Powell, A.W.B. 1979New Zealand Mollusca: Marine, Land and Freshwater Shells, Collins, Auckland (p.267)
Laws, C.R. 1941 Review of the Tertiary and Recent Neozelanic Pyramidellid Mollusca. No. 8 - The Pyrgulinind Genera and the genus Evalea, Transactions and Proceedings of the Royal Society of New Zealand, 71 (p.19)
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 approxomation 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