of interest of the present study. Their findings show the presence of thermal X-ray emission from cooler gas than the intracluster medium. A ROSAT map of the general region, larger than the one analyzed in the 1995 paper, was presented by Böhringer (1994) and shows a ridge of X-ray emission which approximately coincides with the FIR emission ridge to the west of M87. They mention, in particular, the sharp drop in X-ray intensity on the western side of M87. Böhringer (1994) subtracted a model distribution of X-rays from M87 from the ROSAT map and derived a residual map (their Fig. 2) which shows the background cluster A1552 at 12:30+11:30 and a long filament, which is elongated $\sim$north-south at $\alpha\approx$12$^h$30$^m$ and from $\delta\approx$+15 to +6. This filament curves around M87 on its westerly side and seems to follow the contours of the 100$\mu$m emission.

It is tempting to speculate on a possible link between the X-ray and FIR emission presented above, but we caution that this may not be real. One possible factor affecting the morphology of X-ray emiting gas is the amount of foreground HI, which modifies mainly the low energy end of the X-ray spectrum. Shadows in the X-ray 