 Some assume that the two towns formed a single episcopal see, others suppose he was, strictly speaking, Bishop only of Apollonia, but was temporarily in charge also of Byllis during a vacancy of that see.At the Council of Chalcedon in 451, Eusebius subscribes simply as Bishop of Apollonia.In the letter of the bishops of Epirus Nova to the Byzantine Emperor Leo I in 458, Philocharis subscribed as Bishop of what the manuscripts call "Vallidus", and which editors think should be corrected to "Byllis".