The cornutis (horned) is found in some medieval encyclopedias. It is serpent with horns with which it attacks anyone who comes near it. They also have a deadly poison, for which the antidote is theriac, an ancient herbal medicine.

Thomas of Cantimpré uses Gaius Julius Solinus as a source for his account of this serpent. This may be a reference to Solinus's description (27.28) of the cerastes, a serpent with four horns. This is uncertain; Solinus's description of the cerastes does not closely match that of Thomas's cornutis.