In 1952, the week before the first installment of Franquin’s Les voleurs du Marsupilami (Spirou #5), the magazine carried this teaser for the upcoming adventure. It was not included in the album when the story was collected, although it is reproduced (with some rather aggressive blur) in the intégrale collected edition.
Now that Cinebook has released the album in English as The Marsupilami Thieves, perhaps it can again serve its original purpose:
The two pages act as a bridge between the previous adventure, Spirou et les héritiers (Spirou #4, “Spirou and the Heirs”), and its sequel. An interesting thing to notice is that it shows the location of Palombia (the setting of parts of “Heirs” as well as several future adventures) on the map.
The scans are from Rombaldi’s edition of Franquin’s collected works, released in the 1980s.