Poseidonis

Poseidonis is an imagined last remnant of the lost continent of Atlantis, detailed in a series of short stories by Clark Ashton Smith. Smith based Poseidonis on Theosophical scriptures about Atlantis, (such as the The Secret Doctrine by Helena Blavatsky) and his concept of "the last isle of foundering Atlantis" is echoed by the Isle of Meneltarma in J. R. R. Tolkien's legendarium.