Powell, A.W.B. 1979New Zealand Mollusca: Marine, Land and Freshwater Shells, Collins, Auckland (p.397)
Odhner, N. 1924 Papers from Dr. Th. Mortensen's Pacific Expedition 1914–1916. XIX. New Zealand Mollusca, Videnskabelige Meddelelser fra Dansk Naturhistorisk Forening i Kjobenhavn, 77 (p.77) Original Description
Key to Geographical Ranges
The symbols K.A.C.F.M.An. are used to indicate the geographical range of the species.
They have been adopted to give an approximation of the range of each species within New Zealand.
Aupourian - Kaipara Harbour, north around North Cape, encompassing the Three Kings Islands and south to East Cape
Cookian - Lower North Island and the northern part of the South Island