This was great -- one of the early classics of hard SF, about the sorts of very different creatures that you'd get on a fast-spinning, heavy planet. (So it's much like "Dragon's Egg", but written in 1953 rather than 1980 -- not that you'd realise!)
I should probably just buy the entire SF Masterworks series, since all of them that I've read so far have been excellent...
ISBN 0575070943.