Final answer:
The members of the Ordo Decurionum were known as decurions, who served administrative and religious functions in the Roman Empire, comparable to city councillors.
Step-by-step explanation:
The members of the Ordo Decurionum were referred to as decurions or decuriones. These were the officials who belonged to the local municipal senates of cities in the Roman Empire, similar to city councillors. The order was composed of the leading citizens and was tasked with various administrative and religious duties within the city. An example of such a religious association is the Septemviri epulones, involved in organizing public feasts connected to sacred holidays. The Quindecimviri sacris faciundis was another example of a priestly college, with a duty to guard and consult the Sibylline books at the request of the Senate.