The head has a rostral scale that is at least as deep as it is wide, creating a triangular indentation between the internasal scales (rarely separating them). The top of the head is covered with nine large plates. The nasal scale is often divided. There is one (rarely two) preoculars and two postoculars. The temporals number 2+2 or 2+3 (rarely 1+2) . There are seven (rarely eight) upper labials, of which the third and fourth or fourth and fifth border the eye.