According to Johan Weyer, Bathym is a duke of the infernal
regions, also known as Marthin. He has the appearance of a robust
man, but his body ends in a serpents tail. He rides a steed
of livid color and is able to transport men from one place to another
with wondrous speed. He is well versed in the virtues of
herbs and precious stones. Thirty legions obey his behests.
Weyer, Johannes. Witches, Devils and Doctors in the Renaissance
Johann Weyer, De Praestigiis. Edited by George Mora.
Binghamton, N.Y. Medieval & Renaissance Texts & Studies,