It is not certain to what date the famine mentioned by St. Ambrose is to be referred, nor is the name of the prefect of the city certainly known. The Præfectus Urbis was at this time the highest officer of the city, directly representing the emperor, and except to the latter there was no appeal from his decisions. Amongst other duties he exercised a supervision over the importation, exportation, and prices of provisions. As St. Ambrose, § 48, calls him “sanctissimus senex,” he was probably a Christian.