Skulls displaying trepanation 

Caption

Import restricted since 1997.

Section VI.C of the Designated List.

VI. PRE-COLUMBIAN HUMAN REMAINS
The human remains included in this listing demonstrate modifications of the remains due to ritualistic practices or other intentional treatment of the deceased.
C. Skulls displaying trepanation
Trepanation is an operation performed on a skull; the resulting cuts, easily visible on a bare skull, take various forms. Cuts may be less easily distinguished if skin and hair are present:
Principal Techniques
a. Straight cuts: these cuts are pointed at the ends and wider in the center. Openings made this way have a polygonal shape.
b. Cylindrical-conical openings: the openings form a discontinuous line. The resulting opening has a serrated edge.
c. Circular: generally made by a file. The resulting hole is round or elliptical, with beveled or straight edges. This is the most common form of trepanation.