The teams in the West that year was the KC Monarchs, Memphis Red Sox, Atlanta Black Crackers, Chicago American Giants, Indianapolis ABC's Jacksonville Red Caps and Birmingham Black Barons. My educated guess would be that the "A" on the jersey is the previous years Atlanta uniform, the southern teams in particular used obsolete uniforms mixed with new ones on their teams and simply used them till they wore out. Another guess could be one of the old ABC's uniforms, I think I remember seeing them use a large A many years before 1938, but my guess would be it is Atlanta.
My Baseball Card Project:
www.infinitecardset.blogspot.com