"G. Meyer" refers to the book Griechische grammatik by Gustav Meyer. I can't seem to find any mention of κόϊλος or κοῖλος, though. A footnote on Anacreon 9 in Bergk says "...κοϊλώτερα scripsi, vulgo κοιλότερα. Neque vero κόϊλος revocandum in Homericis carminibus, quamquam plurimis locis per versus numerum licet, nam contractam formam satis testificatur Od. [22] 385". Can someone give a good translation of this?