χέλυς

A. tortoise, h.Merc. 33.

2. lyre (since Hermes made the first lyre by stretching strings on a tortoise's shell, which acted as a sounding-board), ib.25,153, Sapph. 45, A. Fr. 314; καθ’ ἑπτάτονον ὀρείαν χ. E. Alc. 448 (lyr.), cf. HF 683 (lyr.).

3. the constellation Lyra, Arat. 268.

II. arched breast, chest, from its like ness of shape to the back of a tortoise, Hp. Anat. 1, E. El. 837; cf. χελώνιον 11. [υ in nom. and acc. sg., h.Merc. 33,153; later υ, Call. Ap. 16, Arat. 268, Opp. H. 5.404.] (Cf. OSlav. žely 'tortoise'.)