In the Roman calendar, February is a month of universal purification, and begins the new year. In book II of his "Fasti", Ovid derives the month's name from "februae" (expiations); lustrations designed to remove spiritual contamination or ritual pollution accumulated in the previous year. On the 1st of the month, a black ox was sacrificed to Helernus, a minor underworld deity whom Dumézil takes as a god of vegetation related to the cult of Carna/Crane, a nymph who may be an image of Juno Sospita. On the same day, Juno's "dies natalis" ("birthday") as Juno Sospita was celebrated at her Palatine temple. On February 15 the Lupercalia festival was held, in which Juno was involved as "Juno Lucina". This is usually understood to be a rite of purification and fertility. A goat was sacrificed and its hide cut into strips, used to make whips known as "februum" and "amiculus Iunonis", wielded by the Luperci. The Juno of this day bears the epithet of "Februalis", "Februata", "Februa". On the last day of the month, leading into March 1, she was celebrated as protectress of matrons and marriages. The new year began on March 1. The same was celebrated as the birthday of Rome's founder and first king, Romulus, and the peaceful union of Romans and Sabine peoples through treaty and marriage after their war, which was ended by the intervention of women.