Charonian

The Charonian journey will soon be taken.

The Elysian plain, near the Catacombs in Egypt, stood upon the foul Charonian canal: which was so noisome, that every fetid ditch and cavern was from it called Charonian. [...] Pliny speaking of some Charonian hollows in Italy, says that the exhalations were insupportable.

[It] possessed the six legs characteristic of Charonian life

Although this casts doubt on an intrinsic source for a present-day Charonian atmosphere, it is possible that Elliot & Young's result can be understood if Charon's gravity causes it to collect escaping gas from Pluto.

The Charonians were proud of their frozen hell. Styxville was like Plutopolis, only less so.