22 THE VERTEBRAL COLUHLV. [chap. 



at least in the Mammalia; but at the contiguous extre- 

 mities of the regions, the characters of the vertebrae of one 

 are apt to blend into those of another region, either nor- 

 mally, or as peculiarities of individual skeletons. 



I. The Cervical rtgxon constitutes the most anterior por- 

 tion of the column, or that which joins the cranium. 



The vertebrae which belong to it are either entirely 

 destitute of moveable ribs, or, if they have any, these are 

 small, and do not join the sternum. 



As a general rule they have a considerable perforation 

 through the base of the transverse process (the vefte- 

 hrarterial canal, Owen), or, as it is sometimes described, 

 they have two transverse processes, superior and inferior, 

 which, meeting at their extremities, enclose a canal. (See 

 Fig. 7 ; Fig. 8, p. 27 ; and Figs. 17 and 18, p. 39.) This, 



Fig. 7. — Anterior surface of sixth cervical vertebra of Dojj, §. ^ spinous process 

 az anterior zygapophj'sis ; v vertebrarterial canal ; t transverse process ; t' its 

 inferior lamella. 



however, rarely applies to the last vertebra of the region, in 

 which only the upper transverse process is usually developed. 

 The transverse process moreover very often sends down 

 near its extremity a more or less compressed plate {iiiferioi- 

 lamella, Fig. 7, /'), which being considered to be serially homo- 



