122 THE CEEATOPSIA. 



On PI. XXVI is given a view of the skull as seen from the left side, with such of the detached 

 fragments placed in their proper positions as we were able to locate. This drawing shows 

 at a glance the very close relationship existing between the present species and T. prorsus and 

 T. brevicornus. From. the former, however, it is readily distinguished by the form of the 

 supraorbital horn cores and the shortness of the nasal horn core, while its greater size should 

 perhaps be taken as distinguishing it from both these species. The principal dimensions of 

 the type are as follows: . -,;■ , 



Principal measurements. 



,_ ~ Mm. 



Diameter of occipital condyle 116 



Expanse of quadrates A 536 



Fore and aft diameter of supraorbital horn core at base. ....... 245 



Transverse diameter of supraorbital horn core at base _ _ 172 



Transverse diameter of supraorbital horn core 10 inches above base . .' 127 



Fore and aft diameter of supraorbital horn cores 10 inches above base 155 



Height of nasal horn core 130 



Transverse diameter of nasal horn core at base 125 



Triceratops serratus Marsh. 1890. 



Type consists of nearly perfect skull with lower jaw (No. 1823, Yale Museum), from Laramie of Converse County, Wyo. 



Original description in Am. Jour. Sci., 3d ser., vol. 39, Jan., 1890, pp. 81-82. 

 Dana, J. D., Manual of Geology, 1895, p. 846. 



Lambe, L. M., Contr. Canadian Pal., vol. 3 (quarto), pt. 2, 1902, p. 69. 

 Lull, R. S., Bull. Am. Mus. Nat. Hist., vol. 19, art. 30. 

 Marsh, O. C, Am. Jour. Sci., 3d ser., vol. 41, Feb., 1891, p. 177; vol. 43, Jan., 1892, p. 84; Mon. U. S. Geol. Survey, vol. 



27, 1897, p. 512. 

 Nopcsa, F. Baron, Foldtani Kozlony, Budapest, 1901, vol. 31, p. 271. 

 Osborn, H. F., Contr. Canadian Pal., vol. 3 (quarto), pt. 2, 1902, p. 14. 

 Woodward, A. S., Outlines Vert. Pal., p. 214. 

 Zittel, K. A. von, Text-book Pal., trans, by C. R. Eastman, p. 244. 



LOCALITY AND HORIZON. 



In the American Journal of Science for January, 1890, Professor Marsh proposed the pres- 

 ent species. The type (No. 1823, Yale Museum) consists of a well-preserved skull, with lower 

 jaw, pertaining to an animal apparently not fully adult, discovered by the late Dr. C. E. Beecher 

 in 1889. It was found incased in a hard calcareous sandstone concretion in the locality desig- 

 nated as +4, PI. LI. The exact locality was on the north side of the middle fork and about 

 3 miles above the mouth of the draw of Dry Creek, which empties into Lance Creek from the 

 west, immediately below the U-L cattle ranch, then long abandoned, but now occupied as a 

 sheep ranch by Mr. Jacob Mills. The horizon was at the base of a stratum of sandstone about 

 20 feet above the bottom of the draw, which here assumes the appearance of a narrow but not 

 deep canyon. I should judge the actual horizon to be somewhat above that which furnished 

 the type of T. horridus. 



ORIGINAL DESCRIPTION. 



Marsh's original description of the species was as follows: 



First in importance of the new discoveries is a nearly perfect skull of the genus Triceratops, a typical example of which 

 (T. flabellatus) was described and figured by the writer in the last number of this journal. The present skull is more perfect 

 than any hitherto found and exhibits admirably the strongly marked characters of the genus. It is likewise of gigantic size, 

 being nearly 6 feet in length (1.8 m.), although the animal was not fully adult. 



A striking peculiarity of this skull, which has suggested the specific name, is a series of bony projections on the median 

 line of the parietal crest. The latter is elevated along this line to support them, and the sides descend rapidly to their union 

 with the squamosals. There is a second series of elevations along the middle of the squamosal bone as it falls away from 

 the base of the horn core, but these are much less prominent. 



The orbit is nearly circular in form instead of oval and is situated above and forward of its position in the species referred 

 to. The quadratojugal meets the anterior process of the squamosal, forming a closer union than in the skull previously 

 figured. In this respect and in the elevations on the squamosal it approaches a much smaller specimen, at present referred 

 i,o the genus Ceratops. 



