CHAPTER XIV. 



THE SKELETON OF THE GREEN TURTLE. 



(Chelone midas.) 



THE most striking feature as regards the skeleton of the 

 Turtle is that the trunk is enveloped in a bony box, the dorsal 

 portion of which is called the carapace, while the ventral 

 portion is the plastron. 



I. EXOSKELETON. 



a. The epidermal exoskeleton in the Green Turtle as 

 in all other Chelonia except Dermochelys, Trionyx and their 

 allies is strongly developed, its most important part consisting 

 of a series of horny shields which cover over the bony plates 

 of the carapace and plastron but do not at all correspond to 

 them in size and arrangement. 



The shields covering over the carapace consist of three 

 rows of larger central shields, five (vertebral) shields being 

 included in the middle row and four (costal) in each lateral 

 row, and of a number of smaller marginal shields. 



Of the marginal shields, that lying immediately in front of 

 the first vertebral is termed the nuchal, while the two suc- 

 ceeding the last vertebral are called sometimes pygal, some- 

 times supracaudal ; the remainder are the marginal shields 

 proper. 



The epidermal covering of the plastron consists princi- 

 pally of six pairs of symmetrically arranged shields, called 



