Definition of "nereids"

Fashion may court the attachés to an embassy for the sake of their presence and perfumes at a party;—revolutions may occasion an interchange of deputations from the Rotunda to Mesdames les Poissardes—those political nereids who preside over the fish-market, and assist any "glorious cause" that may be in hand:—but these moments of fashion and favour are few and far between, and not very sincere at the best of times.

1831, L[etitia] E[lizabeth] L[andon], Romance and Reality. […], volume II, London: Henry Colburn and Richard Bentley, […], pages 269–270