The ornamental design for an inkcartridge, as shown and described.
FIG. 1 is a top, front, right side perspective view of an ink cartridge according to my design;
FIG. 2 is a top, rear, left side perspective view thereof;
FIG. 3 is a right side elevational view thereof;
FIG. 4 is a left side elevational view thereof;
FIG. 5 is a front elevational view thereof;
FIG. 6 is a rear elevational view thereof;
FIG. 7 is a top plan view thereof; and,
FIG. 8 is a bottom plan view thereof.
The dash-dash broken lines in the figures show portions of the ink cartridge that form no part of the claimed design. The dash-dot broken lines in FIGS. 5 and 8 are boundaries that form no part of the claimed design.