Vaianosaurus acutirosfciis, Bro'di. 299 



boiic is sliort, aud, i£ the suture is correctly recoguized, 

 contril)utes scarcely at all to the tub^ra basisphenoidales. 



The basisphenoid is a larj^e bone, whose lower surface is 

 provided with two very pronounced ridges, which, starting 

 at the lubeia, run forwards along the lower surface until they 

 terminate iu front in wcU-devclojied basipterygoid processes, 

 which support the pterygoids by definite articulations. In 

 front of this region the bone is concealed by matrix aud the 

 pterygoids, but through the right orbit it can be seen to be 

 coniinued forwards by a long and very massive parasi)henoid, 

 whose upper bc^rder is grooved in front and supports an 

 ethmoid, the visible portion of which forms a thin median 

 septum. In front the parasphenoid seems to be clasped by 

 an ascending flange of the pterygoid. 



Ptei yyoid. 



The pterygoid is the usual trira:liate bone, articulating by 

 a distinct facet with the basipterygoid process ; the anterior 

 ramus runs forward as a plate on the palate, soon joining 

 with its fellow, so as to leave only a very small interptery- 

 goid vacuity. The internal ramus forms the usual process 

 against the side of the lower jaw, but the structure of the 

 palate cannot be made out. The })osterior ramus is a deep 

 tliin plate running backwards behind the quadrate to the 

 extreme hinder end of the skull; on the left side it can be 

 distinctly seen to come into contact with the squamosal, 

 exactly as in a Stegocephalian. 



Quadrate. 



The quadrate is represented by the anterior part of the 

 pterygoid ramus, which, on the right side, is clearly seen to 

 lie on the outer side of the posterior ramus of the pterygoid 

 as a very thin film of bone. The articular region is well 

 j)rcscrved on the right side. There is a pulley-sha[)ed 

 condyle, above which the bone rises as a massive sheet. 

 The outer surface is obviously covered by membrane-bone, 

 the squamosal, and probably also the quadrato-jugal ; there 

 are, however, only very faint traces of sutures, and no 

 quadrate foramen. 



On the inner side, well abcn'c the condyle, is a dec[) and 

 very well-marked step, which can only have served for the 

 articulation of the outer end of the stapes. 



