Neptunian

When now the Gods have made proud Ilion fall, / and Asia's power and Priam's race renowned / o'erwhelmed in ruin undeserved, and all / Neptunian Troy lies smouldering on the ground, / in desert lands, to diverse exile bound, / celestial portents bid us forth to fare; / where Ida's heights above Antandros frowned, / a fleet we build, and gather crews, unware / which way the Fates will lead, what home is ours and where.

Source: tatoeba (6916441)

We have watched the fortunes of eight successive human species for a thousand million years, the first half of that flicker which is the duration of man. Ten more species now succeed one another, or are contemporary, on the plains of Neptune. We, the Last Men, are the Eighteenth Men. Of the eight pre-Neptunian species, some, as we have seen, remained always primitive; many achieved at least a confused and fleeting civilization, and one, the brilliant Fifth, was already wakening into true humanity when misfortune crushed it. The ten Neptunian species show an even greater diversity. They range from the instinctive animal to modes of consciousness never before attained. The definitely sub-human degenerate types are confined mostly to the first six hundred million years of man's sojourn on Neptune.

Source: tatoeba (8877787)

Near-synonym: Poseidonian

Source: wiktionary

The Tomb disburd'ning, whence the Ghoſt aroſe / Of great Achilles; Such when Thracian Foes / (The Prelude of thy Fates, Troy!) he o'rethrew, / And the white hair'd Neptunian Cycnus [i.e., Neptune's son] ſlew.

Source: wiktionary