Fig. 1.—Human femur with imbedded obsidian arrowhead which has been snapped across just below the surface of the bone. Found in 1907 in the Ellis Landing shellmound on San Francisco bay. 12-2340.

Fig. 2.—Radiograph of same.

Fig. 3.—Radiograph showing the flat side of the head. The point is driven more than halfway through the bone.