The functional role of varices in strengthening the shell was discussed in the previous section. However, an important function of varices is to add stability to the shell when resting on the substrate. They are preferentially placed on the last whorl opposite the outer lip thereby increasing the “footprint” of the shell (Fig. 4A-D, F-G), but varices can also be placed at various other locations of the shell (Fig. 4F-G). In some gastropods a dorsal varix or one or more projecting dorsal tubercles facilitate righting by