Dune

From Author Wars - https://authorwars.com/publications/dune-197881.html

Overview:

Title: Dune
Author: Frank Herbert
Year: Unknown
Publisher: Ace Books
Price: $1.25
Pages: 541
Binding: Paperback
Type: Novel
Title Reference: Dune
Notes:
The printing date is not stated on the copyright page
The catalog #17261 would suggest that it is the 3rd printing (1st #N-3, 2nd #17260) of the 1967 Ace Ed.
Note contents page list map on page 542, but page is unnumbered.