Two unnoticed pieces of medieval polyphony

The two pieces introduced and briefly discussed in this article have so far remained unnoticed because of the manner of their notation. In each case pieces of two-voice polyphony were notated with the two voices separate, instead of in the score notation which has been usual since, roughly, the second half of the twelfth century. In the one case, the sequence Magnus deus in universa terra in a manuscript from Marchiennes of the fourteenth century, a second voice was added at the back of the book in which the usual melody had already been recorded. In the other case, the song Ad honorem regis summi in the so-called Codex Calixtinus, the two voices are notated successively, verse 1 of the text being given with the first voice, verse 2 with the second voice