Investigations in South, African Fossil Eeptilia awl Ampliibia. 101 



elevation, broadened at the level of the postorbital bars, and 

 narrowing posteriorly until it forms the median parietal crest. On 

 each side there is a slight supraorbital crest ; and between this and 

 the median ridge is a well-defined channel. The frontal forms half 

 of the supraorbital border. Its greatest length is in the middle 

 line, the sutures with the pai'ietals passing well forward from a 

 point one-third along the parietal crest nearly to the anterior 

 extremity of the supratemporal fossa. 



The postorbital bar differs from that in Euparkeria and the allied 

 Thecodonts in that its upper end is in advance of the lower. The 

 descending portion of the postorbital is thus inclined backwards 

 instead of forwards, lying in front of the ascending process of the 

 jugal. The postorbital forms most of the outer border of the upper 

 temporal fossa, and a small portion of the upper border of the lower 

 opening, anteriorly articulating with the frontal, and posteriorly 

 overlying a portion of the squamosal. Nowhere does it meet 

 the parietal. 



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

 inferior border of the orbit, and articulates with the lachrymal 

 and maxilla. It does not pass up as far in front of the orbit as 

 in Euparkeria. The ascending process lies behind and superiorly 

 interior to the postorbital and is inclined slightly forwaixls. The 

 posterior process forms most of the zygomatic arch, lying outside 

 the quadrato-jugal. 



From the fact that the postorbital bar slopes in almost a pai'allel 

 direction to the quadrate, 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 this it agrees with Euparkeria, 

 Ornithosuchus, and the Theropodous Dinosaurs, and differs from 

 Erpetosuchus. In the relation between the sizes of the temporal 

 openings, and in the shape of the lower opening, this form is 

 sharply marked off from its nearest allies. Moreover, in both 

 Euparkeria and Omithosuchus the quadrato-jugal is a fair-sized bone 

 whose articulation with the jugal passes downwards and forwards, 

 and which passes up in front of the quadrate to meet the squamosal. 

 In this form, however, the quadrato-jugal is a comparatively small 

 flat bone which lies in the lower posterior corner of the fossa, and 

 whose articulation with the jugal passes downwards and backwards. 

 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 



