The ornamental design for a staffmember and ribassembly for an umbrella, as shown and described.
FIG. 1 is a perspective view from the bottom and one side of the staff member and rib assembly showing four pairs of ribs;
FIG. 2 is a front elevational view of the staff member and rib assembly shown in FIG. 1, the left, right, and rear elevational views being the same;
FIG. 3 is an elevational view of the staff member and rib assembly shown in FIG. 1, taken from a vantage point midway between, for example, the front and left side elevational views;
FIG. 4 is a top plan view of the staff member and rib assembly, shown in FIG. 1; and,
FIG. 5 is a bottom plan view of the staff member and rib assembly, shown in FIG. 1.
The broken lines in all views are included for the purpose of illustrating portions of the staff member and rib assembly for an umbrella that form no part of the claimed design