How does this word act in this sentence? "Admirals". Is it in apposition of "Captains"?

Is "admirals" in apposition of "captians"? And what about "the drak interlopers"? "They had sailed from Deptford, from Greenwich, from Erith—the adventurers and the settlers; kings’ ships and the ships of men on ’Change; captains, admirals, the dark “interlopers” of the Eastern trade, and the commissioned “generals” of East India fleets."(Heart Of Darkness).