124 THE CERATOPSIA. 



specimen it is impossible to determine the exact relations of the pterygoids and the palatines 

 to the posterior portion of the maxillary. It is quite probable, however, that they do not differ 

 materially from those shown in the types of T. horridus and Sterrholophus jlabellatus, but are 

 quite different from those figured by Dr. R. S. Lull as pertaining to a skull, No. 970, in the col- 

 lections of the American Museum of Natural History and described by that author as belonging 

 to the present species. A careful study of the New York specimen would doubtless show that 

 both Doctor Lull's figure and description of this region are erroneous and that the pterygoids 

 do not form the postero-lateral borders of the narial fenestra, but that these borders are formed 

 by the palatines, the anterior limits of the pterygoids being much more reduced than shown 

 by Lull. 



The frontals are small, somewhat rectangularly shaped bones. Anteriorly they overlap 

 the nasals, and together they present a deep median emargination. Medially or internally 

 they are in contact with each other throughout their length, while posteriorly they articulate 

 with the postfrontals and externally or laterally with the prefrontals. The right frontal is 

 pierced at its posterior border by a large foramen, the posterior border of which is formed by 

 the postfrontal. This foramen is absent on the opposite side, and it is probably pathologic. 



The prefrontals occupy a position just external to the frontals and articulate with the latter 

 throughout their entire length. Posteriorly they are broad and flat and oppose the anterior 

 extremities of the postfrontals. Anteriorly they articulate with the nasals, curve downward 

 to form the convex external wall of the skull, and meet below in a straight suture the superior 

 borders of the lachrymals. Posterially their external lateral borders are much thickened where 

 they form the supero-anterior borders of the orbits and give support to the supraorbital horn 

 cores from beneath and in front. ' 



The lachrymals are the smallest of the three bones that articulate with the posterior extrem- 

 ities of the nasals. They articulate with the prefrontals above and the jugals below. Poste- 

 riorly they form the median portion of the anterior border of the orbit, which is not so thick 

 and does not project so far outward as that portion immediately above, which is formed by the 

 prefrontal. Anteriorly, at its inferior angle, the lachrymal sends forward a long projection, 

 which is continued along and within the inferior border of the nasal and with the latter forms 

 the superior border of the elongated lachrymal foramen, which appears to have communicated 

 with the orbit through a large opening confluent also with the narial orifice. 



The jugal has the usual triradiate form commonly seen in the Ceratopsia. Anteriorly it 

 articulates with the lachrymal above and the maxillary below, and sends forward a long, slender 

 process which lies just within the superior border of the maxillary and, together with that bone, 

 forms the inferior border of the lachrymal foramen. Beneath the lachrymal foramen the jugal 

 overlaps externally the superior branch of the maxillary. Above, the jugal forms the antero- 

 inferior border of the orbit, while posteriorly it articulates with the postfrontal and sends 

 backward a broad, thin process which overlaps the external wall of the squamosal and forms 

 the greater portion of the superior border of the lateral temporal foramen, which is bounded 

 in front by the dependent spatulate process of the jugal. The latter overlaps the quadrato- 

 jugal and supports at its distal extremity the epijugal. 



The quadratojugal has the usual irregularly wedge-shaped form, broad in front and thin and 

 pointed behind. It is firmly fixed between the quadrate and the jugal and sends backward 

 along the superior and external wall of the quadrate a triangular process which passes beneath 

 a smaller but similar process that extends forward from the squamosal. These two processes, 

 together with the quadrate, form the inferior temporal arch and inclose below the lateral 

 temporal foramen, which is triangular in outline and is inclosed behind by the squamosal. 



a This question of disagreement has been referred for arbitration to Dr. W. D. Matthew, of the American Museum, who writes (June 6, 

 1905) as follows: "As to the pterygoids and palatines on our Triceratops skull (No. 970), I have compared your figure and photograph with 

 the original as carefully as possible, and there can be no question as to their being correct. The only possible doubt would be as to the correct- 

 ness of your interpretation, the alternative supposition being that what you call palatine is a refolded plate of the maxilla (the fissure between 

 for nutrition of the dental row) and what you call pterygoid is palatine. Looking over the specimen, this appears to me an improbable, 

 but not impossible, explanation. I note, however, that Marsh's interpretation, judging from his description of Triceratops in ' Dinosaurs of 

 North America," agrees with yours; it also harmonizes better with the form and arrangement in the Theropoda." — R. S. L. 



