Here is communication to Professor Radle clarify an issue he raises in his 2011 article:
I was just reading your excellent article on Sinai Gr NE/MΓ 22, where I happened upon a passage in which you say that in my 1997 article on festal cathedral vespers I 'place(s) the singing of the refrain after each half-verse, and mistakenly ascribe(s) this structure to Grottaferrata Γβ 35'.
I can see why you came to that conclusion, but I had no intention of leaving such an impression about the use of half verses. To be honest, when I wrote 'this form' and created the chart, I was thinking only about the sequence of musical performers and their respective styles (which is indeed constant through all the sources). Moreover, had I continued the example with a couple more verses before providing the summary instruction 'The Choirs continue in alternation', you would have begun to see whole verses. Not only was I well aware from Strunk and others that the default in cathedral rite psalmody was to use whole verses in a choral stichologia, but this is also what late Byzantine MSS generally show except for the first pair of choral verses.
In some cases/sources the first choral verse is split to create an exact textual correspondence between the solo intonation and the first choral verse (e.g. the attached Opening Antiphon and Teleutaion, excerpted from the service book for a celebration of Cathedral Rite Vespers based on medieval musical sources served here in Oxford in 2001, as well as the page from Symeon of Thessalonica's Psalter in Athens 2047). I would conclude therefore conclude that a desire for textual parallels with the initial solo verse rather than any kind of 'Hagiopolite-influenced adaptation…of stichometry' is at work here. You can even find this sort of thing in the setting of Ps 18 in Grot. Γβ 35, in which the first pair of choral verses split up 'The heavens are telling the glory of God - Alleluia' and 'The firmament proclaims the work of his hands' before settling in to an alternation of full verses.
At all events, sorry for not having been more clear about the point I was trying to make in that example. In future when I make charts of Constantinopolitan cathedral rite psalmody, I will make sure to add sample extra (full) verses and/or some kind of a caveat about the variations in the textual length of the initial pair of choral verses.
PS A coda about the Dirigatur and its relationship to prokeimena. Stefanos Alexopoulos neglected some evidence that would have strengthened his case, namely that musically notated settings of the Dirigatur are transmitted among the repertories of the Great Prokeimena in the Psaltikon, where they appear as responsorial chants set in the same florid musical style as the prokeimena that surround them. See Hintze, Gisa (1973), Das byzantinische Prokeimena-Repertoire Untersuchungen und kritische Edition (Hamburger Beiträge zur Musikwissenschaft 9; Hamburg: Verlag der Musikalienhandlung); and Harris, Simon (1994), 'The Byzantine Prokeimena', Plainsong and Medieval Music, 3 (2), 133-47.
