This is the Montgomery Ward edition of the Optigan, which is apparently the rarest of all the models. However, as far as I can make out the only difference between this edition and the others is the opening lid.
This must be a desirable feature though, because it reached £871 on Ebay UK recently.
I don't think I've seen one of these before - it's a Magnus toy chromatic accordion. With 20 buttons on the right hand side and 4 buttons on the left hand side this is quite a complex toy instrument. With the box too, it sold for a not inconsiderable £43.