by Raymond H Rich
The Myth Patterns of Latter-Day Primitives, with the full title An Investigation Into the Myth-Patterns of Latter-Day Primitives with Especial Reference to the R'lyeh Text, is a book. It was written by Dr. Laban Shrewsbury and published by Miskatonic University Press in 1913 (and possibly again in 1936). It describes the rites and centers of the cult of Cthulhu.
The book is described for Call of Cthulhu in the Keeper's Compendium Vol. 1 (page 50 in the 2000 edition).
From "Zoth-Ommog" by Lin Carter, "The House on Curwen Street" by August Derleth, The Encyclopedia Cthulhiana by Daniel Harms, and Ex Libris Miskatonici by Joan Stanley.