The ornamental design for a combined bottlecap and collar, as shown.
FIG. 1 is a front plan view of my design that includes a frusto-conical collar having a reflective, silver, mirror-like exterior surface and a transparent cap, the rear plan view being identical to the front plan view.
FIG. 2 is a left side plan view of my design, the right side plan view being identical to the left side plan view.
FIG. 3 is a top plan view of my design.
FIG. 4 shows a view of my design in the direction of arrows 4—4 in FIG. 2; and,
FIG. 5 is a top perspective view of my design.
The broken lines disclose the environment related to the claimed design and form no part of the design.