  We present our preliminary BIMA CO(1-0) images of II~Zw~96 which show huge
molecular gas concentrations outside the merging disks. The dominant extra-disk
CO concentrations in II~Zw~96 correspond to the two star-forming ``knots''
hidden by dust, whereas the others are associated with the two spiral disks.
The unique huge CO concentrations, $\approxgt 5$ kpc away from the merging
nuclei, account for $\approxgt 50 %$ of the total CO emission, yet only at a
moderate gas surface density as compared with that of ultraluminous infrared
galaxies (ULIGs). We tentatively conclude that the huge extra-disk gas
concentrations are most likely the overlap region of the gas disks, not
necessarily coinciding with the stellar disks overlap region. The gas disks
overlap region could be formed prior to the merging of the stellar disks and
become the overlap regions found between the disks like that in Arp~244 (the
``Antennae'' galaxies). These overlap regions would eventually nurture the {\it
extreme starbursts} and evolve into the extended gas disk surrounding the
double nuclei in final merging in most ULIGs.

Astrophysics