THE CERATOPSIA. 149 



DICER ATOPS Lull. 



DlCERATOPS HATCHERI Lull. a 



Original description, Am. Jour. Sci. (4), vol. 20, p. 417. 

 Gilmore, C. W., Proc. U. S. Nat. Museum, vol. 30, p. 609. 



Mr. Hatcher's description is as follows: 



Char, generic: Nasal horn core absent. Squamosal bones pierced by large fenestra, c while smaller ones penetrate the 

 parietals. The inferior border of the squamosal lacks a quadrate notch. 



Type, No. 2412, U. S. National Museum. 



Char, specific: Supraorbital horn cores short, robust, and nearly circular in cross section at base, erect and but slightly 

 curved. Orbits project in front of the horns, the frontal region lying between the horns being concave. Exoccipital 

 processes slender and widely expanded. 



The type (No. 2412, U. S. National Museum) consists of a skull without the lower jaw. The posterior portion of the 

 frill is somewhat weathered, but the specimen appears to have suffered comparatively little from crushing. 



Locality: The specimen was found in a hard sandstone concretiou about 3 miles southwest of the mouth of Lightning 

 Creek, Converse Co., Wyo. [At the place marked +25 on the map, PI. LI.] When found the concretion in which the skull 

 was embedded had entirely weathered out of the surrounding sandstone and stood at an altitude of 5 or 6 feet above the 

 ground, firmly attached beneath to another concretion. The skull stood on its nose with the frill pointing upward. 



The skull: The chief distinctive features of the skull are as follows : 



The supraorbital horn cores are comparatively short, robust, and nearly circular in cross section at the base instead of 

 compressed, as in most other species. They rise more directly upward than in other species and are only slightly curved. 

 The orbits also occupy a position more anterior than that seen in other species; the interior borders of the horn cores rise 

 from about the middle of the superior borders of the orbits, so that the orbits project well in front of the horns. The frontal 

 region between the orbits is concave. The exoccipital processes are rather slender and widely expanded. 



The nasals terminate anteriorly in a rounded rugosity not developed into anything approaching a nasal horn core and 

 resembling that of the type of Triceratops obtusus. The rostral bone is small and firmly coossified with the premaxillaries. 

 The latter are elongate, but not deep. The maxillaries are massive and the lachrymal foramen is elongate and situated 

 below and considerably forward of the orbit. The jugal is broad distally and firmly coossified with the epijugal. The lateral 

 temporal fossa is nearly as deep vertically as longitudinally. The squamosal is elongate, and just posterior to the quadrate 

 groove it is pierced by a large fenestra, c The anteroinferior angle is little produced and there is no quadrate notch, the 

 inferior border in this region describing a widely open concavity. The parietals are broad and thin and on either side of 

 the median line, about 235 mm. in front of the posterior border, there is an elongated fenestra, c with a longitudinal diameter 

 of 150 mm. and a greatest transverse diameter of 52 mm. This fontanelle is completely inclosed on the right side, but on the 

 left the parietal is injured in this region. In the drawings it has been restored from the right side. The supratemporal 

 fossa is elongate. There is a single median postfrontal fontaneDe,& as in Triceratops, but posteriori}' this gives origin to two 

 deep channels, one on either side. These run backward along the surface of the parietal and terminate in two small circular 

 fontanelles, conditions very similar to those which obtain in Torosaurus. 



Measurements of the type. 



Mm. 



Distance from anterior end of rostral to posterior of squamosal 1 , 990 



Distance from anterior end of rostral to anterior of orbits 845 



Distance from inferior border of orbit to lower end of jugal _ . 363 



Distance from posterior border of nasal opening to extremity of beak 614 



Distance from posterior border of orbit to posterior surface of horn core . 175 



Distance between anterior borders of orbits 340 



Circumference of supraorbital horn cores at base 610 



Circumference of supraorbital horn cores 200 mm. above orbit 340 



Vertical diameter of orbits 165 



Antero-posterior diameter of orbits 125 



TOROSAURUS Marsh. 1891. 



Type species, T. lotus. 



Original description in Am. Jour. Sci., 3d ser., vol. 42, 1891, p. 266. 



Marsh, O. C, Am. Jour. Sci., 3d ser., vol. 43, p 81; Nature, vol. 48, 1893, p. 438; Am. Jour. Sci., 3d ser., vol. 50, p. 497; Six- 

 teenth Ann. Rept. U. S. Geol. Survey, 1896, pt. 1, p. 214. 



Dana, J. D., Manual of Geology, 1895, p. 847. 



Lambe, L. M., Contr. to Canadian Pal., vol. 3 (quarto), pt. 2, p. 66. 



Osborn, H. F., ibid., pp. 9, 14, 15, 20. 



Zittel, K. von, Text-book Pal., trans, by C. R. Eastman, vol. 2, p. 245. 



a This form was described by Hatcher, but left without a name. Diceratops is suggested as a generic name, from the absence of the nasal 

 horn core, while the appropriateness of the specific name is self-evident. — R. S. L. 

 6 See footnote on p. 24. — R. S. L. 

 cSee footnote on p. 163.— R. S. L. 



