One thing is clear, Ion marks the incoming of a new race, a race with Zeus and Apollo for their gods. From the blend of this new stock with the old autochthonous inhabitants arose the Ionians. Zeus and Apollo were called ‘ancestral’ at Athens because they _were_ ancestral; the new element traced its descent from them, and presumably the affiliation was arranged by Delphi; but Apollo, though his sanctuary was _on_ the hill, never got _in_side. Ion had for divine father Apollo, but his real human father was Xuthos. This Xuthos, as immigrant conqueror, marries the king’s daughter Creousa. Xuthos was really a local hero of the deme Potamoi[178], near Prasiae. He came of Achaean stock, and therefore had Zeus for ancestor. Hermes, in the prologue to the _Ion_[179], is quite clear. There was war between Athens and Euboea: And Xuthos strove and helped them with the sword And had Creousa, guerdon of his aid, No home-born hero he, but son of Zeus And Aiolos, Achaean. And again[180], when Ion questions his unknown mother as to her husband: _Ion._ And what Athenian took thee for his wife? _Cre._ No citizen: an alien from another land. _Ion._ Who? For a well-born man he needs had been. _Cre._ Xuthos, of Zeus and Aiolos the offspring he. The tomb of Ion, significant fact, was not at Athens but at Potamoi, and Pausanias[181] saw it there. Well may the sanctuaries of Zeus and Apollo stand together. * * * * * To return to the question of topography. That the cave marked Β on the plan is sacred to Apollo admits, in the face of the inscribed votive tablets, of no doubt. But a difficulty yet remains. It was noted in speaking of the cave above the Klepsydra that it was too shallow and too exposed to be a natural scene of the story of Creousa. The same objections, though in a somewhat less degree, apply to the cave marked Β. The difficulty, however, admits of an easy solution. The excavators proceeded to clear out cave Γ, and here they found nothing, no votive tablets, no altar, no inscriptions. But in carrying on their work further East they came on a fourth cave, of a character quite different from that of Α, Β, or Γ. The fourth cave, Δ, has a very narrow entrance; it communicates by a narrow passage with Δ′ and also with Δ″, but Δ″ has been turned into a small Christian church, of which the pavement and a portion of a brick wall yet remain. Here at Δ we have a cave in the full sense of the word, and here we have in all probability the cave or caves, the ‘seats[182]’ (θακήματα) of Pan.