In Roman mythology, the lemures were shades or spirits of the restless or malignant dead, and are probably cognate with an extended sense of larvae (from Latin larva, "mask") as disturbing or frightening. Lemures is the more common literary term but even this is rare: it is used by the Augustan poets Horace and Ovid, the latter in his Fasti, the six-book calendar poem on Roman holidays and religious customs.