8 ROYAL SOCIETY OF CANADA 



A iewed from below, or from the inner side, the squamosal is seen 

 to be thin for a short distance inward from the inner border along three- 

 fifths of its hinder length for the accommodation of the forwardly 

 directed prolongation of the posterior parietal bar. A sudden thickening 

 of the bone marks the outer limit of the surface of contact. A deep 

 pit c, figure 6, in continuation of the outer and larger emargination 

 of the front border, directed obliquely backward and inward, received 

 an elongate conical process from the quadrate which in this manner 

 effected a strong union with the squamosial. The narrow, raised surface, 

 d, figure 6, beneath this pit marks the junction of the outer end of the 

 exoccipital. This surface is broken and reveals the pit for the quadrate 

 more clearly than it would otherwise be seen. Behind this and outward 

 from the longitudinal depression for the parietal the bone is relatively 

 and rather uniformly thick, its surface being undulating and smooth. 

 The bone in advance of the pit for the quadrate and the anterior ter- 

 mination of the depression for the parietal is thin with the inner border 

 bent abruptly downward and inward at some distance from the edge 

 so as to form what may be referred to as a deep triangular excavation 

 in the inner front portion of the squamosal. The inner front border of 

 this excavation indicates that the squamosal here overlapped the post- 

 frontal to some extent, the contact with the jugal being limited to a 

 small surface exterior to this which would include the marginal pit 

 shown in figure 4 at e. A shallow groove, /, figures 6 and 4, extends 

 inward from the raised surface for the exoccipital to the inner border; 

 in its inner course it turns backward, becoming narrower and deeper, 

 and crosses the anterior end of the depression for the parietal obliquely, 

 finally passing to the upper surface over the inner border and ending 

 in the concavity shown at h in figure 4, The surface of the bone behind 

 this concavity, as well as that in the neighbourhood of the well defined 

 depressions or grooves toward the front end of the inner border (figure 

 4) is roughened as if for muscular attachment. Linear vascular impres- 

 sions are present anteriorly as indicated in the same figure. 



The anterior termination of the posterior bar of the parietal, shown 

 in figures 5 and 7, is flat on the side next to the squamosal, 

 and keeled on the lower side, the keel passing from the inner 

 edge behind to the middle of its anterior end where it is most ])rominent. 

 Beyond its contact with the squamosal it is slightly twisted, so as to 

 accommodate itself more exactly to the general plane of the upper surface 

 of the squamosal, and curves a little inward, Imt so little as to suggest 

 a sudden bending inward of the bone more to the rear, or if the in- 

 ward curve were gradual a very great backward development of the 

 parietal portion of the crest along the median line of the head would be 



