Quote:

The word "ruga" or its more common plural form "rugae" means in medicine "an anatomical fold or wrinkle especially of the viscera." The lining of the stomach is full of little ridges called rugae. I believe that Joyce was describing the appearance of an old-fashioned key, which would have had teeth that were cut in a series of ridges or rugae, with "arruginated" being to rugae as "irradiated" is to radiation.



Very interesting. You've thrown a whole new light on the offending word.

A certain Joyce on-line read-through community I sought for help had settled on a glorified "scraped"

Quote:

rugine
\Ru"gine\, v. t. [F. ruginer to scrape.] To scrape or rasp, as a bone;
to scale. [R.] --Wiseman.

rugine
\Ru"gine\, n. [F.] (Surg.) An instrument for scraping the periosteum
from bones; a raspatory.




But I think a key with "rugae" would make more sense here.