The form of the seal face, which is also frequently impressed on tablets of Persian dating, is elliptical or bi-segmental. Animals are most frequently represented. Those rings, which are generally cast in bronze and more rarely in silver, consist usually of a small plate, which, when not engraved as a seal, is set with precious stones, on a plain hoop. [Illustration: FIG. 190.—Rings and their seal impressions. ] [Illustration: FIG. 191.—Cylinder seals and signet with their impressions. ] The most important form of the Babylonian seal was the cylinder (Fig. 191). In addition to these there were at all periods numerous button seals, parallelepipeda, and calottes of circular and ellipsoidal forms; also comparatively early there were scarabs and scaraboids. The materials used included agate, lapis lazuli, marble, flint, magnetite, and sea-shell, as well as glass and frit. All seals were bored, in order that an eyed peg might be fixed into them. If the perforation were long, as with the seal cylinders, it was worked from both ends, and a slight projection may be seen inside in the centre. The usual representations are of divinities and their emblems, heroes and animals in combat with each other, or with gods and champions. The principal gods are symbolised thus: Shamash by the sun’s disc, Sin by the new moon, Ishtar by a star, and here in Babylon more especially, Marduk by a triangle on a staff, and Nebo by a rod. Ornamentation is extremely rare. Inscriptions in cuneiform, the name of the owner and his devotion to a specified god, who is not always necessarily indicated in the representation, are specially frequent on seal cylinders, while Aramaic inscriptions are found only on other forms of seals. Owing to the great number of these objects we can observe the gradual development of art with delightful clearness. The ancient seal, which reaches back into prehistoric times, notwithstanding the primitive tools employed, often shows great vigour of execution. These are merely engraved, but with the discovery of the wheel and drill the art progressed with the development of the means of expression, and gradually and steadily rose to its greatest perfection at the time of the last of the Assyrian and Babylonian monarchs. In consequence of the overwhelming use of the wheel, the art then became gradually though not uniformly so conventionalised that the representations often consist merely of dots and lines. But even at this stage specimens of astounding artistic merit are not rare. Glyptic art in Babylon is always in advance of the other contemporary plastic arts. It is only moulded pottery reliefs that in any degree keep step with it. Modelling in the round, more especially in stone, remains markedly behind the contemporary productions of the stone-cutter. Babylonian plastic art in the round never attained the excellence of the Greek masterpieces of about the fourth century B.C. In