326 report— 1846. 



of the trunk of the human subject according to the archetype with which the 

 segments in the head have been illustrated. 



The first seven segments of the trunk consist each of centrum (fig. 25, c), 

 neurapophyses (w), neuralspine (s), and rudimental pleurapophyses (/?/), which 

 coalesce, in each segment, into one bone, called ' cervical vertebra ' in anthro- 

 potomy. If the haemapoph) r ses (52') have the same relation to their centrum 

 which those of the seventh dorsal vertebra, in the Ciconia Argala, more ob- 

 viously bear to theirs, — that is, being attached below and disunited at their upper 

 ends from their pleurapophyses, which are short, stunted and anchylosed to the 

 centrum, — and if, as the apparent homologues of 52' in fishes would indicate, 

 the atlas be actually the centrum to which such detached and shifted haema- 

 pophyses belong, then the first will be the sole segment of the cervical region of 

 the trunk in which those elements are ossified. 



In the seven vertebrae which succeed the cervicals the pleurapophyses (pi) 

 are progressively elongated; they are shifted from their proper centrum to the 

 interspace between it and the next segment above, or in advance, and retain 

 their moveable joints. The haemapophyses (h) are cartilaginous and articulate 

 with the ends of the pleurapophyses andwith the haemal spines (/is), which are 

 flattened, slightly expanded, and ultimately blended into one bone called ' ster- 

 num.' The haemal spine of the first typical segment remains longest distinct : 

 it receives, also, the extremities of the displaced haemapophyses (52') and has 

 been called ' manubrium sterni.' The haemal spine of the seventh segment 

 commonly continues longer distinct, and is later in becoming ossified, whence 

 it is called ' ensiform cartilage ' : it probabty includes the rudiments of some 

 succeeding haemal spines. In the four succeeding segments the pleurapophyses 

 become progressively shorter, and the haemapophyses, still cartilaginous, are 

 severally attached by their lower attenuated ends to the pair in advance ; 

 leaving the haemal arch incomplete below. In the next vertebra (19th from 

 the skull) the still shorter pleurapophyses resume the exclusive articulation 

 with their proper centrum ; and the correspondingly short and pointed haem- 

 apophyses terminate freely. 



Those pleurapophyses and haemapophyses which directly articulate with 

 haemal spines (sternum) are called collectively 'true ribs ' (costae verae), the 

 proximal element being 'the bony part of the rib' (pars ossea costae), the distal 

 one the ' cartilage of the rib.' The rest of the haemal arches which are in- 

 complete through the absence of the haemal spine, are called ' false ribs ' 

 (costae spuriae) ; and the last, which terminates freely in the origin of the 

 diaphragm, is a ' floating rib.' The centrum, neurapophyses and neural spine 

 of each segment with freely articulated pleurapophyses coalesce into one bone, 

 called ' dorsal vertebra ' in anthropotomy : these vertebrae are twelve in 

 number. Each of the five succeeding segments is represented by the same 

 elements (centrum and neural arch) coalesced that constitute the so-called 

 dorsal vertebrae : they are called 'lumbar vertebrae ' (fig. 25, L.): they have no 

 ossified pleurapophyses ; and the haemapophyses of these segments are repre- 

 sented only 7 by the aponeurotic ' inscriptiones tendineae musculi recti' (h"). 



Certain elements of the five succeeding segments (ib. S.) coalescing together 

 in the progress of growth form the bone called 'sacrum': and are described in- 

 dividually as sacral vertebrae. The first four of these each combine the same 

 elements, coalesced, as in the neck; viz. centrum, neurapophyses, neural spine, 

 and short but thick pleurapophyses * : in the fifth sacral vertebra there are no 



* J. Miiller notices the rudimental ribs in the first and second sacral vertebrae of the 

 human foetus in his Anatomie der Myxinoiden, heft i. 1834, p. 240. Mr. Carlile has 

 described (Report of British Association, 1837, p. 112), and Dr. Knox has figured (Lancet, 

 1839, p. 191) these ribs and their homotypes in the third and fourth sacral vertebra. 



