Fossil unicorn; in Latin, unicornu fossile . Some authors have given this name to a bony substance, similar to ivory or to a twisted horn covered with spirals, that is found, although rarely, within the earth. Mr. Gmelin, in his Siberian voyage, believes that these are fish teeth. He reports that in 1724, one of these horns was found beneath the earth, in the territory of Yakutsk, in Siberia; he assumes that it does not belong to the mythical animal to which the name unicorn has been given; but he believes, and it is very likely, that it comes from the cetacean animal that is called narwhal . The same author speaks of another horn of the same kind that was found in 1741, in swampy terrain in the same country: however, he observes that the narwhal that is commonly found in the seas of Greenland, does not exist in the Arctic Ocean, which borders the North of Siberia.

What would seem to cast doubt on this matter is a fact reported by the illustrious Leibnitz in his Protogoea ; following the account of the famous Otto Guericke, he says that in 1663, someone pulled from a limestone quarry at Mount Zeunikenberg, in the territory of Quedlinberg, the skeleton of a terrestrial quadruped crouched on its hind parts, but on which the head was raised, and which sported on its forehead a horn of five ells, that is to say approximately ten feet in length and as thick as the leg of a man, but ending in a point. This skeleton was broken by the ignorance of the workers and pulled piece by piece from the ground; only the horn and the head remained whole, as well as some ribs, and the spine; these bones were brought to the abbess-princess of Quedlinberg. Mr. de Leibniz provides in this same work the image of this skeleton. He says on this subject that according to the report of Hyeronimus Lupus and Balthasar Tellez, Portuguese authors, a quadruped the size of a horse, on which the forehead is armed with a horn, exists in the land of the Abyssinians. See Liebnitz, Protogoea, pages 63 and 64 . In spite of all these authorities, it is maddening that the skeleton of which Leibniz speaks was not more carefully examined, and there is every reason to believe that that horn really belonged to a fish.

One must not confuse the horn or the bony substance of which it is here a question with another earthy, calcareous, and absorbent substance that some authors have very improperly called unicornu fossile , and that, based on appearances, is a kind of chalk or marl. See Unicornu fossile.