1906.] DIAPTOSAURIAN REPTILE. 593 



perhaps in front there may be only one or two rows. Behind, 

 there are four rows of similar-sized obtusely pointed teeth, and on 

 the inner side of the bone three additional rows of more minute 

 teeth, which apparently do not meet the dentaiy and are unworn. 

 The teeth seem to have a thin layer of enamel and to be implanted 

 in the bone rather than anchylosed to it. When the jaw is worn, 

 the teeth and bone together form a grinding-surface. The exact 

 relations of the teeth to the jaw could be certainly determined only 

 by sectioning one of the fragments, and this I do not feel at 

 liberty to do. 



A large part of the jugal is preserved in specimen B, and in 

 specimen A the cast of almost the whole bone. It forms 

 practically the whole of the lower border of the orbit. In its 

 relations to the maxilla, to the postorbital, and to the quadrato- 

 jugal it is almost identical with that in Paloeohatteria. There is 

 clear evidence of a lower temporal fossa bounded below by the 

 posterior process of the jugal. PI. XL. fig. 3 represents the cast of 

 the jugal in specimen A and fig. 4 part of the jugal in specimen B. 



The postorbital bone is preserved in perfect condition in 

 specimen B. It is ti'iangular, and strikingly like the corre- 

 sponding bone in Sphenodon. It divides the upper from the lower 

 temporal fossa and, in part, both from the orbit. It is represented 

 in fig. 4. 



The postfrontal is preserved in specimen B. It is a small 

 triangular bone not unlike that of Sphenodon. It articulates by 

 a long sutvire with the frontal and by a shoi-t one with the 

 parietal. It is shown in fig. 5. 



The f rontals ai-e broad and rather flat. They form only a short 

 part of the supraoi'bital margins between the prefrontals and the 

 postfrontals. The whole of the supraorbital ridge is slightly 

 elevated, owing to there being a depression along the frontal bone 

 and on to the postfrontal. On the whole of the upper surface of 

 these bones, but chiefly in the depression, are a number of shallow 

 pits, which suggest the possibility of their having lodged glands in 

 connection with the skin. The narrowest pait of the interorbital 

 region measures 10"5 mm., and the greatest measurement across 

 the f rontals is 14 mm. 



The parietals are well preserved in specimen B. They are 

 anchylosed, and like those of Sphenodon form, in their posterior 

 two-thirds, a low median ridge. In the anterior third this median 

 ridge divides intot wo feeble ridges, which pass forwards and 

 outwards and end at the suture between the parietal and the 

 frontal. To the naked eye there appears to be no parietal foramen, 

 but when the bone is examined microscopically there is seen to be 

 a small median foramen about as large as a pin-point. I think 

 there can be little doubt that this is a rudimentary parietal 

 foramen. It measures about -5 mm. in greatest length. 

 Posteriorly the parietals pass outwards to meet the squamosals as 

 in Sphenodon. 



Though portions of the squamosal and probably quadrato-jugal, 

 exoccipitals, and a few other bones are present, they are either too 



40* 



