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
From: The History of Rome, by Theodor Mommsen
Translated with the sanction of the author by William Purdie Dickson
An extension of that community was inevitable; and it was accomplished in the most comprehensive manner, inasmuch as the collective plebeiate, that is, all the non-burgesses who were neither slaves nor citizens of extraneous communities living at Rome under the -ius hospitii-, were admitted into the burgess-body. The curiate assembly of the old burgesses, which hitherto had been legally and practically the first authority in the state, was almost totally deprived of its constitutional prerogatives.
It was to retain its previous powers only in acts purely formal or in those which affected clan-relations --such as the vow of allegiance to be taken to the consul or to the dictator when they entered on office just as previously to the king,(9) and the legal dispensations requisite for an -arrogatio- or a testament--but it was not in future to perform any act of a properly political character.
9. Cf. I. V. The King
Soon even the plebeians were admitted to the right of voting also in the curies, and by that step the old burgess-body lost the right of meeting and of resolving at all. The curial organization was virtually rooted out, in so far as it was based on the clan-organization and this latter was to be found in its purity exclusively among the old burgesses.
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Reference address : https://www.ellopos.net/elpenor/rome/2-01-constitution-magistrate.asp?pg=20