TRICERATOPS (DICERATOPS) HATCHERI 127 



The generic characters, as given by Hatcher, are: "Nasal horn core absent. Squamosal bones 

 pierced by large fenestrae, while smaller ones penetrate the parietals. The inferior border of the 

 squamosal lacks a quadrate notch." Of these characters, 1 would dismiss the second as pathologic; 

 for historically, the squamosal is never fenestrated as a normal character, although repeated instances 

 of perforations through this bone occur, due either to disease or injury. (See Torosaurus latus, 

 p. 131, Text Fig. 42; Arrhmoceratofs brachyops, p. 107, PI. XII; Chasmosaurus brevirostris, 

 PI. VII, A; and Pentaceratops fenestratus, p. Ill, Fig. 40.) The entire region of the left squa- 

 mosal, where the largest of these "fenestrae" occurs, is badly diseased on the under side; more- 

 over, the perforation practically obliterates the area of insertion of one of the most important neck 

 muscles which served to wield the head, so that the animal must have been partly incapacitated as a 

 result. 



The first and third characters are largely differences of degree, rather than of kind. This is 

 especially evident if one compares Diceratops hatcheri and 'Triceratops obtusus. Of specific validity 

 I have no doubt, but real generic distinction from Triceratops is highly questionable. There is 

 nothing like the contrast in crests, for instance, shown in Triceratops and Torosaurus. (See beyond, 

 p. 130.) 



The skull, that of an aged individual, is about 6 feet 1 inch in over-all length, and therefore 

 slightly below the average for Triceratops skulls. It is unique, for no other specimens known to me 

 can be referred to this species. 



The muzzle is long with a comparatively small rostral, although the sutural limits of the 

 latter are not discernible. The inferior border of the rostral is curved downward toward the tip. 

 The dorsal profile of the nasals and of the crest is almost in line, the former being concave, as usual, 

 as contrasted with the convex profile of obtusus. The orbit is an elongated ellipse, with the axis 

 inclined at an angle of about 20° from the perpendicular. 



The descending limb of the jugal is of medium width, with a low ridge posterior to the mid- 

 line. It is approximately vertical. The jugal notch is very shallow, as the outer anterior margin 

 of the squamosal is very little below the summit of the notch. This is evidently Hatcher's third 

 generic character, i.e., absence of quadrate notch. 



The infratemporal fossa is of medium size, oval, with the apex pointing downward and forward. 

 The nasal horn core is lacking entirely, the nasals rounding into the curve of the muzzle without a 

 break in the even contour. The nasals terminate in a broad, rounded, rugose area more suggestive 

 of Triceratops obtusus than of any other form, and, as in the latter, they are twice as broad at the 

 rear as at the forward end. 



The brow horns are comparatively short and robust, erect when viewed laterally, although 

 flaring apart somewhat as seen from in front. There is but a slight forward curve. The horns seem 

 to arise further back than usual with reference to the orbits, but this is more apparent than real, for 

 the erect character of the horns heightens the illusion. The base of the horn is nearly circular in 

 cross-section, instead of being laterally compressed as in most other species. 



The crest is broad, at least twice that of its length, when viewed from above, and its dorsal 

 profile is nearly straight, without undulations but with a slight upward turn toward the rear. 

 Although a portion of this as well as the distal ends of the horns are artificial, the indicated curves 

 are well carried out and are probably correct. The number of epoccipitals is 19, 5 on each squamosal, 

 with 1 over the end of either squamoso-parietal suture, exactly as in Triceratops. The crest is 

 highly vascular above and below with no limited zone on the inferior face. The perforations 

 through the crest number four, and are asymmetrical, the left squamosal containing a large subtri- 

 angular one at about its mid-length, and a lesser, irregular one in front, near the infratemporal 

 fossa. The right squamosal has another irregular aperture in nearly the same place as the larger one 

 on the left, but having less than one-fifth the area of the latter. There is yet another smaller 

 perforation through the right side of the parietal, halfway between the squamosal and the rear 

 margin. Below, the area in front of the largest aperture is tumid, thickened, and irregular, which 

 heightens the impression that all of these perforations are pathologic and may be cystic openings 

 comparable to those through the squamosal of the Torosaurus latus type mentioned above, and 



