Have you ever seen something like this, or do you know what it is?

My father-in-law gave this to me back in the 80's, and I never had time to do much with it. It was in extreme disrepair at the time, but he recognized it as a unique and lovely piece of work. I don't know where he got it. Probably in a second hand shop of antiques up in the gold country between excursions prospecting or treasure hunting. I certainly think he found a treasure in this.
But, try as I might, I've been unable to find anything similar, or any identifying marks on it, with the exception of some faint pencil scratches on the inside surface of the back. I've searched thousands of images on the internet looking for something like it.
There was a cross-grain crack on the back that I undertook to repair back in the days when I probably shouldn't have been trying anything this complicated. I removed the back to do the repair, but was never had time to completely restore the instrument, until now, that is...
It is made of spruce, front, back and sides, and completely overlain with rosewood veneer. The fretboard may be ebony or some stained wood, arched and fretted with very tall, skinny frets, 3 of which are partial.
It was strung with 4 wire strings to machine tuners covered with an engraved metal shroud (which I've mislaid but I know it's around here somewhere). It has 3 small ivoroid or plastic feet projecting from the back (removed in the pictures below) so it sat flat on a surface to be played, I suppose. Don't know if it was plucked, strummed or bowed.

If it's something you can help me learn more about I'd sure appreciate it. I finally have time and opportunity to restore it and would love to know more about it.