Smoothed large-scale 2MASS extended source map (Jarrett et al. 2000). At RA = 06H this map covers more than 60 deg in Dec. High galaxy number density is shown in red, with low density in blue. Overlaid are positions and apparent sizes of X-ray-selected clusters from the HIFLUGCS sample (Reiprich & Böhringer 2002; Reiprich et al. 2003). The A3391/95n/s system is in the middle-left part of the image (three circles, only A3391 is labeled). Similar overdensities to those visible in this distribution of a large number of near-infrared selected galaxies are also very prominently traced by just a handful of X-ray-selected clusters. There is an indication of a large north–south galaxy filament going right through A3391/95.