C. rivertonensis (Altonian, Southland) is more slender and higher-spired than C. wollastoni, and has the shoulder angle situated higher up on later whorls.
Scratchpads developed and conceived by (alphabetical):
Ed Baker,
Katherine Bouton
Alice Heaton
Dimitris Koureas,
Laurence Livermore,
Dave Roberts,
Simon Rycroft,
Ben Scott,
Vince Smith