XXIIl] 



CHELONIA 



593 



On each side there are costal plates; this name is given to 

 broad expansions of the outer surfaces of the ribs (Fig. 293). The 

 ribs curve inwards to join the centrum, and since this, as in all 

 Reptiles, is formed by the ventral intercalary, each rib is nearly 

 opposite the interspace between two centra and sometimes unites 



FIG. 294. Ventral view of the skeleton of Chelone mydas, the Green Turtle 

 x about . The plastron has been removed. 



1. Lower jaw or mandible. 2. Nuchal plate. 3. Ventral process of scapula, 

 the acromion. 4. Scapula (much foreshortened). 5. Marginal bone. 

 6. Coracoid. 7. Ilium. 8. Pubis. 9. Ischium. 10. Centrum 

 of vertebra. 11. Humerus. 12. Radius. 13. Ulna. 14. Carpus. 

 15. Femur. 16. Tibia. 17. Fibula. 



8. & M. 38 



