GNS Science

Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)

New Zealand Cenozoic Mollusca

Galeodea modesta (Suter, 1917)


(Pl. 6l): GS9886, J40/f8823, abandoned railway cutting, Waihao Downs, Bortonian (GNS)

Beu & Maxwell (1990): Chapter 7; p. 106; pl. 6 l.

Synonymy: Galeodes modesta Suter 1917, p. 19-20; Galeodea (Galeodea) modesta, Beu & Maxwell 1990, p. 106, pl. 6 l.

Classification: Cassidae: Cassinae

Description: Size moderate for genus (height 32-45 mm), ovate, spire about 0.25 height. Protoconch broadly conical, of about 4 smooth, convex whorls. Teleoconch whorls 4-5, prominently shouldered near middle on spire; last whorl with 3 or 4 additional, less prominent keels and a strongly twisted neck. Axial sculpture of prominent nodules or tubercles on shoulder angle, somewhat weaker ones on keel immediately below and much weaker ones on other keels; 10-12 per whorl on shoulder angle, those on lower keels typically more numerous and not corresponding to those above. Spiral sculpture of numerous fine threads, somewhat stronger on lower part of base and on neck than elsewhere. Aperture elongate-ovate, constricted at both ends, siphonal canal narrow, bent to left and away from aperture. Outer lip slightly inclined to vertical, with a prominent, flattened varix, inner edge with 13-15 short lirae. Inner lip heavily callused, projecting freely over columella, bearing 1 or 2 narrow lirae adapically and numerous short, irregular wrinkles below.

Comparison: Galeodea modesta is readily distinguished from G. apodemetes (Pl. 20q) by its finer spiral sculpture and by its heavily "armoured" aperture. Another Bortonian species, G. geniculosa (Hampden Beach), also has an armoured aperture but has considerably coarser spiral sculpture; however, it may not be a distinct species in view of the considerable variation noted in living cassids. An undescribed species from the Slip Point Siltstone, Clifden (Clifdenian) is most similar to G. modesta, differing mainly in having a protoconch of only 1.5 whorls, finer shoulder tubercles and a less prominently armoured aperture.

Distribution: Bortonian, Waihao Greensand, Kakahu (type); Waihao Downs. Rare at both localities.

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
ISBN 978-0-478-19705-1
ISSN 1177-2441
(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)


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