FIG. 1 is a perspective view of a jar; FIG. 2 is a front elevation view of the jar; FIG. 3 is a right side elevation view of the jar; FIG. 4 is a left side elevation view of the jar; FIG. 5 is a rear elevation view of the jar; FIG. 6 is a top plan view of the jar; and, FIG. 7 is a bottom plan view of the jar. The broken lines in the drawings depict portions of the jar that form no part of the claimed design.