The Ouroboros consists of one of them biting its own tail, and two of them can be found on the Caduceus.
In one story, Cadmus slays one of these animals sacred to Ares and is subsequently turned into one. In another story, Hera turns Tiresias into a woman after he sees two of these animals mating and kills one of them. Typhon's wife Echidna is usually described as half-nymph and half one of these animals that kill Eurydice. One type of these animals is an enemy of (*) Apollo and is killed by him at the site of the Delphic Oracle. The Ouroboros consists of one of them biting its own tail, and two of them can be found on the Caduceus. Hera sends two of these animals in an attempt to kill a young Heracles. These animals made up the hair of the Gorgon sister Medusa. For 10 points, name these reptiles.
In one story, Cadmus slays one of these animals sacred to Ares and is subsequently turned into one.
{snakes} [or {serpents}; or dragons]