The ornamental design for a lampcover, as shown and described.
FIG. 1 is a front, top, right perspective view of a lamp cover, showing the claimed design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a left side elevational view thereof;
FIG. 5 is a right side elevational view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken lines in the drawings illustrate portions of the lamp cover which form no part of the claimed design. Shading is used to illustrate the curvature of the part and not color. The claimed design is indicated by the relatively dark portions in the drawings, while the relatively light portions are environmental and form no part of the claimed design.