This description reminded me of a dessicated insect corpse I found on a book shelf while I was in France.
This thing really freaked me out as I had never seen anything like it, not in the flesh and not in the literature.
Imagine a centipede about two inches long.
Now imagine it has the colouration and legs of a spider, with the legs getting longer towards the rear until they end with two pairs that are more the twice the length of the others, and angled up then down in an "I can pounce real fast" kind of way.
Also put larger jaws on it.
Eeek.
Anyone have any idea what that ugly fecker was?