It might be, and at f:11 it should only be "Extra-Rapid" if it's a Periscope. But steinheil used the Periskop name for a lot of lenses, many of which never saw the market: My own Steinheil Periskop is an experimental "noname rectilinear".

I'll be shooting with the experimental this spring, as well as with a "true" periskop. Pictures may be posted.