Please note that Mommsen uses the AUC chronology (Ab Urbe Condita), i.e. from the founding of the City of Rome. You can use this reference table to have the B.C. dates
In 558 there was added to the three old colleges of
the augurs, pontifices, and keepers of oracles, a fourth consisting of
three "banquet-masters" (-tres viri epulones-), solely for the
important purpose of superintending the banquets of the gods. The
priests, as well as the gods, were in fairness entitled to feast; new
institutions, however, were not needed with that view, as every
college applied itself with zeal and devotion to its convivial
affairs.
The clerical banquets were accompanied by the claim of
clerical immunities. The priests even in times of grave embarrassment
claimed the right of exemption from public burdens, and only after
very troublesome controversy submitted to make payment of the taxes in
arrear (558). To the individual, as well as to the community, piety
became a more and more costly article. The custom of instituting
endowments, and generally of undertaking permanent pecuniary
obligations, for religious objects prevailed among the Romans in a
manner similar to that of its prevalence in Roman Catholic countries
at the present day.