1200 



THE ANATOMY OF VEETEBEATED ANIMALS. 



not only with its own centrum and neural arch, but with the 

 posterior edge of the centrum of the first vertebra. 



These aiTangements are repeated by the other dorsal 

 vertebraB and ribs, up to the ninth inclusive ; but, in the 

 tenth, the neural arch occupies only the anterior half of the 

 centrum of its own vertebra, and the rib is very small, and 

 has no costal plate. 



The union of the neural and costal plates of the eight 



Fig. 63. 



Fig. 6;3.— Dorsal view of the carapace of Chelone viidas:—Nu, nuchal 

 plate; Jlf, marginal plates ; K, ribs; 1—8, neural plates; CI — C.8, 

 costal plates ; Py, pygal plates. 



dorsal vertebrae, from the second to the ninth inclusively, 

 gives rise to the i^rincipal jjart of the carapace, or dorsal 

 moiety of the bony shell of the Chelonian. The first and 

 the tenth dorsal vertebrae contribute nothing to the cara- 

 pace, their small ribs merely becoming attached to the 

 Costal plates behind and before them. 



In front of the first nem^al plate, and joined A^ath it hy a 



