Coins and gems[103] exhibit increased technical mastery. It must not be forgotten that coin types, being generally of religious significance, are apt to be very slow in responding to the artistic fashions of the day. This is especially the case with Athenian coinage. The Athena type with owl and olive-branch on the reverse is always of a conventional and somewhat archaic character. Elsewhere the coins and gems of the fourth century reach their highest point of perfection, and that is a point which has never been surpassed. As usual, Syracuse is in the forefront for beauty of design, and her new series of tyrants, Dionysius I. and II., revive the glorious types of Gelo and Hiero and improve them. The decadrachms of this period representing the head of the nymph Arethusa surrounded with dolphins and bearing on the reverse a four-horse chariot at full gallop are regarded by numismatists as the most beautiful coins in existence. The best of these bear the signature of their engraver, Euænetus. A gold coinage began here about the time of the repulse of the Athenian Armada. Corinthian coins with the flying Pegasus on the obverse and a head of Athena in a Corinthian helmet on the reverse also attain the summit of their beauty in this century. But even out-of-the-way places like Panticapæum, the corn depot of Southern Russia, and the little island of Tenedos, which to the historian _est in conspectu_ and little more, employed engravers of consummate art. Just before the beginning of the century three cities of the island of Rhodes united to form one republic, which rapidly rose to wealth by way of commerce and good government. It produced a gold coinage of great excellence, the figure of the sun-god Helios on the obverse and a rose (Rhodes) as a punning emblem on the reverse. It is only with Alexander the Great and his successors that the portraiture of mortal rulers begins to appear on Greek coinage. It is then rapidly developed, and some of the barbarian monarchs of the East are portrayed by Greek artists with great vigour and realism.