XIX. The amulet of the Serpent's head is made of stone, red jasper, or paste to imitate red jasper, and carnelian. It was placed on mummies to prevent their being bitten by snakes and other reptiles in the underworld. The 34th chapter of the Book of the Dead, entitled, “ Chapter of not allowing a person to be bitten in the underworld by a serpent,” is sometimes found engraved upon this amulet. In later times glass and faïence models of serpents ro, , were worn by men and women round the neck; they were probably connected in some way with Isis.