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PROCEEDINGS OF THE NATIONAL. MUSEUM 



VOL. 86 



are thickly studded with small tubercles without definite arrange- 

 ment. On the sides of the skull posterior to the orbit the scutes are 

 arranged in longitudinal rows, and they gradually increase in size 

 from above downward, more especially on the posterior half of the 

 skull. The form of their upper surfaces also changes from the highly 

 convex to nearly flat surfaces with the tubercles arranged in three 

 to four concentric rows around the periphery of the scute, the center 

 being filled with smaller tubercles without definite arrangement. The 

 tubercle pattern is similar to that of the type specimen of G. ocellatua 

 Marsh, which is now regarded as a synonym of G. sylvestris.^ This 

 specimen thus offers further proof of the correctness of that conclu- 

 sion. 



FiGORB 5. — Palatal view of skull and Jaw of Olyptosaurus giganteus Gilmore : U.S.N.M. 

 no. 13861. an, angular; bo, basloccipital ;'b«, basisphenoifi ; d, dentary ; Ju, jugal ; mx, 

 maxillary ; oc, occipital condyle ; pi, palatine ; pt, pterygoid ; sa, surangular ; v, vomer. 

 Natural size. 



The orbit is encircled by a complete row of 17 or more scutes. 

 Douglass found 20 surrounding the orbit of G. montanibs. In the top 

 of the right orbit of U.S.N.M. no. 13869 is a row of six scutes that 

 completely covers the projecting edges of the postfrontal, frontal, 

 and prefrontal bones and corresponds in position to the row of five 

 supraorbital plates in Gerrhonotus or the lesser number in Peltosau- 

 rus. 



In front of the orbit the scutes grow progressively smaller from 

 above downward and cover all the bone surfaces except a 3-millimeter 

 strip along the lower edge of the maxillary. All known Glyptosawras 



* Mem. Acad. Nat. Sci., vol. 22, p. 99, 1928. 



