26 THE VERTEBRAL COLUMN. [CHAP. 



ribs of reptiles, which are unquestionably homologous serially 

 with the thoracic ribs. 



The anterior, or more properly inferior, bar of the trans- 

 verse process of the seventh, and occasionally of some of the 

 other cervical vertebrae in Man, is autogenously developed, 

 and has some characters by which it may be placed in the 

 category of rudimentary ribs. 



The transverse processes of the anterior lumbar vertebra? 

 of certain Mammals, as the Pig, are originally autogenous 

 elements, though coalescing very early with the rest of the 

 vertebras. 



In the sacral region, the separate lateral ossifications which 

 connect the vertebral column with the ilium present many 

 characters allying them to ribs. (See Fig. 6.) 



FIG. 6. Anterior surface of first sacral vertebra (human) showing mode of develop- 

 ment, na neural arch ; t centrum ; p distinct (pleurapophysial) ossification fur 

 attachment of ilium. 



Finally, the transverse processes of the caudal vertebra? of 

 some animals (as the Manatee and Beaver) are separately 

 developed, though it is doubtful whether this circumstance 

 alone is sufficient to entitle them to be considered as costal 

 elements. 



Division of the Vertebral Column into Regions. For con- 

 venience of description the whole vertebral column has 



