348 Annals of the South African Museum. 



The jugal is a tripartite bone. Its anterior process forms the 

 inferior border of the orbit, and articulates with the lachrymal and 

 the maxilla It does not pass up in front of the orbit as in Eupar- 

 keria. The ascending process lies behind and superiorly internal to 

 the postorbital and is inclined slightly forward. The posterior pro- 

 cess forms most of the zygomatic arch, lying outside the quadrato- 

 jugal. 



The lower temporal opening has a rhomboidal shape, being bounded 

 by the postorbital, jugal, quadrato-jugal, quadrate, and squamosal. 

 It is slightly bigger than the upper opening. 



In both Euparkeria and Ornithosuchus the quadrato-jugal is a 

 fair-sized bone whose articulation with the jugal passes downward 

 and forward, and which passes up in front of the quadrate to meet 

 the squamosal. In this form, however, the quadrato-jugal is a com- 

 paratively small flat bone which lies in the lower posterior corner 

 of the lower fossa and whose articulation with the jugal passes 

 downward and backward. It lies under the jugal and overlaps part 

 of the quadrate. There is no foramen between it and the quadrate. 



The quadrate is a long, strongly developed, fixed bone with a 

 somewhat expanded lower end. Its upper end is fixed between the 

 squamosal and the opisthotic. The external surface shows a well- 

 marked longitudinal depression at the lower end of the upper 

 half. The front edge of the bone is thin, the posterior border well 

 rounded. 



The squamosal is a strong bone, articulating with the postorbital, 

 quadrate, parietal, opisthotic, paroccipital, and exoccipital. It forms 

 the outer posterior corner of the skull, t. e. half the outer and poste- 

 rior borders of the supratemporal fossa. It passes over on to the 

 occipital plate and takes part in the border of the small posttem- 

 poral foramen. 



The parietal has a strong median crest which divides posteriorly 

 and forms the upper border of the occipital plate. The bone passes 

 over this lateral crest to form part of the occipital plate. It articu- 

 lates on the plate on the inner side with the supraoccipital, on the 

 outer with the squamosal, and below with the exoccipital, forming 

 a small part of the bolder of the posttemporal fossa. Anteriorly the 

 bone articulates with the frontal, and below with the opisthotic and 

 alisphenoid. As in Ornithosuchus there is no interparietal, 



The foramen magnum is an oval opening 12 mm. high and 10 

 mm. broad, lying high in the skull but well in the lower half of 

 the occipital plate. 



The supraoccipital forms a very small portion of the upper border 



