The Philadelphia Transportation Company (PTC) used brass tokens manufactured by the Scoville Company for payment of a fare.  The tokens were unique to the company and imprinted with identification.  The transit tokens often had cutouts to differentiate them at a glance from other carriers.  I have fond memories of my father sitting at the kitchen table on a Sunday night filling his token holder with tokens for the week.  I always worried about him getting home if he lost a token; he never did!