The mouth is common to both; but this difference is to be observed, that the name Ionian2796 is applied to the first part of the gulf only, and Adriatic to the interior sea up to the farthest end, but the name Adriatic is now applied to the whole sea. According to Theopompus, the name Ionian was derived from a chief (Ionius) of that country, a native of Issa; and the name Adriatic from a river, Adrias.2797
From the Liburni to the Ceraunian mountains is a distance of a little more than 2000 stadia. But Theopompus says, that it is six days’ sail from the farthest recess of the bay, but a journey of thirty days by land along the length of Illyria. This appears to me an exaggeration, but he makes many incredible statements. Among other instances, he pretends that there is a subterraneous passage between the Adriatic and the Ægean Seas, grounding his opinion on the discovery of Chian and Thasian pottery in the river Naron.2798 The two seas, he says, may be seen from some pretended mountain. He describes the Liburnian islands as occupying a position so extensive as to form a circle of 500 stadia. According to him, the Danube discharges itself by one of its mouths into the Adriatic.2799 Similar mistakes are to be found in Eratosthenes, which Polybius, when speaking of him and other writers, describes as having their origin in vulgar error.2800