XI.] UNGULATA. 175 



The palate is long and narrow, and extends posteriorly 

 beyond the last molar tooth. The pterygoid fossae are well 

 marked, being chiefly formed by the well-developed ptery- 

 goid plates of the alisphenoid ; the true pterygoids are very 

 slender. There are very long, slender, compressed par- 

 occipital processes, curved forwards. 



The squamosal and tympanic are ankylosed together; the 

 floor of the long, narrow, upward-directed auditory meatus 

 is formed by the tympanic, wedged in a cleft of the squa- 

 mosal, between the hinder edge of the glenoid fossa (there 

 being no postglenoid process) and a long descending post- 

 tympanic process which articulates with the exoccipital. 



Inferiorly the tympanic is dilated into a very prominent 

 bulla, peculiarly elongated vertically, and rather compressed 

 from side to side. The interior of this bulla is filled with 

 cancellous bony tissue. 



The periotic is small and not ankylosed to the tympanic or 

 squamosal. The mastoid portion is quite rudimentary, being 

 merely a short scale-like prolongation upwards and back- 

 wards, lying on the inner surface of the squamosal, and 

 making no appearance on the external surface of the skull. 

 The tympanohyals are very inconspicuous, being small, and 

 situated at the bottom of a deep fossa on the outer and 

 posterior side of the tympanic bulla. 



The mandible has a high ascending portion behind, a 

 transverse condyle, a very small coronoid process, and a flat 

 expanded angle, rounded posteriorly. 



The hyoid of the Pig is very different from that of most 

 other Ungulata. The basihyal is very small. The thyrohyals 

 are large, broad and flat, and ankylosed to the basihyal, but 

 with their extremities cartilaginous even in old animals. 

 There is a well-ossified ceratohyal, not ankylosed with the 

 basihyal, but the greater part of the anterior arch is a long 



