"Marmelady" are an old favorite of mine--they are usually made with a
high proportion of real fruit, berries, etc., along with sugar and
pectin. I discovered them in my study abroad days in St. Petersburg
(the term could be different in Moscow, in fact--I do not know).
Doing a quick search, I see that they are also called (in France, but
in fine candy shops and recipe books in the US as well), "Pâté de
fruits." A google image search for this term will give the basic idea.
However, the "Signs and Symbols" version, with "little jars" and the
absence of the word "candied", makes be believe that the items in that
story are not 'pate de fruits' or marmelady but simply 'fruit
jelly' in the American sense. I've never seen "pate de fruits" sold in
jars.
SB