Unknown Plane

Had this plane for awhile and never been able to figure out what type of plane it is, I've never seen one like it. Any help identifying it would be greatly appreciated. By the way It's not marked as to the maker or previous owner.

It has what I believe is its original butcher blade. At one time it had an adjustable fence on the bottom like it does on the side but someone has placed a permanent fence on it and filled the holes with putty. It has a nicker blade so I'm guessing it's some kind of strangely made panel raising plane. Don't know why it's made in a trapezoid shape and cant understand why someone went through all the time of making the throat opening raised like they did. Seems it would have been easier to leave it one solid block.