Both claws, and their adjacent legs, have matching half-circle notches in them that line up to create a circle-shaped opening when the limbs are tightly pulled against one another. This tubular round opening is called a foramen.
Both claws, and their adjacent legs, possess corresponding half-circular indentations that align to form a circular opening when the limbs are tightly drawn together. This cylindrical round aperture is referred to as an orifice.