Ornamental initials and catchword
Two of the initials (both I) include the fantastic birds which also grace some of the borders throughout the volume. The catchword (fructus) in the lower border of fol. 172v (the last page in quire 19) signals the first word on the next page, fol. 173r (the first page in quire 20). It would have ensured that the quires were put in the right order before the manuscript was bound.