372 University of Kansas Geological Survey. 



surface. They expand rapidly posteriorly, and join the parie- 

 tals by an almost straight suture. The external edges become 

 quite thin, and are concave from in front backwards. They 

 form the upper rim of the orbit for about two centimeters. 

 The lower surface of each bone shows a sharp ridge near the 

 middle ruuning anfcero-posteriorly. This ridge is highest and 

 sharpest near the anterior edge, and the two include between 

 them a deep groove, broadest at the two extremities, and slightly 

 contracted in the middle. 



The parietals are incomplete posteriorly. Anteriorly they join 

 the frontals, and then diverge laterally. They form a part of 

 a very complete temporal roof. From the under side of each 

 bone, a thin vertical plate descends as in Chelonia, and was 

 probably joined to the pterygoids by a slender epipterygoid. 



There is no trace remaining in the specimen described of the 

 postorbito-frontals. In a second specimen of a different species 

 they show much the same outlines as in the modern Chelonia, 

 uniting with the parietal above and malar below. They form 

 the posterior edge of the orbit. 



The jugal joins the posterior end of the maxillary with the 

 quadrato-jugal behind; it is narrow vertically, with a concave 

 lower border, so that the lower line of the skull rises posterior 

 to the maxilla. The upper edge is thin and sharp anteriorly, 

 and forms the posterior part of the lower border of the orbit. 

 The posterior part of the superior margin joins the postorbito- 

 frontal, and a broad process from the inner side joins the ptery- 

 goids. 



The orbit was rather large, roundly ovate in outline, and 

 somewhat broader posteriorly than anteriorly. 



The squamosal joins the upper part of the quadrates laterally, 

 and the quadrato-jugals and postorbito-frontals anteriorly. The 

 internal margin unites with the parietal. The bone is thin 

 and plate-like, somewhat triangular in outline, broad externally 

 and narrower internally, where it is wedged in between the 

 parietal and postorbito-frontal. The posterior margin is quite 

 concave, and is continuous with a similar concavity of the pos- 

 terior margin of the parietal, forming a deep emargination in 



