50 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Apr. 20, 



The nostrils (n), divided by a broad and almost flat base of the 

 premaxillary (figs. 3 and 5 22), are situated, as in Enaliosauria, 

 much nearer the orbits than the muzzle. They are proportionally 

 smaller than in the typical Dicynodonts. 



The orbits (0) are oblong and have a somewhat reniform figure, 

 owing to the production of the superorbital ridge into a protuberance 

 a little behind its middle part ; their posterior boundary describes a 

 strong convex curve between this protuberance and the zygomatic 

 arch. The form of the orbit suggests that the reptile had the power 

 of turning the eye-ball so as to look upward and backward, as well 

 as outward, in a peculiar degree. The cranium has undergone no 

 pressure or distortion to produce this form of orbit. The upper 

 outlets of the temporal fossse (fig. 5 s) are broader than they are 

 long, and wider externally than internally. The palate has a single 

 large oval vacuity at its back part, bounded externally and behind 

 by palato-pterygoid ridges. 



In one orbit a few of the sclerotic plates (fig. 3 s.) were preserved. 



The occipital condyle is subtrilobate, and is formed by the basi- 

 ng. 4 1) and ex-occipitals (ib. 2) in pretty equal proportions. After 

 most careful scrutiny on removal of the matrix from the surface of 

 the fossil bone, I believe the exoccipitals to have coalesced, or to 

 have been connate, with the paroccipitals, analogous to the con- 

 fluence of the ex- and par-occipitals in the Crocodiles*. The ex- 

 occipitals (ib. 2) meet and join together above the foramen magnum. 

 The broad occipital plate or " bone " so formed is emarginate above 

 for the superoccipital (ib. 3) ; and the outer boundary or suture 

 describes a strongly undulating course as it curves outward and down- 

 ward to the paroccipitals. These processes (ib. 4), abutting against 

 the lower part of the mastoids, are divided by a notch from the 

 hypapophyses (Ji) of the basioccipital, which are thicker in proportion 

 to their length than in the Dicynodon tigriceps. Tbe outer surface 

 of the occiput, so defined, is undulating ; but much of the occipital 

 plane at its upper and lateral parts is contributed by the parietals 

 (7) and mastoids (s), especially the latter, which are of great extent. 

 The parieto-mastoid suture runs upward to the middle of the back wall 

 of the upper outlet of the " temporal " fossa. The mastoids unite with 

 the exoccipitals by a deeply indented suture : a ridge is developed 

 where the masto-tynrpanic joins the paroccipital. About an inch ex- 

 ternal to the parieto-mastoid suture the mastoid developes a strong 

 subvertical ridge, which extends forward to meet the postfrontal and 

 malar, and to form the zygomatic outer boundary of the temporal 

 fossa. Between the zygomatic and occipital plates of the mastoid, 

 that bone is deeply and widely excavated externally. Between the 

 top of the superoccipital and the parietal I cannot discern a suture ; 

 and it is by analogy that I regard the lower median portion of the 

 symmetrical two-lobed bone (fig. 43) which enters the upper notch 

 of the coalesced exoccipitals as the superoccipital. The lobes are 

 formed by the convex parietal ridges which are continued forward 



* Geol. Trans. 2nd ser. vol. vii. p. 241, pi. xxxiii. 



