Personally, I would have rendered "leggy thing" as
nogastaya shtukovina. I'm pretty sure that at least one of the two
Russian translators of "Pnin," G. Barabtarlo or S. Ilyin, has done so in
his version.
I'm sorry I'll be absent from the Forum in the next
several weeks. Have too finish my fascinating In vino veritas piece (which has
over 180 pages already). Hope to make you all drunk on my stuff one
day.
best,
Alexey