Package for flowable media having a snap lid and preform for making same

A package for flowable media and a snap lid (2), which package and snap lid are both made from thermoplastic material, in which a collar-shaped head (3) of the package surrounds a pouring aperture (4) of the package, which collar shaped head has a retaining ring (17) on its outside, an inside annular surface (7), and an upper end (10) having an edge (11) with a snap catch (12) which upper end is closed by means of the snap lid (2), said snap lid (2) having a closing wall (20) from which an annular sealing lip (23) projects towards an inside of the package (1), and is brought into contact with an inside surface (13) of the edge (11) in sealing engagement, said closing wall (20) being provided with an outside catch (29) for snap engagement with a snap catch (12) of the edge (11) of the head (3) wherein the head (3) of the package (1) widens outwards and upwards at its edge (11), and both the inner surface (13) of this edge (11) and an outer surface (24) of the sealing lip (23) on the snap lid (2) are curved convexly relative to each other in an engaged and a disengaged position between the lid and the package.