independent cities, in some cases even for two centuries; but the kings who divided his great empire modified the type by introducing real portraits of Alexander, as a deified hero, and later of themselves, as living deities, so that the representation of a ruler's head on coins, which is still practised to-day, began with quasi-religious Greek coin-types. The regularity of the Greek coinage which Alexander established was only temporary, and his influence was fast disappearing when the subjection of the world by the Romans in the first century B.C. merged all provincial issues in the complete uniformity of the Imperial mint. =Roman Coins.=--As gold in the Asiatic coastlands and silver in European Greece, so in Italy the native medium of exchange was bronze. In the earliest times the raw metal was circulated in broken knobs of indefinite weight (_aes rude_), which required in all transactions the use of scales. The rude metal was afterwards superseded by cast ingots of an oblong shape, which bore a device to indicate their purpose as money (_aes signatum_). Yet the weights were still irregular, and no mark of value accompanied the types, so that the pieces were not strictly coins. A survival of this primitive currency is seen in the large ingot which has on one side a tripod and on the other an anchor (No. =37=; fig. 13). This piece itself belongs to a later period, when the lighter coined money was already in use. The special purpose for which this and similar pieces were intended is quite uncertain. The first coinage of Rome was less massive than this, but being entirely of bronze, was still inconveniently large and cumbrous (_aes grave_). The Roman of the fourth century B.C., when he found it necessary to transport any considerable sum, took his money about with him in a waggon.[10] The use of bronze for a token currency, as in Greece, was not possible without a superior coinage of gold or silver to secure its value. [Illustration: FIG. 13.--AES SIGNATUM (NO. 37). 1:3.] [Illustration: FIG. 14.--AES GRAVE (NO. 38). AS, SEMIS, QUADRANS, AND UNCIA. 1:2.]