Here is a sentence from Literature, Technology and Modernity, 1860-2000:
Just as Vickery has been turned into a three-dimensional negative by an electrical storm, the war dead survived, by the industrial light and magic of cinema, as so many shaky on-screen images, not so much signs whose referents have disappeared as mummies.
I was wondering whether there is something missing here concerning "so much signs". Should it be "so much by signs"? Or how to understand the last part?
If we disregard everything that has no relevance to understanding the grammatical construction which you are finding hard to follow, we could rewrite the crucial part of the sentence like this:
They were not so much signs as they were mummies.
Alternatively,
They were mummies more than they were signs.
You are mis-parsing it. The relevant phrase is the complex quantifier "not so much ... as ...".
The clause parses as
[[not so much] [signs whose referents have disappeared] as [mummies]].
or to paraphrase
less like signs whose referents have disappeared than like mummies.
