This article is intended not only to record additions and corrections to Island Gems (published by the Hellenic Society in 1963 as its tenth Supplementary Volume; here abbreviated IGems), but also to discuss a class of engraved stones which was not properly distinguished in that book. The main series of Island Gems belongs to the seventh and early sixth centuries B.C. Most of the stones and a few of their devices copy Bronze Age forms, and the material is generally a distinctive, often translucent, green serpentine (‘steatite’). This series ends in the first half of the sixth century, but it was possible to identify, by their material and technique, some later gems from Island workshops which correspond in style and shape with the contemporary Greek scarabs in harder materials. The comparatively soft material had meant that the intaglio devices on Island gems could be cut without recourse to the drill or cutting wheel, and this technique was retained for the later scarabs. It is evident, however, that for a while already in the sixth century Island artists had experimented with the harder materials then being employed for engraved seals in Greece; and with some shapes which seem to compromise between the old and the new. These stones seem to belong to the middle and second half of the sixth century. A list follows:(i) Oxford 1925.129. plate I. Green steatite tapered scaraboid with convex face. L. 20 (mm.). A lion. IGems no. 349, fig. 6, pl. 13.(ii) Athens, from Sunium. plate I. Green steatite. Shape as the last. L. 20. Contorted bull-headed man. IGems no. 350, pl. 13.(iii) Paris, Bibl. Nat., ex Louvre C 8514. Rock crystal plump lentoid. W. 18. Summary representation of a winged horse.(iv) Boston 27.678 (once Bruschi, Warren), plate I. Chalcedony lentoid with domed back and shallow convex face. W. 21. Facing head of a satyr with fillet ends behind the ears and an arrow marking at the centre of the forehead.
The antisaccade task: Vector inversion contributes to a statistical summary representation of target eccentricities
