THE VERTEBRATE SKELETON 



103 



in part with his own transcendentalism. His main theoretical 

 views are to be found in his volume On tJie Archetype 

 and Homologies of the Vertebrate Skeleton (London, 1848). 

 The master-idea of the book is that the vertebrate skeleton 

 consists of a series of comparable segments, each of 



d-. 



hs 



FlG. 5. Natural Typical Vertebra ; Thorax of a Bird. 

 (After Owen.) 



which Owen calls a vertebra. His definition of a vertebra 

 is, " one of those segments of the endo-skeleton which con- 

 stitute the axis of the body, and the protecting canals of 

 the nervous and vascular trunks" (p. Si). The parts of a 

 typical vertebra are shown in Fig. 4, which is copied from 

 Owen's Fig. 14. 



H 



