Masson's figure of this plant is very badly coloured, as he represents the ground-colour of the corolla-lobes as purple-brown marked with irregular yellow lines and describes them as “purple, with transverse yellow rugosities;” this is really the case, but at the same time the effect produced is that the ground colour is yellow, spotted and lined with purple-brown. [S. mixta and var. pentagona, Rüst in Monatsschr. Kakt. vi. 39, seem to be hybrid forms of var. bufonia, with a large annulus, but smaller flowers than in typical var. mixta; the lobes are coloured as in the lighter forms of var. bufonia and the annulus is of a pale sulphur colour thinly dotted with purple brown on the rim and densely in the cup, very distinctly pentagonal in var. pentagona; outer corona-lobes entire to bifid, with short parallel or diverging teeth, pale yellow, dotted with purple-brown on the apical part and down the centre, with (or in var. pentagona without) a basal spot; outer horn of the inner corona-lobes ascending.]