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
The device of the effigy of Janus, which, like the deity itself, may be attributed to the Latins,(40) is not unskilful, and is of a more original character than that of any Etruscan work of art.
40. Cf. I. XII. Nature of the Roman Gods
The beautiful group of the she-wolf with the twins attaches itself doubtless to similar Greek designs, but was--as thus worked out--certainly produced, if not in Rome, at any rate by Romans; and it deserves to be noted that it first appears on the silver moneys coined by the Romans in and for Campania. In the above-mentioned Cales there appears to have been devised soon after its foundation a peculiar kind of figured earthenware, which was marked with the name of the masters and the place of manufacture, and was sold over a wide district as far even as Etruria.
The little altars of terra-cotta with figures that have recently been brought to light on the Esquiline correspond in style of representation as in that of ornament exactly to the similar votive gifts of the Campanian temples. This however does not exclude Greek masters from having also worked for Rome. The sculptor Damophilus, who with Gorgasus prepared the painted terra-cotta figures for the very ancient temple of Ceres, appears to have been no other than Demophilus of Himera, the teacher of Zeuxis (about 300).
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Reference address : https://www.ellopos.net/elpenor/rome/2-09-art-science.asp?pg=44