  The Sydney University Giant Air-shower Recorder (SUGAR) measured the muon
component of extensive air showers with a unique array of muon detectors. The
SUGAR data allow us to reconstruct the empirical dependence of muon density on
the distance from the axis of the shower, the lateral distribution function
(LDF). We compare the shape of this function with the predictions of
hadronic-interaction models, QGSJET-II-04 and EPOS-LHC, in the energy range
10^17.6 - 10^18.6 eV. We find a difference between the observed data and the
simulation: the observed muon density falls faster with the increased core
distance than it is predicted in simulations. This observation may be important
for interpretation of the energy-dependent discrepancies in the simulated and
observed numbers of muons in air showers, known as the "muon excess".
