Hydrophinnae

Hydrophinnae is a fictional book created by Carl Jacobi in the short story "The Aquarium". Attributed to an author named Gantley, it is part of a set of books dealing with the mysteries of the sea found in the collection of Horatio Lear, who had a morbid fascination with molluscs. Hydrophinnae is said to have "some of the most hideous and horrible illustrations."
The book is repeatedly mentioned in the Cthulhu Mythos stories of Brian Lumley, where it appears in the private libraries of people with an interest in "oceanic lore and legend"-- people like occultist Titus Crow of Blowne House ("Name and Number," "De Marigny's Clock"); Julian Carstairs of The Barrows, near Haslemere, Surrey ("Lord of the Worms") ; Gavin McGilchrist of Temple House in Lothian ("House of the Temple"); Jason Carpenter of Kettlethorpe Farm, County Durham ("Dagon's Bell"); and author Julian Haughtree ("Rising with Surtsey").
Category:Mythos Books (fictional)
Category:Artefacts Originating From Mythos-Adjacent Works