Taken from the Wikipedia article on Iris, messenger of Hera (Greek Mythology):
Iris is frequently mentioned as a divine messenger in the Iliad which is attributed to Homer, but does not appear in his Odyssey, where Hermes fills that role. Like Hermes, Iris carries a caduceus or winged staff.
From article on Caduceus:
This staff was first borne by Iris, the messenger of Hera. It was also called the wand of Hermes when he superseded Iris in much later myths.
So this must be Iris on the stamp I deduce, she that is bandying about the snake-enwrapped wand with sorceress intent no doubt. Probably an older version of the Star Trek communicator.
