Saturday, 15 February will feature the Office of the anticipated Sixth Sunday after Epiphany, as said Sunday has no place at the end of the year. Under Divino Afflatu rubrics, the Office (Semidouble of the Sunday) begins with Vespers on Friday and continues through None on Saturday, yielding completely to Septuagesima, without even a commemoration, that same evening. The antiphons and psalmody are taken from the Psalter for Friday and Saturday, respectively; likewise, the capitula and short responsories at the Hours are ferial. However, being of semidouble rite, there are three nocturnes at Mattins which incorporate the nine lessons proper to the Sunday. This is fairly clear as far as Divino Afflatu goes.
However, in researching how the anticipated Sunday Office was done before 1911 to incorporate into the Ordo here, we have not found a clear set of rubrics to clarify the point of the correct psalmody. So, a question is posed now to readers - since the ferial psalms at Mattins are only designed for one nocturne, are the Dominical psalms prayed instead at Mattins to satisfy the semidouble rite of the Office that day? And likewise, will Lauds and the Hours be completely Dominical or do they incorporate ferial psalmody (at Lauds) and capitula and the like? In short, how is the anticipated Sunday Office arranged according to the Tridentine rubrics?
Update - 2 February:
We found the answer! The problem is that the rubric is buried (and easy to miss in the very small print of our 1854 Breviarium) in the same place (part 4 below) as the rubric governing the allocation of "leftover" Sundays after Epiphany rather than being stated in a separate rubric In the rubrics, section De Dominica, part 4 and continuing into part 5, we find (our emphasis):
"... ponitur in præcedenti Sabbato, quod non sit impeditum Festo novem Lcctionum; alioquin in alia precedenti die similiter non impedita, in qua fiat Officium de Feria, cum commemoratione Festi Simplicis, si occurrat; et in ea legantur tres Lectiones de Homilia Dominicae, omissis Lectionibus Scriptura illius Ferie: et in Laudibus dicatur Antiphona ad Benedictus, et Oratio de Dominica...
5. Cum vero interdum contingat, ut Dominica tertia, vel quarta, vel quinta, velsexta post Epiphaniam supersit, nec possit poni etiam post xxiii. a Pentecoste,tunc de ea fit Officium in Sabbato ante Dominicam Septuagesime, ut dictum est supra, numero præcedenti."Therefore, the Office of said anticipated Sunday after Epiphany is of the Feria (i.e. Mattins and Lauds of Saturday) but with the lessons of the third nocturne of the Sunday read in place of the occurring Scripture and the proper Benedictus antiphon and Collect of the Sunday at Lauds. We presume that there is no Te Deum, though not specified here, because the Office is ferial; hence, the responds, unlike the lessons, would be those of the Feria. We also presume that this Office lacks Vespers (and Compline); hence, the Friday evening preceding it would simply be a purely ferial Office (antiphons from the Psalter, Collect of the preceding Sunday) or a festal Office as the case may be.