[Haskell-cafe] Origins of (x:xs)?

Hi, This may have been asked before, sorry if so. I've wondered where the convention of pattern matching a list to (x:xs) came from? I've read a couple of old papers recently which let me believe it may have started back in the '70s with Miranda and its ilk. Does anyone know why (x:xs)? Is xs meant to be a synonym for 'excess'? Yours curiously, Toby.