Romulius
Could not find Romulium in Logeion dictionaries.
Romulium proper-name adjective neuter vocative singular, proper-name adjective masculine genitive plural, proper-name adjective masculine accusative singular, proper-name adjective neuter genitive plural, proper-name adjective neuter nominative singular, proper-name adjective neuter accusative singular of Romulius
Rōmŭlĭus, (16) v. Romilius.
Romu'lius Denter
is said to have been appointed praefectus urbi by Romulus. (Tac. Ann. 6.11.)