  We consider gamma--ray bursts produced by the merger of a massive white dwarf
with a neutron star. We show that these are likely to produce long--duration
GRBs, in some cases definitely without an accompanying supernova, as observed
recently. This class of burst would have a strong correlation with star
formation, and occur close to the host galaxy. However rare members of the
class need not be near star--forming regions, and could have any type of host
galaxy. Thus a long--duration burst far from any star--forming region would
also be a signature of this class. Estimates based on the existence of a known
progenitor suggest that our proposed class may be an important contributor to
the observed GRB rate.
