S Antonin Historialis: Pars II. Two leaves, previously pastedowns. The first shows the motet Super cathedram/Presidentes/Ruina, known also from F-Pn: 146 and B-Br 19606. The second leaf also shows parts of motets. (Fallows interpreted this as 3 pieces; Lerch as a single piece in 3 voices.) Front and rear covers show mirror image offsets of the pastedowns which have now been lifted.
See also Lerch's reconstruction of these and other fragments as 'F-CA(n)'.