Amphisbaena

The amphisbaena had a head at each end of its body and no way to tell which direction it was going until it was already there. It was born, like many Libyan serpents, from the blood of Medusa's severed head as Perseus flew over the desert. Where the blood dripped, the sand produced snakes, and the amphisbaena was the strangest of them.

Nicander described it in the Theriaca: grey-skinned, small-eyed, moving with either head leading. It could grasp one head in the other's mouth and roll like a hoop, covering ground at a speed that terrified anyone who witnessed it. Lucan confirmed the rolling locomotion and added that it was the first serpent to move after a frost — cold did not slow it as it slowed other reptiles.

Pliny recommended the amphisbaena as a medicinal resource. Wearing a live one around the neck cured rheumatism. A dead one, nailed to a tree, guaranteed a good harvest. Pregnant women who wore one in a bracelet ensured safe delivery, provided they removed it before labour began — otherwise the birth went badly.

The name meant "going both ways," and the creature served as a symbol of ambivalence and duality. Medieval bestiaries adopted it enthusiastically. Dante placed it in the Inferno. Borges included it in his Book of Imaginary Beings.

Modern biology has an amphisbaena too — the worm-lizards of the suborder Amphisbaenia, legless reptiles with blunt tails that can indeed appear two-headed. The Greeks noticed the resemblance first.