The Sirens would appear to have been personifications of those numerous rocks and unseen dangers, which abound on the S.W. coast of Italy. They were sea-nymphs, with the upper part of the body that of a maiden and the lower that of a sea-bird, having wings attached to their shoulders, and were endowed with such wonderful voices, that their sweet songs are said to have lured mariners to destruction.
Source: tatoeba (11120945)