·add. ·- The calendar of the ancient Romans, from which our modern calendars are derived. It is said to have consisted originally of ten months, Martius, Aprilis, Maius, Junius, Quintilis, Sextilis, September, October, November, and December, having a total of 304 days. Numa added two months, Januarius at the beginning of the year, and Februarius at the end, making in all 355 days. He also ordered an intercalary month, Mercedinus, to be inserted every second year. Later the order of the months was changed so that January should come before February. Through abuse of power by the pontiffs to whose care it was committed, this calendar fell into confusion. It was replaced by the Julian calendar. In designating the days of the month, the Romans reckoned backward from three fixed points, the calends, the nones, and the ides. The calends were always the first day of the month. The ides fell on the 15th in March, May, July (Quintilis), and October, and on the 13th in other months. The nones came on the eighth day (the ninth, counting the ides) before the ides. Thus, Jan. 13 was called the ides of January, Jan. 12, the day before the ides, and Jan. 11, the third day before the ides (since the ides count as one), while Jan. 14 was the 19th day before the calends of February.