101 at Annapolis.
(Per Every Hour on the Hour, CERA 130) This was originally built for Maryland Electric Railways in 1913 by Wason. The WBandA rebuilt into a trailer before its sale to the BandA. The photo shows trolley poles on it (but this doesn't mean it can't be a trailer or even a control-trailer).
The Baltimore and Annapolis was the final hurrah for the WBandA, coming into being out of the bankruptcy of the WBandA in 1935. It was run by the BandO, and continued electric operations between Annapolis and Baltimore until 1950
Caption comments from Warren Thompson; photo courtesy the Joe Testagrose collection