110 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 5&. 



the upper or anterior half the parietal. Their junction being indi- 

 cated by the foramen at the extremity of the left cerebellar process.* 

 Brown in discussing the brain case of Anchice7'atops and of a Tracho- 

 dont dinosaur ^ regards this same point as being the position of the 

 suture between these two bones. In none of the specimens discussed 

 above can a suture be detected at this point, and the presence of a 

 sutural surface on the upper end of the bone here called supraoccipital 

 (see s. oc, fig. 3), seems to me to clearly indicate the forward extent 

 of this bone to be as shown in figure 2, S. oc. 



Fig. 6. — Longitudinal section of skull of TuicERArors flabellatus Marsh, from 

 No. 1821, Yale University Museum. One-sixteenth natural size. Bo., basi- 



OCCIPITAL ; D., DENTARY ; EXO., EXOCCIPITAL ; FR., PRE- AND POSTFEONTAL (FRONTAL OF 



Lull) ; h., postobbital horn core ; mx., maxillary ; nas., nasals ; nh., nasal horn 

 CORE ; NO., nasal opening ; pa., dermosupraoccipital (parietal of Lull) ; pd., 

 prbdbntary ; pf., fostfrontal; pl., palatine; pmx., premaxillary ; q., quadrate; 

 K., rostral; so., supraoccipital; sq., squamosal; n., sinuses beneath postfrontal 

 bones; xo., postfrontal fontanelle. (After Lull.) 



SUMMARY. 



The principal facts now established from the latest study of the 

 Ceratopsian skull and brain case are : 



1. The presence in Triceratops of a well-defined pineal foramen. 



2, That neither the frontals nor parietals are visible from a dorsal 

 view of the skull. 



* This foramen appears to go entirely through the bone in specimen No. 2416, shown 

 In figure 2, but In No. 5740, although there Is a deep pit, see v, figure 1, It appears not 

 to reach the outer surface. 



* See Bull. Amer. Mus. Nat. Hist., vol. 33, 1914, p. 547. 



