  The Wolf-Rayet (WR) bubble S 308 around the WR star HD 50896 is one of the
only two WR bubbles known to possess X-ray emission. We present XMM-Newton
observations of three fields of this WR bubble that, in conjunction with an
existing observation of its Northwest quadrant, map most of the nebula. The
X-ray emission from S 308 displays a limb-brightened morphology, with a central
cavity ~22 arcmin in size and a shell thickness of ~8 arcmin. This X-ray shell
is confined by the optical shell of ionized material. The spectrum is dominated
by the He-like triplets of NIV at 0.43 keV and OVII at 0.57 keV, and declines
towards high energies, with a faint tail up to 1 keV. This spectrum can be
described by a two-temperature optically thin plasma emission model (T1 ~
1.1x10^6 K, T2 ~ 13x10^6 K), with a total X-ray luminosity ~2x10^33 erg/s at
the assumed distance of 1.5 kpc.
