Shelf

FIG. 1 Top, front, right side perspective view of an shelf according to the present design;

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

FIG. 3 is a Front elevation view;

FIG. 4 is a Rear elevation view;

FIG. 5 is a Left side elevation view;

FIG. 6 is a Right side elevation view;

FIG. 7 is a Top plan view;

FIG. 8 is a Bottom plan view; and,

FIG. 9 is a Top, front, right side perspective view in a position of use.

The broken lines shown in FIG. 9 are included for the purpose of illustrating environment and form no part of the claimed design.