the true nature of their embedded remains. Nay, even in the middle of the present century, so slow is the growth and spread of organised knowledge, it was possible for a pious Scotchman to ascribe the origin of mountain chains to a cataclysm which, after the fall of Man, had broken up and distorted the once symmetrical surface of the earth;[4] for a Dean of York to essay to bring the Mediæval theory up to date and prove that the whole series of geological strata, with their varied organic remains, were formed by volcanic eruptions acting in concert with the Mosaic Deluge;[5] and for another English divine to warn his readers against any sacrilegious meddling with the arcana of the rocks, because they represented the tentative essays of the Creator at organic forms--a concealed storehouse of celestial misfits![6] The subject-matter of the present inquiry has passed, or is now passing, through stages closely similar to those above described. "Ghosts" and warning dreams have been matters of popular belief and interest since the earliest ages known to history, and are prevalent amongst even the least advanced races at the present time. The Specularii and Dr. Dee have familiarised us with clairvoyance and crystal vision. Many of the alleged marvels of witchcraft were probably due to the agency of hypnotism, which in later times, under the various names of mesmerism, electrobiology, animal magnetism, has attracted the curiosity of the unlettered, and from time to time the serious interest of the learned. These phenomena indeed were made the subject of scientific inquiry, first in France and later in England, during the first half of the present century; have now again, after a brief period of eclipse, been investigated for the last two decades by competent observers on the Continent, and are at length winning a recognised footing in scientific circles in this country. Yet within the last two or three years we have witnessed the spectacle of more than one medical man, of some repute in this island, laughing to scorn all the researches of Charcot and Bernheim, just as their prototypes a generation or two ago ignored the results of Cuvier and Agassiz, and held it an insult to the Creator to accept the scientific explanation of coprolites.