  In a recent letter M. Lilly et al [PRL 82, 394 (1999)] have shown that a
highly anisotropic state can arise in certain two dimensional electron systems.
In the large square samples studied, resistances measured in the two
perpendicular directions are found to have a ratio that may be 60 or larger at
low temperature and at certain magnetic fields. In Hall bar measurements, the
anisotropy ratio is found to be much smaller (roughly 5). In this comment we
resolve this discrepancy by noting that the anisotropy of the underlying sheet
resistivities is correctly represented by Hall bar resistance measurements but
shows up exponentially enhanced in resistance measurements on square samples
due to simple geometric effects. We note, however, that the origin of this
underlying resistivity anisotropy remains unknown, and is not addressed here.
