Arrival directions of cosmic rays with the energy E>4.10^19 eV are analyzed on the basis of the Yakutsk and AGASA extensive air shower arrays. It is supposed that the clusters can be formed as a result of fragmentation of superheavy nuclei. The consequences of this supposition compare with experimental data. Part of clusters with E>2.10^19 eV correlate with the nearest pulsars. The new effect is found - clusters intensify a feature of cosmic rays distribution.