490 



THE RABBIT 



segment is completed above by the supraoccipital (s. oc\ 

 bounding the foramen magnum above ; it has a pitted surface 

 and is marked externally by a shield-shaped prominence. 



The middle, or parietal segment, consists of five bones, a 

 basisphenoid (b.spJi) below, an alisphenoid (a.sph,a.s] on either 

 side, and two parietals* (pa) above. The broad posterior 

 end of the basisphenoid is connected with the basiocci- 



fr 



efh 



a. sp, 

 for 



FIG. 133. Skull of rabbit in longitudinal vertical section. The cartilaginous nasal 



septum is removed. 



sph. alisphenoid ; e. oc. exoccipital ; e. tb. ethmo-turbinal ; eth. ethmoid ; fl. fossa 

 for flocculus of brain ; z. incisors ; mx. tb. maxillary turbinal ; n. tb. naso- 

 turbinal ; pal' . palatine portion of the bony palate ; /. sph. presphenoid ; _?. t. 

 sella turcica, or depression in which the pituitary body lies ; I. point at which 

 the olfactory nerves leave the skull ; II. optic foramen ; V inn. foramen for 

 mandibular division of trigeminal ; VII. for facial nerve ; VIII. for auditory 

 nerve ; IX, X, XI, for glossopharyngeal, vagus, and spinal accessory ; XII. 

 for hypoglossal. Other letters as in Fig. 132. 



pital by a thin plate of cartilage, and tapers in front to a 

 blunt point : it is perforated at about its middle by an oval 

 pituitary foramen, and on its upper surface is hollowed out 

 to form a depression in which the pituitary body lies (s. /). 

 The alisphenoids are wing-like bones, directed upwards 

 and outwards, and firmly united with the basisphenoid : each 

 is produced ventrally into a pterygoid process (as\ consist- 



