The third cervical vertebra shows a well-developed zygosphenal articulation, and stout articular processes. The transverse process is small, only a little larger than that of the axis, though, unlike that, it is strengthened by a ridge continued from the anterior zygapophyses. The hypapophysis is smaller than that of the axis, but, like that, is directed downward and backward. The spine may be distinguished from that of any other vertebra by its stout, trihedral shape; it is directed rather more obliquely backward than in the following vertebrae. The fourth cervical vertebra differs from the third in having stouter transverse processes; in the hypapophysis being directed more nearly downward, and in its smaller size; and in the spine being flattened antero-posteriorly toward the base. The fifth cervical vertebra differs from the fourth in the broader spine, in the stouter transverse processes, and the smaller hypapophysis. In the sixth cervical vertebra, the hypapophysis is reduced to a small ossification, scarcely longer than broad, directed downward. The spine has reached nearly the full width of those of the following vertebrae, though somewhat stouter above. The transverse processes are yet stouter. In the seventh, or last, cervical vertebra the hypapophysis is wanting, or very rudimentary. The under part of the centrum shows a rounded ridge or carina, with a slight projection corresponding to the hypapophysis. MEASUREMENTS OF THE CERVICAL VERTEBRAE. 1. Antero-posterior diameter of intercentrum of atlas 14 millim. Transverse diameter of intercentrum 25 Antero-posterior diameter of lateral piece 20 Vertical extent of articular surface 17 Extent of lateral piece 35 Width of lamina above 16 2. Length of axis 43 Transverse diameter of ball 18 Vertical diameter of ball 17 Expanse of transverse processes 28 Elevation of spine above floor of neural canal 34 Antero-posterior extent of spine 50 3. Length of third cervical vertebra 37 Height of spine above floor of neural canal 36 Depth of hypapophysis below floor of neural canal 34 4. Length of fourth cervical vertebra 37 Height of spine above floor of neural canal 39 Depth of hypapophysis below floor of neural canal 35 5. Length of fifth cervical vertebra 37 Height of spine above floor of neural canal 42 Depth of hypapophysis below floor of neural canal 33 Transverse diameter of ball 17 Vertical diameter of ball 18 6. Length of sixth cervical vertebra 37 Height of spine above floor of neural canal 42