94 



THE CERATOPSIA. 



Red Deer River, Alberta, between Berry Creek and Dead Lodge Canyon. Lambe's original 

 description is as follows: 



This species is founded on a squamosal, part of a parietal, a jugal, a supraorbital horn core, the left ramus of the lower 

 jaw, and an anterior dorsal vertebra, with some other parts of the skull, not yet fully determined, of one. individual. A right 

 ramus of another individual is shown on PI. XVIII [XIX] and a separate horn core on PL XVII [XVIII]. 



A right mandibular ramus, referred to this species on account of its resemblance in form to the one shown above, is described 

 further on. 



The horn core (fig. 18 [fig. 96, PI. XVIII]) rises above the orbit from the postfrontal, of which it -forms a part. The 

 postfrontal unites behind, by suture, with the squamosal and below with the jugal. The orbit is oval, with the longer diam- 

 eter vertical, its upper curve lying close under the base of the horn core, its margins not ridged. The horn core is small, about 



21.6 centimeters long from the upper edge of the orbit to its 

 summit and 22.8 centimeters in circumference near the base, 

 circular in section, and solid. 



Squamosal [PI. XXIII], somewhat triangular in shape, flat, 

 moderately thin, its outer edge smooth, rounded, wavy in out- 

 ■i—h, line, so as to produce six minor convex curves. Shorter and 



more pronounced near the front. Its outer front edge is deeply 

 emarginated, with a shallower concavity limiting the outer ter- 

 mination of the jugal suture (see fig. 18 [fig. 96]), inside of which 

 is the suture for the union with the postfrontal. The inner bor- 

 der is slightly concave. The lower surface near and parallel to 

 the inner posterior end is broadly and shallowly grooved for the 

 reception of a long, slender bone, triangular in section, that 

 projects backward and inward, its outer edge continuing the 

 curve of the squamosal. Probably this slender bone represents 

 Fig. 96.— Monoclonius canadensis; part of the skull from the right the anterior end of a forward bent side extension of the parie- 

 lateral aspect. One-sixteenth natural size, fp, Pdstfrontal; h, ta , such as occurg in the species Monoclonius helix, in which case 

 horn core; o, orbit; s, squamosal; p, right lateral extension ., , - . , . , , ,. . 



from parietal; j, jugal (misplaced nasal*); I, lower jaw. After a fontanelle of moderate s.ze might be expected on the inner 

 Lambe. side of the squamosal. 



In fig. 18 [fig. 96] the underlying bone (imperfect posteriorly) 

 is indicated by a dotted outline under the squamosal, beyond which it projects; its outer free edge shows a round-edged con- 

 vexity in continuation of the sinuosities of the squamosal. The proximal inner margin of the squamosal is bent at right 

 angles to the plane in which the remainder of the bone lies and its under surface is deeply excavated in its inner front part 

 for some distance back from the postfrontal suture. 



Measurements of squamosal, etc. 



Mm. 



Length on curve of outer border .■■. . 0. 576 



Length on curve of inner border . 573 



Length from posterior end to center of front margin . 533 



Thickness near outer border at mid-length . 028 



Breadth across front margin 355 



Thickness near inner border at mid-length . . . . 038 



Length of bone underlying the squamosal (imperfect) 502 



Breadth of same at mid-length 064 



Greatest thickness at mid-length ■ 030 



With the parts of the head shown in fig. 18 [fig. 96] was also found an anterior dorsal vertebra, fig. 19 [fig. 97], of rather 

 small size. The faces of the centrum of this vertebra are slightly concave. 



Next following is the description of a right mandibular ramus, found separately in 1897, but agreeing in size with the one 

 depicted in fig. 18 [fig. 96]. 



Ramus of lower jaw (right) , Cat. No. 284. 



Ramus of lower jaw (PI. XVIII [XIX], figs. 1 and 2) stout, with an inward bend at mid-length, low and thick behind, 

 elevated and laterally compressed in front where the inner surface is shallowly concave. Excavated posteriorly below for 

 nearly one-third of its length, the excavation extending upward along the back surface of the coronoid process and anteriorly 

 as the mandibular canal leading forward to the mandibular groove in the lower border. The dentary canal between the outer 

 alveolar wall and the outer surface enters from the upper and anterior part of the excavation by a large opening. Coronoid 

 process stout, upright, hooked forward and flattened laterally above, its outer upward surface rugosely striated. A broad, 

 low ridge, least defined toward the center, runs at about mid-height along the outer side, the surface, in a general way, above 

 and below, retreating obliquely inward. The dental chamber, straight, starting at a low level behind, inclined strongly upward 

 and slightly outward toward the front, its lower edge making an angle of about 20° with the lower border. Alveolar 



a Referred to as a nasal by Lambe in Trans. Roy. Soc. Canada, 2d ser., vol. 10, sec. 4, p. 7. 



