The ornamental design for a jar, as shown and described.
FIG. 1 is a perspective view of a jar according to my new design.
FIG. 2 is a front elevational view thereof, the rear, right side, and left side, elevational views being identical.
FIG. 3 is a top plan view thereof; and,
FIG. 4 is a bottom plan view thereof.
The dash-dash broken lines shown in the drawings are included for the purpose of illustrating environmental structure and form no part of the claimed design.
The dot-dot-dash broken lines shown at the top of the jar defines the boundary of the claimed design, and forms no part thereof.