I found the basic design in my copy of Seymour's "Antique Gambling Chips". It is coded as PD-AF. Does the coding change when there are additional elements like the horse head on these chips? I sort of wonder if these were used in a club at some point given the level of wear and the presence of the cigarette burns on virtually every chip. The old timers must have been some heavy smokers and never used ashtrays. Maybe that's why the casinos made so many ashtrays - just to keep their chips from being burned.