the days between the ides and the Regifugium were counted down to either the Intercalary Kalends or to the Terminalia. The intercalary month counted down to nones and ides on its 5th and 13th day in the manner of the other short months. The remaining days of the month counted down towards the March Kalends, so that the end of Mercedonius and the second part of February were indistinguishable to the Romans, one ending on and the other picking up at and bearing the normal festivals of such dates. Apparently because of the confusion of these changes or uncertainty as to whether an intercalary month would be ordered, dates after the February ides are attested as sometimes counting down towards the Quirinalia (Feb.17), the Feralia (Feb.21), or the Terminalia (Feb.23) rather than the intercalary or March kalends. The third-century writer Censorinus says: When it was thought necessary to add (every two years) an intercalary month of , so that the civil year should correspond to the natural (solar) year, this intercalation was in preference made in February, between the Terminalia [23rd] and Regifugium [24th]. The fifth-century writer Macrobius says that the Romans intercalated in alternate years (Saturnalia, 1.13.12); the intercalation was placed after 23February and the remaining five days of February followed (Saturnalia, 1.13.15). To avoid the nones falling on a nundine, where necessary an intercalary day was inserted "in the middle of the Terminalia, where they placed the intercalary month". This is historically correct. In 167BC Intercalaris began on the day after 23February and in 170BC it began on the second day after 23February. Varro, writing in the first centuryBC, says "the twelfth month was February, and when intercalations take place the five last days of this month are removed." Since all the days after the Ides of Intercalaris were counted down to the beginning of March Intercalaris had either 27days (making 377 for the year) or 28 (making 378 for the year). There is another theory which says that in intercalary years February had and Intercalaris had 27. No date is offered for the Regifugium in 378-day years. Macrobius describes a further refinement whereby, in one 8-year period within a 24-year cycle, there were only three intercalary years, each of 377days. This refinement brings the calendar back in line with the seasons, and averages the length of the year to 365.25days over 24years. The Pontifex Maximus determined when