The iaculus is a snake with wings. It leaps into the branches of trees, where it hides itself among the leaves. From its leafy perch it watches for animals that pass below. Its prey in sight, it hurls itself down to attack, flying through the air like a missile from a catapult. Thus is it called ‘iaculus,’ the javelin snake.
Acanthus leaves provide a fitting perch for four coiled iaculi on this finely-carved capital, located on entrance porch of the cathedral. While the iaculus on the right devours a human head, the one on the left gorges itself on scaled serpent. The device of placing the head of beast at the corner of a capital and splaying its flanks along the sides appears elsewhere at the cathedral, on a capital carved with rams.