According to Mommsen, the aerarii were originally the non-assidui (non-holders of land), excluded from the tribes, the comitia and the army.
Until the reform of the comitia centuriata (probabl' during the censorship of Gaius Flaminius in 220 B.C.; *see Comitia),` the equites had voted first, but after that time this privilege was transferred to tine cenfury selected by lot from the centuries of ' the equites and the first class.
They were created in the same year as the tribunes of the people (494 B.C.), their persons were sacrosanct or inviolable, and (at least after 471) they were elected at the Comitia Tributa out of the plebeians alone.
All the old republican formalities were most punctiliously observed - even those attendant on the emperor's election to the consulate, so far as they did not involve a restoration of the old order of voting at the comitia.