Passage 8.17.1
μετὰ δὲ τοῦ Αἰπύτου τὸν τάφον ὄρος τε ὑψηλότατον ὀρῶν τῶν ἐν Ἀρκαδίᾳ Κυλλήνη καὶ Ἑρμοῦ Κυλληνίου κατερριμμένος ναός ἐστιν ἐπὶ κορυφῆς τοῦ ὄρους· δῆλα δέ ἐστιν ἀπὸ Κυλλῆνος τοῦ Ἐλάτου τῷ τε ὄρει τὸ ὄνομα καὶ ἡ ἐπίκλησις γεγενημένη τῷ θεῷ.
After the tomb of Aepytus is Mount Cyllene, the loftiest of all the mountains in Arcadia, and upon the peak of this mountain stands a temple dedicated to Hermes Kyllenios, now fallen into ruins. It is obvious that both the name of the mountain and the surname given to the god derive from Kyllenos, the son of Elatus.