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
It was a circumstance of far greater importance that, towards the end of this period, the primitive freehold basis of the right of suffrage began for the first time to be called in question. Appius Claudius, the boldest innovator known in Roman history, in his censorship in 442 without consulting the senate or people so adjusted the burgess-roll, that a man who had no land was received into whatever tribe he chose and then according to his means into the corresponding century. But this alteration was too far in advance of the spirit of the age to obtain full acceptance.
One of the immediate successors of Appius, Quintus Fabius Rullianus, the famous conqueror of the Samnites, undertook in his censorship of 450 not to set it aside entirely, but to confine it within such limits that the real power in the burgess-assemblies should continue to be vested in the holders of land and of wealth. He assigned those who had no land collectively to the four city tribes, which were now made to rank not as the first but as the last.
The rural tribes, on the other hand, the number of which gradually increased between 367 and 513 from seventeen to thirty-one--thus forming a majority, greatly preponderating from the first and ever increasing in preponderance, of the voting-divisions--were reserved by law for the whole of the burgesses who were freeholders. In the centuries the equalization of the freeholders and non-freeholders remained as Appius had introduced it.
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Reference address : https://www.ellopos.net/elpenor/rome/2-03-equalization-orders-aristocracy.asp?pg=40