The characteristic feature of the cervical vertebræ is their transverse process, so called. In each of them it arises by two roots, one from the centrum and one from the arch. These two roots, which are broad and thin, converge and unite so as to enclose a canal or foramen, the =foramen transversarium= (Fig. 11, _g_), for the vertebral artery. Laterad of the foramen the two parts of the process are, in the third cervical, almost completely united, the dorsal part being, however, distinguishable as a tubercle at the caudolateral angle of the thin plate formed by the process as a whole. This dorsal component is the =transverse process proper= (Figs. 10 and 11, _e_), while the ventral portion represents a rib, and is hence known as the =processus costarius= (_f_). The expanded plate formed by the union of these two processes is directed nearly ventrad and somewhat craniad in the third, fourth, and fifth vertebræ. The two components of the process gradually separate as we pass caudad; in the fourth and fifth vertebræ the part which represents the transverse process proper forms a very prominent tubercle at the caudolateral angle of the plate formed by the processus costarius. In the sixth (Fig. 11) the two parts are almost completely separated; the dorsal part forms (_e_) a slender knobbed process, while the processus costarius is divided into two portions (_f_ and _f′_) by a broad lateral notch. In the seventh the ventral part (processus costarius) is usually quite lacking, though sometimes represented by a slender spicule of bone. In the former case the foramen transversarium is of course likewise lacking. [Illustration: FIG. 11.--SIXTH CERVICAL VERTEBRA, CRANIAL END. FIG. 12.--ATLAS, VENTRAL VIEW. Fig. 11.--_a_, spinous process; _b_, cranial articular facet; _c_, lamina; _d_, radix or pedicle; _e_, transverse process proper; _f_, _f′_, processus costarius; _g_, foramen transversarium; _h_, centrum; _i_, vertebral canal. Fig. 12.--_a_, ventral arch; _b_, tuberculum anterius; _c_, lateral masses; _d_, transverse processes; _e_, cranial articular facets; _f_, groove connecting the foramen transversarium with the atlantal foramen; _g_, atlantal foramen; _h_, caudal articular facets.]