The ornamental design for a cover for a turbineroof ventilator, substantially as shown and described.
FIG. 1 is a top plan view of a cover for a turbine roof ventilator,
embodying my new design;
FIG. 2 is a side elevational view thereof, the opposite side being the same
as the side shown;
FIG. 3 is another side elevational view thereof showing the cover rotated
90 degrees from FIG. 2, the opposite side being the same as the side
shown; and