Shelf

FIG. 1 is a front perspective view of a shelf according to my new design;

FIG. 2 is a rear perspective view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a rear view thereof;

FIG. 5 is a left side view thereof, the right side view being a mirror image of the left side view;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken lines illustrating portions of the shelf form no part of the claimed design. The dash-dot-broken lines define the bounds of the claimed design and form no part thereof.