), a river of Gallia Transpadana, and one of the most important of the northern tributaries of the Padus.
It flows beneath the walls of Vercellae (Vercelli
), and joins the Padus about 16 miles below that city. Its name is noticed only by Pliny (3.16. s. 20
) and the Geographer of Ravenna (4.36), who writes the name Sisidus.