304 REPORT—1846. 
its diverging appendage (26), which, in addition to the more constant con- 
nections with 21 and 2, articulates in man with the neurapophysis (10) 
and parapophysis (12) of the frontal vertebra. The distal extremity of the 
second bone (27) of the diverging appendage attains its maximum of expan- 
sion in man, and besides its connection with 26, and the glenoid articulation 
for the hemapophysis, 29, it joins the parietal neurapophysis, 6, and spine, 7, 
and sometimes also (in the melanian race) the spine (11) of the frontal: ver- 
tebra: and it speedily coalesces with the reduced pleurapophysis, 2s, of the 
frontal vertebra, and with the parapophysis (s) of the parietal vertebra, to- 
gether with a portion of the capsule of the acoustic organ. 
In reviewing the general characters of the human skull in reference to the 
vertebrate archetype, we find the occipital segment simplified by the atrophy 
and connation of its parapophyses and hemapophyses; and modified chiefly 
by the excessive growth of its neural spine and pleurapophyses, and by the 
backward displacement of the latter element, as in all other air-breathing 
vertebrates. The parietal segment, retaining, like the occipital one, the more 
normal proportions of its centrum and neurapophyses, is still more remark- 
able for the vast expanse of its permanently bifid spine. As in most cold- 
blooded vertebrates, the parapophysis preserves its independence in respect of 
the neural arch of its own segment. The hemal arch retains its almost foetal 
proportions, but is less displaced than in some of the inferior air-breathing 
vertebrates. The primitive individuality of the centrum of the parietal vertebra 
is a feature by which the human subject, together with all other mammals, 
manifests a closer adhesion to type than is observable in this part of the skull 
in any of the oviparous vertebrates, and it shows the necessity of extending 
comparisons over the entire series, and not deducing the vertebrate arche- 
type exclusively from those inferior forms: for although it may be upon the 
whole best retained in them, yet the modifications superinduced in subser- 
viency to their exigences, and by which they diverge to that extent from the 
common plan, and, as a series of species, from the common vertebrate stem, 
may affect a part which the conditions of existence of higher forms do not 
require to be so masked. The early ossification and large proportional size 
of the hyoidean arch in the human embryo is very significant of its true 
nature and importance, in relation to the archetypal vertebrate structure, 
i.e. as being the hemal complement of a primary segment of the skull. 
Exogenous processes descend, like the pair from beneath the lower cer- 
vical vertebrae of some birds, from the body of the parietal vertebra; but 
the true transverse processes are the mastoids, which always articulate with 
a corner of the parietals. 
The centrum and neurapophyses of the frontal segment retain their ordi- 
nary proportions, and the spine is again the element which, by its extreme 
expansion and its modification in subserviency to the formation of the orbits, 
chiefly masks the typical features of the neural arch. The parapophysis is 
connate and reduced in size, and its vertebral relations with the pleurapo- 
physis of its segment interrupted by the interposition of the diverging appen- 
dage from the antecedent hemal arch: the unusually expanded distal end 
of the same appendage also intervenes between the frontal pleur- and hem- 
apophyses ; the pleurapophysis (2s) being more atrophied in man than in 
most inferior mammals. The hemapophysis and spine are on the other 
hand much developed and modified as above described, for the business of 
mastication, though relatively shorter than in other mammals. 
The compression and extension, both vertically and longitudinally, of the 
centrum (13), the compression and coalescence of the neurapophyses (14),both 
with each other and the nasal capsules (1s), and the corresponding proportions 
