66 



Breadth of coronoid process from point of anterior hook backward 097 



Thickness at centre of upper coronoidal expansion ' 024 



Thickness of coronoid process at its uiid-height 038 



Antero-posterior diameter of symphyseal surface • 055 



Height of same ' 025 



Width of larger alveolar grooves at middle of dental chamber -009 



Six grooves in a space of ... "072 



Height of grooves, from their base to upper edge of outer alveolar wall, at 



middle of dental chamber ' 028 



Height of same anteriorly .... • 044 



A maxillary bone (not figured) with teeth that are double fauged, is referred to this 

 species. One of the teeth is shown on plate XVIII, figs. 3 and 4. 



A separate tooth, presumably from the lower jaw, is also figured on plate XVIII. It 

 was found separately, but on account of its having two roots, agreeing thus with the 

 evidence of the alveolar grooves of the mandibular ramus just described, it is likewise 

 referred to M. canadensis. 



MONOCLONIUS BELLI. Sp. UOV. 



Plate XX, figs. 1 and 2. 



The bone, figured on the above 

 plate, is interpreted as representing 

 the coalesced parietals of the pos- 

 terior crest of an undescribed 

 species of Monoclonius, probably 

 ancestral to such later forms as 

 Torosaurus latus and T. gladius of 

 Marsh, from the Laramie, of Wyo- 

 ming. 



To facilitate an understanding 

 of the view held as to the position 

 the parietals probably occupied 

 relative to other bones of the head, 

 a drawing of the bone, has been 

 applied to the figure, slightly mo- 

 dified, of the skull of T. gladius, as 

 given by Marsh, in the Sixteenth 

 Annual Report of the United States 

 Greological Survey. 



Fig. 20. — Posterior crest of Monoeloum^ hdli, 

 from Red Deer river ; one-ninth natural 

 size. The dotted lines arc from a drawing 

 of the liead of T. i/ladiw). Marsh, as seen 

 from above. P, Parietal ; S, Squamosal ; 



F, Fontanellc. 



