The ornamental design for a marker for radiography specimens, as shown and described.
FIG. 1 is a front view of a marker showing our new design;
FIG. 2 is a left side view of the marker of FIG. 1;
FIG. 3 is a top view of the marker of FIG. 1;
FIG. 4 is a right side view of the marker of FIG. 1;
FIG. 5 is a bottom view of the marker of FIG. 1; and,
FIG. 6 is a rear view of the marker of FIG. 1.
The broken lines in the drawing views are included for the purpose of illustrating portions of the marker for radiography specimens that form no part of the claimed design.