Structure and Affinities of the Endothiodont Beptiles. 263 



The frontals are broad and probably short. The frontal region is 

 slightly concave from side to side, and probably also somewhat 

 concave in the antero-posterior direction. 



At the outer and posterior parts of the frontal region are two very 

 prominent ridges which pass backwards and inwards to form the 

 sides of the parietal crest. These ridges are formed mainly by the 

 post-orbitals, but the most anterior part of each ridge is formed either 

 by the frontal or by the post- frontal. Only a small part of the post- 

 orbital part of the post-orbital bone is preserved, but the greater part 

 of the posterior process is in good condition. This posterior portion 

 forms, as in Anomodonts generally, practically the whole of the 

 inner border of the temporal fossa. 



The parietals are no doubt long and narrow bones, but they are 

 almost completely hidden by the post-orbitals. There is probably 

 a large parietal foramen situated about 5 or 6 cm. behind the plane 

 of the post-orbital arch. 



Of the occiput there are preserved the centre part showing the 

 large condyle, and the foramen magnum, and the whole of the lower 

 part of the left side including the ex-occipital, the lower part of the 

 squamosal and the quadrate. 



The squamosal so far as preserved resembles pretty closely that 

 of Dicynodon and Oudenodon. There are, however, one or two 

 points of difference. As in the Dicynodonts generally the squamosal 

 may be divided into three main parts : the part extending inwards 

 to meet the parietal, the zygomatic portion which passes forwards to 

 meet the jugal, and the descending portion which supports the 

 quadrate. There is reason to believe that beyond the place of union 

 of the zygomatic portion with the main part, the squamosal is con- 

 tinued backwards a considerable distance as a trough-like bony plate. 

 From the centre of radiation of the bone which lies near the point of 

 union of the zygomatic portion, the squamosal in Endothiodon 

 appears to send inwards and downwards a well-developed process to 

 articulate with what is probably either the supra-occipital or the 

 ex-occipital. The state of preservation is not such as to enable one 

 to determine the structure of this portion of the occiput. The shape 

 of the lower part of the squamosal will be better understood by 

 reference to the figure than by description. 



The quadrate bone lies as in the Dicynodonts, below and in front 

 of the lower part of the squamosal. Though it is impossible to 

 describe the bone with any degree of certainty owing to the condition 

 of the specimen, it would appear as if the bone was fairly similar in 

 structure to that of Dicynodon and Oudenodon. The upper portion 

 spreads out like a fan and lies against the concave descending 



