  We describe asymmetrical features in a long exposure X-ray map of M87 made
with the ROSAT High Resolution Imager (HRI). A bright triangular region is
marked by a linear `spur' along one edge. The structure of this spur suggests
an interpretation of a tangential view of a shock front 18 kpc long. None of
the brighter features are spatially coincident with radio or optical structures
so we concur with earlier investigators that most of the emission arises from
thermal processes.
