Fathom deep their bodies lie: Jewsbury echoes Ariel's song from Shakespeare's The Tempest:

Full fathom five thy father lies;
Of his bones are coral made;
Those are pearls that were his eyes;
Nothing of him that doth fade,
But doth suffer a sea-change
Into something rich and strange.
Sea nymphs hourly ring his knell:
(Act I, sc. 2, ll. 397-403)