NO. 1460. RECENT VERTEBRATE FOSSILS— GILMORE. 609 



Sk. 29 is the largest of the Triceratops skulls preserved in the col- 

 lection of this museum. The principal dimensions are as follows: 



(xreatest length from front of beak to back of parietal, 6 feet 5 inches. 

 Greatest length from front of beak to end of occipital condyle, about 4 feet. 

 Height of post-orbital horn-core, 30 inches. 

 Anterior-posterior diameter of same horn-core at base, 12 inches. 



SKULL OF DICERATOPS HATCHERI Lull.« 



Plates XXX 111 and XXXIV illustrate the front and side views of 

 the skull of a new member of the Ceratopsia recently described* bj^ 

 Mr. J. B. Hatcher as pertaining to a distinct genus and species. 



The type, No. 2412'' (originall}' designated by the field number as 

 Sk. 25), was collected about 3 miles southwest of the mouth of 

 Lightning Creek, Converse County, Wyoming, by Messrs. Hatcher 

 and Utterback, in 1891. 



The skull is all that is known of this animal, and when found was 

 inclosed in a hard sandstone concretion. According to Hatcher, this 

 concretion ''had entirely weathered out of the surrounding sandstone 

 and stood at an altitude of 5 or 6 feet above the ground, lirmly 

 attached beneath to another concretion. The skull stood on its nose, 

 with the frill pointing upward.'' 



The tips of the horn-cores and the crest of the parietals had been 

 eroded awa3\ These portions (see Plate XXXIII) have been restored 

 in plaster, but otherwise the skull is very complete and but little dis- 

 torted for a fossil of such robust proportions. 



The absence of a nasal horn-core and the presence of large fenestra 

 on either side of the frill (see Plate XXXIII) in the squamosals consti- 

 tute the essential characters upon which this genus is based. 



Doctor Lull, in a note following the description of this form, makes 

 the suggestion that the openings in the squamosals may possibly be 

 pathologic. While it is true that the two apertures are not S3aiimet- 

 rical, the pathologic character of the anterior border of the larger 

 opening would, to my mind, account for the as^'mmetry of the two 

 fenestrje. A comparison of Hatcher's drawing of the dorsal view (Plate 

 XIII, fig. 2'') with the photograph of the anterior view (see Plate 

 XXXIII of this paper) shows at once that the right opening has been 

 incorrectly placed in the drawing. It will also be noticed that these 



«In editing Mr. Hatcher's Monograph on the Ceratop.sia, Dr. R. S. Lull found in 

 the manuscript a description of this specimen, to which, however, no name had been 

 assigned. Doctor Lull has given it the very appropriate title of Diceratops hatcheri, 

 the generic name being suggested by the lack of the nasal horn, while the specific 

 name serves "to commemorate Mr. Hatcher's work in connection with this remark- 

 able type." 



& American Journal of Science, XX, Dec, 1905, pp. 413-419, pi. xiii, 



c Catalogue number of the U. S. National Museum. 

 Proc. N. M. vol. XXX— 06 39 



