CERATOPSIAN DINOSAURS FROM MONTANA GILMORE S 



F. Sternberg, July 30, 1935, on the north side of Two Medicine 

 River, Teton County, Mont. 



Description of skull parts.— The frontals are represented by the 

 median transverse portions of both elements, as shown in figure 1. 

 Transversely between the orbital borders the superior surfaces of the 

 cojoined frontals are concave from side to side, being much more 

 strongly dished than the corresponding part of the Protoceratops 

 skull. On the posterior border the surface dips downward but is 

 slightly hollowed out on each side of a low longitudinal median ridge. 

 The median posterior border is incomplete and thus gives no indica- 



A 



Figure 1. — Frontals of Leptoceratops sp. (U.S.N.M. No. 13864): Aj ventral view; B, 

 dorsal view, pf, Sutural union for postfrontal ; prf, sutural union for prefrontal. 

 One-half natural size. 



tion of its contact with the parietal. The outer posterior border, 

 which looks backward and outward, has a strongly grooved surface 

 for sutural union with the postfrontal. The outer rounded edges, for 

 a space of 22 mm., form the frontal contribution to tlie orbital rims. 

 The anterior border presents broken surfaces except for portions of 

 the sutural contact for the prefrontals on each side. The superior 

 surface on each side of the midline is perforated by a number of 



