OSTEOLOGY OF THE TORTOISE. 



083 



what slight modifications in the arrangement of the elements of the 

 skeleton such prodigious changes are accomplished. This is well exem- 

 plified in the construction of the carapax of the common Tortoise (Emys 

 Europceus). In this well-known animal (fig. 336) the vertebrse of the 



Fig. 336. 



Skeleton of Tortoise. 



neck and of the tail present nothing particularly remarkable in their 

 structure ; but, being connected together in the ordinary manner, the 

 neck and caudal region of the spine present their usual flexibility. The 

 dorsal vertebras, however, are strangely distorted, the elements of the 

 upper arch being disproportionately developed, while the bodies remain 

 almost in a rudimentary condition. The superior spinous processes of 

 these vertebrae are flattened and converted into broad osseous plates, 

 which form a longitudinal series along the centre of the back, and are 



