Wolf writes to ask if there is any writings by Twain as an "old man" about
Huck Finn.  According to the version of the autobiography the Charles Neider
edited, Mr. Twain mentions a fourth Tom Sawyer/Huck Finn/Jim book that he
destroyed(!), because (and pardon me if this quote is inexact, because I
don't have a copy of the book handy),

"...they had served me well enough and it was time to put (place?) them at

Maybe that is what you heard about?

Rob McMonigal