The name was at first confined to the northern part of what we call the Adriatic Sea, or to a stretch of land near that, and was derived from a once important Etruscan city, Atria, situated at the mouth of the Po. The rest of what we call the Adriatic Sea appears to have been at that time included in the term Ionian Sea or Ionian Gulf. It was only later, with the growth of the Syracusan colonies on the coasts of Italy and Illyria, that the name 'Hadria' came to include the whole Adriatic, and even then, at first, it was the practice to call the southernmost part the Ionian Sea. This reduction of the Ionian Sea to a part of Hadria led, when the name 'Ionian Sea' was transferred to the Sicilian Sea in the W. of Greece, to a misuse of the term 'Hadria.' It was extended to include the Tarentine Gulf, the Sicilian Sea, the Corinthian Gulf, and even the waters between Crete and Malta, as in Ac 27:27.

A. Souter.