The majority of the face bones are in pairs, but two are single; one of these is the lower jaw bone or mandible, Md, Fig. 16; the other is the vomer, which forms part of the partition between the two nostrils.

With what is the floor of the cranium continuous? Where does the cranium present holes through it? What are most of these apertures for? What is the largest aperture called? What enters the brain case through it?

Name the cranial bones. State where each lies. Through which does the foramen magnum pass? Which contains the ear chamber? Which of them arc unpaired?

The paired face bones are : 1. The maxillú or upper jaw-bones, Mx, which carry the upper teeth and form most of the hard palate separating the mouth from the nose. 2. The palate bones, completing the bony palate, and behind which the nostril chambers communicate by the posterior nares (Fig. 20) with the throat cavity, so that air can pass in or out through them in breathing. 3. The malar or cheek-bones, Z. 4. The nasal bones, N, roofing in the upper part of the nose. 5. The lachrymal or tear-bones, L, small and thin, lying between the eye-socket and the nose. 6. The inferior turbinate or spongy bones, which lie inside the nose, one on the outer side of each nostril chamber.