The choir, which has no aisles, measures 56 feet in length by 27 feet wide internally. It has originally been constructed in a light manner, with very wide window arches, having small piers and buttresses between them, and it seems to have been vaulted, or intended for vaulting, the springers of the vaults being visible in the interior (Fig. 562). But this mode of construction was evidently found too weak, and it became necessary to partly build up the great arches of the windows and to introduce much smaller windows within them. The choir is so densely covered with ivy that these features are not easily detected on the exterior (Fig. 563), but in the interior view (see Fig. 562) they are plainly visible. At what period the choir was built it is difficult to say. The exterior buttresses, so far as visible through the ivy, might be considered of an early form, but they resemble those of the lady chapel of Elgin and other structures in the North, which are not very early. The large vesica piscis over the east window arch, and the trefoiled triangle in the gable, are likewise rather late features (see Fig. 559). Keeping in view the great size of the intended windows, which were clearly meant to be filled with tracery, and the small caps of the jambs, both exterior and interior, the building may be ascribed to the fifteenth century. Probably the first design with the very large openings may have been carried out early in the fifteenth century, soon after Alexander the prior was appointed, who was expected to improve the buildings of the priory, which had fallen into decay. The insertion of the smaller windows, and the strengthening masonry within the wide openings, may have formed part of the restoration of the dilapidated structure which William de Boys would be sure to institute when he and his Benedictines took possession of the priory in the middle of the fifteenth century. We shall see that parts of the chapter house and other portions of the structure may be attributed to the same revival. The reduced side windows of the choir contain portions of late tracery, and in the filled in mason work of each is inserted a dedication cross (see Fig. 562), which seems to point to a new dedication of the restored edifice. The design of the smaller windows introduced within the arch of the very large east window is remarkable (see Figs. 559 and 562). The four small pointed arches, surmounted by a traceried window above, faintly recall the east windows of Elgin Cathedral, while the peculiar tracery of the upper window plainly indicates a very late date. [Illustration: FIG. 562.--Pluscarden Priory. Interior of Choir.] [Illustration: FIG. 563.--Pluscarden Priory. Tower, and South-East Angle of Choir and Transept.]