A Roman silver coin first issued B.C. 268 with the Quinarius and Sestertius as its divisions. At that time the Aes Libralis had been reduced to two ounces in weight and the Denarius was equivalent to ten of them.

The original type bears on the obverse the head of Minerva and the numeral X, and on the reverse the Dioscuri on horse- back and the legend ROMA in the exergue. There is a tradition that the Romans won the battle of Lake Regilius, circa B.C. 496, by the aid of Castor and Pollux who ap- peared on the battlefield as youths riding white horses. These early types of De- narii are consequently also known as Cas toriati.

In B.C. 217 the value of the Denarius was changed to sixteen Asses, and the numeral XVI substituted, the latter being generally abbreviated by the sign * .

The Denarius, in A.D. 296, was suc- ceeded by the Ceutenionalis as a silver coin, and the name Denarius was applied to a copper coin, commonly known as the " third bronze." See Follis.

The gold Denarius, of the same weighl as the silver one and of the value of ten, was the same as the half Aureus or Quin- arius. It occurs both in the Roman Con- sular and Imperial series.

The following table shows how exten- sively the silver Denarii were debased, and their corresponding values: Percentage of copper alloy Under Augustus the Denarius was one eighty-fourth of a pound, copper 60 grains 5 Under Nero the Denarius was one nine- tieth of a pound, copper 55 grains 5 to 10 Under Trajan the Denarius was one ninety-ninth of a pound, copper 51 grains 15 to 18 Under Hadrian the Denarius was one ninety-ninth of a pound, copper 51 grains 18 to 20 Under M. Aurelius the Denarius was one ninety-ninth of a pound, copper 51 grains 20 to 25 Under Commodus the Denarius was one one hundred and a third of a pound, copper 49 grains 25 to 30 Under Sept. Severus the Denarius was one one hundred and a fifth of a pound, copper 48 grains 30 to 55