From the Robin Catalogue:
A Guess at the Riddle [and] Notes for a Book to be entitled: A Guess at the Riddle
TS. (corrected), G-c.1890-1, 65 pp., including alternative drafts.
The “Notes” alone were published as follows: 1.354-368; 1.373-375; 1.379-416, with omissions.
Also published in W 6 (166-210) and EP 1 (245-279). The manuscript has been dated 1887-1888 by the Peirce Edition Project.