The WINDOWS in the earliest examples stand alone as single windows; they are also sometimes placed singly in a continuous arcade; later still in triplets under one arch, the centre one being the tallest, and in some instances two lancets are coupled under one arch,--the spandrel between them being frequently pierced with a quatrefoil, or other opening. The PARAPET has occasionally sunk ornaments upon it, and is carried by a cornice having a few deep mouldings, with a flower, or other ornament at intervals, or by a trefoiled Corbel-table, or by a series of blocks. _Interior Compartment._ The PIERS consist most commonly of a cluster of shafts, disposed in a circular form. These shafts sometimes stand entirely free, and surround a large circular or octagonal column, and are banded in the middle. The CAPITALS have sometimes one or two rows of stiff projecting leaves, of a bulbous form, which appear to grow out of the neck of the capital, and sometimes a single or double series of minute deeply cut mouldings; the square form of capital, both in the plan and in the upper edge of the abacus, entirely disappears. The BASES consist almost invariably of a deep small hollow, set between two rounds, standing on a square-edged plinth; and greatly resemble the ordinary Attic base. The PIER-ARCHES usually show three orders, of small deeply cut mouldings of alternate rounds and hollows, the number and depth of which give an exceedingly rich and characteristic appearance to all the arches of this Period. The peculiar ornament called the _dog-tooth_, which is formed by hollowing out the sides of a series of contiguous pyramids notched out of an angular projection, occurs constantly in the arch-mouldings, as well as in almost every other part of buildings where an opportunity of carving it presents itself. The HOOD-MOULDING, resting on small and elegant heads or bosses, is an almost invariable accompaniment of arches of every description. The VAULTING-SHAFT sometimes rises from the floor in front of the principal Pier,--but more usually from a corbel-shaft, resting on a large ornamental corbel, placed immediately over the pier; it consists generally of a triple cluster of small elegant shafts, with hollows between them. The TRIFORIUM-ARCH generally covers two smaller arches; but occasionally, a pair of principal Triforium-arches cover two pair of subordinate arches, which are sometimes plain, and sometimes trefoiled; the spandrel wall above them being ornamented with foliage, or a sunk trefoil, and sometimes pierced through with a quatrefoil or other opening. Sometimes, indeed, one large primary arch covers two secondary arches, which again contain two small tertiary arches; thus fully developing the principle of subordination in this part of the building.