When was the story by Lovecraft that the Xothic legend cycle is based on first published?
Xothic legend cycle: The Xothic legend cycle is a series of short stories by Lin Carter that are based on the Cthulhu Mythos of H. P. Lovecraft, primarily on Lovecraft's stories "The Call of Cthulhu" and "Out of the Aeons". The Call of Cthulhu:  Written in the summer of 1926, it was first published in the pulp magazine "Weird Tales", in February 1928.
February 1928