Cylichna bulloida Dell, 1956 Height 4.3mm, Width 2.5mm, Marine, Endemic Lower North Island and Chatham Rise to Chatham Islands, 280-600 metres CME.
Cylichna thetidis Hedley, 1903 Height 11mm, Width 4mm, Marine. Shell narrow, elongate-cylindrical, white under a pale yellow periostracum. Columella thickened, with a single strong fold Northland to Bay of Plenty and occasional occurences as far south as Wellington. Also New South Wales, Australia KA
Cylichna zealandica T.W. Kirk, 1880 Height 9mm, Width 3.8mm, Marine, Endemic. Closely resembling thetidis, but has a sudden narrowing of the shell at the apex, and the columellar fold is very slight to obsolete North Island down to Cook Strait. In shell sand and dredged to at least 60 metres ACE.
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