NO. 3 NEW CKRATOPSIAN DINOSAUR GILMORE J 



provisionally associated with the type as shown in plates i and 2. 

 This association, however, is only provisional in so far as it applies 

 to the recognition of the proper individual, for it can be said without 

 question that all the bones found belong to the same kind of an 

 animal. 



The dermo-supraoccipital or interparietal, for surely it cannot be 

 the parietal as Hay ' and von Huene ' have clearly shown, is united 

 by suture with the anterior portion of the skull at the postfrontal 

 foramen. The median part of the interparietal is sharply ridged, ex- 

 cepting the posterior extremity, where it flattens out into a thinner 

 portion with an emarginate median border. Between the fenestrse 

 the median bar, in cross section, is triangular. The superior surface 

 of this ridge forward of its narrowest part between the fenestrse 

 presents three low longitudinal swellings arranged one in front of 

 the other. Proximally the median portion is greatly compressed 

 transversely into a short neck, forward of which it again widens into 

 a much depressed end that articulates laterally with the postfrontals 

 and with them forms the upper boundaries of the postfrontal fora- 

 men, see jo, plate 2. Between these two lateral portions the median 

 surface is deeply concave and slopes downward to a heavy truncated 

 border that in all probability was suturally united with the parietals. 

 In Brachyceratops at least, the parietal was entirely excluded from the 

 dorsal aspect, and it is presumed that similar conditions obtained 

 in Triceratops, although von Huene was inclined to regard a small 

 ]:)ortion of the median part of the frill posterior to the postfrontal 

 foramen in that genus as being parietal. 



The bone surrounding the frill fenestrse is very thin, but toward 

 the lateral free edges and posteriorly it becomes thickened. Proxi- 

 mally it remains thin where it forms the floor of the supratemporal 

 fossa but thickens toward the sutural border for the squamosal. The 

 exact shape and extent of the frill fenestrae cannot be accurately 

 determined from the available specimens, but it is readily apparent 

 that they were of comparatively small size. The surfaces of the frill 

 are relatively smooth and without the ramifying system of vascular 

 grooves of the later Ceratopsians. There were no epoccipital bones 

 on the margins of the frill, but on either side of the median emargi- 

 nation a series of prominences give to the periphery much the same 

 peculiar scalloped effect found in the Triceratops frill with its sepa- 

 rate ossifications. 



^ Proc. U. S. Nat. Mus. vol. 2,^, 1909, p. 97. 



' Neues Jahrbuch, 1912, pp. 150-156, figs. 3, 4, 5 and 6. 



