CYDNUS, in Ancient Geography, a river of Cilicia; rising in Mount Taurus, to the north of Tarsus, through whose middle it ran, in a very clear and cold stream, which had almost proved fatal to Alexander on bathing in it; falling into the sea at a place called Rhegma, a breach, the sea breaking in there, and affording the people of Tarsus a station or port for their ships. The water of the Cydnus is commended by Strabo, as of service in nervous disorders and the gout.