HYSSUS(Ὕσσος), a small river in the east of Pontus, 180 stadia to the east of Trapezus. (Arrian, Peripl. p. 6.) There can be little doubt that this river is the modern Sourmun;for the port-town. at its mouth, which bore the name Hyssusor Hyssi portus, was afterwards called Σουσάρμια (Anonym. Peripl. p. 13), and, according to Procopius ( B. G. 4.2), Σουσούρμαινα.This port-town, mentioned by Arrian (l. c.) and by the Anonymus (p. 14), is called in the Tab. Peut. Hyssilime, and seems to have been a place of some importance; for it was fortified, and had the cohors Apuleia civium Romanorumfor its garrison ( Notit. Imp. Orient. 27). [L.S]