Fig. 2
From: Cenomanian rotaliids (Foraminiferida) from Oman and Morocco
The three subspecies of Rotorbinella mesogeensis (Tronchetti 1981): R. m. microformis, R. m medioformis and R. m. mesogeensis. Note the obvious morphological differences (a upper part of the figure) of the three subspecies (with transition forms) along the diameter vs. thickness continuum shown in the graphic (b lower part of the figure). See text for explanations