304 report — 1846. 



its diverging appendage (20), which, in addition to the more constant con- 

 nections with 21 and 27, 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 haemapophysis, 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 haemapophyses ; 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 haemal arch retains its almost fcetal 

 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 haemal 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 haemal arch : the unusually expanded distal end 

 of the same appendage also intervenes between the frontal pleur- and haem- 

 apophyses ; the pleurapophysis (2s) being more atrophied in man than in 

 most inferior mammals. The haemapophysis 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 (i4),both 

 with each other and the nasal capsules (is), and the corresponding proportions 



