The quick Mercury is the next closest in the sequence, showing Mercurius (the Roman version of the Greek Hermes) with his typical iconography. The winged sandals and cap are fairly familiar; the staff with the two intertwined dragons might hint at a Caduceus. Mercurius is accompanied by a rooster, a bird that due to its habit of crowing at dawn became a symbol of the victory of day over night.
Mercurio/Mercury himself - in his original meaning - did not find his way into the traditional Tarot, but ever since the early occultists threw themselves into Tarot studies, Mercury/Hermes evolved into the thrice-bloated Super-Hermes and heavily tainted the poor, unsuspecting Il Bagatto.
Further reading: Mercury (Planets)