Neat Mays card. I hadn't noticed this type before, so I looked it up (from FKW's site
http://centuryoldcards.com):
"RARE - These 2.5" by 3.5" crude blank backed cards are fairly rare, and were attached to a small white plastic statue with a rubber band. They were made by Robert Gould Inc. of New York. There are 2 notches on the sides and 2 holes punched into the card so the rubber band can attach the card to the statue. The individual cards are actually worth roughly six times more than the individual statues. There are 28 numbered cards in the set."