THE RABBIT 325 



On each side of the nasals is the maxillary bone, which bears the 

 premolar and molar teeth (the grinders), and in front of them the 

 intermaxillary, or premaxillary, bone, with the incisor teeth ; these 

 bones form the upper jaw. Projecting backward from the maxil- 

 lary on each side is its zygomatic process, which forms the anterior 

 portion of the zygomatic arch. The middle portion of the arch is 

 formed by the malar bone, which is often fused with the process. 



Exercise 48. Draw a view of the dorsal aspect of the skull, with out- 

 lines of the bones which appear. 



Exercise 49. Draw a view of the posterior aspect ; carefully label all 

 the structures mentioned. 



The Lateral and Ventral Aspects. The temporal bone occupies 

 the space between the orbit and the occipital bone and is seen in 

 its entire extent. It is made up of three principal portions : a dor- 

 sal expanded portion, the squamosal, which bears the zygomatic 

 process ; a tympanic portion, which forms the tympanic bulla and 

 the external auditory meatus; and the petrous portion, which is 

 the hinder and inner part and contains the inner ear. The petrous 

 portion bears the mastoid process, which is a slender projection 

 lying in front of and parallel to the long, slender jugal process of 

 the occipital bone and against the bulla. Immediately in front 

 of the mastoid process is the stylomastoid foramen, through 

 which the facial nerve finds an exit from the cranial cavity. Note 

 the glenoid cavity. Note in the lateral surface of the upper jaw the 

 extensive fenestrated area of the maxillary bone. 



In the ventral aspect of the skull, at its hinder end, the large 

 basi-occipital bone is seen extending forward between the tym- 

 panic bullae, and directly in front of it in the median area the 

 basisphenoid, a narrow triangular bone the apex of which is 

 directed forward. In the middle of the basisphenoid is a round 

 hole which leads into the interior of the bone. Extending laterally 

 and dorsally from the basisphenoid on each side is the broad wing, 

 or alisphenoid, which forms a large part of the hinder wall of the 

 orbit ; it extends forward also, to meet the hinder end of the pala- 

 tine bone, this part being the pterygoid process. This prominent 

 process projects ventrally; it has a curved form (being concave 



