  Graphite surfaces interact weakly with molecules compared to other conducting
surfaces bringing the molecule-molecule interaction to the foreground. C$_{60}$
on highly oriented pyrolytic graphite is a model system for studying the
molecular self-assembly on surfaces. Our scanning tunneling microscopy
measurements at liquid nitrogen temperatures confirm the previously observed
island growth mode. Our results indicate that there is an epitaxial
relationship of the molecular islands and the substrate with three possible
orientations of the islands. For one of these orientations, we determine this
epitaxial relationship by analyzing in detail an image taken across a C$_{60}$
island step edge. In this image we have obtained high resolution on both the
molecular island and the substrate. The result of this analysis is confirmed by
two-dimensional Fourier analysis.
