Douglass : Some Oligocene Lizards. 



279 



vertical diameter is nearly the same as the distance between their upper 

 borders. There is a superior temporal arcade. The mandible is mod- 

 erately heavy. The teeth are smooth, have low rounded chisel-shaped 

 crowns, and are pleurodont. Those on the maxillary are directed 

 slightly backward. The skull is nearly covered with tuberculated osse- 

 ous shields which are arranged in a concentric manner around the orbits. 

 These shields are not large but vary somewhat in size and form. They 

 are convex on the upper surfaces and are covered with minute tubercles, 

 which are nearly equal in size. 



Fig. 2. Glyptosaurus? montanus. Type No. 1050. Side view of skull. 

 of plates posterior to the orbit restored from the other side, f . 



Part 



Detailed Description. — The parieto-frontal plane of the skull is flat 

 and very broad, twice as broad as the space between the orbits. 

 Beginning above the anterior portion of the orbits the superior plane 

 of the skull slopes downward to the anterior portion of the muzzle. 

 The orbits are large and elliptical, the longer axis being in the direc- 

 tion of the long axis of the skull. 



There is a superior temporal arcade, and the jugal arch is heavy. 

 The upper surface of the parietal was covered with shields. On re- 

 moving these plates along the anterior border of the parietal and the 

 matrix from the under surface of the bone it was seen that there was 

 no contact with the frontal or any bone anterior to the parietals, except 

 what appears to be a small thread of bone from the antero-external 

 surface of the parietal to the frontal or post-orbital. I am not able to 

 say whether this is a normal condition or not, as there is no other skull 

 with which to compare the type. The space between the bones, like 

 the remainder of the roof of the skull, was covered with hard bony 



