DESCRIPTIONS OF FOSSIL LIZARDS — GILMORE 25 



anterior and posterior sides. The crowns have an obtuse longitudi- 

 nal cutting edge that is rounded anteroposteriorly. One tooth near 

 the middle of the series presents a small denticle, anterior to the 

 center of the cutting edge. 



The crowns, except those of the most posterior teeth, which are 

 shorter, curve slightly inward. In the center of the dental series 

 there are 5i/^ teeth in a space of 5 millimeters. 



Similarity of the emplacement of the teeth strongly suggests rela- 

 tionship with the genus Harpagosaurvs^ to which it is provisionally 

 assigned. This species is distinguished from Harpagosaurus exidens, 

 which occurs in these same beds, and also from H. parvus of the 

 Lance formation by its much larger size, spatulalike form of the 

 tooth crowns, and their longer protrusion below the parapet of the 

 maxillary. Likewise these spatulalike teeth at once distinguish it 

 from the wedge-shaped crowns of Peltosaurus sp., which also occurs 

 in the Fort Union No. 2. 



The species name is in honor of A. C. Silberling, who collected the 

 type as well as many other specimens now in the National Museum 

 collections. 



Figure 9. — Left maxillary of Paraprionosaurus icyomingensis, new species : Type (U.S.N.M. 

 no. 12955), lateral view. Mve times natural size. 



PARAPRIONOSAURUS, new genus 

 PAKAPRIONOSAURUS WYOMINGENSIS, new species 



Type. — U.S.N.M. no. 12955, consisting of a nearly complete left 

 maxillar}^, containing 16 perfect teeth. Collected by Charles W. 

 Gilmore, 1931. 



Type locality. — Two miles north of Lone Tree P. O., Bridger 

 Basin, Uinta County, Wyo. 



Horizon. — Horizon D, Bridger, Eocene. 



Description. — The type specimen consists of a nearly perfect left 

 maxillary, wdth 16 teeth in situ, and there is evidence of 23 teeth in 

 the complete dental series. This specimen is preserved attached to 

 a small block of matrix and for fear of doing irreparable damage to 

 it removal has not been attempted, and for that reason the internal 

 side is not available for study at this time. It is presumed that the 

 teeth are pleurodont in the manner of attachment to the maxillary. 

 There are 91/2 teeth in a space of 5 millimeters. 



