The ornamental design for an inkcartridge, as shown and described.
FIG. 1 is a top view of an ink cartridge, showing our new design;
FIG. 2 is a bottom view of an ink cartridge; thereof;
FIG. 3 is a front view of an ink cartridge thereof;
FIG. 4 is a rear view of an ink cartridge thereof;
FIG. 5 is a perspective view of an ink cartridge thereof;
FIG. 6 is a left view of an ink cartridge thereof; and,
FIG. 7 is a right view of an ink cartridge thereof.
The broken line showing other elements of the ink cartridge is included for the purpose of illustrating environmental structure and forms no part of the claimed design.