Amalda depressa
species of mollusc
Amalda depressa, common name the depressed ancilla, is a species of a small sea snail, a marine gastropod mollusc in the family Ancillariidae.
Description
The length of the shell varies between 11 mm and 26 mm.
(Original description) The spire is shorter than in Amalda australis, and the thickened callus of the columella and spire gives greater width to the top.
Distribution
This marine species is endemic to and occurs off New Zealand.
References
Hutton, F.W. (1885). "Descriptions of new Tertiary shells - Part 2". Transactions of the New Zealand Institute. 17: 325.
Powell A W B, New Zealand Mollusca, William Collins Publishers Ltd, Auckland, New Zealand 1979 ISBN 0-00-216906-1
Michaux, B. (1991). "The Evolution of the Ancillinae with Special Reference to New Zealand Tertiary and Recent Species of Amalda H. & A. Adams, 1853 (Gastropoda:Olividae:Ancillinae)".
Begin with the source’s own compact description: “Amalda depressa” is species of mollusc. The dossier treats that line as a proposition to test through Amalda, depressa and species, not as a finished interpretation.
Why this record matters
The phrase “species of mollusc” supplies a clear boundary for inquiry. It also exposes the unanswered questions: who defined that boundary, when it became stable and which sources sit outside it.
The date and method of observation matter as much as the stated conclusion, especially where classification or consensus has changed. The source revision retrieved here is dated May 21, 2026. The linked authority identifier is Q3137913. The first chronological checks are 1885, 1979, 1991 and 1853.
Current terminology should not be projected backward without checking the classification used when the underlying evidence was created. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
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Three-step research path
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This entry incorporates text from “Amalda depressa” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.