Teleostomi(1) There are a lot of mice, but much fewer cats in the room.

(2) There are a lot of mice, but many fewer cats in the room.

Which is correct, or wrong?

Sentence 1 is correct.

much fewer: fewer is an adjective and is modified by much as an adverb of degree.

Many is a determiner, that is, a noun modifier, and can not modify an adjective.

Interesting.

the google hits:

"many fewer"------772,000

"much fewer"-------570,000

How to explain?

Maple
Interesting.

the google hits:

"many fewer"------772,000

"much fewer"-------570,000

How to explain?

Look for 'unviersity' in Google, and you'll be able to get a lot of examples. You cannot depend on Google to prove your point!

I agree that you can't rely on Google exclusively, but with almost 3/4 of a million hits, and more hits than the thus-far preferred "much fewer" you have to take the results seriously.

I would say "far fewer" as my first choice, "many fewer" as my second. "Many," like "fewer," is used for things you can count. "Much, like "less," is used for things you cannot count. Therefore "much" and "

Simple Search of BNC-World

Your query was

much fewer 

http://sara.natcorp.ox.ac.uk/cgi-bin/A0.html#A04 439 A well-known picture book of Italian art alone contains more than 4,000 reproductions, yet histories of art, as we have s

Native speakers seem to be just as confused as anybody.

BNC (British National Corpus) search results:
http://sara.natcorp.ox.ac.uk/cgi-bin/saraWeb?qy=much+fewer

BNC search results:
http://sara.natcorp.ox.ac.uk/cgi-bin/saraWeb?qy=much+fewer
http://sara.natcorp.ox.ac.uk/cgi-bin/saraWeb?qy=many+fewer

Many

Re: "Ten items or less"

A supermarket I often shop at has two express lanes side by side.
One has the sign "Ten items or less".
The other, "Ten items or fewer"!

I think it's called covering all bases!

Seriously? That's funny! Or sad. I'm not sure which. When a supermarket near me switched from "or less" to "or fewer" I told the girl at the register that it made me happy and she looked at me like I had two heads. And the person I was with at the time (I'm no longer dating him, thank you) thought it was just so weird that I would even notice, let alone be happy about it.