The ornamental design for a bookmark, as shown and described.
FIG. 1 is a perspective top view of a bookmark having a body portion in the shape of a cross, attached to a ring having multiple ribbons looped there around the ring and through a hollow bead holding the ribbons in place on the ring, the underneath side of the bookmark being identical thereto.
FIG. 2 is a frontal view of the bookmark of FIG. 1, the back side being identical thereto, the ribbons have been shown as truncated for ease of illustration.
FIG. 3 is a side edge view of the bookmark of FIG. 1, the opposing side being identical thereto, the ribbons have been shown as truncated for ease of illustration.
FIG. 4 is a top end view of the bookmark of FIG. 1; and,
FIG. 5 is a bottom end view of the bookmark of FIG. 1.