I claim the ornamental design for a medallion, as shown and described.
FIG. 1 is a front perspective view of a medallion, showing my new design;
FIG. 2 is a front elevational view of a medallion, showing my new design;
FIG. 3 is a rear elevational view of a medallion, which is environmental matter and forms no part of the claimed design;
FIG. 4 is a top plan view thereof;
FIG. 5 is a bottom plan view thereof;
FIG. 6 is a left-side elevational view thereof; and,
FIG. 7 is a right-side elevational view.
As seen in FIG. 1 and FIG. 2, the lettering, design elements, circumference of the medallion, and the area within the circumference of the medallion are all flat and coplanar in my claimed design. The broken lines showing a Roman numeral in FIG. 1 depict environmental matter and form no part of the claimed design. The broken lines showing the rear view forms no part of the claimed design.