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.

From: Berens, E.M. The Myths and Legends of Ancient Greece and Rome. New York: Maynard, Merril, & Co., 1880. Text in the public domain.

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