302 : REPORT—1846. 
The centrum, 5c, of the parietal vertebra gives, in the human fcetus, the 
same evidence of its essential individuality, by the same absence of the mask 
of connation which somewhat concealed it in the oviparous classes, as 
we have already noticed in the lower mammal (fig. 24). The newrapo- 
physes (6) rise higher to reach their proper spine (7) in the lofty cranial dome 
of man, of which that divided and enormously expanded element forms the 
greatest part of the roof: but the base of the neurapophysis continues to be 
perforated by the homologous divisions of the nerve (¢r) that notches it in 
the cod-fish (fig. 5, 6 ér). The parapophysis (s) retains its autogenous or 
independent character in relation to its proper neural arch, the ‘ additamental’ 
suture by which it manifests its normal relations to the neural spine (7) being 
persistent; but it speedily coalesces with the acoustic capsule, 16 (from 
which it is artificially separated in fig. 25), and with the modified plewrapo- 
physis, 28, as has been already explained in the chapter on ‘ Special Homo- 
logy’ (Mastoid, pp. 197-210). 
The proper pleurapophysis (3s) of the parietal vertebra ordinarily becomes 
confluent with contiguous and coalesced portions of the parapophysis, s, and 
acoustic capsule, 16; and the ossified portion of the hemapophysis, a0 h, is 
separated from it by a long ligamentous tract, and becomes confluent with 
the hemal spine, 41hs. The entire inverted arch exhibits the usual arrested 
growth characteristic of the air-breathing vertebrates, and its appendages 
are represented by the still retained ‘hypobranchial’ elements, 46, of the 
splanchnic arches, which are so voluminously developed in the fish. 
The centrum and neurapophyses (9, 10) of the frontal vertebra manifest the 
same speedy coalescence as in other mammals. The spie, 11, though developed 
from two lateral moieties, regains its normal unity, as a general rule, in man 
by the obliteration of the median suture: its transverse and vertical expanse 
here attain their maximum. The parapophysis (12) is developed, as in the 
occipital segment, as an exogenous process, called ‘external angular or or- 
bital’ in anthropotomy, but from the neural spine instead of the neurapo- 
physis. This element is perforated by its characteristic nerve (op). The pleur- 
apophysis, 28, is now separated from its parapophysis, 12, by both parts, 27 and 
26, of the diverging appendage of the maxillary arch ; but yet it is interesting 
to note that it is still connected through the medium of these with the same 
element to which, agreeably with the greater retention of the vertebrate 
archetype, it directly articulates in the fish (fig. 5, 12, 2s a-d). The inter- 
calated piece (27) further interposes itself, as in other mammals, between 
the pleurapophysis, 2s, and heemapophysis, 29, of the frontal segment, directly 
articulating with the latter and leaving the proximal element of the arch (2s ) 
reduced in man to its subordinate function of sustaining the ear-drum. The 
hemapophysis,29,and hemal spine, 32, are connate, and soon coalesce with their 
in the Anguis, Pseudopus, and some other limbless and snake-like lizards. The usual pre- 
dominating development of the scapular appendage has bred so prevalent an idea of the sub- 
ordinate character of the supporting arch, that the existence of the arch minus the append- 
age, is adverted to not without a note of surprise in the above-cited and other excellent works. 
General homology, however, teaches that a vertebral arch is a more constant and important 
part than its appendages ; and, that, being anterior in the order of development, it may be 
expected, in cases where development is arrested, whether normally in accordance with the 
nature of the species or abnormally as an individual defect, to be present when the diverging 
appendages are absent. Sir Charles Bell, well recognising the primary function of the modi- 
fied occipital rib in relation to breathing, observes, in reference to the above-cited case, ‘“‘ We 
would do well to remember this double office of the scapula and its muscles, that, whilst it is 
the very foundation of the bones of the upper extremity, and never wanting in any animal 
that has the most remote resemblance to an arm, it is the centre and point d’appui of the 
muscles of respiration, and acts in that capacity where there are no extremities at all!” 
p. 52. 
