NUMBER OF VERTEBRA. 



[CHAP. 



movably articulated ribs. The lumbar vertebrae are those 

 that intervene between the thoracic and sacral regions. The 

 artificial and conventional definition of the sacral vertebrae 

 as those that are ankylosed together in the adult state to 

 form a single bone has been generally adopted in default of 

 a more scientific one of universal application. In the 

 Cetacea, the first caudal is that which bears upon its hinder 

 edge the first pair of chevron bones. 



It must never be forgotten that although the division of 

 the vertebral column into distinct regions is convenient for 

 descriptive purposes, at the contiguous extremities of the 

 regions the characters of the vertebrae of one region are 

 apt to blend into those of the next, either normally or as 

 peculiarities of individual skeletons. 



