Jake, jack and little sousoucie

The letter is signed by Jake and Jack – Shem and Shaun and "sousoucie" (French sosie: double, counterpart) – Issy.

The signature also contains the initials J. J. S. which is both James Joyce and John Jameson & Son. (And maybe James Joyce & James Stephens. J.S. was supposed to finish FW, at times when Joyce couldn't stand it anymore. JJ thought about using the JJS pun for the book's title page.)