Wildlife Spotting

This is a very unusual spider. I caught it in the act of making a new bridge thread for its web, which you can see coming out of the rear spinnerets. It has an interesting pattern on its back, of amorphous black and white. It looks to me like a Peking Opera mask. The palps are very short, so I believe this is a female.
The legs are mostly black, and very hairy. At metatarsus and patella joints on each leg, there is a small patch of brown.
The spider was about half a centimeter in size.