The ornamental design for a butterflyfinger-mounted teether, as shown and described.
FIG. 1 is a bottom plan view of a butterfly finger-mounted teether showing my new design;
FIG. 2 is a right side view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is a left side view thereof; and,
FIG. 5 is a top view thereof.
In FIGS. 1 and 5, the equal-length broken lines depict portions of the butterfly finger-mounted teether that form no part of the claimed design. In FIG. 1, the dash-dot-dash line indicates the boundary of the claim.