Le genre Murciella (Foraminifère, Rhapydionininae), dans le Crétacé supérieur de Grèce (zone de Gavrovo-Tripolitza)

Several new species are described, of which theendoskeletal features present strong similarities with YaberinellaVaughan. Each chamber consists of: 1) a single peripheral layer of tubular «primary chamberlets perpendicular to the septa they join, 2) concentric inner layers of tubular «secondary chamberlets oriented obliquely to the preceding, each layer inclined in the contrary sense to its inner and outer neighbour, and the inclination being symmetrical with respect to any radial plane. Thus the secondary chamberlets form two helices, each with the same axis, which is also the axis of the chamber and the axis of growth: this is called «helicoidal structure. Lateral connections exists between the tubes of different layers («stolons).The chamber arrangement, and above all the presence of a preseptal space equipped with buttresses exclude the new species from Yaberinella and permits their assignment to the sub-family Rhapydionininae, more precisely to the genus MurciellaFourcade, of which several known sections (particularly the holotype of the type-species) seem to show the same organisation.The mode of coiling shown by some of the new forms, together with the lateral connection between chamberlets (the function of which might be the same as that of the preseptal space) permit the advocation of a development from Murciella (Tethysian, Upper Cretaceous) to Yaberinella (central American, Eocene).