16 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 87 



cannot believe that the correct answer to this perplexing problem 

 has yet been found. Sternberg, I believe, has correctly determined 

 the limits, and sutural unions of the so-called parietal and frontal 

 bones in the Styracosaurus skull, for they are in perfect accord with 

 my original assembly of the scattered elements of the Brachyceratops 

 skull and substantiated by the adult specimen under discussion. My 

 objection to accepting the proposed identifications rests entirely on 

 the fact that neither of these bones gives any indication on their 

 ventral surfaces of ever having participated in the formation of the 

 brain case, which they do in all reptilian skulls of which we have 

 knowledge. If it can be shown that they do enter into the formation 

 of the brain case, I will then be willing to accept this latest 

 interpretation. 



The presence on one side or the other of most of the lateral elements 

 of the skull now permits of a second restoration of the skull (fig. 11). 

 This reconstruction presents details of some of the structure not given 

 in the first attempt and presents for the first time an illustration of a 

 nearly adult skull of this genus. 



Though there is probability of error in assembling the disarticu- 

 lated elements of a skull, some parts of which were slightly distorted, 

 it is believed this reconstruction gives a fairly accurate representation 

 of the cranium. The more striking growth changes of this specimen 

 as contrasted with the juvenile skull are the development of promi- 

 nent epoccipital processes along the borders of the frill and the 

 lengthening of the facial region. The latter may be slightly exag- 

 gerated in the reconstruction. That fenestra were present in the 

 frill appears to be indicated by the extreme thinness of the bone, 

 although nowhere do the broken borders give any indication of a 

 finished edge. The opening has been tentatively indicated in the 

 drawing. 



The left jugal preserved with specimen U.S.N.M. No. 14765 shows 

 for the first time in Brachyceratops its exact relationships to the 

 surrounding elements, as this bone was missing in the type specimen. 

 In form it closely resembles the jugal in Monoclonius, from which it 

 differs only in minor details. As in Monoclonius and Gliasmosaurus 

 the infratemporal fossa lies principally within the jugal, only its 

 posterior border being formed by the squamosal. Above it forms 

 about one-third of the orbital rim, articulating with the postorbital 

 by a diagonally directed suture at the back of the orbit, and with the 

 lachrymal at the front of the orbit. 



Anteriorly the jugal sends forward a short process that is widely 

 notched for union with the superior process of the maxillary. As in 

 THceratops a slender, forward-directed spur is interposed between 

 the lachrymal and maxillary. Posteriorly the lachrymal articulated 



