The first, skilfully worked in the form of a Mandarin duck with its young, detailed with incised plumage and rendered grasping in their beaks a long leafy lotus stream, the pale green stone with russet inclusions, Jin/ Yuan dynasty, 6.4cm (2 1/2in) wide; the second, carved as a recumbent goose with wings tucked behind, its head turned backwards as if resting, the greenish stone with yellow russet inclusions, Song/ Yuan dynasty, 4cm (1 5/8in) wide; the third, carved with the crested head facing ahead, the white stone with russet skins, Song dynasty, 6cm (2 3/8in) wide; the fourth, carved with its head looking backwards, the wings held close and tail outstretched, the smoothly polished stone of yellow tone with black inclusions, Song dynasty, 5cm (2in) wide. (4).