Furrina is of ancient origins, likely from the time of the Etruscans. She began as a Goddess of a sacred grove and spring (lucus) on Janiculum hill. At some point in the early Republic, worship of Furrina spread beyond Rome (we have evidence for the worship of Furrina at Satricum,60 km southeast of Rome, and Arpinum, 120 km southeast of Rome). It was likely as this point that Furrina was assigned a flamen, and worship of Furrina was likely at its greatest extent. However, as the demographics of Janiculum became less Latin-speaking and increasingly Syrian, the worship of Furrina began to decline. Furrina was later confused with the Furies, after the killing of Gaius Gracchus within Her sacred grove. By the time of the late Republic, worship of Furrina had virtually ceased, leading Varro to write in De lingua latina libri XXV “honour was paid to her among the ancients, who instituted an annual sacrifice for her, and assigned to her a special priest, but now her name is barely known, and even that to only a few.” Furrina’s annual sacred festival, the Furrinalia, was held on 25 July, but nothing is known of the ancient celebration.
Goodhue, Nicholas. The Lucus Furrinae and the Syrian Sanctuary on the Janiculum. Amsterdam: Adolf M. Hakkert, 1975.
Savage, S. M. “The Cults of Ancient Trastevere.” Memoirs of the American Academy in Rome 17 (1941), 26-56.