Arsia

A´RSIA a small river of Istria, still called Arsa, which became the boundary between Italy and Illyricum, when Istria had been annexed by Augustus to the former country. (Plin. Nat. 3.5. s. 6, 19. s. 23; Tab. Peut.) Florus represents it as having been at an earlier period the limit between the Illyrians and Istrians (2.4). It flowed into the Flanaticus Sinus ( Golfo di Qeuarnero), on the E. coast of Istria, just beyond the town of Nesactium ( Castel Nuovo). The existence of a town of the name Civitas Arsia,rests only on the authority of the geographer of Ravenna (4.31), and is probably a mistake.
[E.H.B]