It is well known that composers of Renaissance polyphony often incorporated in their works elements that carried extra-musical associations. Sixteenth-century polyphonic settings of the Agnus Dei were often especially rich in symbolism, through various devices: canonic tenors, cryptic canons, added voices and number of breves. This article explores two of the most notable symbolic elements in anonymous Masses in the Alamire manuscripts, which have not yet been approached from this point of view. The composer of the overtly Marian Missa supra Salve Regina used number symbolism and reduced scoring in the Agnus Dei to represent the Holy Trinity, and the Missa Du bon du cueur will be shown to have been especially important to Duke Wilhelm IV of Bavaria, based on its cryptic Agnus Dei canon. [ABSTRACT FROM AUTHOR]