dorsal 

 depression called the sella 

 turcica ; the paired alisphen- 

 oids fused to the sides of the 

 basisphenoid ; the median pre- 

 sphenoid, which forms the 

 lower margin of the optic pr 

 foramen between the two <"" 

 orbits; the paired orbitosphen- 

 oids, fused to the presphenoid, 

 sutured to the alisphenoids 

 and squamosalSi and surround- 

 ing the optic foramen ; the 

 vertical pterygoids attached 

 at the junction of basisphenoid 

 and alisphenoids ; the partly 

 vertical palatines, united above 

 to the presphenoid and behind 

 to \h& pterygoids and alisphen 



NCI 

 -INCH 



PMX 

 >A.PMX 



m.occ 



FOR: 



S.OC 



FIG. 385. Under surface of rabbit's 

 skull. 



oids, separating the posterior ,_.... T ,, , . 



, Inc. /., First incisors; Inc. //., second in- 



nasal passages from the < >its, dsors . PMX . t premaxilla ; PA. PMX., pala- 

 tal process of prems>xilla ; MX., maxilla; 

 PAL., palatine; Z , zygomatic arch; BS., 

 basisphenoid ; /., posterior part of jugal ; 

 BO., basioccipital^ PAR.OCC., paroccipital 

 process of exoccipital ; SOC., supraoccipital ; 

 C., one of the condyles ; A ^W., external audi- 

 tory*' meatus ; TB., tympanic bulla; GF. t 

 glenoid fossa ; P T., pterygoid. 



and uniting to a slight extent 

 in front to form the posterior 

 part of the bony palate ; the 

 median vertical mesethmoid 

 cartilage extending in front 

 of the presphenoid, separating 

 nasal 



the two nasal cavities, pos- 

 teriorly ossified and expanded into the sieve -like cribriform piates 

 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 maxilla and premaxilte), which in the rabbit is very 

 incomplete. 



Wedged in between the occipitals, the squamosals, and the bones of 

 the basisphenoid region, there is on each side a periotic bone surround- 



