E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Sir James Emerson Tennent, speaking of the dugong, a cetacean, says, Its head has a rude approach to the human outline, and the mother while suckling her young holds it to her breast with one flipper, as a woman holds her infant in her arm. If disturbed she suddenly dives under water, and tosses up her fish-like tail. It is this creature which has probably given rise to the tales about mermaids.