This cosmic serpent belongs in the mythology of ancient Egypt. Mehen guards the boat in which the sun god Ra travels through the underworld. Ra was constantly under threat from the serpent Aapep as he journeyed in his sun boat through the night. Mehen set himself to protect Ra against this adversary.
John and Caitlin Matthews, The Element Encyclopaedia of Magical Creatures, 2013, Mehen, p 311