Shelf

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

FIG. 2 is a rear, right side, bottom perspective view thereof;

FIG. 3 is a front elevation view thereof;

FIG. 4 is a rear elevation view thereof;

FIG. 5 is a bottom plan view thereof;

FIG. 6 is a top plan view thereof;

FIG. 7 is a left side elevation view thereof;

FIG. 8 is a right side elevation view thereof; and,

FIG. 9 is a front, right side, top perspective view thereof shown in reduced scale and in an environmental arrangement therefor.

The broken lines in FIG. 9 represent an environment for the shelf of FIGS. 1 - 8 and form no part of the claimed design.