The caduceus is typically depicted as a short
herald's staff entwined by two serpents in the form of a double
helix, and sometimes is surmounted by wings. This staff first
was borne by Iris, the messenger of Hera. It also was called the
wand of Hermes when he superseded Iris in much later myths.
In later Antiquity the caduceus may have
provided the basis for the astrological symbol representing the
planet Mercury and in Roman iconography was often depicted being
carried in the left hand of the Greek god Hermes (Roman god,
Mercury), the messenger of the gods, guide of the dead and
protector of merchants, gamblers, liars and thieves.
The caduceus is sometimes used as a symbol for
medicine, especially in North America, through confusion with
the traditional medical symbol, the rod of Asclepius, which has
only a single snake and no wings.