  We have investigated the F0V star V398\,Aurigae (= 9 Aur) under the
assumption that it is undergoing non-radial gravity mode oscillations and that
the two principal periods given by Krisciunas et al. (1995) are correct. We
find that the two periods are manifestations of an $\ell=3, |m|=1$ spheroidal
mode and its toroidal corrections due to the rotation of the star. As far as we
know, this is the first detection of toroidal correction terms in a real star.
The two modes probably are the result of rotational splitting.
  Our analysis provides for the first time a physical explanation of certain
characteristics of the observed behavior of the star. The amplitude of the
radial part of the pulsation for $f_1 = 0.795$\,d$^{-1}$ is a factor of 4
larger than the one for $f_2 = 0.346$\,d$^{-1}$. Since the photometric
variability is determined mostly by temperature variations, which in turn are
determined by the radial part of the pulsation, the photometric variability is
dominated by the mode with frequency $f_1$. On the other hand, $f_2$ is the
more pronounced one in all three spectroscopic moment variations (including the
radial velocity), reflecting that the transverse displacement of $f_2$, and not
the one of $f_1$, dominates the velocity behavior.
