Adapted http://www3.cpdl.org/wiki/images/source/pal-die1.sib. Transposed back to original pitch level, also reversed alto and tenor in mm. 7576 so that they would match the Casimiri Opere complete edition (vol. 3, no. 1). Altered ficta to match Peter Schubert, "Mode and Counterpoint," in Music Theory and the Exploration of the Past, ed. Christopher Hatch and David W. Bernstein, 103-36 (Chicago and London: University of Chicago Press, 1993), 106-17 (attached for reference). Ficta included in score (all accidentals are ficta).
Basis for Palestrina's 4v parody Missa
"Dies sanctificatus" (http://elvis.music.mcgill.ca/node/219).
From Palestrina's 1st book of motets (1563)