Transitional plate

A small plate at the proximal end of the cingulum in some peridinialeans, so termed because it can be considered either a cingular plate or a sulcal plate. The right accessory sulcal plate in gonyaulacaleans is sometimes also considered to be a plate transitional between the sulcus and cingulum. See also Kofoid tabulation system. Refer to Text-Figure 58E,E\'.