REPTILIA : CASK A 



"3 



comparison the structure of the skull will be finally determined 

 with accuracy and completely. Of the material secured from this 

 bone-bed there yet remains fully one-half inclosed in large blocks 

 of matrix, and it is very probable, indeed almost certain, that 

 several skeletons of this form will yet be found among them. For 

 this reason, with the single skull I have not thought it worth while 

 to give hypothetical sutural lines, or attempt to discuss its intimate 

 structure. The skull is remarkably broad and flat, concave above 



Fig. 28. — Cased broil ii Williston. Skull, from above, natural size. 



transversely as preserved, perhaps in life less so or nearly flat. The 

 nasal region is protuberant and bulbous, overhanging the teeth both 

 in front and on the sides; there is an enormous parietal foramen, 

 larger even proportionally than in Diadectes, and the largest I 

 know in any vertebrate; the single vacuity, clearly the lower one, is 

 not large, and is invisible from above; and the teeth are remarkable 

 for their large size, small number, and obtusely conical shape— 

 they are evidently phytophagous. The upper surface of the skull 

 is strongly rugose for a zygocrotaphic reptile. The rugosities are 



