Mermaids and Mermen, in the popular folklore of Europe, a class of beings more or less like men, living in the sea, but in some circumstances capable of social relationships with men and women. The typical mermaid has the head and body of a lovely woman to the waist, ending in the tail of a fish with fins and scales. She has long and beautiful hair, and is often seen above the surface of the water, combing it with one hand while in the other she holds a mirror. She often discloses what is about to happen, and not seldom gives supernatural knowledge and powers to a favoured mortal—a thing in perfect keeping with primitive notions of sorcery, which easily attributed exceptional powers to beautiful women, as Lilith and Circe. Again, she sometimes exercises a special guardianship over an individual, and avenges his wrongs; but her relation to man most often brings with it disaster. There are many stories of mermaids who have fallen in love with men, or been detained through the possession of the skin which they had stripped to dance on the shore, and who have been faithful wives and mothers until they found an opportunity to return to the sea. And there are examples of the converse case of a mermaid falling in love with a man and enticing him to go and live with her under the sea, as well as of a merman bewitching and carrying off a mortal maiden.
Such are the principal forms of mermaid stories found everywhere, with more or less artistic elaboration. The Danish Hafnand or Maremind, the Irish merrow or merruach, the Breton Marie-Morgan, the Russian rusalka or stream-fairy and vodyany or water-sprite, some forms of the Teutonic nixies, and the enchanting Sirens of classical mythology have all close affinities with each other in the dangers they bring to men, the beauty and joyousness of their lives, and yet the gloom of sadness that overhangs them. In their malignant aspect they touch the general doctrine of Demonology (q.v.), and may be explained on an animistic theory of its origin. To the beauty of the conception and the elaborations of which it is capable in the popular imagination we owe some of the loveliest of our folk-tales as well as such delightful artistic tales as Undine and many fine poems of the ages of literary culture. One of the most detailed stories of this class is that of Melusine (q.v.). The mermaid had a firm hold of the imagination of our fathers, and, besides the witness of heraldry, we have stories supported by excellent evidence of their appearance and capture. One caught at Edam in 1403 was carried to Haarlem and kept there many years. She learned to spin and showed a becoming reverence for the cross. See Baring-Gould's Popular Myths of the Middle Ages, and Sébillot's Contes des Marins (1882).