490 



THE RABBIT 



CHAPo 



the auditory aperture (aud. me). The occipital 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. sph) below, an alisphenoid (a. sph, 

 as) on either side, and two parietals* (pa) above. The 

 broad posterior end of the basisphenoid is connected 



FIG. 133. Skull of Rabbit in longitudinal vertical section. (Nat. size.) The 



cartilaginous nasal septum is removed. 



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

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

 turbinal ; pal', palatine portion of the bony palate ; p. sph. presphenoid ; s. /. 

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

 the olfactory nerves leave the skull; II, optic foramen; V mn. 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. 



with the basioccipital 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.t). 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), consisting of two 



