  A system of hard spheroplatelets near an impenetrable wall is studied in the
low-density Onsager approximation. Spheroplatelets have optimal shape between
rods and plates, and the direct transition from the isotropic to biaxial
nematic phase is present. A simple local approximation for the one-particle
distribution function is used. Analytical results for the surface tension and
the entropy contributions are derived. The density and the order-parameter
profiles near the wall are calculated. The preferred orientation of the short
molecule axes is perpendicular to the wall. Biaxiality close to the wall can
appear only if the phase is biaxial in the bulk.
