either side of a central axis on which are threaded units of ornament, and which starts from a mass of detail and terminates in a mass of detail; systems of radial lines diverging from the central axis and terminating in centres of ornaments of greater or less size, arranged in all sorts of groupings; garlands, pendants, and ribbons, vases, trophies, shields, birds, beasts, and nondescript combinations, foliage, conventional and natural, forms, human and superhuman, all in varying scales, all in surfaces undulating, now rising into sharp relief with clear-cut edges, now sinking and melting into the background; and the whole so carefully balanced, so exactly distributed, that no portion should be too strong for another, no detail but should be equally refined. It is not an easy matter to succeed in a design of such requirements." "It is well into the latter part of the fifteenth century before this pilaster treatment is prevalent. The Quattrocento work contains much less of it than the Cinquecento. The garlands and trophies, lions' and bulls' heads, dolphins and griffins, tridents and shells and rosettes, and numberless familiar forms appear in a new guise; the new forms being, for the most part, heraldic motives or town arms, such as the fleur-de-lis of Florence, the Biscione or viper of Milan, and lions which are rampant, a condition unknown to their classic prototypes. Shields, though used before, have a new form, and ribbons are developed into all sorts of knots and waving ends, the loops having the same cadences in relative size as other decorative compound motives." [Illustration: XLI. Panel from the Choir Stalls, Church of S. Pietro, Perugia, Italy.] [Illustration: XLII. Panel from the Choir Stalls, Church of S. Pietro, Perugia, Italy.] [Illustration: XLIII. Panel from the Choir Stalls, Church of S. Pietro, Perugia, Italy.] [Illustration: XLIV. Panel from the Choir Stalls, Church of S. Pietro, Perugia, Italy.] [Illustration: XLV. Panel from the Choir Stalls, Church of S. Pietro, Perugia, Italy.] [Illustration: XLVI. Panels from the Choir Stalls, Church of S. Pietro, Perugia, Italy.] [Illustration: XLVII. Panels from the Choir Stalls, Church of S. Pietro, Perugia, Italy.] XLI to XLVII. PANELS FROM THE CHOIR STALLS, CHURCH OF S. PIETRO, PERUGIA, ITALY. The principles governing the design of these panels so well explained in the foregoing quotation can all be seen exemplified in the plates. They are all built upon a central axis, and the proportion and distribution of the various motives most carefully studied and beautifully carried out. Although all are shorter than the usual pilaster, the design is exactly similar to that usually employed for this purpose. Even the horizontal panels in plates XLVI and XLVII follow precisely the same rules of design. [Illustration: XLVIII. Panel from the Chamber of Commerce, Perugia, Italy.] XLVIII. PANEL FROM THE CHAMBER OF COMMERCE, PERUGIA, ITALY.