These terms are applied primarilyto the “psychic epidemics” which have at times swept through an entire population. The most vivid examples are the dancing manias and lycanthropies that occurred in many parts of Europe between the eleventh and seventeenth century. As Arieti and Meth (1959) point out, these disorders should not be classified as psychoses but as “psychoneuroses of a hysterical nature which were induced by the effect the crowd had on the predisposed person. The atmosphere of superstition, ignorance, and intense religiosity predisposed unstable individuals to this form of collective hypnosis.” The term “mass hysteria” therefore seems more apt than collective psychosis.The dancing mania can be traced as far back as the tenth century in Italy. People would gather near a church and sing and dance for several days and nights until many of them had convulsions and lost consciousness. The condition was named tarantism or taran- tulism by Baglivi, since the participants thought they had been bitten by a spider, lycosa tarantula, and as a result danced about in great fear and excitement. They also believed that music would be an effective treatment, and the “tarantella” has remained a popular type of dance music in Italy to this day. Some authorities point out the similarity between the dancing manias and the orgiastic rites of ancient Greece,and offer the conjecture that secret gatherings kept the custom alive when it was banned by Christianity, but that in time the rites lost their original meaning and became symptoms of emotional disorder or reactions to the stresses of the period (Gloyne, 1950). Sigerist(1943) gives this description based on a report of a physician in thirteenth-century Italy:“The disease occurred at the height of the summer heat . . . People, asleep or awake, would suddenly jump up, feeling an acute pain like the sting of a bee. Some saw the spider, others did not, but they knew that it must be the tarantula. They ran out of the house into the street, to the marketplace, dancing in great excitement. Soon they were joined by others who like them had been bitten, or by people who had been stung in previous years. . .“Thus groups of patients would gather, dancing wildly in the queerest attire . . . Others would tear their clothes and show their nakedness, losing all sense of modesty . . . Some called for swords and acted like fencers, others for whips and beat each other . . . Some of them had still stranger fancies, liked to be tossed in the air, dug holes in the ground, and rolled themselves into the dirt like swine. They all drank wine plentifully and sang and talked like drunken people . . .”The dancing mania spread to Germany and the Flemish countries, where it became known St. Vitus’ Dance. The name is believed to have been adopted after a tragedy at Utrecht in 1278, when two hundred people danced so violently on a bridge over the Rhine that it collapsed into the river. Many of them lost their lives in the water, but some were treated in a chapel dedicated to St. Vitus—hence the name.A second type of collective disorder, lycanthropy, occurred in isolated areas, and is still occasionally reported in mountainous villages of Italy. People afflicted with this illness imagine that they are transformed into wolves. Stone(1937) cites a case from 1541 in which a lycanthrope (literally, wolf-man) told his captors in confidence that he was actually a wolf but that his skin was smooth because his hairy coat was turned inward. In an effort to cure him of this conviction, his arms and legs were amputated, but he died unconvinced. Many other victims committed violent crimes while under this delusion, and it therefore became the custom to arrest and execute anyone afflicted with the disorder. During an epidemic in France, one judge is said to have condemned six hundred lycanthropes, or “werewolves,” to death.In their comments on this disorder, Arieti and Meth state that while some of the victims were probably schizophrenics, it is possible that the majority were affected by some form of collective hysteria. They point out that the belief that men can be transformed into animals is the basis of many ancient myths. They also recall that Nebuchadnezzar thought he was a wolf, and that St. Patrick is said to have transformed Veneticus, the King of Gallia, into a wolf. These authors suggest that the disorder may arise from a strong sense of guilt and unworthiness which makes the individual feel he does not deserve to belong to the human race. This feeling makes him afraid he will undergo a metamorphosis, and he later acts out this fear by behaving like an animal. This is especially likely to happen when he sees other people behaving in this way, so the disorder spreads from one person to another.Other collective epidemics have been reported in convents where the nuns suddenly abandoned their religious discipline and performed some bizarre action for a short time. In the fifteenth century a German nun developed a compulsive urge to bite her associates. The mania was taken up by the other nuns and within a few months had spread to convents in Germany, Holland, and Italy (White, 1896). Another historian, Ferrio (1948), relates that in about 1700 the nuns in a convent near Paris started to mew as if they had been transformed into cats. These cases are probably another expression of lycanthropy.In present-day psychiatry the term lycanthropy is usually reserved for those rare cases of schizophrenia or paranoia in which the patient has an outright delusion that he has been transformed into an animal. One such case was recently reported in which a boy of four labored under the delusion that he was a dog. He crawled about on all fours, barked instead of talked, and would only eat out of a bowl placed on the floor