8 
MUSEUM BULLETIN NO. 12. 
angular and longer than broad, its greatest length being about 
one and a half times the maximum breadth. In lateral outline 
the outer free border forms a sinuous convex curve to the posterior 
pointed end, and the inner border a concave one to the same ter- 
mination. The front edge, constituting the base of the triangle, 
displays, in succession from below upward, the posterior margin 
of a deep quadrato-jugal notch, the hinder half of a rather large 
lateral temporal fossa, a short suture for contact with the jugal 
which overlapped it, and a long one for the postfrontal. 
Both the outer and inner surfaces of the bone are remarkably 
smooth. A few inconspicuous vascular grooves occur on the 
outer surface back of the suture for the jugal. Superiorly in 
front the bone is bent inward about at right angles to the general 
plane of its outer surface, forming a strong angulation which 
descends backward from the postfrontal suture in continuation 
of the postfrontal angulation behind the horn-core. The bone 
is here thin and comes to a sharp inner edge, which constitutes 
the outer boundary above of the supratemporal fossa. The 
lower free border flares outward somewhat causing the general 
surface of the bone to be concave in a longitudinal direction, 
but it is difficult to say whether this is normal or accentuated 
by pressure. 
The coalesced parietal portion of the neck-frill is known 
only from the slender postero-lateral bar by means of which a 
union was effected with the squamosal. This parietal bar 
(Plate I) passed forward beneath the inner border of the squa- 
mosal, which was grooved to receive it, to a point slightly in 
advance of the latter's length. It is of nearly the same breadth 
for the greater part of its length, tapering slightly in front for a 
short distance before it apparently terminates. That part of 
the bar which underlies the squamosal is triangular in cross 
section. Its upper surface is flat where it comes in contact 
with the squamosal, but beneath there is a ridge which passes 
with decreasing prominence from the middle of the lower anterior 
surface obliquely backward to the inner edge. Behind the 
squamosal, in its free part, the bar is lenticular in cross section, 
curves slightly inward, and gives evidence, where it is broken 
off, of having expanded horizontally but to what extent is not 
