Olmstead's family tree This is a family tree of the story's protagonist and narrator, Robert Olmstead, as described in The Shadow over Innsmouth and in Lovecraft's notes. Inspiration Both of Lovecraft's parents died in a mental hospital, and some critics believe that a concern with having inherited a propensity for physical and mental degeneration is reflected in the plot of The Shadow over Innsmouth. It also shares some themes with his earlier story, "Facts Concerning the Late Arthur Jermyn and His Family". Cthulhu, an entity from previous Lovecraft stories, is the overlord of the sea creatures. The mind of the narrator deteriorates when he is afforded a glimpse of what exists outside his perceived reality. This is a central tenet of Cosmicism, which Lovecraft emphasizes in the opening sentence of "The Call of Cthulhu": "The most merciful thing in the world, I think, is the inability of the human mind to correlate all its contents." Lovecraft based the town of Innsmouth on his impressions of Newburyport, Massachusetts, which he had visited in 1923 and fall 1931. The real Newburyport features as a neighboring town in the narrative. A likely influence on the plot is Lovecraft's horror of miscegenation, which is documented by Lovecraft biographer L. Sprague de Camp and others. Robert M. Price cites two works as literary sources for The Shadow over Innsmouth: Robert W. Chambers' "The Harbor-Master" and Irvin S. Cobb's "Fishhead". Chambers' story concerns the discovery of "the remnants of the last race of amphibious human beings," living in a five-mile deep chasm just off the Atlantic coast. The creature of the title is described as "a man with round, fixed, fishy eyes, and soft, slaty skin. But the horror of the thing were the two gills that swelled and relaxed spasmodically." Lovecraft was evidently impressed by this tale, writing in a letter to Frank Belknap Long: "God! The Harbour-Master!!!" "Fishhead" is the story of a "human monstrosity" with an uncanny resemblance to a fish: his skull sloped back so abruptly that he could hardly be said to have a forehead at all; his chin slanted off right into nothing. His eyes were small and round with shallow, glazed, pink-yellow pupils, and they were set wide apart on his head, and they were unwinking and staring, like a fish's eyes. Lovecraft, in "Supernatural Horror in Literature," called Cobb's story "banefully effective in its portrayal of unnatural affinities