cutting tool of some sort .... "Mystery Too"l

I came across this tool in an antique mall. A stand had a nice assortment of old tools, and while rummaging thru the pile, this caught my eye. I couldn't identify it then and after trying to trace it down, I still can't find its use. It has no makers name on it. It is approx. 9" long, with an adjustable beveled blade that is about 3/8" wide. Has anybody any idea as to its usage? Is it a tool that someone made to use on a particular job?
Thanks for your help gang.