The ornamental design for a casket, as shown and described.
FIG. 1 is an isometric view of a casket showing the new design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a side elevation view thereof, showing the side opposite that visible in FIG. 1; and,
FIG. 4 is an end elevation view thereof, showing the end opposite that visisble in FIG. 1.
The broken lines showing the wood grain and knot structure of natural log portions included in the design are for illustrative purposes only and form no part of the claimed design. The irregular surfaces of the natural log portions are illustrative of the inherent irregularities of the natural log surfaces which are part of the claimed design.