The versipellis was the werewolf. One night, during a Full Moon (luna plena), a friend encountered a centurion. (A Full Moon arrives October 20, 2021.) The friend hailed the centurion, but the centurion said nothing. Then the centurion removed his tunic. Ecce! Centurio evanuit (vanished). Ingens lupus (a giant wolf) suddenly appeared. The werewolf ran into the forest and left his tunic behind. The friend cautiously inspected the tunic. Ecce! Tunica erat lapidea (the tunic had turned to stone). 
The Metamorphoses of Apuleius reportedly does not deal with werewolfery per se but with shape-shifting.  The Roman centurion had shape-shifted into a giant wolf.
Intrabunt lupi rapaces in uos, non parcentes gregi (Rapacious wolves shall enter in among you, not sparing the flock – Acts of the Apostles, 20: 29).
Some say rationalism is the answer, yet truly only irrationalism can reveal deeper meanings. The mere somatist, the rationalist, in his “eagerness to expiscate and explain the manner of all mysteries in earth and heaven, will not be slow to broach and argue his newest superstitions, the fruit of trivially profound research, vagaries which can neither interest, instruct, nor yet entertain the true scholar of simpler vision and clearer thought, since in the end these veaking inquirers commonly arrive at nothing, and like the earth-born sons of Cadmean tilth it has been proved in the past that again and again do they painfully destroy themselves by internecine war.” 
It was a weird somnambulism which sent forth the creatures during the Full Moon.  “Night fear, night cramps, and somnambulism always followed the appearance of specific lunar phases, reaching maximum expressions at full moon.” 
Roman author Pliny the Elder reportedly comments upon the werewolf legends of Greece in book VIII, chapter 22 of his Natural History: Homines in lupos verti, rursumque restitui sibi, falsum esse confidenter existimare debemus, aut credere omnia, quae fabulosa tot saeculis comperimus.  (Google Translate renders this, We must confidently think that men are turned into wolves, and again be restored to themselves, to be false, or to believe all things, which we have learned so many fables for centuries.)
The founders of Rome, Romulus and Remus, had been nursed by a she-wolf. “In new Rome there walked three men, a Judas, a Brutus and a spy,” wrote Union counter-intelligence chief Colonel Lafayette Baker in secret coded messages. 
——- Sources ——-
 Cambridge Latin Course (Unit 1), by Ed Phinney, Patricia E. Bell, et al. Cambridge University Press, 1988.
 The Werewolf in Lore and Legend, by Montague Summers. Originally published 1933. Reprint by Dover Publications, Mineola, NY, 2003.
 Lost Science, by Gerry Vassilatos. Kempton, IL: Adventures Unlimited Press, 1999.
 “Who Will Guard the Guards?”, Ersjdamoo’s Blog, August 13, 2018. https://ersjdamoo.wordpress.com/2018/08/13/who-will-guard-the-guards/