Vigils
The Vigil of the Nativity of the Lord and the vigil of Pentecost were privileged vigils. The Vigils of the Ascension of Our Lord, the Assumption of the Blessed Virgin Mary, Saint John the Baptist, Saints Peter and Paul and Saint Lawrence were to be common vigils and, if they occurred on a Sunday, were not to be anticipated, but simply omitted. All other vigils, including those marked in particular calendars, were suppressed.
Read more about this topic: General Roman Calendar Of Pope Pius XII