Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 56k): Retusa n. sp.; GS9685, J41/f9499B, Pukeuri road-cutting, Oamaru (Altonian)
Beu & Maxwell (1990): Chapter 17; p. 391; pl. 56 k.
Description: Height 3-5.8 mm, cylindrical or subcylindrical, spire very low, flat or sunken. Protoconch smooth, flush or slightly projecting. Last teleoconch whorl very large, almost enveloping earlier whorls; smooth or with growth ridges and/or spiral threads. Aperture large, constricted over much of its length, anterior end rounded; columella straight or concave, smooth or with a weak plait.
Comparison: Retusa is distinguished from other members of the family by the cylindrical or subcylindrical shape, by the very low spire (many species have a sharply truncate posterior end), and in not having the last whorl completely enveloping earlier whorls.
Distribution: Duntroonian-Recent, New Zealand; cosmopolitan, Middle Jurassic-Recent.
Cite this publication as: "A.G. Beu and J.I. Raine (2009). Revised
descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990). GNS
Science miscellaneous series no. 27."
© GNS Science, 2009
(Included with a PDF facsimile file copy of New Zealand Geological Survey Paleontological Bulletin 58 in CD version from: Publications Officer, GNS Science, P.O. Box 30368 Lower Hutt, New Zealand)