2419. Dates are expressed either by cardinals with a plural substantive
or by ordinals with a singular substantive: as,
#dictātor factus est annīs post Rōmam conditam CCCCXV#, _Fam._ 9, 21, 2,
_he was made dictator_ 415 U. C. (1393). #annō trecentēsimō
quīnquāgēsimō post Rōmam conditam, Nōnīs Iūnīs#, _RP_. 1, 25, _on the
5th of June_, 350 U. C. (1350). The ordinal is also used with a
substantive not used in the singular: as, #mancipia vēnībant
Sāturnālibus tertiīs#, _Att._ 5, 20, 5, _the slaves were sold on the
third day of the Saturnalia_. As the Romans, however, had no fixed
official era, they had no dates in the modern sense, and marked the year
by the names of the consuls.