[Illustration: Knot No. 1, derived from either a three-cord or a six-cord plait] [Illustration: Knots 3 and 4, derived from a six-cord plait] [Illustration: Evolution of Knot No. 1 from a six-cord plait] Examples of the two knots, Nos. 4 and 5, which are derived from No. 3, are to be seen at Baglan, Glamorganshire, and Penally, Pembrokeshire. Knot No. 6, in a single row, occurs at Llantwit Major, Glamorganshire, and its second derivative, No. 8, at Llantwit Major, and also at Neuadd Siarman, Brecknockshire. Its first derivative, No. 7, is only used in a double row on the Welsh crosses, as at Silian and Maes Mynach, Cardiganshire, and at Penally, Pembrokeshire, where the knots have an extra spiral twist. The direction of the twist of the spirally bent cord is the same in both the right-hand and left-hand vertical row of knots, although the positions of the knots are different. The more usual arrangement is to make the cords twist in opposite directions, as on the annexed diagram, in which the evolution of the pattern is shown. (Page 271.) The clearest proof that the spiral knot No. 7 was developed from plaitwork in the manner explained is that on stones at Llangenydd, Glamorganshire; Whithorn, Wigtownshire; Abercorn, Linlithgowshire; and Aycliffe, Co. Durham; the successive stages of development can be easily traced. [Illustration: Evolution of Knot No. 7 from an eight-cord plait] [Illustration: Evolution of Knot No. 7 from an eight-cord plait] I have coined the term _circular knotwork_ to describe a particular class of interlaced-work, in which the circular curves made by the cords give the pattern its distinctive appearance. The best example of circular knotwork in any of the Hiberno-Saxon MSS. occurs on one of the ornamental cross-pages of the Book of Durrow.[452] Circular knotwork is not used in the decoration of the Irish ecclesiastical metalwork, probably because it is only suitable for application to larger surfaces than are to be found on comparatively small metal objects. Circular knotwork is characteristic of the Irish and Scottish sculptured monuments of the best period; it is unknown in Cornwall and the Isle of Man and there is only one instance of its occurrence in Wales. Very good examples of circular knotwork may be seen on sculptured monuments in Ireland[453] at Kells, Co. Meath; Monasterboice and Termonfechin, Co. Louth; Boho, Co. Fermanagh; Kilfenora, Co. Clare; and Drumcliff, Co. Sligo; and in Scotland[454] at Collieburn, Sutherland (now in the Dunrobin Museum); Tarbet (now at Invergordon Castle), Brodie, Elginshire; Nigg, Ross-shire; Aberlemno, Monifieth (now in the Edinburgh Museum), and Eassie, Forfarshire; and Rossie Priory and St. Madoes, Perthshire. [452] J. R. Allen and J. Anderson’s _Early Christian Monuments of Scotland_, p. lxxviii.; J. A. Bruun’s _Illuminated Manuscripts of the Middle Ages_, pt. I, “Celtic MSS.,” p. 8. [453] H. O’Neill’s _Crosses of Ancient Ireland_.