The medieval chronicler Gervase of Tilbury associated the
transformation with the appearance of the full moon, but this
concept was rarely associated with the werewolf until the idea
was picked up by modern fiction writers. When the change from
human to beast occurs, the features blur and coarsen, the body
and palms of the hand become covered with fur, the eyes redden
and glow, the nose runs, the mouth salivates, speech is replaced
by guttural sounds and the werewolf drops to an animal position
on all four with its nails extended into claws. It gains accrued
senses and the ability to locate his prey several kilometers
away. The usual way for a werewolf to kill its victims is by
biting through the jugular vein and feasting on the remains. It
was believed in the Middle Ages that the fur of the werewolf was
under the normal human skin and were reversed during the
metamorphosis. The idea of the skin being reversed is a very
ancient one: versipellis occurs as a name of reproach in
Petronius, Lucilius, and Plautus,