We claim the ornamental design for a bathtub, as shown and described.
FIG. 1 is a perspective view of the claimed design;
FIG. 2 is a front view of the claimed design shown in FIG. 1;
FIG. 3 is a rear view of the claimed design shown in FIG. 1;
FIG. 4 is a side view of the claimed design shown in FIG. 1;
FIG. 5 is another side view of the claimed design shown in FIG. 1;
FIG. 6 is a top view of the claimed design shown in FIG. 1; and,
FIG. 7 is a bottom view of the claimed design shown in FIG. 1.
The ornamental design that is claimed is shown in the drawings as solid lines and surfaces having surface shading: The broken lines in the drawings are for illustrative purposes only and form no part of the claimed design. For example, broken lines formed by equal length dashes show unclaimed portions of the design. Broken lines formed of unequal length dashes (i.e., dash-dot) show boundaries between either claimed and unclaimed portions of the design or between unclaimed and unclaimed portions of the design. Break lines having a jagged element are not part of the claimed design and show unspecified lengths of the portion are possible. The appearance of any portion of the article between the break lines forms no part of the claimed design. Cross-hatching provided on cut surfaces is for illustrative purposes only and forms no part of the claimed design.