Vertebral Column 



29 



second gives 8 : 13, in the third it is 8 : 12-5, while in the fourth it suddenly changes to 

 10 : 13. After this the measurements give : 



5- " : 13 + 

 6, ii : 13 -f- 



7- 12 : 13 + 

 S, 12-5 : 13-5 



9. 13 : I4-5 

 in, 13 : 14-5 



". I4'5 



In the last two bodies the facets do not reach the margin of the body. 



FIG. 24. Tracings to scale of the upper surfaces of the dorsal bodies. 



the smallest body. 



Notice that the third is 



Considering these figures it may be said that the fourth is the first body in which 

 the typical dorsal shape is undoubtedly apparent. Moreover, the body of this vertebra 

 is, owing to this fact, more wedge-shaped than that of the third segment, so that it 

 gives the impression cf being smaller when seen from the front : it is evident, however, 

 that it is not the smallest body, which is really the body of the third. From this down 

 the bodies increase in size, and in the last two the increase is considerable, especially 

 in the transverse diameter, thus showing a tendency to approach the lumbar type. 

 In the same way the bodies, ascending from the fourth, show an increasing approach 

 to the cervical type, and the upper surface of the first body is strongly suggestive of 

 the appearance of a cervical vertebra : the first vertebra also presents the two antero- 

 lateral prominences on the lower border of its body that are seen in the cervical region. 



