The =long pastern= (first phalanx) (Fig. 4, _A_) is about one-third the length of the cannon; its upper and thicker end presents two condyloid cavities (_a_) (glenoid cavities), separated by a median groove, which exactly fit the condyles and ridge at the lower end of the cannon. The lower end of the long pastern is smaller than the upper, and is provided with two condyles, between which is a shallow groove (_e_). The anterior face of the bone is smooth, rounded from side to side, and blends into the lateral borders. The posterior face is flatter, and shows a clearly marked triangle to which ligaments attach. The two =sesamoid bones= (Fig. 4, _B_) are small, and somewhat pyramidal in shape, and, lying against the posterior part of the condyles of the cannon bone, increase the articular surfaces at the upper end of the long pastern. [Illustration: FIG. 4. Os suffraginis with both sesamoid bones in position, as in Fig. 3. _A_, os suffraginis; _B_, sesamoid bones; _a_, upper joint-surface of long pastern; _b_, joint-surface of sesamoid bones; _c_, roughened surface at upper end; _d_, roughened surface at lower end, both for attachment of ligaments; _e_, lower joint-surface.] The =short pastern= (second phalanx) (Figs. 5 and 6) lies under the first phalanx and above the os pedis; it is somewhat cubical in shape. Its upper articular surface (Fig. 5, _a_) presents two glenoid cavities to correspond with the condyles of the first phalanx. The lower articular surface (Fig. 5, _d_) resembles the lower end of the first phalanx. The upper posterior border of this bone is prominent and prolonged transversely (Fig. 6, _a_), to serve as a _supporting ledge_ for the first phalanx, as a point of attachment for the perforatus tendon, and as a gliding surface for the perforans tendon. [Illustration: FIG. 5. Short pastern (os coronæ) viewed in front and in profile: _a_, upper joint-surface; _b_, anterior surface; _c_, lateral surface; _d_, lower joint-surface.] [Illustration: FIG. 6. Short pastern seen from behind: _a_, smooth surface over which the perforans tendon glides; _b_, lower joint-surface.]