The ornamental design for an adjustable length crib skirt, as shown and described.
FIG. 1 is a front, left side perspective view of an adjustable length crib skirt showing my new design, the rear, right side perspective view being a mirror image;
FIG. 2 is an enlarged fragmentary perspective view thereof, in which the top and right edge are shown undulated to indicate that the crib skirt is broken away at that point;
FIG. 3 is an enlarged fragmentary elevational view of the top strips of adjustable length crib skirt unfastened and separated, it being understood that the top and right edges are shown undulated to indicate they are broken away at that point; and,
FIG. 4 is an enlarged fragmentary perspective view of the adjustable length crib skirt with the bottom strip removed.
The broken line showing of the crib and portions of the crib skirt are for illustrative purposes only and form no part of the claimed design.