47S THE RABBIT chap. 



inner and anterior region of each is given off, op- 

 posite the third cheek-tooth, a horizontal, inwardly 

 directed process [pal'), which, articulating in the middle 

 line with its fellow of the opposite side and in front 

 with the palatine process of the maxilla, forms the pos- 

 terior part of the bony support of the hard palate. The 

 pterygoids are small irregular plates of bones attached 

 to the posterior edge of the corresponding palatine and the 

 pterygoid process of the alisphenoid ; each ends ventrally 

 in a backwardly curved process. 



The squamosals * {sq) are a pair of plates which overlap 

 and complete the side-walls of the brain-case (p. 474) in 

 front of the periotics : they articulate with the frontals, 

 parietals, orbitosphenoids, and alisphenoids. From the 

 outer face of each is given off a strong zygomatic process, 

 which bears on its under surface the articular facet for 

 the lower jaw, and further back a slender process 

 [p.t.sq.) arises which is applied to the outer surface 

 of the periotic. 



The zygomatic processes of the squamosal and maxilla 

 respectively are united by a flat bar of bone, the jiigal* (y)i 

 which in the adult is fused with the last-named bone. 

 All these three bones therefore take part in forming the 

 zygomatic arch. 



Most of ihe apertures for the transmission of tlie cerebral nerves have 

 so far not been mentioned ; the branches of the olfactory nerve, as we 

 have seen, pass out through the numerous apertures in the cribriform 

 plate (P"ig. 123, e//i), and the optic foramen {II) is situated between the 

 orbitosphenoid and presphenoid. Behind and below the optic foramen 

 is a vertical aperture — the sphenoidal fissure isph.f] — between the basi- 

 sphenoid and alisphenoid, which transmits the third, fourth, and sixth 

 nerves, as well as the opththalmic and maxillary divisions of the fifth. 

 Between the periotic and alisphenoid is a large space (Vw«), through 

 the anterior part of which the mandibular division of the trigeminal 



