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
Lastly Rome, as head of the Romano-Italian confederacy, not only
entered into the Hellenistic state-system, but also conformed to the
Greek system of moneys and coins. Up to this time the different
communities of northern and central Italy, with few exceptions, had
struck only a copper currency; the south Italian towns again
universally had a currency of silver; and there were as many legal
standards and systems of coinage as there were sovereign communities
in Italy.
In 485 all these local mints were restricted to the issuing
of small coin; a general standard of currency applicable to all Italy
was introduced, and the coining of the currency was centralized in
Rome; Capua alone continued to retain its own silver coinage struck in
the name of Rome, but after a different standard. The new monetary
system was based on the legal ratio subsisting between the two metals,
as it had long been fixed.(43)