Undated letters which could not be placed in order on internal evidence have, so far as was possible, been left in the positions in which they came to the Library. Lists of F. Mendelssohn Bartholdy's letters are in MS. M. Deneke Mendelssohn d. 18, fols. i-iii.

Here can be found 38 letters or parts of letters from F. Mendelssohn Bartholdy, including:

(fol. 37) Note from Cécile to F. Mendelssohn Bartholdy, 19 Sep 1840.

(fols. 88-89, 112-113, 134-135, 154-155 and 169-170) Five letters from Lea to Mme. Jeanrenaud.

(fols. 160-161) Letter from Lea to her grandson Karl Mendelssohn Bartholdy, 3 Jul 1842.

(fols. 197-198 and 200) Two letters from Fanny Hensel to Mme. Jeanrenaud