Dan Parmenter,
Re: score of years. Right, there are all these different races hinted at, yet so few investigated in any detail, so "20 year lifespan" might =not= apply to Inire and Cumaean.
O, B, & F seem to burn up perhaps as much as ten years (half their lives!) at Severian's court before tracking back further.
The saucer, otoh, is just a time rover they are using to explore Urth. They came in on the big ship Tzadkiel, after all. (This idea of flying saucers as time machines from our future rather than space machines from alien worlds is straight from Jacques Vallee, I believe.)
The ship that picked up Severian from the Ascian camp and dropped him off at the beach with a few aquastors (that could only be sustained for a few hundred years of distance) was another time rover, I think. Maybe it looked more like a flier?
=mantis=