  We discuss membranes in four-dimensional N=1 superspace. The kappa-invariance
of the Green-Schwarz action implies that there is a dual version of N=1
supergravity with a three-form potential. We formulate this new supergravity in
terms of a three-form superfield in curved superspace, giving the relevant
constraints on the field strength. We find the corresponding membrane soliton
in the new supergravity and discuss how the extended supersymmetry algebra
emerges from the symmetries of the flat superspace background.
