A titular see of Byzacena in Africa. Nothing is known of the history of this city; it is mentioned by Ptolemy (IV, 3, 10) and with variations in the spelling of the name by the Peutinger Tables (ii) which call it a municipality, and by other ancient geographical documents, according to which it was thirty-two miles from Thysdrus (today El Djem) and twenty-eight miles from Thaenae (Benshir Tina). The ruins are known as Inshilla, among them being the remains of a Byzantine basilica. We have the names of six bishops of Usilla: Felix, present at the Council of Carthage (256); Cassianus, at the Council of Carthage (349); Theodore, one of the Donatist partisans of Maximianus, who at the Council of Cabarsussi (393) condemned Primianus, and in turn at the Council of Bagai (394) was condemned by the partisans of the latter, as one of the consecrators of Maximianus; Privatus, present at the Conference of Carthage (411); Victorinus, exiled by Huneric (484); Laurentius, a signer of the letter addressed by the Council of Byzacene (641), to the Byzantine emperor against the Monothelites.

SMITH, Dict. of Greek and Roman Georgr., s. v. Usilla; MULLER, Notes on Ptolemy, ed. DIDOT, I, 623; TOULOTTE, Geog. de l' Afrique chretienne, Byzacene et Tripolitaine (Montreuil, 1894), 227-29.

S. Pétridès.