Countess di Civillari
(The). A bog, sewer, cesspool, into which falls the filth of a city. Two wags promised Simon da Villa an introduction to the Countess di Civillari, and tossed him, in his scarlet gown, into a ditch where farmers “emptied the Countess of Civillari for manuring their lands.” Here the doctor floundered about half the night, and, having spoilt his robes, made the best of his way home, to be rated soundly by his wife.
(Boccaccio: Decameron, Eighth day, ix.)
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894