662 
MR. W. K. PARKER ON THE STRUCTURE AND 
Here it curves forwards because of the original Batrachian form of this arch ; there it has 
no prepalatine spur, and naturally grows backwards, as seeking its next segment the 
pterygoid. The long tape-like pedicle, and the stout, subconical otic process (Plate 60. 
figs. 5, Q,pd., ot.p.) cannot be traced as distinct processes now; the former is lost, as a 
process, along the front of the outstretched otic masses ; and the latter [ot.p.) may be 
seen as cartilage between the squamosal and the fenestra (figs. 1, 3, 4, 9, sg., pro.). 
With this out-thrusting of the auditory mass the quadrate ( q .) is carried from the head 
a great distance, and is, in its hinder margin, opposite the occipital condyles. Its own 
condyle (figs. 2, 3, 4, 9) is sinuous (cylindroidal), and much of its substance is ossified 
as a true quadrate bone, enclothed with the squamosal ( sg .). The facet has a pyriform 
outline, with the narrow end looking forward and outward ; its broad end is below and 
in front of the posterior margin of the quadrate bone. In front of and below the 
otic process, the pterygoid (pg.) passes forwards nearly at a' right angle with the 
transverse otic masses. This front part of the pterygoid is a large, leafy bar, with 
oblique fibrous markings ; it is narrower and thicker behind, broader and thinner 
forwards ; the outer edge (figs. 2 & 4) is grooved and contains some unchanged cartilage, 
its inner edge is soft. This falcate part is grooved below for the jugal end of the 
maxillary ( m.x .), which it largely overlaps ; their overlapping ends are pointed. This 
fore part is the shaft of the hammer-shaped pterygoid; it joins the head in a curved 
manner, running inwards, and the inner part of the head is the longer. Where the inner 
part clasps the coalesced and undistinguishable pedicle, there is, proximally, an eleva- 
tion of the bone ; it then runs in and stops short suddenly, leaving exposed the roughly 
ossified pedicle and contiguous part of the auditory capsule. Further back it is longer 
and more splintery, and reaches one of the steps of the parasphenoid. Behind that 
spike there is another tract of rough inner bone, and then the long exoccipital ; the 
two bones, externally, fit by a squamous suture. The short end of the “ head ” runs 
outwards and backwards, strongly clamping the inner face of the quadrate. 
The free mandible (figs. 5, 6) is a strongly bent, rib-like structure ; the condyle is also 
cylindroidal, and seen from above (fig. 5) it has a squarish outline, and is traversed by 
a concavity ; it is obliquely set on the top of the inbent, solid “ articulare ” ( ar .), which 
bends outwards beneath the condyle. The articulare runs to within a short distance of 
the chin, and is covered by the dentary ( d .), which is two thirds its length ; the transverse 
front ends of the dentaries form a fibrous symphysis, without an “ os Meckelii ; ” the 
cartilage is almost entirely changed. 
The auditory masses, as seen from above and behind (figs. 1 & 3), are, with their 
intermediate occipital arch, a most rugged and strong structure. 
Already, in the ripe young (Plate 61. fig. 2), these parts were like small stony fruits, the 
occipital arch being thoroughly ossified by ankylosis of the exoccipitals above; but now 
it asks some care, if the parts are to be interpreted. The foramen magnum (fig. 3 ,f.m.), 
like the entrance of some stony cave, is surmounted by rough, projecting blocks of 
hone. The lower pair of these jutting snags overarch the 9th and 10th nerves (9, 10) 
