......lots of casinos used generic design Roulette chips. So, it would not be unusual to see them on the table at the Willows Casino in 1931. The regulation requiring a casino name and town on chips was not put into place until much, much later. Even in the 1990s you can find Roulette chips with no casino name or town on them, i.e. Clown face Roulettes at Circus Circus in Las Vegas ( although the clown face was a Casino Logo of sorts).
Someone else may have info on the exact dates when names and towns were required to be put on casino rack chips and also Roulette chips.
Take care,
Jerry