650 



SKELETON. 



would not be more like the clavicle (1) than bar vertebra, why not also from the equal of 



it is in its present situation. " u - "' _...-i-i i . ^ , 



In fig. 476., the pubic bone (2) occurs op- 

 posite to the sacral vertebral rib (1), and the 



Fig. 476. 



thoracic costo-vertebral archetype ? If the 

 caudal bone gives evidence of the fact that its 

 present condition is owing to the loss of the 



Fig. 4-77. 



The sacral vertebra and pubic forms of the Crocodile' 

 forming the whole quantity. 



whole form is thereby completed as the sterno- 

 costo-vertebral-archetypal quantity. The part 

 2, of fig. 476., may, therefore, as appro- 

 priately be termed a pubic rib as a costiform 

 pubis. This pubic bone (2, fig. 476.) is sepa- 

 rated from the sacral rib by an interval equal 

 to the iliac bone, and this latter is regarded 

 by a high authority * to be of costiform cha- 

 racter ; but in the present reading I have no 

 need to view the bone in this regard. 



PROP. XXXVI. Chevron bones and ribs are 

 identical parts of the costo-vertebral whole quan- 

 tities or archetypes. As every part which 

 shall appear plus upon a cervical or lumbar 

 vertebra, such as cervical or lumbar ribs, may 

 be referred to the original whole quantities 

 from which the cervical or lumbar vertebrae 

 have been metamorphosed, and gain their 

 proper interpretation accordingly, so may 

 those parts which now and then appear plus 

 upon the caudal vertebras, such as " chevron 

 bones" (4, of fig. 477.), be likewise referred to 

 the original whole quantities from which those 

 caudal vertebrae have been degraded. We 

 have seen reason to interpret the caudal bone 

 as the centrum of the vertebra, of which 

 vertebra ? Of the thoracic plus vertebra ; for 

 why not of this plus archetypal form, as well as 

 of any other form less in quantity than this 

 archetype ? If the caudal bone be considered 

 as a part degraded from the equal of the lum- 



* The author of the " Homologies " entertains the 

 opinion that the iliac bones are the "pleurapo- 

 physeal " (costal) elements of the sacral vertebra, 

 and thereby lie connects the pubic arches (his hae- 

 mapophyses) with their proper vertebral pieces in 

 the sacrum. This opinion as to the costiform cha- 

 racter of the ilium or haunch bone, is by no means 

 that which I hold respecting it, nor can I believe 

 that any other anatomist will discover the similitude 

 between an iliac bone and a rib, any more than be- 

 tween a scapula and a rib, or any more than they 

 will find to exist between a sternal piece and a 

 spinal vertebral form, even though the imposing 

 names of Oken, Meckel, and Ue Blainville intro- 

 duce this latter opinion. 



Tlie caudal vertebra of the Ditgong, 



Showing that it is not the typical or whole vertebral 

 quantity. 



neural arch, the spinous process, and trans- 

 verse-costal processes, and if it elicits accord- 

 ingly the interpretation that had those ele- 

 mental quantities still persisted, that which 

 is now the caudal would have been equal 

 to the lumbar vertebra ; so, on the like 

 grounds, we may elevate ourselves to the 

 reading, that if the thoracic ribs and ster- 

 num, the neural arch and spine still per- 

 sisted, that which is now the caudal bone 

 would have been equal to the thoracic arche- 

 type. Such a reading I here venture to put 

 forth respecting the caudal bones {fig. 477.), 

 and when these develope the chevron os- 

 sicles (4), I interpret them as being proximal 

 parts of the costal arch (1, 2, 3), left standing 

 after the degradation of the whole archetypal 

 quantities. If a thoracic costo-vertebral 

 archetype, such as fig. 478., whose costal 



Fig. 478. 



caudal vertebra of the Dugong, 



Showing how the costal quantities are metamor- 

 phosed into the chevron bones. 



arch is 1, 2, 3, undergoes such an amount of 

 degradation as to sternal and costal quantity, 

 that the proximal or vertebral ends (2) of tlie 

 ribs (2, 3) alone remain persistent ; and if 

 these ends (2, 3) of the ribs, while remaining 

 still articularly appended to the vertebrae, are 

 bent towards each other and to the median 

 line, taking the place of the parts 4, 5, then 



