(2) the lower jaw or mandible;
(3) the hyoid.
(1) The Cranium.
The cranium is a very compact bony box, containing a cavity in which the brain lies, and which is a direct continuation of the neural canal of the vertebrae.
Fig. 38. The skull of the Green Turtle (Chelone midas). × ½. A, posterior half, B, anterior half. (Brit. Mus.)
| 1. parietal. | 13. angular. |
| 2. squamosal. | 14. supra-angular. |
| 3. quadrate. | 15. premaxillae. |
| 4. basisphenoid. | 16. maxillae. |
| 5. basi-occipital. | 17. jugal. |
| 6. quadratojugal. | 18. postfrontal. |
| 7. opisthotic. | 19. vomer. |
| 8. exoccipital. | 20. prefrontal. |
| 9. foramen magnum. | 21. frontal. |
| 10. splenial. | 22. external auditory meatus |
| 11. articular. | leading into tympanic |
| 12. dentary. | cavity. |
Like those of the skull as a whole its component bones may be subdivided into three sets:—
1. those forming the brain-case or cranium proper;