Initial M with Christ among the Apostles
Lewis E M 64:2 and E M 64:13 are sister leaves. A fourth leaf from the same manuscript is in Princeton, NJ, Princeton University Art Museum, 30.35. These leaves can be dated to ca. 1430.
This initial begins the Introit for the Mass of the feast of the Apostles, "Michi autem nimis honorati sunt ..." (To me, indeed, are you most honored). The decorative borders feature a griffin in the lower margin, and in the outer margin, two so-called "wild men" combatting apes and another playing a lute.
Digital Scriptorium ShelfMark:
Rare Book Department