XL UNGULATA. ' 171 



extends considerably on the side of the face, and posteriorly 

 sends a process upwards to meet the postorbital process of 

 the frontal, and is continued backwards to join the zygomatic 

 process of the squamosal. 



The palate bones {PI) are of moderate extent; their 

 horizontal plate is deeply notched posteriorly. The pterygoids 

 {Pt) are broad above, but end below in a narrow lamella, 

 with a hamular process projecting backwards. The basi- 

 occipital {BO), seen from below, is square, with eminences 

 for muscular attachments at each of its four angles. The 

 basisphenoid {BS) is much contracted laterally. The pos- 

 terior clinoid processes are large, and the pituitary fossa 

 deep. 



The squamosal is small, and scarcely appears in the interior 

 of the skull. The glenoid facet is rather extensive, and 

 slightly convex, and there is a postglenoid process and 

 foramen. The tympanic is not ankylosed to the periotic; it 

 forms a complete tubular external auditory meatus, and a 

 considerable, but simple, bulla, narrowing to a sharp-pointed 

 process anteriorly (7)'). The periotic {Per) is rather small, 

 without any fossa for the flocculus ; its mastoid portion 

 forms a distinct, narrow, rough surface on the outer side of 

 the skull, between the hinder border of the squamosal and 

 the exoccipital. The tympanohyal is very large, cylindrical, 

 curved, and almost completely embedded in the tympanic, 

 between the inferior wall of the meatus and the outer wall 

 of the bulla. 



The extracranial portion of the hyoid consists of large 

 coitipressed stylohyals {sh), with a prominent posterior 

 process near the upper end, short but well-ossitied epi- 

 hyals (eh) and ceratohyals {ck), and a basihyal represented 

 by a small rounded nodule of bone, to which the straight 

 thyrohyals {th) are not ankylosed. 



