DESCRIPTIONS OF FOSSIL LIZARDS GILMORE 



13 



pmx-v^^^ ^ 



narrowing of the maxillary as compared with B. sterribergii^ ap- 

 proaching R. hatcherii more nearly in this respect. 



Viewed from above (see fig. 1, B) the skull is more regularly 

 elongate, with a relatively narrower occipital region than in any of 

 the other known species. The paired f rontals are deeply emarginate 

 at the center, but their superior surfaces are perfectly smooth, not 

 roughened as in R. hatcherii and R. sternbergii. The anterior pa- 

 rietal surface is flattened and gradually slopes off on either side, in- 

 stead of being angular as in the 

 other species. There is no trace of 

 a median sagittal ridge more pos- 

 teriorly, the surface rounding over 

 evenly from side to side. There is 

 faint indication of the sutural con- 

 tact with the supraoccipital as 

 shown in figure 1, B. None of the 

 other sutures of the occipital region 

 can be differentiated. 



The nose is slightly incomplete, 

 as the thin part of the nasal bones 

 forming the covering for the nares 

 is eaten away, and in figure 1 it 

 has been restored after Carnegie 

 Museum specimen no. 423A. Un- 

 fortunately, only a few of the 

 sutures separating the individual 

 elements can be distinguished. 



Since the premaxillary is com- 

 plete only at the center, its lateral 

 extent cannot be certainly deter- 

 mined. On the ventral surface it 

 bears a single tooth (see fig. 1, C), 

 as in the other species. Its pos- 

 terior extent between the nasals is 

 not certainly determined as shown 

 in the illustrations. 



The maxillary carries six small, sharply pointed teeth. It is tri- 

 angular in outline, relatively narrower and slenderer in front than 

 the maxillary of R. sternbergii. A row of small foramina extends 

 along the lower edge parallel with the alveolar border. About mid- 

 way of the length of the maxillary the three anterior teeth are 

 separated by a considerable space from the posterior three. This 

 same arrangement prevails in R. sternbergii but not in specimens 

 of R. hatcherii. 



Figure 1. — SkuU of Rhineura minutua, 

 new species, type (U.S.N.M. no. 

 12158): A, Lateral view; B, dorsal 

 view ; C, ventral view, an, angular ; 

 ar, articular ; h», basisphenoid ; o, 

 coronoid ; d, dentary ; f, frontal ; mx, 

 maxillary ; n, external nares ; na, na- 

 sal ; oc, occipital condyle ; p, parietal ; 

 pmx, premaxillary ; pa, presphenoid ; pt, 

 pterygoid ; a.oc, supraoccipital ; t, pre- 

 maxillary tooth. Five times natural 

 size. 



