SAUK0PTERYG1A 215 



depressed face, of which the premaxillary part is the narrowest. 

 The nostrils, consequently, although distant from the orbits 

 by half the diameter of the latter, are yet nearer the fore end 

 of the skull than in the above-cited Sauropterygian genera. 

 The nostrils are relatively nearer to each other, the intervening- 

 bony tract being due to the premaxillaries, which, relatively 

 to the breadth of the skull, are much narrower in Simosaurus 

 than in Notho- or Pisto-saurus. 



The profile of the skull rises from the internasal to the 

 interorbital regions much more than in the Nothosaur, and 

 the depth of the skull behind the orbit is greater in propor- 

 tion to its length. The post-frontals are most clearly produced 

 backwards, along the upper border of the zygoma to the mas- 

 toids. The malars are co-extended, and connected with the 

 post-frontals, but terminate freely and obtusely a little beyond 

 the co-prolonged hind part of the maxillary, without being- 

 met by or joining a squamosal. 



Most complete and extensive is the ossification of the roof 

 of the mouth in this genus. The pterygoids are expanded 

 into one broad unbroken imperforate fiat expanse of bone, 

 from about one-third of the distance from the snout to the 

 occipital condyle ; they are united by a median suture, and 

 underlap the whole of the sphenoid. The teeth, compared 

 with Nothosaurus, are few and large, and are subequaL save 

 one or two at the fore and hind extremity of the series. The 

 crown expands a little above the fang, is conical, sub-bifurcate, 

 and impressed by a few coarse longitudinal ridges ; some are 

 obtuse, others acute ; but all are shorter and thicker than in 

 Notho- or Pisto-saurus. 



The vertebne have fiat or very slightly concave articular 

 surfaces on the body ; the neural arch articulates therewith 

 by suture. In these characters, and in their general propor- 

 tions, they resemble those of Notho- and Plcsio-saurus. It is 

 significant of some difference in respoct of tlm arrangement of 



