The ornamental design for a lampbase, substantially as shown and described.
FIG. 1 is a top, three quarter view of the lamp base showing my new design,
the fluorescent lamp being shown in broken lines for illustrative purposes
only;
FIG. 2 is a front elevational view thereof on an enlarged scale, the rear
being identical;
FIG. 3 is a right side elevational view thereof on an enlarged scale, the
left side being identical;
FIG. 4 is a top plan view thereof on an enlarged scale;
FIG. 5 is a bottom plan view thereof on an enlarged scale.