One of the titles in a recueil in the Marienbibliothek at Halle/Saale is an edition of the Tractatus logicalis de demonstrationibus sive de syllogismis demonstrativis cuiusdam excellentissimi philosophi Parisiensis, without date or place of printing and with no printer's name. Polain lists this edition in his catalogue of incunabula in Belgian libraries as probably from the Netherlands and pre-1501. M. E. Kronenberg and B. Kruitwagen follow Polain without investigating further, probably because the copy - at Ghent - described by Polain was no longer available. Other incunabula bibliographies do not mention this edition. On the basis of the types the author demonstrates that the edition must have been printed by Jacob van Breda, which does not necessarily mean that it belongs to the incunabula, since Jacob van Breda also printed after 1501. The same recueil in the Marienbibliothek also contains an edition by the same printer dating from 1506 (to be discussed in a future article). Closer examination shows that the types used in the Tractatus logicalis only appear in editions printed after 10 April 1497. The possibility that the work is an incunablc remains open, therefore, although it cannot be proved that the book was not published after 1501.