The Stoat, also known as Ermine when white,
http://en.wikipedia.org/wiki/Ermine (http://en.wikipedia.org/wiki/Ermine)
The black tip of the tail was traditionally used for a very famous seatrout pattern, the "Stoat´s Tail". It is said to have "magical" properties for attracting fish! Of course it hasn´t ! Apart from which you only get a couple of flies out of one Stoat´s tail, as the black tip is not very big!.The white ermine fur was used for many things, especially trimming ceremonial robes and suchlike.
The fur from an Ermine ( Stoat in white winter coat) can be dyed well, and is very useful as dubbing and other things. I don´t have a full stoat skin right now ( at least I don´t think so!), I have a few tails somewhere still. When I find them I will post photos.