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Description. 



The fossil now under examination is Ше upper part 

 of a broad depressed skull, sub-triangular in form, with 

 sides converging pretty acutely. The muzzle and lower 

 jaw are absent. 



The sutures generally are concealed or abraded and 

 it would therefore be imprudent to define positively the 

 exact limits of the cranial bones. A little of the exter- 

 nal pitted sculpturing or honeycombed structure is still 

 traceable on the anterior part of the maxillary. Pre- and 

 post- frontal bones divide the orbits from the frontals. 

 The post-orbilals are indicated by radiating lines from 

 their centres of ossification. The sutures of the malars 

 or jugals, supra-temporals and quadrate-jugals cannot be 

 traced, but the parietal foramen in the median suture of 

 the parietals is moderately large. The temporal fossae 

 are, as just implied, roofed over, herein difTering from 

 Eichwald's Zygosaurus. A retral ridge has been preser- 

 ved, which I presume to be one of the exoccipitals. The 

 orbits are large, sub-elliptical, narrower at the anteri- 

 or end, with a diagonal direction. There is no sign of 

 the bevelled orbital border characteristic of Mastodon- 

 saurus. The triangular lachrymals occupy the anterior 

 boundary of the orbital apertures, but their limits are 

 obscure. The maxillary mucous grooves are strongly 

 marked. The middle line of the cranium is depressed 

 into a broad groove passing down the frontal 

 and interorbital tract. 



Part of a laniary tooth is exposed at the an- 

 terior end of the right maxillary (fig. 2) with a 

 ^^s- 2. backward and inward direction. When perfect 

 its form was evidently conical. It is marked externally 



