Alvania gradatoides

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Alvania gradatoides (Finlay, 1930).[1]

Alvania gradatoides was originally discovered and described as Linemera gradatoides by Harold John Finlay in 1930.[1] Finlay's original text (the type description) reads as follows:

« Linemera gradatoides n. sp. (Fig. 40).

A Recent descendant of gradata (Hutton), nearer to it than is any other Recent species. Apex the same, but a little less depressed; 3¾ shell whorls follow. Whorls not quite so flat (due to the stronger and more median second spiral); suture still more canaliculate, the peripheral and shoulder angles being further from the suture; margined above but not below. Axial ribs a little stronger, more distant (1½ times their width apart), 16-17 on penultimate whorl, hardly more crowded near aperture, otherwise as in gradata. Four spirals on spire whorls, the lowest as in gradata, the upper three more crowded together, subequal and subequidistant; the difference is most noticeable with the second spiral, which is strong and submedian instead of subobsolete, low down, and close to third. The first and second become wider apart on body whorl, and a very weak interstitial riblet may develop between them. The fourth spiral continues strongly on base below periphery, as in gradata, and 4 more subequal, close, and subequidistant smooth cords occupy the rest of the base; the groove between peripheral spiral and the one below is relatively deeper and wider than in gradata, and the segregation of the basal spirals is thus better marked. Umbilical chink and aperture as in gradata.

Height, 3 mm.; width, 1.6. mm.

Locality—50 fathoms off Oamaru, many specimens.

Type in Finlay collection.



This article icorporates public domain (public domain in the New Zealand; it will be public domain in the USA on January 1, 2026) text from the reference[1]

  1. 1.0 1.1 1.2 Finlay H. J. (1930). "Additions to the Recent Molluscan Fauna of New Zealand. No. 3." Transactions and Proceedings of the Royal Society of New Zealand. 61: page 222-247.