[353] εἰς Ἀίδαο: all rivers called Acheron were supposed to communicate with the lower world. Diodorus (14. 31) mentions the legend that it was by the outlet of this river near Heraclea that Heracles dragged up Cerberus; cf. also Xen. An. 6. 2. 2.
καταιβάτις: cf. 3. 160.