The slab to which the head belongs was removed from its original position at some early time, probably at the conversion of the Parthenon into a church, when an apse was built at the eastern end. In 1672 it stood on the ground (cf. Michaelis, pp. 47, 258), and the faces seem to have suffered deliberate mutilation. The exquisite preservation of the head of Iris is explained if, as is suggested, it was broken off in the sixth century, and immediately built into a Byzantine wall (Waldstein, _American Journ. of Archæology_, v. pl. 2, p. 1). [Sidenote: 30-34.] Between the group of Gods just described and the corresponding group on the right side of the centre, we have a group of five figures. We must suppose that these figures are in front of the two groups of Gods who sit in a continuous semicircle. (Murray, ii. pl. 1.) [Illustration: Fig. 10.--Slave with seat.] No. 30 is a maiden holding an uncertain object, perhaps a casket in her left hand, and supporting on her head a seat ([Greek: diphros]) covered with a cushion, not unlike the seats on which the Gods are, but smaller. She has a small pad ([Greek: tylê]) on her head to make the weight easier to bear. The legs of the seat are now wanting, but a rivet hole near the maiden's right elbow shows where one leg was attached. The other may have been painted on the ground of the frieze. The cut (fig. 10), showing one of the slaves of Cepheus carrying a stool with a cushion, is taken from a vase in the British Museum, No. E. 188.