On the basis of the available powder X-ray diffraction data, chemical composition, Raman spectrum and synthesis P-T conditions, it is concluded that the so-called new phase claimed by Ohtani et al. [1997> is in reality the phase D reported earlier by Liu [1987>, Irifune et al. [1996> and Kuroda and Irifune [1997>. Phase F first reported by Kanzaki [1991> is also probably in reality the phase D. The powder X-ray diffraction pattern of the so-called phase F studied by Kudoh et al. [1995> bears no resemblance to that reported by Kanzaki [1991>, suggesting a totally different material was employed in the study of Kudoh et al. [1995>. ¿ 1998 American Geophysical Union