'The skin is one Graha, and that is seized by touch as the Atigraha, for with the skin one perceives touch. These are the eight Grahas and the eight Atigrahas.'

In plain words: The skin is a grasper, and it is held by touch, because we feel touch through the skin. Yagnavalkya says these are all eight graspers and their eight over-graspers.