Passage 8.17.5
ἔχεται δὲ ἄλλο ὄρος Κυλλήνης Χελυδόρεα, ἔνθα εὑρὼν χελώνην Ἑρμῆς ἐκδεῖραι τὸ θηρίον καὶ ἀπʼ αὐτῆς λέγεται ποιήσασθαι λύραν. ἐνταῦθα Φενεάταις καὶ Πελληνεῦσιν ὅροι τῆς γῆς εἰσι, καὶ τοῦ ὄρους τῶν Χελυδορέων οἱ Ἀχαιοὶ τὸ πλέον νέμονται.
Next to Cyllene is another mountain, Chelydorea, where Hermes, having found a tortoise, is said to have stripped the animal of its shell and from this fashioned a lyre. At this point lie the boundaries between the lands of Pheneus and Pellene. The greater part of Mount Chelydorea is held by the Achaeans.