On Tu-o Neir Species of Dicynodonts . 453 



bones are irregularly quadrangular in shape, and form the upper 

 margin of the orbits to the extent of about 45 mm. In front where 

 the frontal meets the prefrontal and the nasal the breadth is 47 mm., 

 while behind where it joins the post-orbital the breadth is 55 mm. 



The post-orbital on the left side is moderately complete, though 

 slightly crushed. Where it forms the posterior border of the orbit 

 it is fairly massive and averages 23mm. in breadth. On its posterior 

 edge is developed a well-marked ridge which passes almost directly 

 upwards, inwards, and backwards, forming the anterior border of 

 the temporal fossa, and then curving mainly upwards and backwards 

 forming the side of the parietal crest. As it appears in the present 

 condition the anterior part of the parietal crest rises abruptly from 

 the frontal plane and forms with it an angle of about 120. As that 

 part of the post-orbital bone which is preserved is scarcely appreciably 

 injured, and as the lower portion which forms the post-orbital arch 

 is somewhat displaced forwards, it necessarily follows that the 

 parietal crest must originally have formed a less obtuse angle with 

 the frontal than in the present condition. 



The parietal is partly missing, and the exact development of the 

 anterior part has not been displayed. 



In front, the frontals meet the prefrontals and the enormously 

 developed nasals. The prefrontals are irregularly triangular in 

 shape. The outer side forms the border of the orbit for a distance 

 of about 35 mm. The articulation with the frontal measures about 

 28 mm., and that with the nasal about 37 mm. ; while the articula- 

 tion with the lachrymal, not counting that portion within the orbit, 

 measures about 17 mm. 



The lachrymal is moderately large and meets the prefrontal, the 

 nasal, the maxillary, and the malar bones. It extends forwards 

 from the margin of the orbit for a distance of 35 mm. 



The nasals are of large size, and together form as large a roofing 

 as is formed by the frontals and prefrontals together. Down the 

 middle line where the bones of the two sides meet there is formed a 

 well-marked ridge which rises to the height of about 7 mm. above 

 the arch of the nasals. The nasals form a gentle curve in an antero- 

 posterior direction, while, they form laterally a very regular arch 

 interrupted only by the median ridge. In the fossil the anterior 

 part of the nasals is missing, but from the position of the back of 

 the nostril which is preserved it is probable that but little of the left 

 nasal is lost. The length of the nasals would probably be about 

 95 mm. ; while the greatest breadth of each nasal measuring round 

 the arch is 60 mm., and the transverse breadth of the two nasals 



