In the oldest Roman calendar, which the Romans believed to have been instituted by their legendary founder Romulus, the first month was "Martius" ("month of Mars", March), and the calendar year had only ten months. "Ianuarius" and "Februarius" were supposed to have been added by Numa Pompilius, the second king of Rome, originally at the end of the year. It is unclear when the Romans reset the course of the year so that January and February came first. "Ianuarius" is conventionally thought to have taken its name from Janus, the dual-faced god of beginnings, openings, passages, gates and doorways, but according to ancient Roman farmers' almanacs Juno was the tutelary deity of the month.