  This is a corrected version of my paper published in Journal of Geometry and
Physics 25(1998), 205-226. I added missing cases to the classification theorem
1.1, namely the $SO(n+1)$-manifold $SO(n +2)/ (SO (n) \times SO(2))$, the
$SO(3)$-manifold $C P^2$ and the $SU(3)$-manifold $C P^1 \times C P^1$.
