The table provides parameters (dip, intercept, and adjusted R2) of a linear regression of the coordinates of suture points in shells of G. scitula in relation to the shell centre of spiralization. For this, the xy-coordinates were transformed into polar coordinates with the parameters theta (angle between suture point and spiralization centre) and t (distance between suture point and spiralization centre), normalized for a unity maximum diameter of t=1 per specimen. This coordinate notation allowed to describe a spiral (i.e. periodic function) more efficiently. The coordinates could then be logarithmically plotted as theta over t, and subjected to a linear regression to determine the dip (theta/t) and intercept (theta) as well as the adjusted R2 of the resulting line of regression.