From 1975 - 1981 Leisure Books sold illustrated wildlife flashcards through a mail subscription called the Illustrated Wildlife Treasury. Each card had a color photo on the front and a detailed description on the back. Every month new decks of cards were sent out to subscribers. Collectors could then sort them alphabetically in their official Wildlife Treasury carrying case.
I loved my Wildlife Treasury cards and carrying case. Remember those commercials? Oh man did I want a safari pith helmet!