whereupon its coupling lugs 10 can be arranged in front of the recesses 11 in the end walls 8 9 and then released for relaxation so that the coupling lugs 10 engage into the recesses 11 and thus fix the areal element 5 in place securely and exactly positioned by the return of the areal element 5 into its extended shape in the case of fig2 the length of the areal element 5 is selected such that it assumes a planar form in the fixed position fig3 shows an embodiment in which the length of the areal element 5 is selected to be greater than the distance between the two end walls 8 9 of the lamp housing 2 since in this case the length of the areal element 5 means that it cannot relax in a planar manner after coupling with the lamp housing 2 a concavely arched structure of the cover 3 is achieved due to the residual stress of the areal element 5 fig4 shows a basic arrangement corresponding to fig3 with a correspondingly dimensioned areal element 5 however in this case the arching of the areal element has been carried out in the opposite direction so that a concavely arched cover structure results in the latched state of the areal element 5 since the lamp cover in accordance with the invention consists of individual areal elements the number of the areal elements to be used in an individual case and also their relative positions can be freely selected depending on the desired radiation characteristics with in the event of different relative.