Lernaean Hydra

Origin and tradition

Greek myth describes the Hydra as a many-headed marsh serpent slain by Heracles, with heads that regrew when cut.

Illustration in this atlas

A swamp serpent with multiple necks, venomous breath, and a central deathless head hidden among the rest.

References and further reading

1. en.wikipedia.org — Lernaean Hydra

These references offer further reading. Accounts and depictions vary; the atlas illustration is interpretive artwork, rather than historical or scientific evidence.