Promylaia ("the one that stands before/protects the mill") was another name for a goddess of the mills, who was worshipped in the same fashion as Eunostus. Both Eunostus and Promylaia could actually have been mere epithets of Demeter.
This article incorporates text from a publication now in the public domain: Smith, William, ed. (1870). Dictionary of Greek and Roman Biography and Mythology. Missing or empty
Ancient Greek deities by affiliation