so PEOF. W. K. PARKER ON THE STRUCTURE OF 



and reaching round the great temporal space to articulate with the squamosal (sq). 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 (j). 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, sq, j)). 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. c) can be seen. The 

 hind fork descends as a straight process to articulate with the " otic process " of the 

 quadrate {q, ot. j)). On the other side of the archway the squamosal sets its fore foot 

 upon the thick top of the jugal (j). 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 (/./j) forms the broad hinder third of the roof, behind the coronal 

 suture, which is slightly concave in front ; tlie wings of this T-shapcd 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.o) 

 From the tubercular growths that surround the fontanellc {fo) in the hollow of this 

 hind part of the frontal, the interparietal arises (covered there with tubercles) into a 

 hugej flat, falcate, free crest, whose convex margin is above, and the concave margin of 

 which, at its proximal third, rests directly upon a crest tliat grows upwards from the 

 supraoccipital (figs. 1 and 4, i.jj, s.o). At its highest part, behind, it is thickened and 

 knobbed, and is embraced by the top part of the parietals {})), 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.o) 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 

 {i.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 infcro-lateral series of bones are like a Gothic 

 arch ; the key-stone of this arch is formed by the premaxillary {p-v), which is a wedge 



