The abomasa of 40 wild ruminants (18 red deer, 9 roe deer, 13 European bison) shot in the Bieszczady Mountains and another 8 European bison shot in Bialowieza Primeval Forest, were examined for worms. Ashworthius sidemi was found in all of the animals from the Bieszczady Mountains, and the intensity of infection was usually massive. In Bialowieza Forest few specimens of A. sidemi were noted among three bison. Wild ruminants were infected by A. sidemi from June to September. The nematodes originating from this infection only attained sexual maturity in June of the following year, and from September the process of expelling the parasites of that generation began. From June to autumn, two generations of nematodes, one consisting of mature individuals from the previous year and the other of the current year comprising fourth stage larvae as well as juveniles, occur in these hosts. In the winter and spring periods until June, only one generation of the parasite, arrested fourth-stage larvae and juveniles, occurs in the hosts.

A list of 19 polymorphic species of the genera Ostertagia, Orloffia, Teladorsagia, Marshallagia and Spiculopteragia is presented. The morphs of the polymorphic species in question have identical females and show similarities in some male features, e.g. the structure of the oesophagus, the synlophe and the shape of the rays of the copulatory bursa. However, they differ by characters which are recognised as generic features, e.g. the structure of spicules, gubernaculum and genital cone. The presence or lack of minor morphs is a generic feature in the Ostertagiinae. Each polymorphic genus has a defined type of minor morph.

A l'occasion de la récente description d'une nouvelle espèce d'Angiostrongylus, parasite de petits mammifères sauvages dans le sud de la France, l'auteur, après avoir fait l'historique des concep tions systématiques du genre (sensu lato), propose une nouvelle répartition des espèces connues en deux genres, le premier, Angio strongylus, lui-même divisé en deux sous-genres (Angiostrongylus et Parastrongylus), le second, nouveau, sous le nom de Stejanskostrongylus. La nouvelle systématique proposée repose sur des caractères morphologiques (particularités de disposition et tailles relatives des côtes latérales et de la côte dorsale de la bourse du mâle) et bio logiques (ordres de mammifères parasités et localisations des vers adultes, soit dans les vaisseaux sanguins de la petite circulation, soit dans les bronchioles ou dans des kystes communiquant avec celles-ci).