I claim the ornamental design for a portable lantern, as shown and described.
The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.
1. Portable lantern
1.1 is a top, front perspective view of a portable lantern showing my new design;
1.2 is top, front, right side perspective view thereof;
1.3 is top, rear, left side perspective view thereof;
1.4 is a partial front, left side detailed view showing the portable lantern with its handle in a partially tilted position;
1.5 is a partial view showing a central portion of the handle in a fully tilted position.