80 PROF. W. K. PARKER ON THE STRUCTURE OF 
and reaching round the great temporal space to articulate with the squamosal (sg). It 
has a sharp, crested, ornate upper part, which passes, hollow and flat, to the roof; then 
it descends as a long, subtriangular spike behind the orbit, which spike binds on the 
front of the upturned malar or jugal bone (7). Where it articulates with the prefrontal, 
there it shows an orbital part articulating with the frontal over the eyeball. The squa- 
mosal (sq) is a very sharp bone: but it appears to be larger than it is; for the ascending 
part, which runs up to the interparietal crest, is half of it due to another bone, and 
the suture can be faintly seen even in the adult (fig. 1, sg, p). That other bone 
is a subarcuate thickish rod, all that remains of the parietal. From the point of fusion 
downwards the squamosal enlarges and forks, one fork passing forwards to -articulate, 
by a long sinuous suture, with the postorbital, and the other behind a round arched 
space; under this archway the anterior canal and its ampulla (a. s.¢) can be seen. The 
hind fork descends asa straight process to articulate with the “otic process” of the 
quadrate (9, of. p). On the other side of the archway the squamosal sets its fore foot 
upon the thick top of the jugal (7). The inner face of the hinder fork does not directly 
bind upon the parotic wings (fig. 4, op, sq), but there is another temporal bone (s.t) 
wedged in between those two parts: this is a wedge-shaped bone, sharp above and 
thick below; it reaches halfway to the parietal above, and nearly down to the qua- 
drate below. 
The interparietal (¢.p) forms the broad hinder third of the roof, behind the coronal 
suture, which is slightly concave in front; the wings of this T-shaped bone articulate 
obliquely with the broadest part of the huge postorbital ( pt.o); and then each wing 
of the bone ends by a gently concave margin which overroofs the occipital arch (s.0) 
From the tubercular growths that surround the fontanelle (fo) in the hollow of this 
hind part of the frontal, the interparietal arises (covered there with tubercles) into a 
huge, flat, faleate, free crest, whose convex margin is above, and the concave margin of 
which, at its proximal third, rests directly upon a crest that grows upwards from the 
supraoccipital (figs. 1 and 4, 7.p, s.o). At its highest part, behind, it is thickened and 
knobbed, and is embraced by the top part of the parietals (p), which expand somewhat 
to articulate with its double thickening. Below and behind it is a rather thin lamina ; 
and for some depth the supraoccipital (s.0) is as thin as the plate which rests upon it. 
The upper view (fig. 3) shows to what an extent the hinder part of the three parietals 
(.p,p) have shot up out of the reach of the cranial cavity, relatively lessened to a tithe 
of its original bulk (see Plate XV.); and now these bones mainly enclose the largely 
open temporal space right and left; in the young we see them lying down upon the great 
fontanelle of the tumid cranium. Here the huge temporal space is bounded by the inter- 
parietal within, and by the postorbital and combined squamosal and parietal outside. 
Seen from below or above, the infero-lateral series of bones are like a Gothic 
arch; the key-stone of this arch is formed by the premaxillary (px), which is a wedge 
