Shelf

FIG. 1 is a front perspective view of a shelf, showing my new design;

FIG. 2 is a rear perspective view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a rear elevational view thereof;

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

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The broken lines in the figures are for the purposes of illustrating portions of the shelf, which form no part of the claimed design.