“…In decreasing order of generality, we mention v-spherical distributions, as introduced in an, as yet, unpublished paper by the present authors (Cent.ER Discussion Paper 9374, Tilburg University), henceforth denoted by FOS, ly-spherical ciistributions, cíefined in Osiewalski and Steel (1993b), and spherical distributiou,, ati discussc~d in Ke~lker (1970), Cambanis et aL (1981), Dickey and Chen (1985) and Faufi ct a.l. (1990, Chapters 2-4).…”