Shell height and maximum diameter.
“Shell height” in this account refers to the distance from the apex of the spire to the base of the aperture along/parallel to the axis of coiling (h). Some authors, such as Reimchen (see Dof6 06 Differentiation L. obtusata/L. fabalis ) equate “maximum diameter” (d) with height. On many adult shells the two measures are very similar, but they can be quite different, as on this juvenile Littorina (h 3.8mm but d 4.7mm). Reimchen’s graph is of adult L. fabalis.