the cup there is located the head k containing the delivery mechanism of the dispenser a pump element consisting of a flexible bellows 5 which extends in dome like fashion over a pump chamber 6 and is fastened in a cover 7 of the dome forms a part of the delivery mechanism the cover 7 in the present embodiment is part of an insert 8 an inlet valve v1 and an outlet valve v2 are furthermore a part of the pump element the inlet valve v1 is seated in the central region 7 39 0 of the cover 7 this central region is arranged slightly lowered with respect to the rest of the peripheral annular section of the cover 7 in the direction of the supply chamber 9 which is formed by the housing 1 and contains the pasty composition m from this there results a well defined insertion trough for the cylindrical wall region 10 of the bellows 5 which is tapered on the front side beyond the lowered region the transition place between the central region 7 39 and the remaining peripheral region forms an annular groove 11 inserted into this the wall region 10 produces a practically double sided seal i e on the outside and on the inside the outer sealing region continues up to the height of the curvature zone of the bellows 5 it is an annular wall 12 the latter extends from the top of the cover 7 and passes into an inwardly directed projection 13 this projection is gripped under by an oppositely projecting annular rib 14 of the bellows 5 the.