[en] Optically bright and very cool AFGL carbon stars have been analyzed in order to find a common evolutionary sequence according to indications in this sense derived from papers which have treated only the first or the second group of stars separately. An apparent discrepancy existing between the stellar parameters has been overcome following an inverse procedure which provides these values by means of the shell parameters. The results seem to indicate that AFGL stars, whose variability nature is still unknown, should be Mira or Mira-like according to the values of their dust shell temperatures. Dust shell masses have been estimated for both samples of stars finding an inverse dependence with the effective temperature, Msub(d) approx. Tsub(*)^-9sup(.)¹. This may be interpreted in terms of evolutionary sequency in the sense that the cooler the stars the larger their shell masses. (orig.)