The head, which is slightly flattened and more elliptical in shape than triangular, is not covered with numerous small scales like most other vipers, but with large shields like the colubrids and the elapids.
•
The fangs have a ridge at the tip lateral to the discharge orifice, as well as a blade-like structure on the ventral surface otherwise seen only in some opistoglyphous and atractaspid snakes.