A term for an artificial monster made out of the remains of certain fishes, especially skates or rays. The nostrils, mouths, and gills of these fishes in their natural state look rather like an evil, grimacing face. With judicious cutting, partially separating the pectoral fins from the body, they can be made to resemble monsters: winged snakes, dragons, or whatever other creature the manufacturer thinks credulous visitors will buy. In medieval times, Jenny Hanivers were often passed off as basilisks mythological creatures who were so ugly and poisonous that their very breath could kill. Buyers believed that the basilisk’s hide, when made into a medicine, would prove a potent remedy for poisoning.
Sixteenth-century Swiss naturalist Conrad Gesner, who was the first writer since classical times to compile an encyclopedia of animal life, described a Jenny Haniver in his Historia Animalium (1558). Gesner published a drawing of the Jenny Haniver, along with a description of one that he saw in a shop in Zurich. Gesner stated that the shopkeeper who also sold quack medicines believed that the monster was a small basilisk. Gesner himself, however, explained that the Jenny Haniver had in fact been made from a ray, and he warned his readers not to mistake such forgeries for winged serpents or small dragons.