Project Gutenberg title screens imply that this is the source for both Ebook #1353 (see at ISFDB), an edition of the Introduction and Off on a Comet or Hector Servadac, and Ebook #1355 (see), an edition of The Underground City or The Black Indies.
Title page undated
1911 is the year of stated copyright by Vincent Parke and Company.
HathiTrust Digital Library provides full interior views of all volumes in this F. Tyler Daniels edition, with this Volume Nine (v9) represented by a single copy from University of California.
Relying on comparison of v9, interior pages of the F. Tyler Daniels and the Vincent Parke editions are nearly identical. Title leaves differ only in the publisher names on the title page, second line from the bottom, and the location of copyright data on the verso page.
• t.p. verso, as F. Tyler Daniels Company, Inc.
• t.p. verso, as Vincent Parke and Company (also viewed at HathiTrust)
"Contents, Volume Nine" listings are short titles: Introduction; Off on a Comet; The Underground City.
The full essay title and first novel title appear only as headings above the text, pages 1 and 3.
The second novel is named thus on its interior title page, and as a heading above the text:
• p[277]: The Underground City or The Black Indies (Sometimes Called The Child of the Cavern)
• p279: The Underground City