Continuous Lines from Isolated Splotches

[dozerman]

Pic related was extracted from an image of a fossil by using wavelet decompose and the selection tool. I want the eventual image to be a kind of stencil of the skeleton's outline. I'm almost to where I want to be, but I can't figure out how to connect all of the disparate splotches into one continuous outline without doing it manually. 

I've already tried messing with the threshold on the select tool without much luck.