The dorsal arch of the =atlas= bears a large tuberosity. The ventral tubercle is long, compressed laterally, and projects back under the axis. The wing is flattened and bears a posterior tuberosity. The foramen transversarium passes through the posterior border of the wing to the fossa under the latter, and is not visible dorsally; it is sometimes very small or absent. The sides of the vertebral foramen bear two lateral projections which partially divide it into a ventral narrow part, which receives the odontoid process, and a dorsal larger part for the spinal cord. In the fresh state the division is completed by the transverse ligament, which is attached to the projections. The =axis= has a large spinous process, which is directed upward and backward. The odontoid process is a thick cylindrical rod. The transverse process is very small and the foramen transversarium is often incomplete. [Illustration: FIG. 106.—ATLAS OF PIG, DORSAL VIEW. _a_, Wing; _b_, ventral tubercle; _c_, foramen transversarium; _d_, alar foramen; _e_, intervertebral foramen; _f_, dorsal tuberosity; _g_, articular surface corresponding to that of posterior articular process of typical vertebra; _h_, facet on ventral arch for odontoid process. (Ellenberger-Baum, Anat. d. Haustiere.) ] [Illustration: FIG. 107.—AXIS OF PIG, LEFT LATERAL VIEW. _a_, Odontoid process (dens); _b_, spinous process; _c_, anterior articular process; _d_, posterior articular processes; _e_, transverse process; _f_, foramen transversarium; _g_, bar of bone which bounds _h_, intervertebral foramen; _i_, vertebral foramen. (Ellenberger-Baum, Anat. d. Haustiere.) ]