STRUCTURE OF CHELONIA 



691 



(Dennatochelys) coriacea, the only living species, the largest modern 

 Chelonian, sometimes measuring 6 ft. in length. It is widely, but now 

 sparsely, distributed in intertropical seas, and is said to be herbivorous. 



Fig. 403. — Internal view 

 tortoise skeleton. 



of 



H., Humerus ; 

 SC, scapula running dorsally ; 

 PC, precoracoid ; 



C, coracoid ; 

 E.C., epicoracoid cartilage ; 



P., pubis ; 

 I.L., ilium running dorsally 



sacral vertebrae; 

 IS., ischium ; 

 D.V., dorsal vertebrae fused 

 carapace ; 

 R., head of a rib ; 

 CE.V., cervical vertebrae free ; 

 CA.V., caudal vertebrae free. 



to 



m 



II. Thecophora. Dorsal vertebrae and ribs fused in the carapace. 

 Parietals prolonged downwards. Including the following and 

 other families : — 



Chelonidae, marine turtles, with fin-like feet, and partially ossified 

 carapace. They occur in intertropical seas, and bury their soft -shelled 



Fig. 404. — Dissection of Chelonian 

 heart. — After Huxley. 



r.v., Right half of ventricle ; 

 5., septum ; 



Lv., left half of ventricle ; 



r.a., right auricle ; 



La., left auricle ; 

 Lao., left aortic arch ; 

 r.ao., right aortic arch ; 

 p.a., pulmonary arch. 



eggs on sandy shores. The green turtle (Chelone viridis) is much 

 esteemed as food ; the hawk's-bill turtle {Caretta imhricata) furnishes 

 much of the commercial tortoise-shell. 



Testudinidas, land tortoises, with convex perfectly ossified carapace, 

 and feet adapted for walking. They are found in the warmer regions 



