Evolution of the abundance of clusters with redshift z for three distinct cosmologies. Only clusters with mass ﹩M\geq 8\times 10^{14}\,h^{-1}\,M_{\odot }﹩ within their virial radius ﹩R_{\mathrm{vir}\,}﹩ are considered. The solid curve represents an open universe (﹩\Omega _{0}=0.3,\Omega _{\Lambda }=0﹩), the dashed curve a flat universe (﹩\Omega _{0}=0.3,\Omega _{\Lambda }=0.7﹩), and the dotted curve a closed universe (﹩\Omega _{0}=1.0,\Omega _{\Lambda }=0﹩).