up there now

This is exceedingly generous. Thank you.

In the front of the Liber (p. xv) is a section called "Rubrics for the Chant of the Mass"; that instruction authorizes the use of additional verses for the propers.

Until a more authoritative answer comes along, here's what I've observed:

• The 1974 Graduale Romanum includes citations for Psalm verses that may be sung between reiterations of the Communion Antiphon. It's my understanding that these citations are from of old and not just arbitrarily chosen.
• The Offertoriale Triplex is a collection of Offertories with verses set to ornate melodies. No Scriptural citation is supplied, but to the relatively unlearned (i.e., me), the manuscripts suggest that these melodies are of ancient origin. That would supply the historical basis for me. (Richard Rice's booklet linked at the top of this thread uses the Latin found in that book.)
• The Introit as found in the 1974 Graduale usually includes the first verse of its respective Psalm in question; there are a few Introits that include more than one verse.
• Omitting verses from the Graduale may simply boil down to a pragmatic approach to publishing. For example, the physical Communio volume is about as thick as the Graduale itself, and only a subset of the choir would be singing these verses.

Hope this helps; corrections welcome.

May I possibly say the heretical and say that I've tried using the PBC for an EF Mass and found it very difficult to keep switching from it to my notebook of propers? I've gone back to printing out everything in order for my group to put in their folders. The magic of Photoshop makes it possible to even patch on the proper Psalm terminations for Vespers. We still use it for the Missal section though.

If I may say so, the scholarship on the offertory behind de musica sacra and the rubrics in the Liber was imperfect. The point is that the offertory is a responsory, not an antiphon, and so its verses are melismatic, like the gradual or alleluia, not recitative (psalm-tone), like the introit or communion. Hand missals before the council often designated offertories as antiphons, and liturgical scholars concerned with the texts only sometimes did so as well.

The medieval transmission of offertories, however, contained melismatic verses. These can be seen in an edition by Ott from the 1930s (available on the CMAA website), which was the basis of the Offertoriale triplex. These are the authentic offertory verses. Ott's edition also specifies the repetition of the choir after the verses, and it usually only the final portion of the responsory, as is the case for responsories of the office. There are usually only two verses, though some chants have more, and because they are melismatic, this is enough to accompany the offertory rite complete with incensation in the EF; one verse is usually sufficient for the OF with incensation. Thus there is never a consideration of the provision of a Gloria Patri as the conclusion of offertory verses; this should only be specified for recitative psalm verses, which presume the possibility of singing a whole psalm.

Offertories have a half-way position, both stylistially and functionally between the processional chants (introit, communion) and the meditational chants (gradual, alleluia). They accompany some activity, incensation as at the introit and the offertory procession (though this procession was not prevalent in the middle ages; it is a revival from the 20th century). In the Middle Ages, the extent of time required for the longer verses may have been the fact that incensation sometimes provided that members of the choir were incensed individually.

The offertory is a time that provides a few moments of recollection and repose between the two major parts of the Mass. It is preceded by the series of lessons, possibly a sermon, and the Credo, all activities with many words. After the offertory there is the centrally significant action of the preface, the Sanctus, and the Canon. Between these two parts, the offertory provides some reflection, some repose. This is well projected by the offertory chant, with its melismatic verse. Here the musical style suggests meditation: offertories are somewhat more melismatic than introits and communions, and there is a modicum of end-melisma, in my view, the hallmark of meditation chants. (End melisma is simply the placement of a somewhat long melisma upon the unaccented final syllable of a word, especially of a whole sentence.)

The melismatic offertory verses deserve considerable attention; they are an authentic part of the heritage of Gregorian chant from the earliest period of musical notation; the presence of staffless neumes in the Offertoriale triplex is witness to their antiquity. They are sometimes highly expressive and include repetitions fo text not usually in offertory responsories. Perhaps the most spectacular set of verses is that for the offertory Vir erat (27th Sunday in Ordinary Time in OF, 21st Sunday after Pentecost in EF). The offertory in our graduals is hardly sufficient textually, since it only sets the scene for the narrative which proceeds in the four melismatic verses. These verses include significant repetitions, on "calamitas" in the first verse and "ut videat bona," an effective conclusion to the whole narrative in the fourth verse. Look at this series of verses in the Offertoriale, p. 122 on our website.

I do not object to the singing of offertory verses to psalm tones, as long as it is understood that this is a temporary solution to providing a long enough offertory to suit the liturgical action, in the absence of the ability to sing the melismatic verses. It is not the proper chant, but only a substitute; this contrasts with the psalm-tone verses for the communiosn, which are the proper way to sing verses to communion antiphons. I would recommend trying some of the melismatic verses; they can be sung by one or two capable cantors in alternation with the choir singing of the responsory. This is a beautiful and effective way to make a musical complement to the liturgy of the offertory.

With thanks to Prof. Mahrt, I hope no one mistakes the relative merits of any of my chant adaptations with that of the authentic repertoire. It is a distinction the CMAA website could perhaps make more transparent than it currently does. Elsewhere we have discussed reorganizing the materials presented here, and I hope some savvy web design type would volunteer for the job.

In the end, of course, it is up to individual music directors in concrete liturgical situations to determine what constitutes a "temporary solution", and what is, in fact, "the best we can possibly hope for here".

Thank you all for the comments, which are a lot more in detail than I expected for answers. I will take Prof. Mahrt's recommendation of trying melismatic Offertory verses into consideration. Happy New Year!