(54 



Squamosal somewhat triangular in shape, flat, moderately thin, its outer edge 

 smooth, rounded, wavy in outline so as to produce six minor convex curves, shorter and 

 more pronounced near the front. Its outer front edge is deeply emargiuated, with a 

 shallower concavity limiting the outer termination of the jugal suture (see figure 18), 



Fig. 18. — Monoclonius cayiaden-tia ; part of the skull fi-oni the right lateral aspect ; one-eightli uatiual size, fp, postfrontal ; 

 h, horn core ; o, orbit ; .s, squamosal ; p, right lateral extension from parietal ; j, jugal ; /, lower jaw. 



inside of which is the suture for the union with the postfrontal. The inner border 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 c\ir re of the squamosal. 

 Probably this slender bone represents the anterior end of a forwardly bent, side extension 

 of the parietal, such as occurs in the species Monor.hnivs belli, in which case a foutauelle 

 of moderate size might be expected on the inner side of the squamosal. 



In figure 18 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 convexity 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 soma 

 distance back from the postfrontal suture. 



Measurements of sqitamosal, d:c. 



Length on curve of outer border 



Length on curve of inner border 



Length from posterior end to centre of front margin 



Breadth across front margin 



Thickness near outer border, at mid-length 



M. 



•576 



•573 



•533 



■355 



•028 



