It is difficult to ascertain the exact date of the adoption. Herodian’s statement of the year 220 is easily refuted, both by epigraphic and numismatic evidence. These give, as near as possible, 10th July in the year 221, by means of the following deductions:—(1st) The fasti of a priestly college, probably the Sodales Antoniniani, dated either 2nd or 10th July in that year, describe Alexianus as “Marcus Aurelius Alexander Nobilissimus Caesar,” and either Imperii _consors_ or _heres_, on which discrepancy of words hangs a future tale; (2nd) the earliest Alexandrian coins which call Alexianus Caesar are dated LΕ, or subsequent to 29th August 221; (3rd) there is an inscription found amongst those of the 7th Cohort of the Vigiles, which was set up on 1st June of that year, and commemorates the Imperatores Antoninus et Alexander. The earliest date is therefore 1st June, the latest the end of July or beginning of August. The probabilities lie between the two, as the early police inscription has been accounted for on the grounds that, along with her money, Mamaea had circulated a report of the adoption before it took place. The numismatic evidence points to a middle date, because, as far as we can judge, the Alexandrian mint was most expedite in issuing its coins, and here, if the adoption took place early in June, they would seem to have allowed a month or so to elapse between the time they got the news and the first issue of the coins. Other mints also issued their first coins, calling Alexander Caesar, towards the end of 221.