DESCRIPTIONS OF FOSSIL LIZARDS — GILMORE 19 



specimens show this strip to be free of osseous scutes, nor have any 

 been found attached to the lower jaws. There is a tendency for these 

 cranial scutes to fuse with the underlying bones. The fusion or non- 

 fusion of the scutes is probably largely determined by the age of the 

 individual. 



Palate. — The palatal region of U.S.N.M. no. 13861 is quite complete, 

 lacking only the left pterygoid and portions of the basioccipital and 

 basisphenoid, and for the first time gives an adequate conception of 

 the palatal structure in the genus Glyptosaurus as shown in figure 5. 



Most of the occipital condyle and the processes are missing from 

 the basioccipital. It is coossified by a straight transverse suture with 

 the basisphenoid. The basipterygoid gives off two wide divergent 

 processes near its anterior termination for articulation with the ptery- 

 goids. These are relatively shorter than in Peltosaurus. The ptery- 

 goid extends forward and inward from the quadrate with which it 

 was in contact. Forward of its contact wdth the basisphenoid, the 

 inner border continues straight forward to the palatine. On the inner 

 side of the ventral surface, beginning immediately in advance of the 

 pterygoid-basisphenoid articulation, is an elongated narrow patch of 

 so-called pterygoid teeth. These teeth are tubercular, closely and ir- 

 regularly crowded together, and collectively resemble the pattern on 

 some of the dermal scutes (see fig. 5). 



The palatine bone is short, with a bifurcated anterior end, the outer 

 branch articulating with the inner side of the maxillary, the inner 

 branch with the vomer. Much of the palatal surface is covered by a 

 rounded patch of palatine teeth. These tubercular teeth are similar 

 in form and distribution to those of the pterygoid, differing only in 

 the extent and shape of the aggregation, which is shorter and more 

 rounded than the long narrow patch on the pterygoids. In the pres- 

 ence of patches of toothlike structures on both the pterygoids and pala- 

 tines Glyptosaurus closely resembles Melanosaurus of the "Wasatch. 

 The presence of patches of tooth structures on both pterygoid and 

 palatine bones shows that I was in error in ascribing all fragmentary 

 parts having tooth patches in Glyptosaurus to the pterygoids.* In 

 my figures the rounded shape of the tooth patches shows them to be 

 palatine, not pterygoid, as erroneously designated. 



The vomers are separated from one another along the median line 

 except toward their anterior ends. They are elongate, with rounded 

 swollen palatal surfaces. The posterior end is reduced to a slender 

 rod that articulates with the inner anterior branch of the palatine. 

 There is no indication of vomerine teeth, though they are present in 

 the related Melanosaums. They are also absent in Peltosaurus. 



* Mem. Nat. Acad. Sci., toI. 22, pi. 15, flgs. 4, 8 ; pi. 19, fig. 10, 1928. 

 85354—38 2 



