Neptune

"Neptune, which definitely is a Saturnian planet, can be fit into this configuration. We do not know anything of this planet from mythology (except for references in the Quiche Popol Vuh). The name for the planet was selected in AD 1846 to match classical mythology as being one of the Titans banished by Zeus (Jupiter), as related by Hesiod. (Uranus was similarly named, but the planet certainly is not the Uranus, "Father Sky," who was the father of Kronos, Saturn.)

"Although it might turn out that Neptune could be associated with one of the Gods or Goddesses of antiquity, it is unlikely that Neptune was ever seen, since it would have been directly above Saturn and certainly was close enough, 0.8 million miles. Saturn is twice the diameter of Neptune. Saturn and its rings would have easily obscured Neptune." (Cook, Appendix B)