It’s a Polyhymnia, as we are informed here inside the lid.
Thomas Mann -- The Magic Mountain
They were Clio the muse of history, Euterpe of music, especially the flute, Thalia of comedy, Melpomene of tragedy, Terpsichore of dancing, Erato of erotic poetry, mistress of the lyre, Polyhymnia of sacred poetry, Urania of astronomy, Calliope of eloquence and epic poetry.
Ralph Waldo Emerson -- Selected Essays
They were thirteen in all, not including Wenzel the Bohemian, who kept himself available for tending to Polyhymnia’s needs and, having now readied her for service, took a place on a stool toward the middle of the room behind the others.