Byzantine conventional ornament appears to be of two types,--the one usually used in mosaics, of thin scrolls, terminating in flowers or symbols, displayed upon a ground which is much greater in quantity than is the ornament; the other, usually confined to sculpture, an intricate interlace of ribbon lines with spaces filled with Byzantine acanthus, the ornament much greater in proportion than the ground, which only shows in small separate pieces. Apart from these are the borders, occasionally of overlapping leaves, often of small repeated units, such as Greek crosses and squares and diamonds, or else meanders or guilloches. The guilloche takes a new form in Byzantine design, and instead of being a continuous succession of small circles enclosed in an interlacing ribbon, it assumes the form of alternating small and large circles, or of small circles alternating with large squares, and often progressing in both directions at once, horizontally and perpendicularly, and thus forming an all-over pattern. The roses of ornament are often incorporated into this form of guilloche. Sculpture of the human form becomes more and more feeble and crude. The acanthus, however, went steadily through successive variation until it attained the virile form seen in the best Byzantine work. It is no longer the olive type of the Romans, or the heavy, stupid leaf of the earlier centuries of the Christian era, but has again turned towards the sharp-pointed, vigorous leaf of the Greeks. Its lobes are divided into three or five tines, each sharp at the tip; its centre lines, radiating from a central stem, bend like flames; its surfaces are concave, with deep V cutting, and it has one very marked peculiarity, that is, that as far as possible no tine is left displayed alone on the ground, but the tip of each is made to touch either the tip of a neighboring tine or the ribbon or moulding bounding the space in which the ornament occurs. The tines are of nearly equal size throughout, and the spaces of ground left by the ornament are also of comparatively equal size, and if possible symmetrically grouped. The one almost universal moulding is decorated with acanthus units, and the capitals have acanthus leaves around their bells. These caps are of two types. One, that is manifestly an adaptation of a classic cap, is a union of an Ionic and a Corinthian, or at other times of a Roman Doric and a Corinthian capital. The other is peculiar to Byzantine work, and is that shown in Plates XXI. to XXIV. in the last number. This cap, as at S. Vitale, is often supplemented by another plainer cap above. The lower cap has its faces decorated with scrolls, acanthus wreaths, etc., and usually the corners are strengthened with a decorative unit, leaf or other motive.