REPTILIA. 545 



Fig. 244. 



(594.) The skeleton we choose for particular description is that 

 of the Crocodile, one of the most interesting that can possibly be 

 offered to the contemplation of the comparative anatomist ; inas- 

 much as it exhibits, developed to a medium extent, a greater num- 

 ber of the elements which we have supposed to enter into the 

 composition of a perfect or typical skeleton than any other with 

 which we are acquainted : we, therefore, beg the attention of the 

 student while we investigate this important piece of osteology. 



(595.) A glance at the skeleton of the Crocodile (jg. 245) 

 at once shows us that in consequence of the addition of a thorax, 

 and the connection which now necessarily exists between the pelvis 

 and the spine, the vertebral column becomes- divisible into dis- 

 tinct regions : viz. the cervical, containing seven vertebrae ; the 

 dorsal, formed by those vertebrae which support the thoracic ribs ; 

 and the lumbar vertebrae intervening between these and the sa- 

 crum. The number of bones entering into the composition of the 

 sacrum, that is, which are connected with the ossa ilii of the pelvis, 

 are in this case two in number; while, behind these, six and thirty 

 vertebrae enter into the composition of the tail. 



In the cervical, dorsal, lumbar, and sacral regions, no inferior 

 spinous processes exist ; but in the caudal portion of the vertebral 

 column these elements are found greatly developed, as in fishes, 

 and obviously with the same intention, namely, to increase as much 

 as possible the vertical extent of the tail, and thus convert this 



