This supplement contains thirteen undated letters that seem to relate to Darwin's work on Expression of the emotions. Since they cannot be assigned to a particular year, they would normally be published in the next general supplement of letters or a later one, depending on their likely date range, but since they are relevant to Expression, which was published in 1872, it has been decided to publish them as a special supplement to this volume.

From Mary Lubbock to H. E. Darwin [8 May 1866 – 29 August 1871]

Goringes, | Farnborough, | Kent.

Dear Miss Darwin

We hope to have a few friends here to play croquet on Thursday between 4 & 7 oClock & shall be very glad if you & your sister2 will join us, if it should be fine.

Àpropos of the conversation we had with Mr. Darwin the day I was at yr. house—I have heard since that Babies vary very much as to the age when tears begin to show in their eyes—as my sister in law told me, one of hers, a very forward child at a few days old had tears in her eyes from her efforts to talk & coo!

With kind regards to Mr & Mrs Darwin | I am yours very sincerely | Mary Lubbock.

From F. J. Wedgwood [1867–72]

I, Cumberland Place, N.W.

My dear Uncle Charles

I enclose you the extract from Charma, on the origin of nodding & shaking the head, which I promised so long ago. I have marked so X the passage itself, what goes before is merely to make it clearer. I at first omitted the clause of the sentence about “sa faible tête” as I thought it was truer without any reference to the repetition of the signs however what he means is clearer written at length.