302 report — 1846. 



The centrum, 5 c, of the parietal vertebra gives, in the human foetus, 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 neurapo- 

 physes (&) 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 (7r) that notches it in 

 the cod-fish (fig. 5, 6 tr). 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, ie (from 

 which it is artificially separated in fig. 25), and with the modified pleurapo- 

 physis, 28, as has been already explained in the chapter on ' Special Homo- 

 logy' (Mastoid, pp. 197-210). 



The proper pleur apophysis (3s) of the parietal vertebra ordinarily becomes 

 confluent with contiguous and coalesced portions of the parapophysis,, 8, and 

 acoustic capsule, ig ; and the ossified portion of the haemapophysis, 40 h, is 

 separated from it by a long ligamentous tract, and becomes confluent with 

 the haemal spine, 41 hs. 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 spine, 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, 2s, is now separated from its parapophysis, 12, by both parts, 27 and 

 20, 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, 28 a-cT). The inter- 

 calated piece (27) further interposes itself, as in other mammals, between 

 the pleurapophysis, 28, and haemapophysis, 29, of the frontal segment, directly 

 articulating with the latter and leaving the proximal element of the arch (23) 

 reduced in man to its subordinate function of sustaining the ear-drum. The 

 hcemapophysis, 29, and haemal 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 tbe sub- 

 ordinate character of the supporting arch, that the existence of the arch minus tbe 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. 



